Patent Application
20220306549
The present invention relates to the field of integral nutrients for supplying crops in order to increase their yield. More particularly, the invention is related to a granulated agricultural composition comprising a macronutrient in combination with a micronutrient.
The current agricultural model seeks to maximize crop yields, usually expressed as weight of harvested crop per unit of harvested area. Considering this model, the contribution of traditional nutrients known as macronutrients to crops, which are incorporated through organic and inorganic compounds, are often insufficient and do not achieve the expected results. Thus, it is necessary to incorporate other nutrients known as micronutrients, which are essential to achieve yield optimization objectives.
Micronutrients are nutrients that are extracted over time from the soil by crops, which, although absorbed at a low rate, they become deficient over the years, requiring their replenishment. Particularly in La Pampa region (PAR) micronutrient deficiencies, especially boron (B) and zinc (Zn), have started to be observed in certain extensive crops, such as sunflower, corn, wheat and alfalfa. The OM and nutrient levels in some areas represent only 50% of the original level (Lavado, R. 2006. La region Pampeana: Historia, características y use de sus suelos. En: Materia Orgánica “Valor Agronómico y Dinámica en Suelos Pampeanos” (ed. R Alvarez). Editorial. Facultad de Agronomia, Universidad de Buenos Aires. pp. 1-12). In the case of soybean, there is evidence that B, Cobalt-Molybdenum (CoMo), Manganese (Mn) and Zn could potentially be limiting in La Pampa region of Argentina and other regions of the world.
In particular, Zinc (Zn) is a microelement whose relevance and notoriety has notably increased in recent years. Its main function is that of enzyme activator, catalyzing innumerable reactions in metabolic processes such as respiration, chlorophyll and protein synthesis. It is also a precursor of tryptophan and indole acetic acid (Fancelli, A L. 2006. Micronutrientes en la fisiologia de las plantas. pp 11-27. En: M Vázquez (ed). Micronutrientes en la agriculture. Asociación Argentina de la Ciencia del Suelo. Buenos Aires, Argentina. pp 207).
Zn deficiency is a worldwide problem in almost all crops. Accurately evaluated through soil analysis, grasses are particularly sensitive to Zn deficiency. Nearly 50% of soils used for cereal production have low levels of Zn availability, which not only reduces crop yields but also their nutritional value (Graham, R. D. and R. M. Welch. 1996. Breeding for staple-food crops with high micronutrient density. Agricultural Strategies for Micronutrients. pp 1-72. Working Paper No. 3. Washington, D.C.: International Food Policy Research Institute). International literature mentions critical thresholds in the range of 0.5 to 1 mg kg−1, depending on the author and region. Below this range, availability may be considered low and vice versa. The traditional way of application consists of seed and foliar treatments. Foliar applications could serve as a vehicle to incorporate other relevant elements, such as nitrogen (N), which is the key element in determining yield and quality.
These traditional ways of application often show restrictions in logistics and practicality of use. Seed treatments have shown to be efficient, allowing yield increases at low doses, with nutrients being available from the beginning of culture process. However, there is only one specific time for application, after which this practice is not possible. Foliar treatments may require an additional cost, if they do not concur in time with the application of a phytosanitary product. Thus, it is important to develop alternative ways of application, in order to broaden the range of possibilities available to the user.
Another micronutrient that is suspected to be deficient in La Pampa region of Argentina is Boron (B). The concentration of B in soils ranges from 2 to 100 mg kg−1, but the most frequent range is from 7 to 80 mg kg−1. In soil, B exists in two forms: adsorbed on the surface of clays and/or Fe and Al hydroxides bound to organic matter, and as boric acid (H3BO3) in soil solution (Goldberg, S., H. S. Forster, and E. L. Heick. (1993). Boron adsorption mechanisms on oxides, clay minerals, and soils inferred from ionic strength effects. Soil Sci. Soc. Am. J. 57:704-708). The adsorption of B usually increases with increasing pH, temperature, ionic strength and the nature of the adsorbed ions. At pH lower than 7, the predominant species in the soil solution is H3BO3. This species is easily leached, so B is considered a mobile micronutrient. On the contrary, at pH higher than 7, the concentration of [B(OH)4]—, which is adsorbed on Fe and Al sesquioxides, Mg hydroxide, calcium carbonates, organic matter and, to a lesser extent, on silicate clays, increases. Anionic competition in B uptake is low, and follows the order P>Mo>S.
Due to its mobility, soils with water excess can suffer leaching of boric acid (H3BO3). Similarly, under water stress, plants cannot absorb it from the soil solution. Both situations have been reported as causes of induced nutrient deficiencies. The concentration of B in soil could be a reference indicator, although its dynamics and mobility in soil determine the need to adjust depth and seasonality in sampling. Unlike Zn, visual deficiency symptoms are unlikely to be observed in PAR, even though the nutrient could potentially be deficient.
In sandy soils of western Buenos Aires, B responses in sunflower were associated with the level of extractable B in soil, in petioles and situations of drought or excess water. It is considered that 80% of the area cultivated with sunflower in the Pampean Prairie could present B deficiencies (Ratto, S. E. 2006. Los microelementos en el sistema productivo del área pampeana. En: M Vázquez (Ed.) Micronutrientes en la agriculture. AACS, Argentina. pp 79-111). This crop has shown the highest level of response among the extensive agricultural species in the PAR. Taking into account experimental results, B is probably the main limiting micronutrient in alfalfa production. (Fontanetto, H., O. Keller, D. Giailevra, L. Belotti y C. Negro 2010. Manejo de la fertilización de la alfalfa en la región central de Santa Fe. Available on line. www.inta.gov.ar/rafaela). As it happens with other highly mobile nutrients, B deficiency could be induced by the demand of a high yielding crop, which would rapidly deplete the nutrient level in the soil inducing the expression of response. This was observed in General Arenales (Argentina), in a high yielding soybean crop on a loam soil with no physical or other nutrient impedances, but with moderate organic matter content and initial fertility due to its texture. (Ferraris, G., L. Couretot y J. Ponsa. 2005. Evaluación de la utilización de molibdeno, cobalto, boro y otros nutrientes en soja de primers. En: Soja. Resultados de Unidades demostrativas del Proyecto Regional Agricola, año 2005. CERBAN. Áreas de Desarrollo Rural EEA INTA Pergamino y General Villegas. pp 62-65).
There exist in the prior art compositions comprising combinations of macronutrients and micronutrients, in particular in the form of macronutrient granules coated with micronutrients.
The U.S. Pat. No. 3,941,578 patent is directed to a fertilizer based on urea particles coated with zinc oxide as a micronutrient, which may contain other metal oxides.
The U.S. Pat. No. 3,353,949 patent is directed to a method for preparing a primary granular fertilizer having micronutrients uniformly distributed on the surface.
The U.S. Pat. Nos. 3,423,199 and 3,523,019 patents are directed to obtaining granules of hygroscopic fertilizer salts coated with micronutrient powders.
The U.S. Pat. Nos. 4,494,976 and 4,563,208 patents are directed to urea particles coated with metal oxides, e.g. Micronutrients.
The U.S. Pat. No. 5,152,821 patent is directed to the preparation of a granular fertilizer coated with micronutrients.
The WO 2015/13225 patent application is directed to a method for incorporating micronutrients into an outer layer of a urea-based particle.
However, there is a need to provide new fertilizer compositions that serve as integral nutrients containing both macronutrients and micronutrients, in order to optimize the yield of the crops of interest.
Correspondingly, it is an aspect of this invention to provide a granulated agricultural composition comprising:
In a particular embodiment, the macronutrient is selected from the group consisting of Urea, MAP (Monoammonium Phosphate), SSP (Single Superphosphate), Triple Superphosphate, DAP (Diammonium Phosphate), Calcium Carbonate, potassium chloride, potassium sulfate, magnesium sulfate, potassium nitrate, sulfur, potassium, calcium, ammonium sulfate, potassium sulfate, phosphorus pentoxide, potassium dioxide, and magnesium dioxide.
In another particular embodiment of the invention, the micronutrient is selected from the group consisting of a boron (B) source, a chlorine (Cl) source, a cobalt (Co) source, a copper (Cu) source, an iron (Fe) source, a manganese (Mn) source, a molybdenum (Mo) source and a zinc (Zn) source. Preferably, the micronutrient is selected from the group consisting of a B source and a Zn source.
In another particular embodiment of the invention, the at least one coadjuvant comprises a compound selected from the group consisting of minerals of the alumina silicate family, iron, calcium, magnesium and alkaline minerals, such as mica derivatives, and/or polymeric materials of the plastomer type and pigments derived from resins, titanium dioxide, cobalt oxides, copper oxides and carbazoles, and mixtures thereof.
Preferably, the composition of the invention comprises a mixture of coadjuvants, in particular, comprising a mineral of the mica family, a polymeric material of the plastomer type, titanium dioxide and pigments derived from resins. More preferably, the plastomer-type polymeric material is a polyolefin.
In a particularly preferred embodiment, the mixture of coadjuvants comprises titanium dioxide, a mineral of the mica family, polyethylene and a mixture of pigments derived from resins.
In another particular embodiment of the invention the macronutrient and the micronutrient are present in an amount ratio of between 200:1 and 5:1.
Another aspect of this invention is to provide a method for preparing a granulated agricultural composition in accordance with the present invention, comprising:
It is another aspect of this invention to provide a method for increasing the yield of a crop comprising applying to said crop an effective amount of a granulated agricultural composition in accordance with the present invention.
The present invention is related to a technology for homogeneously and effectively integrating traditional and non-traditional sources in integral nutrients, which is practical, efficient, effective, and differentiating, allowing to achieve a demonstrated and significant crop growth, impacting on yield increases versus the application of traditional nutrients and micronutrients separately.
The invention is versatile allowing to combine nutrients adapting in types and dosages according to their availability in the soil, to maximize crop growth, making feasible the incorporation of other components such as growth hormones and plant growth promoting microorganisms.
Although in general crops already respond positively to traditional nutrition, improving their growth, photosynthetic efficiency and grain yield, the inventors have found through field studies that an improved and enhanced response is obtained when using granulated agricultural compositions prepared through impregnation treatments of traditional sources with accompanying elements (micronutrients), forming integral nutrients, which enter the soil and are better used by crops.
It is therefore an object of the present invention to provide a granulated agricultural composition comprising:
The term “macronutrient” refers to any compound traditionally used to fertilize a crop. The term includes, but is not limited to, a nitrogen (N) source, a phosphorus (P) source, a potassium (K) source, a sulfur (S) source, a calcium (Ca) source, or a magnesium (Mg) source. The macronutrient must be a compound that can effectively and efficiently deliver the above elements to the crops.
Preferably, the macronutrient is selected from the group consisting of Urea, MAP (Monoammonium Phosphate), SSP (Single Superphosphate), Triple Superphosphate, DAP (Diammonium Phosphate), Calcium Carbonate, potassium chloride, potassium sulfate, magnesium sulfate, potassium nitrate, sulfur, potassium, calcium, ammonium sulfate, potassium sulfate, phosphorus pentoxide, potassium dioxide, and magnesium dioxide. More preferably, the macronutrient is selected from the group consisting of Urea, MAP and SSP.
In a particular embodiment of the invention, the granulated agricultural composition comprises a second macronutrient, which is not coated with the mixture of micronutrient and coadjuvant.
The term “micronutrient” is used in this description as it is usually understood in the field of agriculture, to denote those elements essential for crops that occur in extremely low concentrations in soils and plant tissues. The low requirement of micronutrients broadens the spectrum in terms of sources and forms of application.
Preferably, the micronutrient is selected from the group consisting of a boron (B) source, a chlorine (Cl) source, a cobalt (Co) source, a copper (Cu) source, an iron (Fe) source, a manganese (Mn) source, a molybdenum (Mo) source and a zinc (Zn) source. Preferably, the micronutrient is selected from the group consisting of a B source and a Zn source.
A particularly preferred source of B is the mineral ulexite, which is a hydrated sodium calcium borate, of formula NaCaB5O9.8H2O, while a particularly preferred source of Zn is zinc oxysulfate.
The micronutrient is preferably incorporated into the composition in solid form, which may be a granular or powdered form.
The amounts of each nutrient to be applied will depend on the size and type of crop, among other factors. The technical expert will know how to determine these quantities in order to optimize the yield of the crop in question. Although the absolute amounts depend on the application situation, preferably the macronutrient and micronutrient are present in an amount ratio of between 200:1 and 5:1, more preferably between 100:1 and 10:1. In particular embodiments of the invention, the macronutrient and micronutrient are present in an amount ratio selected from 100:1, 50:1, 40:1, 25:1, 12.5:1 and 10:1.
The coadjuvants are components that are introduced during the process of obtaining the compositions of the invention, and which act as adhesives, dust suppressants, biocides and colorants, since they contain pigments that provide coloring to the nutrients, allowing differentiation of the different combinations of macro and micronutrients. Therefore, they function on the one hand as indicators of both the appropriate mixing of the compounds to obtain the formulations, and of the recommended homogeneous distribution on the fertilized surfaces.
According to the present invention, different coating, damp barrier, dust control and adhesive coadjuvants can be used, which may contain minerals of the alumina silicate family, iron, calcium, magnesium and alkaline minerals, such as mica derivatives, and/or plastomer-type polymeric materials and pigments derived from resins, titanium dioxide, cobalt oxides, copper oxides, carbazoles, as colorants that can provide a complete range of colors required to identify the final products.
In a particular embodiment, the composition of the invention comprises a mixture of coadjuvants comprising a mineral of the mica family, a polymeric material of the plastomer type, titanium dioxide and pigments derived from resins. Preferably, the plastomer-type polymeric material is a polyolefin. More preferably, the mixture of coadjuvants comprises titanium dioxide, a mineral of the mica family, polyethylene and a mixture of pigments derived from resins. The mixture of pigments can be adapted according to the combination of macronutrients and micronutrients used, to differentiate between different combinations.
Additionally, the mixture of coadjuvants may also contain some additional component, such as preservatives normally used in the technique.
The coadjuvants are present in the composition of the invention in such quantities as to permit adequate adhesion and impregnation of the micronutrient on the macronutrient granules. Preferably, the coadjuvants are present in the composition in an amount of between 0.5 and 2.0 L/ton of composition.
In a particularly preferred embodiment of the invention, the composition comprises a mixture of coadjuvants comprising titanium dioxide in a concentration of less than 10% w/w, a mineral of the mica family in a concentration of less than 10% w/w, polyethylene in a concentration of less than 5% w/w, and a mixture of pigments, the concentration of which the person skilled in the art will know how to adapt according to the pigments used.
In a particularly preferred embodiment, the granulated agricultural composition of the invention comprises:
In another particularly preferred embodiment, the granulated agricultural composition of the invention comprises:
In another particularly preferred embodiment, the granulated agricultural composition of the invention comprises:
Another aspect of the present invention relates to a method for preparing a granulated agricultural composition in accordance with the present invention. The method comprises the steps of:
Production batch sizes are defined according to the needs of the areas where field applications will be made. These sizes are variable; in general, at least 1000 kg are required.
According to the preparation method of the invention, the macronutrients are introduced into a mixer type tank with constant centrifugal agitation. The time required to homogenize the mixture can range from 20 to 40 minutes.
The coadjuvants are applied in two stages by means of injectors, preferably electronic injectors. The coadjuvants are incorporated at a time-dependent flow rate depending on the product density, preferably dissolved in a suitable solvent system, which any expert in the art will be able to determine. A preferred solvent system for incorporating the coadjuvants into the composition is a mixture of methanol and propylene glycol. Preferably, the final incorporation of the coadjuvants is done by microdroplet spraying (similar to a sprayer) in the last minute of homogenization of the mixture prior to final packaging.
Another aspect of the present invention relates to a method for improving the yield of a crop comprising applying an effective amount of the granulated agricultural composition of the invention to said crop.
The application of the composition can be done at different times of the crop cycle. Preferably, the application is made at the time of sowing.
In a particular embodiment of the invention, the crop to which the composition is applied is selected from the group consisting of corn, wheat, soybean and sunflower.
By means of the present invention, granulated agricultural compositions are provided that offer numerous advantages over traditional compositions, such as:
The following examples of embodiments evidence the improvements obtained by means of the present invention.
In all the examples below the granulated agricultural compositions evaluated were prepared using a mixture of coadjuvants with the following formulation (where the concentrations are expressed as a function of the total weight of the granulated agricultural composition).
A field experiment was carried out at the EEA INTA Pergamino, on a Pergamino Series soil, typical Argiudol, (USDA-Soil Taxonomy V. 2006), use capacity: I; IP=85. The trial was planted on October 4th and was spaced at 0.7 m between rows, achieving a final density of 75,000 plants·ha−1. The chosen cultivar was Nidera Ax 7822 VT3P. Good productive conditions were ensured, keeping the crop free of weeds, pests and diseases. Impregnation treatments with Zn powder are evaluated over traditional sources such as MAP or urea. The design corresponded to randomized complete blocks with 4 replications and 6 treatments, as shown in Table 1.
In the V10 state, NDVI was determined by means of the Green seeker sensor. At flowering, accumulated dry matter, number of photosynthetically active leaves, vigor, cover, plant height and green index by Spad were measured. At harvest, yield components, number of spikes·m−2 (NS), grains·spike−1 (GS), number of grains·m−2 (NG) and weight (WGx1000) of grains were determined. Harvesting was done manually, with stationary threshing of the samples. For the study of the results, analysis of variance and mean comparisons were performed.
The season was drier and cooler than the last three seasons. All months, from September to March, had nights with absolute minimum temperatures close to zero, measured outdoors at 5 cm above the ground (Source: Climatología INTA EEA Pergamino). Rainfall was especially low during November, January, February and March. The low spring temperatures and low rainfall in November resulted in a low crop size, with limited biomass, which would have conditioned yields.
A medium productivity corn crop requires a consumptive use of approximately 550 mm of water. During the cycle, the present received 328 mm of rainfall and contained 150 mm of usable water at 1.5 m depth. This means that the crop would have maximized the use of reserves and rainwater, in a very tight water balance especially at the end of the cycle. The antecedent moisture from the previous cycle and the very timely rainfall in December explain the good yields and the efficient use of water.
Light conditions were average. The photothermal quotient (Q) (December 11-January 10) was 1.65, lower than in the preceding El Nino years (2015/16: 1.72; 2014/15: 1.70) but nevertheless much higher than in warm years (2013/14: 1.35; 2016/17: 1.58) (
A) Zn Powder
In Table 3 the morphological and physiological crop variables and yield components are presented, while in
B) Granulated Zn
In Table 4 the morphological and physiological crop variables and yield components are presented, while in
A) Zn Powder
Yields reached an average of 9892.4 kg ha−1, being slightly higher than in its analog treated with Zn powder. The acceptable level achieved is mainly explained by the initial reserves in the soil and the good rainfall in December (
Differences in yield were statistically significant (P<0.0001; VQ=4.2%). A strong response to P was verified, as well as to Zn. In contrast to what was observed with the granulated formulation, in this experiment the MAP treatments seemed to show a better performance than the Urea treatments, especially at low doses. The higher dose of 4 kg ha−1 increased yields with respect to its lower alternative, especially the impregnation on Urea.
The variables with the highest relationship with yields were NG (r2=0.88), WGx1000 (r2=0.75), AIE (r2=0.69), GS (r2=0.69), leaf N content estimated by Spad (r2=0.55) and NDVI measured by Green Seeker (r2=0.55).
The results obtained show a statistical response to the use of phosphorus and zinc, of great magnitude in the case of phosphorus and significant for the micronutrient. The low fertility of the site, observed in the similar experiment carried out with the granulated formulation, is reaffirmed.
The source of Zn used was effective in increasing yields, and the impregnation was an appropriate medium to transport it. The average yields of this experiment were higher than the one conducted with the alternative formulation. However, it seems to be more sensitive to the source on which the impregnation is performed, with better performance in those performed on MAP. Probably the in-line location would favor the performance of this one over Urea, applied in coverage. Likewise, there was a dose effect, with the best results in the higher dose, especially when the impregnation is on Urea.
B) Granulated Zn
Yields averaged 9154.2 kg ha−1. They were conditioned by the level of degradation of the lot, low spring temperatures and lack of rainfall. However, the soil had good reserves and rainfall in the key month of December was acceptable. The yields of the control without P show the nutritional deficiency to which an early sown crop is subjected in a soil typical of the region (Table 4).
Significant differences were found between treatments (P<0.0001; VQ=5.1%). Response to P and Zn was verified. In Zn, not only response to the nutrient was determined, but also to doses of this element, reaching the maximum yield in T4 and T5, which provided 10 kg ha−1 Zn oxysulfate. In contrast, no differences were found between MAP or Urea impregnation, even though the latter was applied in full coverage.
The most representative variables with the highest correlation with yields were NG (r2=0.97), subjective vigor rating (r2=0.79), WGx1000 (r2=0.76), NDVI by Green Seeker (r2=0.71), Leaf N content estimated by Spad (r2=0.60), GS (r2=0.57), NS (r2=0.45) and Light interception at flowering (r2=0.44).
The results obtained show a statistical response to the use of phosphorus and zinc. The site proves to be very poor in these elements. On the other hand, the source of Zn used was effective in increasing yields, and the impregnation was an appropriate medium to transport it. There was also a dose effect, with the best results at the higher dose. In contrast, there was no difference between MAP or Urea impregnation.
During the year 2018, two field experiments were conducted at EEA INTA Pergamino, on a soil Serie Pergamino, Class I-2, typical Argiudol, fine family, illitic, thermal (USDA-Soil Taxonomy V. 2006). The trial was planted on October 2nd and was spaced at 0.7 m between rows, achieving a final density of 80,000 plants ha-1. The chosen cultivar was Dow Next 22.6 PW. Good productive conditions were ensured, keeping the crop free of weeds, pests and diseases. In the experiment, a randomized complete block design with 4 replications was used, whose treatments are detailed in Table 5. In addition, in Table 6, the soil data of the experiment are presented.
Impregnation treatments with Zn oxysulfate, in its granulated and powdered physical forms, were evaluated at two doses of Zn for each of them, respectively. In Experiment 1 a granular source was evaluated, and in Experiment 2 the same source in powder form, impregnated on MAP or Urea (Table 5). The MAP treatments were applied in-line incorporated, while in the case of using Urea as a substrate, they were applied on the surface.
The season was very favorable, although somewhat excessive in rainfall, which was concentrated in short periods of time (
In Tables 7 and 8, data from observations taken during the crop cycle are presented, while in
In
The 2018/19 cropping season was characterized by the development of appropriate environmental conditions for growing corn, with abundant rainfall centered around the critical period and during grain filling. The site shows a strong limitation of P, determining statistical responses to its application.
Yields averaged 12591 kg ha−1. Significant differences were found between treatments (P=0.0009; VQ=5.7%). The Zn treatments showed significant response, with slight advantages in the MAP treatment compared to Urea at the lowest dose of Zinc (5 kg), compensated when the highest dose (10 kg) was applied. I.e., while no dose response was verified in the treatment with MAP, it was detected when the base source was Urea (Table 7 and
The crop variables that showed the highest correlation with yield were NG (r2=0.99), plant vigor rating (r2=0.96), NDVI determined by Green seeker (r2=0.96), radiation interception at flowering (r2=0.94), spike insertion height (r2=0.90), plant height (r2=0.75) and initial biomass (r2=0.68).
Impregnations with Zn Powder on MAP or Urea
Yields averaged 12366 kg ha−1. Significant differences were found between treatments (P=0.004; VQ=5.9%). As with the granular sources (
The crop variables that showed the highest correlation with yield were NG (r2=0.99), NDVI determined by Green seeker (r2=0.99), plant vigor rating (r2=0.95), plant height (r2=0.96), radiation interception at flowering (r2=0.93), spike insertion height (r2=0.92) and initial biomass (r2=0.84).
Using spectral indexes on aerial photography, it was determined that the NDRE index showed a higher correlation with yield than NDVI or OSAVI. The NDRE reflects variations in chlorophyll content. Zn treatments would have favored N uptake.
The results obtained suggest a positive effect of Zn fertilization in a soil limited in this element. In addition, in general, the granulated formulation tended to perform better. Likewise, the joint treatments with MAP showed slight superiority compared to Urea, and little response to Zn doses. The exception was the Blend of Urea+granulated Zn, which did show a dose response (
Even assuming this slight advantage for MAP and Urea, both sources were suitable for impregnation from an agronomic point of view, and did not present operational difficulties for their implementation.
During the 2017/18 season, a field experiment was conducted aimed to evaluate the impact of different fertilization strategies on soybean crop productivity. The treatments were applied top quality soybean. The experiment was planted at the EEA INTA Pergamino, on a Pergamino Series soil, typical Argiudol, mixed family, loam, thermal, Class I-2, IP=85. Planting was carried out on November 15th, with the DM 40R16 STS variety, in rows spaced 0.40 m apart. The experimental site registers a continuous agricultural rotation with a high level of intensification and crop rotation. The predecessor was corn. During the cycle, insecticides and fungicides were applied to prevent attacks by bollworms, bugs and diseases. The plots were kept completely free of weeds and pests.
The test design was a randomized complete block design with four replications and six treatments. Details of the treatments evaluated are described in Table 9. The soil analysis of the sites is presented in Table 10.
Emerged plants were counted for 15 days. In R4, NDVI was determined by means of the Green seeker sensor and the radiation interception. Likewise, the N content was also estimated using a Minolta Spad 502 chlorophyll meter, and vigor was rated according to the general condition of the plot, its uniformity and health. An evaluation of nodulation was carried out, considering number, weight, size and location of nodules. Harvesting was carried out with an experimental self-propelled harvester. Yield components, number of nodes, pods, NG and WG were determined on a harvest sample. The results were analyzed by partition of variance, mean comparisons and regression analysis.
In
In Table 11 presents parameters that characterize crop nodulation, while in Table 12 presents the yield, its components and other variables determined during the crop cycle.
The 2017/18 season was low in rainfall (
Nodulation presented a good quality. Fertilized treatments clearly differed from the Control, especially in size and location (Table 11). The size of the nodules with the highest correlation with yields (Table 11).
Differences in yields were at the limit of statistical significance (P=0.17; VQ=6.3%). However, the absolute differences reached a considerable magnitude, determined up to 490.1 kg ha−1 over the Control (
Evaluated through the coefficient of determination (r2), the variables that most explained yields were NG (r2=0.78), No. nodes·plant−1 (r2=0.68), nodule size (r2=0.53) and No. pods·plant−1 (r2=0.40) (Table 12).
The results of the present experiment allow us to conclude on the positive effects of fertilization on soybean. The Zn-impregnated formulations performed well.
During the 2018/19 season, an experiment was conducted on top quality soybeans to evaluate the impact of different P and micronutrient fertilization technologies on soybean crop productivity. The experiment was planted at the EEA INTA Pergamino, on a Pergamino Series soil, typical Argiudol, mixed family, loam, thermal, Class I-2, IP=85. Planting was carried out on November 21st, with the DM 46R18 STS variety, in rows spaced 0.40 m apart. The experimental site registers a continuous agricultural rotation with a high level of intensification and crop rotation. The predecessor was corn. During the cycle, insecticides and fungicides were applied to prevent attacks by bollworms, bugs and diseases. The plots were kept completely free of weeds and pests. A base inoculation was performed to ensure nitrogen (N) supply.
The treatments were applied top quality soybean. Details of these experiments are presented in Table 13.
The test design was a randomized complete block design with four replications and four treatments. Details of the treatments evaluated are described in Table 13. In addition, the soil analysis of the sites is presented in Table 14.
The biomass accumulated in R3 (kg ha−1) was quantified. In R4, the NDVI was determined by means of the Green seeker sensor, and the coverage was determined by processing with specific digital image software. Likewise, the N content was also estimated using a Minolta Spad 502 chlorophyll meter, and vigor was rated according to the general condition of the plot, its uniformity and health. Harvesting was carried out with an experimental self-propelled harvester. Yield components, number of nodes, pods, NG and WG were determined on a harvest sample. On four occasions a flight was performed with an Ebee Parrot aircraft equipped with a Sequoia_4.0_1280×960 (Green), Sequoia_4.0_1280×960 (Red), Sequoia_4.0_1280×960 (Red Edge), Sequoia_4.0_1280×960 (NIR) high resolution camera. The photographs obtained, with a pixel size of 14×14 cm, were processed and the OSAVI and NDRE indexes were calculated.
OSAVI (Optimized Soil Adjusted Vegetation Index) is a vegetation index corrected for soil reflectance. It provides additional information and represents an improvement over NDVI by showing greater sensitivity to cover variations in sparsely vegetated areas where the ground is visible through the canopy. It is also advisable to use it at the end of the cycle where vegetation cover is maximum, since it saturates at higher levels of leaf area with respect to NDVI.
NDRE (Normalized Difference Red Edge) is an index highly sensitive to the chlorophyll content of vegetation. The variation of this index allows inferring nutrient deficiencies that cause chlorosis in the tissues, such as nitrogen, sulfur and some microelements.
The results were analyzed by partition of variance, mean comparisons and regression analysis.
In
In Table 15 an evaluation of nodulation is presented, while in Table 16 the yield, its components and other variables determined during the crop cycle, for the different locations.
The 2018/19 season was favorable for the crop, with abundant rainfall, although concentrated in December-January, and significantly better than the previous season. The initial reserve, abundant rainfall together with favorable temperatures and good physical conditions of the lot helped to achieve very good yields. Productivity reached an average of 5332.8 kg ha−1 (Table 16), which is close to the potential achievable by the crop in the region.
Significant differences were found between treatments (P=0.08; VQ=6.4%). A consistent response to Zn supply was determined, which reached its peak with powder impregnation at the maximum dose (
None of the treatments evaluated showed phytotoxicity on seeds or damage to emergence. Zn impregnation did not change this behavior. The addition of P, and P+Zn increased initial biomass (r2 vs yield=0.69), NDVI by Green seeker (r2=0.43), interception (r2=0.46), subjective vigor rating (r2=0.76), plant height (r2=0.88), NG (r2=0.97) and WG (r2=0.47). That is, the behavior of the fertilized treatments and their agronomic response could be anticipated by numerous variables.
The results of the present experiment allow us to conclude on the positive effects of novel technologies for P and Zn addition. According to the obtained results, impregnation with Zn powder, at its highest dose, was the most successful strategy in the present experience.
During the year 2018, two field experiments were conducted at EEA INTA Pergamino, on a soil Serie Pergamino, Class I-2, typical Argiudol, fine family, illitic, thermal (USDA-Soil Taxonomy V. 2006). On June 20th, the SY 120 variety, an intermediate cycle cultivar with no vernalization requirements, was planted. According to the sanitary profile of the crop, this variety shows tolerance to all rust species except stem rust, as well as to leaf spots—Dreschlera and Septoria—. It also shows good behavior to ear blight.
In the experiment, a randomized complete block design with 4 replications was used. Despite the good health of the cultivar, fungicides and insecticides were applied at Zadoks 32 and Z41 phenological stages. The treatments evaluated are described in Table 17. In addition, the soil analysis of the site is presented in Table 18.
Impregnation treatments with Zn oxysulfate, in its granulated and powdered physical forms, were evaluated at two doses of Zn for each of them, respectively. In Experiment 1, impregnations were evaluated on MAP (0-23-0) (Table 17.a), and in experiment 2 on Urea (46-0-0), in both cases incorporated (Table 17.b).
A count of emerged plants was made 15 days after emergence. In Z65, cover, NDVI by Green seeker, and vigor, green index by Spad and plant height were quantified. The harvesting was carried out mechanically, harvesting the entire plot.
In the vicinity of anthesis, a flight was conducted with an Ebee Parrot aircraft equipped with a Sequoia_4.0_1280×960 (Green), Sequoia_4.0_1280×960 (Red), Sequoia_4.0_1280×960 (Red Edge), Sequoia_4.0_1280×960 (NIR) high resolution camera. The photographs obtained, with a pixel size of 14×14 cm, were processed and the OSAVI and TCARI indexes were calculated.
OSAVI (Optimized Soil Adjusted Vegetation Index) is a vegetation index corrected for soil reflectance. It provides additional information and represents an improvement over NDVI by showing greater sensitivity to cover variations in sparsely vegetated areas where the ground is visible through the canopy. It is also advisable to use it at the end of the cycle where vegetation cover is maximum, since it saturates at higher levels of leaf area with respect to NDVI.
TCARI (Transformed Chlorophyll Absorption Ratio Index), is sensitive to the chlorophyll content of the vegetation, and therefore could express changes in nitrogen supply in an adjusted form. The variation of this index at the plot scale allows inferring nutritional N deficiencies, allowing re-fertilization decisions to be made. If the N supply is uniform, it could represent effects of other chlorophyll-related elements, such as sulfur (S).
Yield components—number (NG) and weight (WG) of grains—were evaluated on a harvest sample. The results were analyzed by variance partitioning and correlation analysis.
At sowing, the profile had a moderate level of storage. Even though the previous summer was very dry, the abundant rainfall in April allowed a reasonable level of recharge of the soil moisture profile. Between August 20th and October 10th, precipitation decreased sharply, depleting moisture reserves (
In Tables 20 and 21, data from observations taken during the crop cycle are presented, while
The yields, which averaged 5187 and 5161 kg ha−1, respectively. They were satisfactory, although with lower yields compared to the previous season. Water availability was the main constraint to productivity during the season.
The site recorded a poor initial P content, which determined a consistent response to fertilization. Something similar occurred with respect to N. The level of Zn was also below the proposed critical limit of 1 mg kg−1 (0-20 cm). The presence of a positive response site enables the comparison of different sources, doses and substrates for impregnation.
Significant differences were found between treatments (P=0.001, VQ=10.3%). Treatments with granulated Zn were slightly higher than powdered Zn (Table 20 and
Significant differences were found between treatments (P=0.001, VQ=8.9%) (Table 21). Even when the urea treatments were located in the mid-row, somewhat farther away from the plant line than MAP, the response to Zn application was not diminished. Probably the separation of the lines made it possible to determine a greater dose response. Treatments with granulated Zn were slightly higher than powdered Zn (Table 21 and
All intermediate variables showed a high correlation with yields. Among them, NG (r2=0.99), plant vigor rating (r2=0.97), radiation interception at Z65 (r2=0.90), initial biomass (r2=0.85), WG (r2=0.83) and height (r2=0.76) stand out.
Using spectral indexes on aerial photography, it was determined that both the OSAVI and TCARI indexes were correlated with yields, although the latter was more highly correlated with yields. This index was developed to predict chlorophyll content and N availability, and Zn metabolism is largely associated with N metabolism.
The results obtained suggest a very significant effect of Zn fertilization in a soil limited in this element. On the other hand, the granulated formulation performed better in the MAP treatments, but was equivalent in the Urea treatments. Additionally, at the lower dose, more response was verified in the MAP treatments, but no dose response was determined. It is likely that, when applied in-line, the efficiency is maximized, but greater risks of phytotoxicity are assumed. However, the greater spacing of the seedlings would determine a more linear behavior in urea, with a smaller initial increase but a greater response to dose.
Both substrates, MAP and Urea, were suitable for impregnation from an agronomic point of view, and did not present operational difficulties for their implementation.
A field experiment was carried out at Wheelwright, Santa Fe, Argentina, on a Hughes Series soil, typical Argiudol, (USDA-Soil Taxonomy V. 2006), use capacity: I; IP=100. The trial was planted on December 12th and was spaced at 0.525 m between rows. The chosen cultivar was DK7220 VT3P. Good productive conditions were ensured, keeping the crop free of weeds, pests and diseases. The design corresponded to randomized complete blocks with 4 replications and 5 treatments, as shown in Table 22. Impregnation treatments with B were evaluated over traditional sources such as MAP or urea. The soil analysis of the site is presented in Table 23.
In the V7 stage, the accumulated biomass was determined. In V8, NDVI was calculated using the Green Seeker sensor and nitrogen content was estimated using the Minolta Spad chlorophyll meter. In female flowering (R1), vigor was rated on a subjective scale (1: minimum-5 maximum) according to the general condition of the plots, and intercepted radiation was measured. At harvest, final plant height, % of broken and tipped plants, yield components: kernels·spikel−1, number of kernels·m−2, kernel weight and yield were determined. Harvesting was done manually, with stationary threshing of the samples. For the study of the results, analysis of variance, mean comparisons and multivariate analysis by the principal components method were performed.
In
A) B Powder
In Table 24 the morphological and physiological crop variables and yield components are presented, while in
B) Granulated B
In Table 25 the morphological and physiological crop variables and yield components are presented, while in
A) B Powder
Yields reached an average of 11,530.3 kg ha−1, which was very acceptable for the climatic year, given the scarcity of rainfall. The contribution of the nappe was the key factor, when the rains were discontinued and the crop could have entered a deficit. In addition, the adequate reserves with which the crop started its cycle and the low daily demand typical of a late planting made it possible to sustain the yield components. It is confirmed that, in the region, a corn planted in the first part of the “window” for late planting dates has little effect on its potential yield.
The differences obtained did not reach statistical significance (P=0.18; VQ=5.5%). The highest yields were obtained in the combination of MAP+Urea impregnated at maximum dose (T5). The yields of this treatment resembled those obtained with MAP or Urea impregnated with Granulated Ulexite, in a similar experiment carried out at the same site by the inventors. The response is still interesting for a microelement whose adoption so far is minor, compared to Zinc (Zn), the most relevant and widespread so far. Most of the experiments conducted with B so far have been carried out through foliar applications, and in crops such as sunflower, alfalfa or soybean. So the present combination represents a novel advance in research on this nutrient. Considering the mobility and the results obtained, it seems an acceptable strategy to impregnate MAP with Zn and Urea with B, using for impregnation the source selected on the basis of its agronomic performance in the field.
Response was anticipated in order of correlation by subjective rating of vigor (r2=0.94), cover and interception (r2=0.92), NG (r2=0.84), NDVI by Green Seeker (r2=0.78), Plant height (r2=0.73) and Cumulative dry matter at V8 (r2=0.64). The variables that contributed most to explaining yields were related to growth and NG, rather than other physiological or metabolic processes (Table 24).
The late seeding date does not seem to limit the response to fertilization. If the water environment is more comfortable in late seeding, even with greater availability of nutrients and resources in the soil, the response to the technology could be superior to that observed in the traditional September seeding.
Although the differences obtained did not reach statistical significance, the maximum response was similar to that obtained in the Granulated Ulexite treatments, although the mean difference was lower. The nutrient evaluated (B) was limiting for corn yields. The combination of MAP impregnated with Zn+Urea with B seems to be a suitable combination for the supply of both elements.
B) Granulated B
Yields reached an average of 11,786.8 kg ha−1, which was very good for the climatic year, given the scarcity of rainfall. The contribution of the nappe was the key factor, when the rains were discontinued and the crop could have entered a deficit. In addition, the adequate reserves with which the crop started its cycle and the low daily demand typical of a late planting made it possible to sustain the yield components. It is confirmed that in the region, a corn planted in the first part of the “window” for late planting dates has little effect on its potential yield.
Significant treatment effect was determined (P<0.001; VQ=2.0%). The impregnation treatments on MAP, regardless of the dose, and the maximum dose applied on Urea allowed obtaining the maximum yield (
The late seeding date does not seem to limit the response to fertilization. If the water environment is more comfortable in late seeding, even with greater availability of nutrients and resources in the soil, the response to the technology could be superior to that observed in the traditional September seeding. This raises the question of whether the lower yields sometimes observed in December crops are not limited by management and fertilization, rather than by the physiology and potential of the crop at this second date.
The results obtained allow us to conclude that the nutrient evaluated was a limiting factor in corn yields and that the technologies evaluated were an appropriate means of supplying it, with less dependence on doses when a phosphorus fertilizer was used as a means of supplying it to the soil.
During the 2017/18 season, a field experiment was conducted aimed to evaluate the impact of different fertilization strategies on soybean crop productivity. The treatments were applied top quality soybean. The experiment was planted at the EEA INTA Pergamino, on a Pergamino Series soil, typical Argiudol, mixed family, loam, thermal, Class I-2, IP=85. Planting was carried out on December 21st, with the DM 40R16 STS variety, in rows spaced 0.40 m apart. The experimental site registers a continuous agricultural rotation with a high level of intensification and crop rotation. The predecessor was corn. During the cycle, insecticides and fungicides were applied to prevent attacks by bollworms, bugs and diseases. The plots were kept completely free of weeds and pests.
The test design was a randomized complete block design with four replications and six treatments. Details of the treatments evaluated are described in Table 26. The soil analysis of the sites is presented in Table 27.
Emerged plants were counted for 15 days. In R4, NDVI was determined by means of the Green seeker sensor and the radiation interception. Likewise, the N content was also estimated using a Minolta Spad 502 chlorophyll meter, and vigor was rated according to the general condition of the plot, its uniformity and health. An evaluation of nodulation was carried out, considering number, weight, size and location of nodules. Harvesting was carried out with an experimental self-propelled harvester. Yield components, number of nodes, pods, NG and WG were determined on a harvest sample. The results were analyzed by partition of variance, mean comparisons and regression analysis.
In
In Table 28 presents parameters that characterize the nodulation, while in Table 29 presents the yield, its components and other variables determined during the crop cycle.
The 2017/18 season was low in rainfall (
Nodulation presented a good quality. The fertilized treatments clearly differed from the Control, replicating what happened in a similar experiment conducted by the inventors where Zinc (Zn) impregnations were evaluated. The most representative variables were number and size, which showed the highest correlation with yields (Table 29).
Differences in yields were statistically significant (P=0.05; VQ=7.99%). The best results were obtained by impregnation with granulated Ulexite. Both in this source and in the powder formulation, no differences between doses were recorded. The maximum response reached 652.4 kg ha−1 over the Control (
Evaluated through the coefficient of determination (r2), the variables that most explained yields were plant height (r2=0.92), NG (r2=0.89), NDVI determined by Green seeker (r2=0.76), No. nodes·plant−1 (r2=0.60) and No. pods·plant−1 (r2=0.60) (Table 29).
The crop, despite its stability and late seeding date, achieved a significant response to fertilization. The impregnation strategies allowed obtaining the maximum statistical performance, outperforming the control. Although tradition points to B as a paradigm of foliar-applied elements, the existence of alternatives with good performance has been demonstrated that broaden the range of options available to the user.
During the year 2018, two field experiments were conducted at EEA INTA Pergamino, on a soil Serie Pergamino, Class I-2, typical Argiudol, fine family, illitic, thermal (USDA-Soil Taxonomy V. 2006). The trial was planted on October 2nd and was spaced at 0.7 m between rows, achieving a final density of 80,000 plants·ha−1. The chosen cultivar was Dow Next 22.6 PW. Good productive conditions were ensured, keeping the crop free of weeds, pests and diseases. In the experiment, a randomized complete block design with 4 replications was used, whose treatments are detailed in Table 30. In addition, in Table 31, the soil data of the experiment are presented.
Impregnation treatments were evaluated with Ulexite, source of B. In Experiment 1 a granular physical form was evaluated (Table 30.a), and in experiment 2 the same source in powder form, impregnated on MAP or Urea (Table 30.b). The MAP treatments were applied in-line incorporated, while in the case of using Urea as a substrate, they were applied on the surface.
The dry mass accumulated in V6 was quantified. In V6 and V10, N content was estimated by a nondestructive dimensionless reading with the Minolta Spad 502 chlorophyll meter. In V9, NDVI was determined by means of the Green seeker sensor. At flowering, accumulated dry matter, number of photosynthetically active leaves, vigor, cover and plant height. Successive flights with a drone were carried out to determine the Normalized Difference Vegetation Index (NDVI), the Green Index not affected by ground reflectance (OSAVI) and the Normalized Difference Red Edge (NDRE).
At harvest, yield components, number of spikes·m−2 (NS), grains·spike−1 (GS), number of grains·m−2 (NG) and weight (WGx1000) of grains were determined. Harvesting was done manually, with stationary threshing of the samples. For the study of the results, analysis of variance and mean comparisons were performed.
The season was very favorable, although somewhat excessive in rainfall, which was concentrated in short periods of time (
In Tables 32 and 33, data from observations taken during the crop cycle are presented, while
In
The 2018/19 cropping season was characterized by the development of appropriate environmental conditions for growing corn, with abundant rainfall centered around the critical period and during grain filling. The site shows a strong limitation of P, determining statistical responses to its application. The abundance of rainfall makes the site less predisposed to B deficiencies. Nevertheless, favorable responses to its addition were verified.
A) Granulated B
Yields averaged 12556 kg ha−1. Significant differences were found between treatments (P=0.0001, VQ=4.7%). A considerable response to P and also in the case of B was determined, being even greater than that observed in a similar experiment with Zn (Table 32 and
The crop variables that showed the highest correlation with yield were NG (r2=0.98), plant vigor rating (r2=0.70), NDVI determined by Green seeker (r2=0.70), spike insertion height (r2=0.64), initial biomass (r2=0.68), plant height (r2=0.60) and N content estimated by Spad at V6 (r2=0.64).
B) B Powder
Yields averaged 12541 kg ha−1. Significant differences were found between treatments (P=0.003; VQ=6.7%). As with the granular sources (
The crop variables that showed the highest correlation with yield were NG (r2=0.98), plant vigor rating (r2=0.86), NS (r2=0.70), NDVI determined by Green seeker (r2=0.61), initial biomass (r2=0.88), N content estimated by Spad at V10 (r2=0.82), radiation interception at flowering (r2=0.78), spike insertion height (r2=0.68) and plant height (r2=0.65).
On average of both carriers, the response to B was higher in powdered Ulexite at the LOW DOSE, while it was higher in granulated B-Ulexite at the HIGH DOSE, suggesting higher solubility in the former than in the latter.
Using spectral indexes on aerial photography, it was determined that the NDRE index showed a higher correlation with yield than NDVI or OSAVI. It is very interesting the development of new crop indexes, which contribute to characterize and monitor the occurrence of deficiencies. This would allow identifying a possible deficiency during the cycle and, if detected in early stages of growth, correcting it through the application of sources such as urea impregnated with B in total coverage.
The results obtained suggest a positive effect of B fertilization in a soil limited in this element. On the other hand, the physical form of B-Ulexite powder showed a superior performance at LOW DOSAGE, while the granulated formulation showed a more outstanding performance at HIGH DOSAGE of B, possibly evidencing differences in solubility between sources. As a substrate, MAP or Urea performed well, with Urea being slightly superior especially at high doses of B, where in-line applications could be phytotoxic.
During the 2018/19 season, an experiment was conducted on top quality soybeans to evaluate the impact of different P and micronutrient fertilization technologies on soybean crop productivity. The experiment was planted at the EEA INTA Pergamino, on a Pergamino Series soil, typical Argiudol, mixed family, loam, thermal, Class I-2, IP=85. Planting was carried out on November 21st, with the DM 46R18 STS variety, in rows spaced 0.40 m apart. The experimental site registers a continuous agricultural rotation with a high level of intensification and crop rotation. The predecessor was corn. During the cycle, insecticides and fungicides were applied to prevent attacks by bollworms, bugs and diseases. The plots were kept completely free of weeds and pests. A base inoculation was performed to ensure nitrogen (N) supply.
The test design was a randomized complete block design with four replications and four treatments. Details of the treatments evaluated are described in Table 34. In addition, the soil analysis of the sites is presented in Table 35.
The biomass accumulated in R3 (kg ha−1) was quantified. In R4, the NDVI was determined by means of the Green seeker sensor, and the coverage was determined by processing with specific digital image software. Likewise, the N content was also estimated using a Minolta Spad 502 chlorophyll meter, and vigor was rated according to the general condition of the plot, its uniformity and health. Harvesting was carried out with an experimental self-propelled harvester. Yield components, number of nodes, pods, NG and WG were determined on a harvest sample. On four occasions a flight was performed with an Ebee Parrot aircraft equipped with a Sequoia_4.0_1280×960 (Green), Sequoia_4.0_1280×960 (Red), Sequoia_4.0_1280×960 (Red Edge), Sequoia_4.0_1280×960 (NIR) high resolution camera. The photographs obtained, with a pixel size of 14×14 cm, were processed and the OSAVI and NDRE indexes were calculated.
OSAVI (Optimized Soil Adjusted Vegetation Index) is a vegetation index corrected for soil reflectance. It provides additional information and represents an improvement over NDVI by showing greater sensitivity to cover variations in sparsely vegetated areas where the ground is visible through the canopy. It is also advisable to use it at the end of the cycle where vegetation cover is maximum, since it saturates at higher levels of leaf area with respect to NDVI.
NDRE (Normalized Difference Red Edge) is an index highly sensitive to the chlorophyll content of vegetation. The variation of this index allows inferring nutrient deficiencies that cause chlorosis in the tissues, such as nitrogen, sulfur and some microelements.
The results were analyzed by partition of variance, mean comparisons and regression analysis.
In
In Table 36 an evaluation of nodulation is presented, while in Table 37 the yield, its components and other variables determined during the crop cycle, for the different locations.
In
The 2018/19 season was favorable for the crop, with abundant rainfall, although concentrated in December-January, and significantly better than the previous season. Radiation, temperature and humidity conditions were determined that allowed the crop to express itself clearly. Productivity reached an average of 5009 kg ha−1 (Table 37), which is close to the potential achievable by the crop in the region.
Significant differences were found between treatments (P=0.10; VQ=5.5%). A significant response to B fertilization was observed, obtaining the maximum with its granulated version at the highest dose (T4). Although it did not differ statistically from the rest of the treatments that provided B, it was the one that managed to outperform T2 (SPS 100) and T1 (control without fertilization). As soluble B and this combination is the one with the highest nutrient supply (8 kg B ha−1), it is likely that these results are suggesting a response to micronutrient doses. The results are in line with those obtained in the 2017/18 season (
None of the treatments evaluated showed phytotoxicity on seeds or damage to emergence, being perfectly tolerated and presenting a rapid emergence and better initial coloration in the presence of B. The addition of P and P+B increased initial biomass (r2 vs. yield=0.56), NDVI by Green seeker (r2=0.48), radiation interception (r2=0.43), plant height (r2=0.34) and NG (r2=0.96). The level of the NDRE spectral index, related to the red edge, also improved.
The results obtained allow us to identify the granulated source at maximum dose as the one with the best yield expression and agronomic response.
During the year 2018, two field experiments were conducted at EEA INTA Pergamino, on a soil Serie Pergamino, Class I-2, typical Argiudol, fine family, illitic, thermal (USDA-Soil Taxonomy V. 2006). On June 20th, the SY 120 variety, an intermediate cycle cultivar with no vernalization requirements, was planted. In the experiment, a randomized complete block design with 4 replications was used. Despite the good health of the cultivar, fungicides and insecticides were applied at Zadoks 32 and Z41 phenological stages. The treatments evaluated are described in Table 38. In addition, the soil analysis of the site is presented in Table 39.
Impregnation treatments with B-Ulexite, in its granulated and powdered physical forms, were evaluated at two levels for each of them, respectively. In Experiment 1, impregnations were evaluated on MAP (0-23-0) (Table 38.a), and in Experiment 2 on Urea (46-0-0) (Table 38.b), in both cases incorporated into the soil at crop sowing.
A count of emerged plants was made 15 days after emergence, and at Z 31 the biomass accumulated by the crop was determined. In Z65, cover, NDVI by Green seeker, and vigor, green index by Spad and plant height were quantified. The harvesting was carried out mechanically, harvesting the entire plot.
In the vicinity of anthesis, a flight was conducted with an Ebee Parrot aircraft equipped with a Sequoia_4.0_1280×960 (Green), Sequoia_4.0_1280×960 (Red), Sequoia_4.0_1280×960 (Red Edge), Sequoia_4.0_1280×960 (NIR) high resolution camera. The photographs obtained, with a pixel size of 14×14 cm, were processed and the OSAVI and TCARI indexes were calculated.
OSAVI (Optimized Soil Adjusted Vegetation Index) is a vegetation index corrected for soil reflectance. It provides additional information and represents an improvement over NDVI by showing greater sensitivity to cover variations in sparsely vegetated areas where the ground is visible through the canopy. It is also advisable to use it at the end of the cycle where vegetation cover is maximum, since it saturates at higher levels of leaf area with respect to NDVI.
TCARI (Transformed Chlorophyll Absorption Ratio Index), is sensitive to the chlorophyll content of the vegetation, and therefore could express changes in nitrogen supply in an adjusted form. The variation of this index at the plot scale allows inferring nutritional N deficiencies, allowing re-fertilization decisions to be made. If the N supply is uniform, it could represent effects of other chlorophyll-related elements, such as sulfur (S).
Yield components—number (NG) and weight (WG) of grains—were evaluated on a harvest sample. The results were analyzed by variance partitioning and correlation analysis.
At sowing, the profile had a moderate level of storage. Even though the previous summer was very dry, the abundant rainfall in April allowed a reasonable level of recharge of the soil moisture profile. Between August 20th and October 10th, precipitation decreased sharply, depleting moisture reserves (
In Tables 41 and 42, data from observations taken during the crop cycle are presented, while
The yields, which averaged 4696.6 and 5572 kg ha−1, respectively. The upper limit to yield would have been set by water availability.
The site recorded a poor initial P content, which determined a consistent response to fertilization. Something similar occurred with respect to N. The level of Zn was also below the proposed critical limit of 1 mg kg−1 (0-20 cm). The presence of a positive response site enables the comparison of different sources, doses and substrates for impregnation.
A) Impregnations on MAP
Significant differences were found between treatments (P=0.0001, VQ=6.2%). The mean response to the nutrient was of lower magnitude than that observed in the Zn-treated experiments. Also on average, the powdered source showed superior performance to the granulated source. In both cases, the lower dose allowed the maximum yield to be achieved.
The variables with the highest correlation with yield were NG (r2=0.97), plant vigor rating (r2=0.91), radiation interception at Z65 (r2=0.88), PG (r2=0.76), initial biomass (r2=0.47) and plant height (r2=0.67) (Table 41).
B) Impregnations on Urea
As in the previous experiment, significant differences were found between treatments (P=0.0001, VQ=4.4%) (Table 42). The response to B in relative terms was similar to that obtained in the MAP impregnations (Tables 41 and 42). This is to be expected considering B as a mobile element in the soil profile.
Both sources of B, granular and solid, behaved on an equal plane, with no differences between doses (Table 42 and
The hierarchy of variables in terms of their ability to anticipate yields was similar to that observed in the MAP treatments. Those with the highest correlation with yields were NG (r2=0.99), plant vigor rating (r2=0.96), radiation interception at Z65 (r2=0.79) and final plant height (r2=0.76), WG (r2=0.66) and finally initial biomass (r2=0.42).
Using spectral indexes on aerial photography, it was determined that both the OSAVI and TCARI indexes were correlated with yields, although the latter was more highly correlated with yields and sensitivity.
The results obtained suggest a significant effect of B fertilization in a soil with moderate agricultural history, good management and medium fertility. The response, however, was lower than that obtained after Zn impregnation. This element would be more determinant for yield in winter cereals. On the other hand, both granular and powdered sources behaved similarly. However, in the impregnations on MAP the mean response was higher for the powdered source. This also allowed for better coverage and visualization, which would make it more easily adoptable. Additionally, the response was similar in MAP or Urea impregnations. The high mobility of B in soil would facilitate the free choice of substrate, probably allowing treatments in total coverage without incorporation, which have not been evaluated in the present experiment.
| Number | Date | Country | |
|---|---|---|---|
| 63162787 | Mar 2021 | US |
