Patent Application
20170217847
This disclosure relates to a method for controlling nutrient depletion in soil and reducing nitrogen and phosphorus runoff in agricultural applications.
Agricultural fertilizers commonly include the active ingredients nitrogen and phosphorus. After fertilizer is applied to the soil of an agricultural field, these constituents are often prematurely depleted, which can have detrimental effects on the environment and significantly reduce the pool of available nutrients.
A schematic of the nitrogen cycle in soil is shown in
In certain applications, gaseous ammonia is applied to the soil of an agricultural field by metal application shanks that are introduced into the soil. If the soil is not thoroughly covered and packed behind the shanks, ammonia gas and its constituent nitrogen are lost from the soil surface before being absorbed into the soil water and converted to ammonium, which adsorbs to the soil particles.
Surface volatilization of nitrogen can also occur when ammonium forms of nitrogen (e.g., ammonium sulfate, di-ammonium phosphate, etc.) are applied to the surface of calcareous soils having a pH greater than 7.5. The reaction products formed when such ammonium fertilizers react with calcium carbonate tend to volatilize and dissipate into the atmosphere.
Another cause of nitrogen depletion from agricultural fertilizers is denitrification. This occurs when nitrate (NO3−) is present in the soil, but not enough oxygen is present to supply the needs of the bacteria and microorganisms in the soil. If oxygen levels are too low, such microorganisms strip the oxygen from the nitrate. This produces nitrogen gas (N2) or nitrous oxide (N2O), which volatilize readily from the soil. Denitrification increases when the soil is wet or compact or when excessively warm temperatures are encountered.
Leaching of nitrate is yet another cause of unwanted nitrogen loss. This occurs when the soil receives more incoming water (by either rain or irrigation) than it can hold against the force of gravity. As water migrates downward though the soil, nitrate-N, which is water soluble, moves with the water and is lost into the groundwater, from where it cannot travel against gravity back up into the soil profile. Although ammonium (NH4) forms of nitrogen tend to leach very little in most soils, ammonium leaching can be significant in coarse-textured sands and some muck soils.
Both nitrogen and phosphorus can also be subject to premature depletion through runoff.
Such runoff tends to occur when the soil receives more incoming water through rain or irrigation than the soil can accommodate. As water moves over the soil, some of the soil may be loosened and move with the water. The excess water can then carry the dislodged soil and any adsorbed fertilizer nitrogen and phosphorus away from the agricultural site. The offsite movement of such nitrogen and phosphorus due to runoff can be particularly severe in sloped or hilly terrains.
The depletion of nitrogen and phosphorus described above presents a number of problems and disadvantages. Because a significant portion of the plant-enhancing nutrients are lost, many agricultural fertilizer treatments tend to be inefficient and not optimally effective. A considerable amount of the active nitrogen and phosphorus nutrients applied to the field are wasted, plant growth may be slowed and/or an inferior crop may result. Applying additional fertilizers to make up for the nitrogen/phosphorus depletion can add considerable cost, both to the grower and to the consumer. Another problem associated with depletion of nitrogen and phosphorus from agricultural fertilizers is the adverse environmental effects that frequently result. In particular, leaching of nitrates and urea as well as runoff of nitrogen and phosphorus-bearing sediments can contaminate and pollute nearby surface water (e.g., streams, rivers, lakes, ocean, etc.) and ground water (e.g., aquifers). Nitrate leaching is a significant environmental problem, because above certain levels, nitrate in drinking water is toxic to humans.
In addition, volatile nitrogen oxides, such as nitrous oxide (N2O), are known to be contributors to greenhouse gas (GHG), which can adversely affect the environment. Fertilizer runoff can cause phosphorus pollution of surface waters. When the amount of fertilizer applied to a site is increased to compensate for depletion, this only adds to the volume of potentially polluting crop nutrients introduced into the environment.
The present disclosure relates to methods for controlling the depletion rate of nutrients in soil. In addition, the method also greatly reduces the adverse environmental impact previously caused by such fertilizers.
Accordingly, provided herein is a method for controlling the depletion rate of a nutrient in soil, comprising applying a nutrient depletion-restricting substance (hereafter referred to as “NDRS”) and a fertilizer to soil or applying a NDRS to soil which has been fertilized, wherein the depletion of the nutrient is reduced by about 40 to about 80% by weight. In one embodiment, the depletion of the nutrient is reduced at about 30 hours after applying the fertilizer to the soil.
In certain embodiments, the method controls nutrient depletion from agricultural fertilizers by reducing one or more of: (i) ammonia (or nitrogen) volatilization, (ii) nitrogen loss due to denitrification, (iii) nitrogen loss due to nitrate leaching, (iv) nitrogen adsorption at the surface of the soil (v) attendant surface runoff, and/or (vi) a larger pool of nitrogen uptake by the crop, and hence not available to be lost by the other mechanisms described. In certain embodiments, the nutrient is nitrogen or a nitrogen component and/or phosphorous or a phosphorous component.
In one embodiment is a method of inhibiting nitrogen volatilization from soil, comprising applying a nutrient depletion-restricting substance (NDRS) and a fertilizer to soil or applying a NDRS to soil which has been fertilized, wherein the amount of nitrogen loss via volatilization is reduced by at least about 40% by weight after about 7 days after applying the nitrogen-based fertilizer at a temperature of about 15-30° C.
In one embodiment, provided herein is a method for restricting nutrient depletion in agricultural fields, turf and sod grass farms and other planting sites.
As such, provided herein is a method for stabilizing nitrogen in an agricultural fertilizer such that it remains in the vicinity of a plant's root zone. In one aspect, provided is a method for reducing the volume of fertilizer conventionally required to effectively fertilize an agricultural field or other planting site.
In a further aspect, provided is a method of increasing nitrate immobilization and/or mineralization in soil by at least about 25% after about 100 days. In certain embodiments, the method comprises applying a NDRS to soil at a concentration of at least about 0.1 milligrams of NDRS per 100 grams of soil.
In a further aspect, provided is a method for limiting the risk of nitrogen and phosphorus contamination of the environment that has previously accompanied the use of agricultural fertilizers. Thus, provided herein a method for reducing the amount of fertilizer needed to effectively sustain an agricultural field or other planting site without creating an undue risk of polluting the nearby environment and, in particular, nearby surface and ground water.
In a further aspect, provided is a method of decreasing nitrate leachate from soil by at least about 50% after about 3 weeks. In certain embodiments, the method comprises applying NDRS to soil at a concentration of at least about 0.1 mg of NDRS per 100 grams of soil.
In another aspect, provided is a method for increasing nitrogen uptake within a crop, comprising applying a NDRS and optionally a fertilizer to soil or applying a NDRS to soil which has been fertilized. In certain embodiments, the weight of nitrogen contained in the biomass of the crop is increased by least about 15% by weight versus the weight of nitrogen contained in the biomass of a crop where a NDRS was not applied to the soil.
In yet another aspect, provided is a method of inhibiting nitrogen volatilization from soil, comprising applying a NDRS and a nitrogen-based fertilizer to soil or applying a NDRS to soil which has been fertilized. In certain embodiments, the amount of nitrogen loss via volatilization is reduced by at least about 40% by weight after about 7 days after applying the NDRS and/or nitrogen-based fertilizer.
In one embodiment, the disclosure relates to a method for reducing water and/or air pollution caused by the use of a fertilizer in soil, comprising applying a NDRS and a fertilizer to the soil. In one embodiment, disclosed herein is method for inhibiting and/or mitigating transformation of nitrate (NO3−) and/or ammonium (NH4+) to nitrogen or ammonia gas, comprising applying a NDRS to a soil, optionally in the presence of a fertilizer. In certain embodiments, the NDRS is applied to the soil within a time period of from about 3 hours before to about 3 hours after applying the fertilizer. In some embodiments, the amount of fertilizer applied to the soil is decreased by at least about 50%.
In one embodiment, the disclosure is directed to methods for reducing a variety of nutrient depleting factors through the use of a single formulated product rather than using a variety of different products that are each directed to a respective problem.
Disclosed herein is a method for controlling or reducing nutrient depletion from fertilizer applied to an agricultural field or other planting site. An agricultural fertilizer, which may include a nitrogen and/or phosphorus based fertilizer is applied to the soil of the site. In certain embodiments, the fertilizer is applied to the soil at a rate of at least about 50% less, or about 50% less, or about 40% less, or about 30% less, or about 25% less or about 20% less than is used in the absence of a NDRS, in order to achieve substantially the same result (e.g., reduced nitrogen volatilization, etc.). At substantially the same time, or immediately prior to or thereafter (e.g., within a time period of about 3 hours before or after), a nutrient depletion-restricting substance is applied to the field. In one embodiment, the nutrient depletion-restricting substance includes a liquid formulation comprising one or more of the following components:
(1) a plant extract from algae, seaweed, or their derivatives;
(2) a liquid plant growth modification composition of the type produced by the methods described in U.S. Pat. Nos. 4,698,090 and 4,786,307, issued to Marihart; and/or
(3) a humic extract from a genuine humic source, e.g., leonardite.
In one embodiment, two or all three of the foregoing constituents are included in the nutrient depletion-restricting substance.
By applying a NDRS and a fertilizer, in solution or otherwise in a relatively contemporaneously manner, to the agricultural field or planting site, ammonia volatilization, denitrification and nitrate leaching losses are all significantly reduced and improved nitrogen absorption in the vicinity of the root zone is achieved. By the same token, surface runoff of nitrogen and phosphorus are significantly reduced. As a direct result of reduced depletion, a greater percentage (e.g., up to about 25% more) nutrients are available for use by the plants. In addition, environmentally damaging runoff of nitrogen and phosphates is significantly mitigated and release of GHGs (greenhouse gases) is reduced.
Application of the NDRS may be done once or throughout various times of the crop cycle. For example, in annual crops, there is either one application around planting time or the application may be split throughout the growing season. In one embodiment, the applications are split up through the mid-reproductive phase. In one embodiment to perennial crops, the application may be done at various times from bud break until dormancy (e.g., throughout the year).
Other features and advantages will occur from the following description and the accompanying drawings.
NDRS compositions in soils collected from (a) Tulare; (b) Kern and (c) Monterey.
Definitions
It is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.
List of Abbreviations
It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a nutrient” includes a plurality of nutrients.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. As used herein the following terms have the following meanings.
As used herein, the term “comprising” or “comprises” is intended to mean that the compositions and methods include the recited elements, but not excluding others. “Consisting essentially of” when used to define compositions and methods, shall mean excluding other elements of any essential significance to the combination for the stated purpose. Thus, a composition consisting essentially of the elements as defined herein would not exclude other materials or steps that do not materially affect the basic and novel characteristic(s) claimed. “Consisting of” shall mean excluding more than trace elements of other ingredients and substantial method steps. Embodiments defined by each of these transition terms are within the scope of this disclosure.
The term “about” when used before a numerical designation, e.g., temperature, time, amount, and concentration, including range, indicates approximations which may vary by (+) or (−) 10%, 5% or 1%.
The term “fertilizer” is intended to refer to is any material of natural or synthetic origin (other than liming materials) that is applied to soils or to plant tissues (usually leaves) to supply one or more plant nutrients essential to the growth of plants. In certain embodiments, the fertilizer comprises one or more of a urea component, an ammonium component, a nitrate component, an ammonia component, an organic nitrogen component, and/or a phosphorus component.
The term “nutrient” is intended to refer to one or more macronutrient, such as nitrogen (N), phosphorus (P), potassium (K); calcium (Ca), magnesium (Mg), and/or sulfur (S).
The term “applying” or “applied” to the soil is intended to refer to any suitable method for applying a fertilizer and/or a NDRS to soil. The term is intended to encompass methods for applying liquid, solid, or other form or mixture thereof to the soil. In certain embodiments, the “applying” or “applied” to the soil comprises one or more of spraying, flooding, soil injection and/or chemigation.
The term “depletion rate” is intended to refer to the rate at which a fertilizer (or one or more nutrients) are depleted from the soil. In certain embodiments, the fertilizer is depleted at a rate of or less than about 50%, or less than about 40%, or less than about 30%, or about 20%, or less than about 10% as compared to fertilizer alone. In certain embodiments, the amount of nutrient (e.g., nitrogen) used to fertilize a crop may be reduced by at least about 25%, or at least about 40-50%. In certain instances, the nitrogen depleted from the soil is recovered in the biomass of the resultant crop grown therein. In certain embodiments, at least about 50 Lbs/acre of nitrogen may be recovered in the biomass of the resultant crop.
The term “reducing water and/or air pollution” is intended to refer to the reduction in one or more of nutrient loss by volatilization, leaching, and/or surface runoff In certain embodiments, the water and/or air pollution is reduced by at least about 50%, or at least about 40%, or at least about 30%, or at least about 20%, or at least about 10% as compared to fertilizer alone.
The term “nutrient availability” is intended to refer to the proportion of the total nutrient amount in soil can be taken up and utilized by plants. This fraction is called the available fraction, and depends on the chemical nature of the nutrient in question, as well as soil type and other influences from within the soil environment (see, e.g., Marscher, P. Mineral Nutrition of Higher Plants (Third Edition), 2012, Elsivier, Amsterdam).
Nutrient Depletion-Restricting Substances
The nutrient depletion-restricting substance (NDRS) includes a liquid formulation containing at least one, two and/or all three of the following components:
(1) plant material extracted from at least one of the group consisting of seaweed, algae and derivatives thereof;
(2) a plant growth stimulating composition produced as described in Marihart, U.S. Pat. Nos. 4,698,090 and/or 4,786,307 (the disclosures of which are incorporated herein by reference in their entirety);
(3) a humic extract from a genuine humic source, e.g., leonardite.
In some embodiments, the NDRS comprises a combination of Component 1 and Component 2, each at one to three parts by weight. In another embodiment, the NDRS comprises a combination of Component 2 and Component 3, at one part each by weight. In another embodiment, the NDRS comprises a combination of Component 1 at one to three parts by weight, Component 2 at one to three parts by weight and Component 3 at one to three parts by weight.
The humic extract (Component 3 above) can comprise any humic substance, including Component 2. For example, it can comprise one or more of a plant growth stimulating composition produced as described in Marihart (see, U.S. Pat. Nos. 4,698,090 and 4,786,307, the disclosures of which are incorporated herein by reference), or a humic substance (HS) comprising humic acid, fulvic acid and humin. Humic substances (HS) are defined by the IHSS (International Humic Substances Society) as complex, heterogeneous mixtures of polydispersed materials formed by biochemical and chemical reactions during the decay and transformation of plant and microbial remains (a process called humification). HS are naturally present in soil, water, peats, brown coals and shales. Traditionally these substances have been isolated into three fractions: humic acid, fulvic acid and humin. These fractions are operationally defined based on solubility in basic and acidic solutions. Leonardite, a brown coal, is known to be rich in humic acid.
In certain embodiments, the NDRS may optionally comprise one or more chelating agents (e.g., carbohydrates). The chelating agent can be any one or more of sodium, potassium, ammonium, copper, iron, magnesium, manganese, zinc, calcium, lithium, rubidium or cesium salt of ethylene diamine tetraacetic acid, hydroxyethylene diamine triacetic acid, diethylene triamine pentaacetic acid, nitrillo triacetic acid, or ethanol diglycine. In one embodiment, the chelating agent is a carbohydrate or a carboxylic acid, such as one selected from the group consisting of an ammonium or metal salt of a variety of organic acids. Non-limiting examples of organic acids, include citric acid, galactaric acid, gluconic acid, glucoheptoic acid, glucaric acid, glutaric acid, glutamic acid, tartaric acid, and tartronic acid.
A representative NDRS to be used in the methods provided herein can be prepared according to U.S. Pat. No. 4,698,090. For example, one exemplary NDRS can be prepared by adding 9 parts (by weight) of leonardite ore to 75 parts of water, previously heated to a temperature of 170° F. -195° F. but to no greater than 225° F. A carbohydrate or a carboxylic acid, such as one selected from the group consisting of an ammonium or metal salt of various organic acids (as described above), such as potassium tartrate (15 parts by weight), is added and the liquid composition is mixed for five hours and then allowed to settle in multiple stages. Depending upon the desired planting environment, the extracted liquid may be used in its resulting acidic condition. Alternatively, the pH may be adjusted by adding sodium hydroxide or potassium hydroxide.
In one embodiment, the NDRS can be prepared by adding 15-22 parts (by weight) of leonardite ore to 30-55 parts of water, previously heated to a temperature of 170° F. - 195° F. A carbohydrate or a carboxylic acid consisting of a metal salt such as potassium tartrate (9-16 parts by weight) is added. The liquid composition is oxygenated for a total of 15-300 minutes and a strong base at 5-12 parts is added, followed by the removal of some of the insoluble components of leonardite ore.
In one embodiment, an exemplary nutrient depletion-restricting substance (NDRS) comprises disaggregated humin (e.g., from about 2% to about 5%) in a colloidal suspension, as well as humic acid, fulvic acid, and optionally certain plant growth modification compositions and/or additional plant material extracts.
In certain embodiments, the composition may also comprise another source of nutrient, such a plant material extracted from at least one of the group consisting of seaweed, algae and derivatives thereof. In one embodiment, the composition also comprises seaweed.
In one embodiment, the NDRS is applied to the soil in combination with a fertilizer. The fertilizer may comprise any nitrogen and/or phosphorus containing fertilizer used for agricultural or other plant growth enhancing purposes. The fertilizer as used herein can comprise one or more of a urea component, an ammonium component, a nitrate component, an ammonia component, an organic nitrogen component, and/or a phosphorus component.
In certain embodiments, the fertilizer and the NDRS are pre-mixed in solution prior to the addition to the soil. Their respective concentrations may range from 1% to about 20%, or from 1% to about 15%, or from 1% to about 10% by weight NDRS to fertilizer. In certain embodiments, the weight/weight ratio of NDRS to fertilizer is about 1:100 to about 2:1. Exemplary ratios further include about 1:90, about 1:75; about 1:60; about 1:50; about 1:25; about 1:10; and about 1:1. .
Methods
In one aspect, the present disclosure involves treating the soil of an agricultural, turf or sod grass field or other planting site with a nitrogen and/or phosphorus based fertilizer in combination with a nutrient depletion-restricting substance as described herein. The soil to be treated can be any soil type, including, but not limited to, clay, loam, clay-loam, silt-loam, and the like. In some embodiments the soil comprises about 30-70% sand, about 20-60% silt, about 10-25% clay and about 0.5 to 3% organic matter. In some embodiment, the soil comprises about 20-40% sand, about 30-50% silt, about 20-40% clay and about 0.5 to 5% organic matter. In some embodiments, the soil comprises about 40% sand, about 45% silt, about 17% clay and about 3% organic matter or about 40% sand, about 45% silt, about 17% clay and about 3% organic matter or about 30% sand, about 40% silt, about 29% clay and about 1% organic matter, or about 65% sand, about 20% silt, about 14% clay and about 1% organic matter.
Conventional application techniques such as spraying, fertigation or shank injection may be employed. In certain embodiments, soil has been fertilized (i.e., fertilizer may have been pre-applied to the soil).
The amount of NDRS to be applied maybe calculated in a variety of ways. For example, the amount of NDRS may be expressed in a variety of units, including mass or volume of material per mass or volume of soil, area of land, or mass of fertilizer. In one embodiment, the rate may be the mass of NDRS per mass of fertilizer or mass of nitrogen or phosphorous in the fertilizer. Suitable rates include:
In one embodiment, NDRS is applied in a range of from about 20 to about 50 Liters per hectare of soil. In one embodiment, the NDRS is applied in a range of from about 2 to about 12 Liters per 100 kilograms of nitrogen or phosphorous in the fertilizer.
The nutrient depletion-restricting substance (e.g., NDRS) as described herein is particularly preferable to known substances for restricting nutrient depletion because it affects the standard nitrogen cycle at multiple points, whereas each prior product is designed to act at a single point. The present method thereby eliminates the need to use multiple overlapping products, which are unduly expensive and tend to compound the adverse environmental effects commonly exhibited by each of those products.
Provided herein is a method for limiting the risk of nutrient contamination of the environment that has previously accompanied the use of agricultural fertilizers.
The methods described herein significantly control and reduce the depletion of the plant nutrients, such as nitrogen and phosphorus, present in the soil, by about 10% to greater than 50% and make this portion of those nutrients available for plant usage as the crop matures as compared to the use of a fertilizer alone. In certain embodiments, the present disclosure relates to a method for controlling the depletion rate of a nutrient in soil. The depletion rate can be a measure of nitrogen loss by any method, for example, volatilization and/or leaching. In one embodiment, the method comprises applying a NDRS and a fertilizer to soil or applying a NDRS to soil which has been fertilized, wherein the depletion of the nutrient was reduced by about 40 to about 80% by weight at about 30 hours after applying the NDRS and/or fertilizer to the soil. In other embodiments, the depletion of the nutrient was reduced by about 40%, or about 45%, or about 50%, or about 55%, or about 60% or about 65%, or about 70%, or about 75%, or about 80% by weight at about 24-36 hours after applying the NDRS and/or fertilizer to the soil.
In particular, as shown in
As depicted in
In one embodiment, provided is a method for increasing nitrogen uptake within a crop, comprising applying a NDRS and optionally a fertilizer to soil or applying a NDRS to soil which has been fertilized. In certain embodiments, the weight of nitrogen contained in the biomass of the crop is increased by least about 15%, or about 50%, or about 45%, or about 40%, or about 35%, or about 30%, or about 25%, or about 20%, or about 15%, or about 10% by weight versus the weight of nitrogen contained in the biomass of a crop where a NDRS was not applied to the soil.
It is contemplated that the combined application of fertilizer and NDRS delays reaction of the nitrogen within the fertilizer with the urease enzymes in the soil. This in turn slows the conversion of urea by urease thereby reducing nitrogen losses due to urea volatilization. Instead, the nitrogen remains as urea able to be moved into the soil with rainfall or irrigation. When urea converts into ammonium in the root zone, nitrogen is adsorbed by the soil particles, stabilized and utilized effectively, as needed, by the growing plants. Subsurface nitrogen adsorption also minimizes accumulation of nitrates and ammonium in the surface soil, which can otherwise lead to denitrification and resultant volatilization of nitrogen gas or nitrous oxide from the soil or runoff with rainfall.
Accordingly, provided herein is a method of inhibiting nitrogen volatilization from soil, comprising applying a NDRS and a nitrogen-based fertilizer to the soil, wherein the amount of nitrogen loss via volatilization is reduced by at least about 40%, by at least about 45%, by at least about 50%, by at least about 55%, or up to about 60% by weight after about 7 days after applying the NDRS and/or nitrogen-based fertilizer. In certain embodiments, the temperature is from about 22 to about 35° C. In certain embodiments, the fertilizer is nitrogen based and comprises ammonia, ammonium, nitrate and/or urea. In certain embodiments, the NDRS is applied to the soil at a concentration of less than about 0.1 milligram of NDRS per 100 grams of soil, or less than about 0.5 milliliter of NDRS per 100 grams of soil, or less than about 0.1 milliliter of NDRS per 100 grams of soil.
It is believed that the beneficial reduction in leaching may occur due to, at least in part, the nutrient depletion-restricting substance chemically bonding to one or more of the two inorganic nitrogen molecules found in the soil and/or the three nitrogen molecules used in commercial granular and liquid fertilizers (urea, nitrates and ammonium) as well as the phosphorus molecules utilized in commercial granular and liquid fertilizers. This bond likely reduces leaching from recently applied fertilizer nitrates and urea in response to rainfall or irrigation. As a result, the runoff from the field caused by irrigation or rainfall is much less likely to contain levels of nitrogen or phosphorus which could contaminate or pollute nearby surface or subsurface bodies of water such as streams, rivers, lakes, aquifers, etc. In addition, nitrogen from the fertilizer is stabilized and resists moving with the soil water below the root zone when high volumes of rain fall or irrigation are encountered and the plant-supporting nitrogen remains in the root zone and provides needed nutrient to the growing plants.
In certain embodiments, provided herein is a method of decreasing nitrate leachate from soil by at least about 50% after about 3 weeks, comprising applying a NDRS to soil at a concentration of at least about 0.1 mg of NDRS per 100 grams of soil. In some embodiments, the nitrate leachate from soil is decreased by at least about 50% after about 100 days. Although it is contemplated that the present methods are effective in any soil type, in certain embodiments, the soil comprises about 40% sand, and may further comprise about 45% silt, about 17% clay and about 3% organic matter. In another embodiment, the soil comprises about 30% sand, and may further comprise about 40% silt, about 29% clay and about 1% organic matter.
In certain embodiments, the amount nitrate leached from the soil may be decreased by at least about 80%, or about 80%, or about 70%, or about 60%, when compared to soil which has not been treated with a NDRS as described herein. In some embodiments, the soil comprises about 65% sand, and may further comprise about 20% silt, about 14% clay and about 1% organic matter.
In another aspect, provided herein is a method for enhancing microbial activity as measured by the amount of CO2 evolved from aerobic microbial respiration. The increased release of CO2 indicates that as the microbial population increases, nitrogen is immobilized or stored in the microbial biomass to later provide nutrients to the developing crop. In effect, the increased production of carbon dioxide indicates that the microbial biomass is increasing and therefore requiring a greater amount of nitrogen than the control. The microbes' production of this carbon dioxide indicates that nitrogen is being effectively immobilized and stabilized in the root zone and not lost to leaching.
Use of fertilizer and a NDRS as described herein therefore effectively immobilizes nitrogen from nitrogen based granular and liquid fertilizers, crop residues, manures and manure slurries/wash water. This slows nitrification and denitrification and delays urease activity, which, in turn, minimizes rapid and/or large accumulation of nitrates in the soil. As the soil nitrate-N appears more slowly, this allows for crop demand to synchronize and increase proportionally with the increase of nitrogen availability. Microbial activity, as exhibited by
Although the present methods may be used with any type of soil, in certain embodiments, the soil comprises about 65% sand, and may further comprise about 20% silt, about 14% clay and about 1% organic matter. In certain embodiments, the microbial activity is measured by evolution of carbon dioxide from the soil. Thus, in some embodiments, carbon dioxide evolution is increased by at least about 2 fold after about 45 days, and the soil comprises about 30% sand, and may further comprise about 40% silt, about 29% clay and about 1% organic matter.
In practice, organic residues may be added to the field following harvest. Decomposition of such residues and nitrogen release therefrom (mineralization) is seldom synchronized with crop growth. Use of the present method to treat such residues helps to promote nitrogen mineralization so that the nitrogen in the residue also becomes available as a plant nutrient at a time that beneficially coincides with the crop's need for nitrogen for optimum growth. This provides nitrate uptake before the nitrates overly accumulate in the soil and are more prone to leaching. Periodically adding the formulations of this disclosure to organic residues reduces depletion considerably compared to standard practices.
Provided herein is a method of increasing nitrate immobilization and/or mineralization in soil by at least about 25% after about 100 days, comprising applying a NDRS to soil. In certain embodiments, the NDRS is applied to the soil at a concentration of at least about 0.1 mg of NDRS per 100 grams of soil, or between about 0.1 mg and 1 gram of NDRS per about 100 grams of soil. In certain embodiments, the nitrate immobilization and/or mineralization is increased by at least about 50%, or at least about 45%, or at least about 40%, or at least about 35%, or at least about 30%, or at least about 25% after about 100 days. In certain embodiments, the immobilizing comprises inhibiting and/or mitigating transformation of nitrate (NO3−) and/or ammonium (NH4+) to nitrogen or ammonia gas.
As a further benefit, the NDRS to be used in the methods described herein are generally safer (e.g., to humans and the environment) and offer handling advantages over many other products which reduce nitrogen loss, some of which are labeled and licensed to be used as pesticides. In contrast, most existing chemicals used to prevent nutrient depletion pose risks to human health and the environment, depending on the exposure level.
Still further, the methods described herein reduce environmental hazards due to runoff. For example, phosphorous is lost in soil during erosion caused by rain. As shown in Example 9, by applying NDRS of the invention, it is contemplated that phosphorous runoff will be reduced.
Certain methods described herein are performed by applying a fertilizer and a NDRS concurrently or separately, at or about the same time (e.g., within about 3, or about 2, or about 1 hour of each other), to the soil of the agricultural field being treated. In certain embodiments of the methods described herein, the NDRS is applied to the soil with less than about three hours, or less than about two hours, or less than about one hour, or less than about 30 minutes, or less than about 20 minutes, or less than about 10 minutes, or less than about 5 minutes before or after applying the fertilizer. In certain embodiments, the fertilizer and the NDRS are pre-mixed and applied as a single composition. Application of the fertilizer and the NDRS within such a time window can avoid excessive nitrogen and phosphorus depletion and accomplish more effective and efficient nutrient delivery to the plantings.
In one embodiment, the NDRS and the fertilizer are pre-mixed in solution prior to the addition to the soil. Their respective concentrations may range from 1% to about 20%, or from 1% to about 15%, or from 1% to about 10% by weight NDRS to fertilizer. In certain embodiments, the weight/weight ratio of NDRS to fertilizer are from about 1:100 to about 2:1. Exemplary ratios further include about 1:90, about 1:75; about 1:60; about 1:50; about 1:25; about 1:10; and about 2:1.
The amount of NDRS applied to the soil may vary, and typically ranges from about 0.001 mL to about 100 mL of NDRS per kilogram of soil, or about 0.1 mL of NDRS per kilogram of soil, or about 0.03 mL per kilogram of soil, or about 0.05 mL per kilogram of soil, or about 1 mL of NDRS per kilogram of soil, or about 10 mL of NDRS per kilogram of soil, or about 20 mL of
NDRS per kilogram of soil, or about 30 mL of NDRS per kilogram of soil, or about 40 mL of NDRS per kilogram of soil, or about 50 mL of NDRS per kilogram of soil. In certain embodiments, the amount of NDRS applied to the soil ranges from about 0.001 mL to about 50 mL of NDRS per kilogram of soil.
In each of the following Examples, the NDRS used are shown below.
OA-4 can be prepared by adding 14 parts (by weight) of dry leonardite ore to 52 parts of water, previously heated to a temperature of 185° F. A carbohydrate or a carboxylate metal salt such as potassium tartrate (16 parts by weight) is added and mixed for 2-3 hours. The liquid composition is oxygenated for 270 minutes and 10 parts of a strong base is added followed by the removal of the insoluble components of leonardite ore. The liquid composition is then isolated and pH adjusted with 1 part strong base. OA-4 can be considered either Component 2 or Component 3 (see description above under “Nutrient Depletion-Restricting Substances” and throughout this application).
OA-9 can be prepared by adding 1 to 3 part OA-4 plus 3 to 1 parts Suboneyo Seaweed. Suboneyo Seaweed is considered as Component 1 (see description above under “Nutrient Depletion-Restricting Substances” and throughout this application), and is commercially available from Suboneyo Chemicals Pharmaceuticals.
In each of the following Examples, the soils used are shown in the Table below.
The data shown in
In one series of treatments, the NDRS labeled OA-4 was mixed in solution with urea at a concentration of 1 milliliter per 100 grams. In a second series of treatments, a second NDRS OA-9 was mixed in solution with urea also at a concentration of 1 milliliter per 100 grams. Finally, a urea and water only control solution was used. Each solution was added to each different types of soils sampled from the representative soils in California (respectively the Tulare soil and the Kern soil). Treatments were replicated three times. The solutions were then incubated for a week and ammonia volatilization was measured and averaged. As depicted in
It is further contemplated that the combined application of fertilizer and NDRS delays reaction of the nitrogen within the fertilizer with the urease enzymes in the soil. This in turn slows the conversion of urea by urease thereby reducing nitrogen losses due to urea volatilization. Instead, the nitrogen remains as urea able to be moved into the soil with rainfall or irrigation. When urea converts into ammonium in the root zone, nitrogen is adsorbed by the soil particles, stabilized and utilized effectively, as needed, by the growing plants. Subsurface nitrogen adsorption also minimizes accumulation of nitrates and ammonium in the surface soil, which can otherwise lead to denitrification and resultant volatilization of nitrogen gas or nitrous oxide from the soil or runoff with rainfall.
The results demonstrate that over the first four weeks of the experiment, a much smaller amount of nitrates leached out of the soil treated with the NDRS than leached from the untreated control. After 8 weeks, a significant residual amount of nitrate was present in the samples of soil treated with OA-4 and OA-9 both at high and low rates. The amount of nitrates leaching from the control after 8 weeks was much less, thereby indicating that most of the nitrates already had leached from the control during the eight week interval. Far less had leached during the same period from the soil treated with NDRS accordance with this disclosure. Reduction in the rate of leaching yields a greater amount of residual nitrate within the soil, which is then available for use by the planted crops as needed. The application of mixtures effectively immobilizes the nitrogen molecules resident in the soil to reduce the downward movement or leaching of the nitrogen in the soil solution. This maintains more available nitrogen in the plant root zone and minimizes premature leaching and loss of the plant nutrients into the subsurface ground water. When the cumulative amount of NO3− leached was calculated, it became clear that cumulative NO3− leached was significantly lower under the NDRS treatments, compared to the control (
The increased release of CO2 indicates that as the microbial population increases, nitrogen is immobilized or stored in the microbial biomass to later provide nutrients to the developing crop. In effect, the increased production of carbon dioxide indicates that the microbial biomass is increasing and therefore requiring a greater amount of nitrogen than the control. The microbes' production of this carbon dioxide indicates that nitrogen is being effectively immobilized and stabilized in the root zone and not lost to leaching. Use of fertilizer and a NDRS as described herein therefore effectively immobilizes nitrogen from nitrogen based granular and liquid fertilizers, crop residues, manures and manure slurries/wash water. This slows nitrification and denitrification and delays urease activity, which, in turn, minimizes rapid and/or large accumulation of nitrates in the soil. As the nitrates in the soil slowly accumulate, this allows for crop demand to synchronize and increase proportionally with the increase of nitrogen availability. Microbial activity, as exhibited by
The objective of this study was to compare NH3 volatilization following broadcast a mixture of urea plus exemplary NDRS (5:1 ratio) to three different soil types. NH3 above the soil in a closed system was measured five times over 48 hours. Cumulative NH3 losses from urea were reduced by >50% when urea is applied with exemplary NDRS to soils with low clay content and neutral pH. Volatilization was the least in the soil that had high clay content and high pH. Urease enzyme is a basic molecule and is more stable at high pH or when clay content is high. However, the hydrolysis of urea occurred very rapidly in all soils as indicated by enhanced NH3 flux between 6 and 30 hours after application of urea or urea-humic NDRS mixture.
Soils: 100 g in each jar. Tulare County, Kern County, and Monterey County.
Treatment 1: OA-4 plus urea.
Treatment 2: OA-9 plus urea.
Treatment 3: Urea only.
OA-4 and OA-9 each contained about 10-11% total carbon (weight/weight) with a pH in of about 11 to about 13. OA-4 and OA-9 contained a negligible amount of nitrogen (<1% by weight).
In a 500 mL volumetric flask, 125 g urea was dissolved and 25 mL of OA-4 or OA-9 was added and dissolved. The mixture was brought to the 500 mL mark and mixed well. This mixture contained 250 mg/mL urea and 50 mg/mL OA-4 or OA-9 (assuming a density of 1 g/mL). In Treatment 1 and Treatment 2, 25 mL of the Urea-OA mixture was added into a jar containing 100 g soil. The 25 mL mixture contained 6,250 mg urea and 1,250 mg OA-4 (in the case of Treatment 1) or OA-9 (in the case of Treatment 2). The concentrations in soil were 62,500 mg urea/kg soil and 12,500 mg OA-4 or OA-9/kg soil. Urea control received 25 mL of 250,000 μg/mL of urea solution alone. Each soil treatment has duplicates and untreated controls. Ammonia was measured after 6, 24, 30, and 48 hours where gas evolving from the soil is passed through an acid trap (0.05 M H3PO4) and measured by gas chromatography (see, e.g., Rochette, P. et al. Soil & Tillage Research, 2009, 103: 310-315). Volatilization rate (flux) was calculated from the 6 and 30 hours measurements (24 hours flux).
List of treatments:
Several potential reasons for the reduction of NH3 volatilization by the NDRS OA-4 and OA-9 are contemplated. For example,
1. The substances may interact with/adsorb to urea, slowing its conversion into ammonium carbonate and then NH4+;
2. The substances may inhibit the urease enzyme;
3. The substances may provide for an increased adsorption surface for the ammonia (which reduces gas loss from the soil surface);
4. The substances may adsorb to NH4+, slowing or preventing its conversion to NH3;
5. The substances may stimulate plant growth, which in turn increases uptake of NH4+, decreasing its conversion into NH3; and/or
6. Some combination of the above.
The results of this study support the conclusion that the NDRS reduce the size of the soil NO3− pool compared to that found in the native soil without the applied materials. That is, these materials act as a nitrogen stabilizer. It is contemplated that this is due to one or more of the following mechanisms:
Surface soils from Tulare County (Soil 1), Kern County (Soil 2), and Monterey County, California (Soil 3) were collected from cultivated agricultural land. These soils were chosen because they represent typical soils used for crop production. The soils were collected, passed is through a 2 mm screen and homogenized. Before starting the incubation experiments, samples were preconditioned with water and incubated at 25° C. for 1 week.
Soils treatments consisted of an untreated control and two rates each of OA-4 and OA-9. The rates were 0.25 mL and 5 mL of liquid per 100 g soil. Each treatment was replicated three times. The treatment list is shown in Table 1.
No other potential nitrogen source was applied to the soil during the study. The method used for determining nitrogen mineralization was similar to those described by Ajwa et al. (Ajwa, H. A. et al. Soil Sci. Soc. Am. J., 1998, 62:942-951). For leaching of the mineralized inorganic nitrogen (NH4+ and NO3−), 100 g of soil was packed into a leaching cup to a bulk density of =1.4 g cm−3. To avoid crusting of the soil surface and to prevent displacement of the soil, 2 g of fine HCl-washed Ottawa sand were added on top of the soil and a thin glass wool pad was placed over the surface.
At approximately weekly intervals from initial treatment until 100 days later, the core was leached with 100 mL of 0.01 M CaCl2 solution in increments of 20 mL. The leachate recovered in the bottle below and was brought up to 100 mL with 0.01 M CaCl2 solution. After leaching, 20 mL of a nitrogen-free nutrient solution were added to the cores to replenish nutrients lost by leaching. The nitrogen-free nutrient solution was prepared with KH2PO4, K2SO4, MgSO4, and CaSO4 to contain 100, 24, 113, 0.5, and 4 mg/L of Ca, Mg, S, P, and K, respectively. The core then was drained for 6 h with a vacuum pump to obtain a uniform soil water potential of 0.033 MPa. The leachate was analyzed for NO3−. Between leachings, the samples were incubated at 25° C. Untreated controls did not receive experimental treatments, but were leached exactly like the treated soils.
Expected cumulative NO3− concentration over time in soil was calculated by adding the initial NO3− concentration to each successive measurement, for each treatment and soil type. Furthermore, the effect of OA-4 or OA-9 on net mineralization/immobilization was measured as the difference between two rates, expressed in mg NO3− per kg soil per unit time, as follows:
R
t
=S
t
−N
t (Equation 1),
where St is the rate of mineralization/immobilization during time interval t associated with the humate treatment, while Nt is the native rate (control without humate treatment) of mineralization/immobilization during the same time interval. Where St or Nt is negative, immobilization is indicated. Where St or Nt is positive, mineralization is indicated.
When Rt was positive, it indicated that the treatment effect was to increase mineralization vs. the native rate. When Rt was negative, it indicated that the treatment effect was to increase net immobilization vs. the native rate. Thus, the magnitude of Rt indicates the magnitude of the treatment effect. Further, the magnitude of the change can be expressed as a percentage of the native rate, as follows:
%Effect=(Rt*100)/Nt (Equation 2)
This parameter compares the slope of the curve of the various treatments to the slope of the control curve for each soil and duration tested. This parameter was calculated for the first 21 days of the experiment across 7 day intervals. Each treatment was replicated three times.
1. The NDRSs have a priming effect on the soil microbial pool, which in turn immobilizes soil N in the forms of NO3− and NH4+;
2. The NDRSs interact with NH4+, slowing its transformation to NO3−;
3. The NDRSs act as a nitrification inhibitor;
4. The NDRSs reduce the potential for NO3− leaching, based on the reduced pool of nitrate found;
5. The NDRSs form complexes with, and or adsorbs to, NO3− to slow its leaching loss in the soil profile; and/or
6. Some combination of the above.
For the sake of simplicity, in the remaining discussion, the term “mineralization” is used to describe the phenomena associated with increasing soil NO3− pools, while “immobilization” is used to describe decreased NO3− pools.
The effect seemed to be more pronounced in soils containing low soil organic matter (Monterey and Kern soils), but was less pronounced, although still present in soils that contained high (>4%) soil organic matter (Tulare). This suggests that number 1, above, may be the most plausible explanation of the results observed. The NDRSs contain both labile and refractory carbon chains, both of which could have a beneficial effect on soil microorganisms.
Across the three soils, the effect of the rate of the NDRS was much larger than the difference between the NDRSs. However, some differences among the NDRSs were observed (
Magnitude of the %Effect of NDRSs (from Equation 2)
The data for the two NDRSs was pooled to observe the net %Effect. Tables 2 and 3 show the effect of application rate on the apparent rate of immobilization/mineralization, expressed as a percentage of the native rate (Equation 2). Table 2 shows the %Effect of low rate of treatment on apparent mineralization/immobilization as measured by NO3− leachate in three soil types. The calculation method is shown in Equation 2. The numbers in the table are the means of the two treatments, the effects of which were similar.
Table 3 shows the effect of high rate of treatment on apparent mineralization/immobilization as measured by NO3− leachate. The calculation method is shown in Equation 2. The numbers in the table are the means of the two treatments, the effects of which were similar.
From Tables 2 and 3, it can be seen from the tables that in almost all soil type over time, the % Effect was negative, which means that NDRS treatment was strongly associated with net immobilization vs. the native rate. Only two cases (Table 2) showed a positive percent effect, associated with increased mineralization. In addition, the magnitude of the effect was stronger with the higher rate of NDRS.
The results of this study support the conclusion that the NDRS reduces the size of the soil NO3− pool compared to that found in the native soil without the applied materials. In other words, these materials act as a nitrogen stabilizer, which is likely due to one or more of the following mechanisms:
This study shows that the NDRS stimulates soil microorganisms which release CO2 during their growth and maintenance respiration. In at least one case, there was a clear “priming effect” of the NDRS, where the soil microbes were stimulated to consume carbon from native soil organic matter, which they did not consume in the absence of NDRS.
Microbial activity was significantly stimulated by both NDRSs, at both low and high rates. Such microbial activity may have a positive impact on immobilization of mineral nitrogen, which in turn would reduce the potential for leaching in soils treated with NDRSs.
Surface soils from Tulare County (Soil 1), Kern County (Soil 2), and Monterey County, Calif. (Soil 3) were collected from cultivated agricultural land. These soils were chosen because they represent typical soils used for crop production. The soils were collected, passed through a 2 mm screen and homogenized. Before starting the incubation experiments, samples were preconditioned with water and incubated at 25° C. for 1 week.
Soils treatments consisted of untreated control and two rates of OA-4 and OA-9 (see Example 1). The rates were 0.5 mL and 10 mL of product per 200 g soil. Untreated controls did not receive organic acids. Each treatment was repeated 3 times.
The method used for determining nitrogen mineralization was similar to those described by Ajwa et al. (Ajwa, H. A. et al. Biol. Fertil. Soils, 1994, 18:175-182). A 200 g soil sample was placed in 500 mL jar and the NDRS solution (0.5 mL or 10 mL) was applied to the soil. The jar was then sealed with a cap that has a rubber septum for gas sampling.
The CO2 evolved from the soil was determined for 45 days by taking a gas sample from the headspace in the Mason jar through the rubber septum. The concentration of CO2 was determined with an Agilent 3000A micro gas chromatograph equipped with a Porapak Q column at 60° C. and a thermal conductivity detector at 70° C. After the CO2 was measured, the jar was opened and allowed to equilibrate with the atmosphere. Between measurements, the jars were incubated at 25° C. The treatments are shown in Table 4.
The following study was performed to show if the carbon in the CO2 evolved in this experiment is coming directly from carbon in the NDRSs, from the native carbon in soil organic matter, or a combination thereof. Accordingly, the mass of the carbon being evolved as CO2 was considered. Table 5 shows the carbon additions from OA-4 in this example.
As shown in Table 5, about 330 mg C/kg soil was applied in OA-4 at the low rate.
However, in the Monterey soil, the difference in CO2 evolution between OA-4 and the untreated control was >400 mg C/kg soil at 45 days Since this was greater than the total amount applied as OA-4 the source of at least some of this carbon was the soil organic matter. This confirms that OA-4 acted as stimulant or “primer” of soil microorganisms, the activation of which caused a release of carbon. This stimulation of soil microbes is also a strong indication of immobilization, which causes a labile pool of nitrogen, held in living and subsequently decaying microbial biomass, which is slowly released over time and becomes plant available.
In the case of the high NDRS application rate, Table 5 shows that 6,591 mg C/kg soil was added. In no case did CO2 evolution exceed this level, therefore it could not be determined whether the C source for CO2 evolution was the NDRS, the soil organic matter, or some combination of the two.
The results of this study support the conclusion that the NDRS stimulates soil microorganisms which release CO2 during their growth and maintenance respiration. In at least one case, there was a clear “priming effect” of NDRS, where the soil microbes were stimulated to consume carbon from native soil organic matter, which they did not consume in the absence of the NDRS.
Microbial activity was significantly stimulated by both NDRS formulations, at both low and high rates. Such microbial activity is expected to have a positive impact on immobilization of mineral nitrogen, which in turn would reduce the potential for leaching in soils treated with NDRSs.
Urea is known to disrupt hydrogen bonds in protein biochemistry. It can act as both a H-bond donor and acceptor. In agriculture, urea is a commonly applied nitrogen fertilizer. NDRSs might be beneficial in slowing the conversion of urea to ammonium ion and eventually to nitrate or to NH3. Results show that urea interactions are more pronounced with NDRSOA-4 as compared to control.
In this experiment dialysis was used to measure the interaction of urea with OA-4.
Dialysis Materials
Solutions
1. A control solution of base, a chelating agent and water at similar concentrations to OA-4. (Equivalent to OA-4 without any humic extract).
2. OA-4
Dialysis Conditions
The starting conditions for dialysis were as shown in Table 6.
The concentration above is equivalent to 20 lbs of Control/OA-4 in 3000 gallons and 50 lbs of nitrogen in 3000 gallons of water.
A Urea Assay Kit (Bioassay Systems, DIUR-500) utilizing an improved Jung Method was used to quantify Urea. Samples at each time point were run in triplicate.
Volumetric was used for preparation (equivalent to 20 lbs in 3000 gallons).
Solution has a pH below 9. If needed, a few drops of HCl were added.
Volumetric was used for preparation (equivalent to 71 mM Urea Solution, or 107.25 lbs Urea in 3000 gal, or 50 lbs N in 3000 gal). Solution has a pH below 9. If needed, a few drops of HCl were added.
4. Solution 1: Control solution
Volumetric was used for preparation (equivalent to 20 lbs in 3000 gal). Solution has a pH below 9. If needed, a few drops of HCl were added.
Volumetric was used for preparation (equivalent to 71 mM Urea Solution, 107.25 lbs Urea in 3000 gal, or 50 lbs N in 3000 gal). Solution has a pH below 9. If needed, a few drops of HCl were added.
Section 2: Prepare a Float-A-Lyzer for each solutions.
1. 10% (v/v) Isopropanol Solution (IPA). The solution was added to the Float-A-Lyzer.
2. The IPA filled Float-A-Lyzer was soaked in a 50 mL tube with IPA for 15-20 minutes.
3. The Float-A-Lyzer was washed with ultrapure water and soak in ultrapure water for 1-2 minute.
The IPA solution removes glycerin and allows for maximum membrane permeability.
a. A 500 mL graduated cylinder was filled with 450 mL of OA-4 2.
b. 100 μL of OA-4 2 was collected. Time 0 sample (TO).
c. 100 μL was collected of OA-4 3. Standard (CO).
d. Float-A-Lyzer was filled with 10 mL of OA-4 3.
e. Float-A-Lyzer was then placed in 450 mL graduated cylinder.
f. OA-4 2 was stirred during dialysis.
g. A 100 μL sample was collected from the graduated cylinder after 4, 8, 10, 26, 28, 30, 32, and 34 hours.
h. After the last collection from the graduated cylinder (T8), two full pipette samples were collected from inside the dialysis chamber.
i. Samples placed in Refrigerator until analysis.
j. Repeated three times.
a. A 500 mL graduated cylinder was filled with 450 mL of Solution 2.
b. 100 μL was collected of Solution 2. Time 0 sample (T0).
c. 100 μL was collected of Solution 3. Standard (C0).
d. Float-A-Lyzer was filled with 10 mL of Solution 3.
e. Float-A-Lyzer was placed in 450 mL graduated cylinder.
f. Solution 2 was stirred during dialysis.
g. A 100 μL sample was collected at the same time as OA-4.
h. After the last collection from the graduated cylinder (T8), two full pipette samples were collected from inside the dialysis chamber.
i. Samples placed in Refrigerator until analysis.
j. Repeated three times.
The control and OA-4 dialysis experiments were both run in quadruplicate. The results in
As shown in Table 7, the difference between the control solution and OA-4 at equilibrium is statistically significant (i.e., not due to random error). Table 7 displays the P-value for the T-Test, which is very low.
Equilibrium dialysis data clearly shows that urea interactions are more pronounced in OA-4 compared to control. The preferential interaction of urea with OA-4 was measured by quantifying the amount of urea in the counter buffer at equilibrium. Due to molecular interactions with OA-4, urea has a lower concentration in the counter buffer at equilibrium.
A vial study was conducted using a 15N isotope dilution technique in soils treated with OA-4 over 3 days of incubation showed that NDRSs increase nitrogen immobilization by from about 200 to about 340%.
Four surface soils from Fresno County, Monterey County, Tulare County, and Kern County were collected from the upper 12 inches of soil. The soils were passed through a 2 mm screen and homogenized. Before starting the experiments, samples were preconditioned with water or with 0.2% of OA-4 and incubated at 25° C. for 1 week.
Soils treatments consisted of:
1. untreated control,
2. soil treated with 50 μg NO3-N/kg soil (applied as KNO3 solution),
3. soil treated with 0.2% OA-4 plus 50 μg NO3-N/kg soil (applied as KNO3 solution), and
4. soil treated with 50 μg NH4-N/kg soil (applied as (NH4)2SO4).
The gross rates of N mineralization (m), consumption (c), and nitrification (n) were determined using laboratory isotope dilution procedures. In brief, 50 g dry soil was placed in a 500 mL flask with 10 mL deionized water, covered, and incubated at 22° C. for 3 d. After incubation, 25 mL of an N-15-labeled (NH4)2SO4 solution or a KNO3 solution were added to obtain an application rate of 50 μg N g−1 soil. The flask was immediately placed on a magnetic plate, stirred for five minutes using a magnetic stirrer. One-half of the samples were extracted with 2 M KCl extraction solution. The NH4+-N and NO3−-N in the soil-solution mixture were determined. Another extraction was done after three days of incubation. A known amount of the filtrate (20 mL, determined gravimetrically) was used for the determination of 15N by a known diffusion procedure (see the methods described by the UC Davis Stable Isotope Facility). The 15N and 14N were determined by a GC-MS isotope analyzer. Throughout the experiment, the samples were aerated twice a day by removing the cover and shaking the flasks for a few minutes. Untreated soil samples (without addition of nitrogen) were also extracted as described above to measure the background 15N enrichment.
Gross rates of nitrogen mineralization were determined by NH4+ isotope dilution, and gross rates of nitrification were determined by NO3− isotope dilution methods as described by Davidson et al. (Davidson, E. A., et al. Ecology 1992, 73:1148-1156).
The following equations of Kirkham and Bartholomew (1954) were used:
where M0=initial 14+15N pool (μg N g−1 dry soil)
M1=post-incubation 14+15N pool (μg N g−1 dry soil)
H0=initial 15N pool (μg N g−1 dry soil)
H1=post-incubation 15N pool (μg N g−1 dry soil)
m=mineralization rate (μg N−1 soil d−1)
c=consumption rate (μg N g−1 soil d−1)
t=time (1 d for the present study)
and where m≠c. Kirkham & Bartholomew (1954) provide another equation for the condition when m=c, which was not encountered in this study.
For NH4+-N transformation, m and c are used. For NO3-N, n (nitrification) is used instead of m. The NH4+ immobilization rate is then determined by subtracting the gross nitrification rate from the gross NH4+ consumption rate. The gross NO3-consumption rate is equivalent to the gross rate of NO3-immobilization. Further details for the experiment are as follows.
Protocol for Diffusing Inorganic N to Determine 15N/14N by Mass Spectrometry
a. Preparation of 15N solutions: (purchased from Aldrich Chemistry, St. Louis, Mo., USA. 15N—KNO3; 15N-(NH4)2 SO2).
b. Preparation of 100 mg N/L as KNO3:
687.5 mg of KNO3 was dissolved in 1 L deionized water
c. Preparation of 100 mg N/L as (NH4)2SO4
456.1 mg of (NH4)2SO4 was dissolved in 1 L deionized water
d. Preparation of 2 M KCl solutions:
149.1 g of KCl was dissolved in 1 L or 298.2 g in 2 L.
a. A field-moist sample (50 g soil) was placed in a 250 mL bottle.
b. 10 mL deionized water was added to the 4 control bottles, which were then covered, and incubated at room temperature for 24 hours.
c. 10 mL of OA-4 solution having a concentration of 10 mg OA-4/mL deionized water was added, the bottle covered and incubated at room temperature for 24 hours, resulting in a 0.2% OA-4 in soil.
d. After incubation for 24 hours, 25 mL of 100 mg N/L of 15N labeled (NH4)2SO4 or KNO3 solution was added to obtain an application rate of 50 μg N/g soil at 99% 15N.
e. 25 mL of 100 mg N/L was applied to 50 g soil.
The soils were extracted with 2 M KCl after one minute (Time zero) and one week. For the extraction, 100 mL 2 M KCl was added to the soil, the bottles placed on a shaker for 10 minutes and the extract filtered. Take 50 mL subsample for NH4+-N and NO3−-N analyses. 20 mL of the extract was used for the 15N diffusion procedure described below.
2.5 M KHSO4 (10 μL/sample) prepared by carefully adding 7 mL of concentrated H2SO4 to 50 mL deionized H2O; add 22 g K2SO4, adding more deionized H2O; mixing until salt is dissolved; bringing to 100 mL final volume.
Devarda's Alloy (0.4 g/sample, KCl only), finely ground (40-mesh) MgO (0.2 g/sample)
Concentrated H2SO4
Concentrated NaOH (1:1 NaOH:H2O by weight)
1. Before diffusing, the reagents were measured to achieve:
a. 20-100 μg N at 10-30 atom %
b. 100-200 μg N at 1-10 atom %. 2. A filter disk was placed on the pin.
3. 5 μL of 2.5 M KHSO4 was pipetted onto the disc. (trapping capacity is 350 μg N total; never exceed 50-60% of this).
4. The pin was placed in the glass culture tube.
5. The tube was simultaneously placed with the pin/filter paper and 1 scoop MgO (or stronger base, if diffusing digests) and/or devarda's alloy (see below) into specimen cup containing 20 mL sample. This was capped immediately and swirled.
6. Samples allowed to diffuse for 6 days at room temperature (22° C.), swirled daily.
7. After diffusing, the trap was removed from the sample with forceps, rinsed with deionized water into a specimen cup, placed on blotting paper, and dried in a desiccator with concentrated H2504 for 4 h. After drying, both disks were wrapped in a 5×8 mm tin capsule.
For samples to be diffused for 15NH4: 0.2 g scoop of MgO was added. For sample to be diffused for 15NO3: 0.2 g scoop of MgO was added, mixed (swirled), and left open for 4 days. The reaction vessel was mixed daily thereafter to allow NH3 to escape. After 5 days, 0.4 g Devarda's Alloy and 0.2 g of MgO was added along with an acid trap. The reaction vessel was capped and mixed daily, then left to sit for 6 days.
Diffuse extraction blanks as though they were samples. Determine the mass of N diffused by adding up all the beams on the mass spectroscopy output. For KCl extracts, 3 blanks for each batch of KCl used were run.
Standards-General considerations
Make 2 types of standards: diffused standards and non-diffused standards.
Non-Diffused Standards: Use the stock solution
1. Place a filter paper disk onto a stainless steel wire and place in tube.
2. Pipette 5 μL of 2.5 M KHSO4 onto each disk.
3. Pipette in enough 10,000 ppm stock to provide the desired mass of N.
a. For standards to receive=60 μg N, pipette half of the total volume of standard stock solution onto each disk.
b. For standards to receive=50 μg N, pipette the entire volume of standard stock solution onto the top disk.
4. Dry in dessicator over conc. H2SO4 overnight and wrap in both disks into one tin capsule.
Diffused Standards: Dilute the stock solution by 10
1. Make a 1,000 ppm (1,000 mg N/L) solution from the 10,000 ppm stock.
2. Measure out a 40 ml volume of 2 M KCl for each standard.
Pipette in enough 1,000 ppm standard to provide the desired mass of N.
Gross rate of NO3− immobilization in soils amended with OA-4 was more than 200 greater than immobilization in soils without OA-4. The gross rate of NH4′ immobilization in soils amended with OA-4 was from about 5 to more than about 10 times greater than the mineralization rate across soil types.
The carbon to nitrogen (C:N) ratio of organic material decomposing in soil is only an approximate indicator to net nitrogen mineralization, largely because the elemental ratio takes no account of the rates at which the different forms of carbon and nitrogen in the organic material (e.g., carbohydrates, lignin, etc.) become available to microorganisms. Changes in net mineralization may arise from differences in gross nitrogen mineralization or immobilization or loss or all three. Gross nitrogen mineralization is primarily determined by the amount and availability of nitrogen in soil organic matter, while immobilization is largely a function of the available carbon.
In this study, the greater immobilization rates than mineralization (or nitrification) rates indicated that application of OA-4 may have solubilized some of the native soil organic carbon (priming effect) and resulted in a larger C:N ratio than 9/1, which induced immediate immobilization.
This study was conducted to determine the efficacy of OA-4 added to UAN on reducing nitrogen losses in the field in corn. Products were applied at specific timings to determine which treatment produced highest yields, best stand, and best plant vigor, and what effect upon soil nitrogen, in particular, soil nitrate, which is frequently a source of significant nitrogen loss from agricultural soils. Based on the data, it is contemplated that one or more of the following occurs:
OA-4 reduces nitrogen losses.
OA-4 reduces the nitrification rate.
OA-4 reduces the potential for denitrification.
OA-4 reduces the size of NO3− pool in soil.
OA-4 reduces leaching of NO3−.
OA-4 slows urease activity.
OA-4 forms complexes with, and or adsorbs to NO3− to slow its leaching loss in the soil profile.
OA-4 increases immobilization (the adsorption of mineral nitrogen into soil microbial biomass).
More nutrients are available to the crop with OA-4 treatment.
OA-4 increases N concentration in crop biomass.
OA-4 increases total N content (mass of N) in crop biomass.
OA-4 increases crop growth.
OA-4 increases crop yield (
A. Site Location: Whitewater, Wisconsin, Jefferson County
B. Test Crop: Grain Corn
C. Plot Description:
D. Experimental Design: Randomized Complete Block (RCB) 1 factor study
E. Replication No. and Units: Four
F. Treatments: A standard application of 3 gal/acre ammonium polyphosphate was applied to the entire trial area to act as a pop-up fertilizer for field and crop uniformity. The components were applied to the soil at the following rates using a plot tractor.
*V3, V6 etc. is a standard measure of the corn crop's development stage, as measured by leaf number. V3 means the corn, on average, has 3 emerged leaves, V6 means there are 6 leaves, etc.
(At each application, the rate of OA-4 was 4 gallons/100 lbs N. The low rate of OA-4 was equivalent to about 1 mL/100 gram soil or a little more than 1 mg PR/100 gram soil)
G. Test Procedures: The treatments were replicated four times and randomized using randomized complete block design. Plot size was 10′×50′
H. Sampling Procedures:
Typical N losses from placement of UAN applications are considered minimal, unless environmental conditions favoring denitrification, leaching of nitrate or ammonia volatilization are severe. In Midwestern soils, 1″ of rainfall can move nitrate 6″.
Pretreatment soil samples showed no differences in NH4+ or NO3− levels (
The third set of soil samples were taken 1 week in advance of the beginning of the crop's reproductive growth phase. Because the third application was surface applied, ammonia volatility from the UAN may have occurred. Ammonia flux appears to not have been excessive, even from the standard treatment, as no phytotoxicity was recorded. Reduction in ammonia volatilization could have occurred in addition to the other potential fates of nitrogen mentioned previously increasing the difference between soil NH4 between treatments to the greatest amount of the 3 post treatment samplings. Available N in the soil for crop growth was significantly increased continued through the VT stage of crop development, over 2 months after corn planting. Through July, we see significantly more available N in the ammonic form (NH4+), than control in the soil in these 14″ deep samples. Even with the slightly higher NO3− levels in the control soil samples, there was about 45 lbs more N/acre with the OA-4 treatment going into tasseling.
Additional available soil N translated into higher plant tissue N at the 3 timings leaf sampling was performed. Higher plant and soil N translated into greater plant biomass at the 3 biomass samplings. A quick calculation of biomass times nitrogen content of the dry matter reveals a greater uptake of nitrogen with the OA-4 treatment.
Two types of corn yields were measured; one for silage and one for grain. Both silage yield and silage yield adjusted to 65% moisture were significantly greater than control. Corn grain yield was significantly greater than the grower standard as well.
Total N uptake by the crop is calculated by grain yield at a constant N content plus the nitrogen in the stover remaining after harvest. Based upon the International Plant Nutrition Institute (IPNI) plant nutrient uptake calculator, the OA-4 treated Corn removed 39 pounds more nitrogen per acre than the standard control (
The calculation is as follows:
Increased nitrogen in grain=180−157=23
Increased nitrogen in stover*=121−105=16 (Stover is the aboveground biomass of the corn, excluding the grain portion).
Total nitrogen increase=23+16=39 lbs N/acre.
It can be stated alternatively that this amount of nitrogen was lost from the soil-plant system in the grower standard, compared to the OA-4 treatment.
At tasseling, when 30% of the crop's N need remains to be taken up, the grower standard UAN had 44 lbs/acre less mineral N available than the OA-4 treatment NDRS. Therefore, there was a greater depletion of soil N measured in the grower standard.
The OA-4 material added to conventional N and applied in an acknowledged efficient manner resulted in a significant reduction of N loss to environmental factors and a consequent increase in nitrogen uptake by the crop (about 15% increase in nitrogen uptake by the crop). This increased retrieval of N from the soil increased yield and reduced N free in the soil to be lost before the next crop is planted.
The nutrients phosphorus and NH4+ are not normally lost to leaching into groundwater. However, it is known that surface runoff during soil erosion events is a significant source of phosphorus and NH4+ pollution of surface waters. When runoff/erosion occurs, both the soil material, which contains adsorbed nutrients, as well as the water that carries them, moves nutrients laterally into surface waters adjacent to agricultural sites. This is a concern for phosphorus, NH4+ and NO3−. Prior research has demonstrated that soil phosphorus runoff likelihood was found to be closely correlated to the standard agricultural soil tests appropriate for the soil pH range (Bray or Olsen's). It was only necessary to analyze the top 2 cm of soil for P in order to predict amount of dissolved reactive phosphate (DRP or runoff P) in runoff. (Bundy, Larry G. Understanding Soil Phosphorus [Powerpoint slides]. Retrieved from http://www.soils.wisc.edu/extension/materials/P_Understanding.pdf; also: Allen, B. L. et al. Soil and Surface Runoff Phosphorus Relationships for Five Typical USA Midwest Soils (2006). J. Environ. Qual. 35:599-610). The objective of this experiment was to measure the extent to which OA-4 can reduce the amount of phosphorus and/or NH4+ in surface runoff.
Methods
Tranquillity Clay soil was screened to 2 mm and mixed very well with an equal weight of fine sand for improved drainage. Coarse sand and a cellulose filter were placed at the bottom of each cup for air flow. Cups are 500 ml Nalgene Rapid Flow vacuum filter units. Soil was packed into cups with a pestle for a Bulk Density of 1.4 g/cc.
Prior to adding treatments, samples were preconditioned with 0.01M CaCl2 and incubated at 77° F. for 7 days.
All treatments were added to a soil surface roughened to 1 cm.
Treatments:
Results and Discussion
P content in the surface 2 cm of soil indicates reduced P runoff potential and associated reduction in nutrient depletion, in the presence of OA-4. Chemical bonding/interaction between the OA-4 and the fertilizer P would increase the mobility of P in soil, where it is widely considered to be immobile. Increased phosphorus mobility would increase its movement into the soil with water. Additionally, a statistically significant quantity of the fertilizer P was redistributed to the 2-4 cm depth, where it is recognized to not be a significant runoff concern. The P level with OA-4 treatment at the 4-6 cm level was not significantly different from the fertilizer only treatment, but was higher than the no fertilizer control. This suggested that fertilizer P moved below the runoff susceptible depth with OA-4 application. The fertilizer only treatment didn't differ significantly from the control. The 29% reduction of phosphorus in the location and form that is susceptible to run off the field is noteworthy in terms of reduced nutrient depletion.
Similar results were observed with ammonium (
Nitrification, i.e., the transformation to NO3−, of fertilizer N had begun by the end of this experiment. Both treatments with added N had higher levels of nitrate at the surface than the no fertilizer control (
The performance of OA-4 to reduce both ammonium and phosphate in the most run off susceptible 0-2 cm depth of the soil column is strongly indicative of its ability to reduce fertilizer runoff from heavy rains or irrigations in field situations. These results are clearly supportive of the nutrient depletion-reducing properties of OA-4.
This application claims the benefit under 35 U.S.C. §119 of U.S. Application No. 62/032,867, filed Aug. 4, 2014, the contents of which is incorporated herein by reference by its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2015/043645 | 8/4/2015 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62032867 | Aug 2014 | US |
