Patent Application
20240365730
The present disclosure is in the field of Agriculture. This application relates to a hydroponic method for rapidly growing a vegetable crop. More particularly, this application relates to hydroculture, particularly to apparatuses, systems, and methods for the sterilization of growth trays and other materials used in hydroponics.
Hydroculture and its subset hydroponics have been a rapidly growing system for growing corps using mineral nutrient solutions in water as a solvent. It is typically done in a green house or similar structure to provide a controlled environment. It can be done anywhere in the country and at any time during the year.
However, there is still room for substantial improvement in the technology. These improvements include use of light, design of the flats that hold the plants, and other improvements to eliminate harmful pests, bacteria and fungi that can cause extensive damage in a hydroculture operation.
In the last two decades, lettuce and basil production have increasingly moved indoors from fields to Controlled-Environment Agriculture (CEA) facilities like greenhouses or warehouse-style vertical farms. A primary reason for this trend is that lettuce and basil plants are well-suited to the commercial hydroponic systems on the market today in terms of growth habit and with the exception that they are susceptible to certain plant pathogens. Vertical farms along with greenhouses taking advantage of sunlight using systems such as the Nutrient Film Technique (NFT) and Deep-Water Culture (DWC) systems provide space-efficient growing environments for skilled operators who strive to make a margin on these crops in premium markets. With growing systems from the likes of Green Automation, Prims, and American Hydroponics for NFT systems or Dry Hydroponics, Hydronov, or Viscon system for DWC, many hectares of production have been added in North America with this trend accelerating as weather changes in the West. Spinach on the other hand, although it's consumed in similar quantities in the US, is produced by very few CEA facilities. The main reason for this is that spinach is much more susceptible to root pathogens that other leafy greens.
Once an infection by root pathogens starts in a facility, it has the capacity to infect all portions of the growing facility including plumbing, trays, equipment, etc. and decimate crops rapidly. Infection by the oomycete pathogen Pythium is a common cause of “damping-off” in spinach and other crops, which is plant pathology nomenclature for having an early root infection just after germination that can stunt growth and even kill the plant. Even when infection is not fatal to plants, Pythium can severely reduce yields and affect shelf-life of harvested product.
Pythium is a genus of oomycete organisms with some strains being aggressive root pathogens of spinach, as well as other commonly grown hydroponic crops including cucumbers, lettuce, arugula, and cannabis. Pythium belongs to Kingdom Chromista, neither animal, plant, nor true fungus. Moreover, it has a unique life cycle. Pythium is ubiquitous and can be introduced into hydroponic systems by seeds, growing substrate, insect pests, employees, and even by the wind.
Spinach has relatively high susceptibility to pythium in the field, and especially in hydroponic systems which provide an ideal environment for pythium to proliferate if unchecked. It's been suggested that spinach's vulnerability to pythium in hydroponics could be partially due to Spinach producing an especially large amount of root exudates which may serve as a chemotaxic signal to swimming pythium zoospores.
There has been significant research on pythium in hydroponic production, including spinach. Many solutions have been tested and there are countless products on the market today that claim to reduce pythium infection. Some of these solutions include supersaturation of Nutrient Solution (NS) with nanobubbles or ozone, water filtration and various methods of water disinfection including ozone, oxidizing chemicals, and UV lights. In field production it is common to use systemic fungicides in irrigation water or as a coating for seeds. These pesticides are not labeled for hydroponic production. Other solutions that have been tested include quarantining crops to prevent backflow of pathogens, beneficial microbial inoculants, aeroponic production, and sonication/pasteurization of the NS to name a few.
The disclosed tubs, systems, and methods to sterilize trays more effectively are directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.
Consistent with the present disclosure, there is described a seed tray configured to contain and germinate plants. In some embodiments, the seed tray is configured to sit and float on an aqueous solution that is contained in a tub. The seed tray typically has a top surface and a bottom surface with a plurality of openings completely through the top surface and the bottom surface, wherein the plurality of openings are configured to hold soil and germinate seeds in the soil. In some embodiments, the plurality of opening comprising at least three regions: a top region having a top opening sufficient for sprouting plants to grow through the top surface and sidewalls having a tapered shape to a more narrow transition region; the transition region having sidewalls that further taper to a more narrow end region; and an end region having straight sidewalls with a bottom opening for plant roots to grow through the bottom surface and contact the aqueous solution that is contained in a tub.
In some embodiments, the described a seed tray is made of expanded polystyrene (EPS) and configured to sit and float on an aqueous solution that is contained in a tub. In some embodiments, the seed tray has a top surface and a bottom surface with 400 to 450 oval-shaped openings completely through the top surface and ending at a circular shaped opening at the bottom surface, wherein the oval-shaped openings are configured to hold soil and germinate seeds in the soil. As described, the openings may comprise at least three regions: a top region having a top, oval-shaped openings having as its longest axis a diameter of 18-20 mm and tapered sidewalls having a taper angle of 2 to 4 degrees relative to a vertical plane drawn through the center of the openings, wherein the top region has a concaved shape bottom leading into a transition region. The transition region typically has tapered sidewalls with a taper angle of 26 to 28 degrees relative to a vertical plane drawn through the center of the openings that lead to a more narrowed end region. The end region typically has straight sidewalls with a bottom opening having a round shape and a diameter of 8-10 mm that allow plant roots to extend down through the bottom surface and contact the aqueous solution that is contained in a tub.
Consistent with the present disclosure, there is described tub configured to hold an aqueous mixture of water and a nutrient solution for growing plants. In some embodiments, the tub comprises: a top portion having a rectangular shape and including a lip around the internal circumference that is configured to receive a seed tray; a bottom closed portion having a rectangular shape smaller in size than the top portion, the bottom closed portion comprising at least one attachment mechanism for removably attaching the tub to a frame, and an air diffuser configured to create a turbulent flow of the aqueous mixture located in the tub. In some embodiments, the sidewalls taper from the top portion to the bottom closed portion, wherein the tapered sidewalls are configured to allow the roots hanging from the seed tray to grow toward the center of the tub.
In some embodiments, there is disclosed a system for hydroponically growing plants, whereby the plants are grown in isolated batches, comprising a seed tray and a tub, as described herein. For example, the system comprises a seed tray configured to contain and germinate plants, wherein the seed tray has a top surface and a bottom surface with a plurality of openings completely through the top surface and the bottom surface. As previously indicated, the plurality of openings are configured to hold soil and germinate seeds in said soil, the plurality of opening comprising at least three regions: a top region having a top opening sufficient for sprouting plants to grow through the top surface and sidewalls having a tapered shape to a more narrow transition region; the transition region having sidewalls that further taper to a more narrow end region; and an end region having straight sidewalls with a bottom opening for plant roots to grow through the bottom surface and contact the aqueous solution that is contained in a tub.
The system further comprises a tub configured to hold an aqueous mixture of water and a nutrient solution for growing plants, the tub comprising: a top portion having a rectangular shape and including a lip around the internal circumference that is configured to receive a seed tray; a bottom closed portion having a rectangular shape smaller in size than the top portion, the bottom closed portion comprising at least one attachment mechanism for removably attaching the tub to a frame, and an air diffuser configured to create a turbulent flow of the aqueous mixture located in the tub; and sidewalls that taper from the top portion to the bottom closed portion, wherein the tapered sidewalls are configured to allow the roots hanging from the seed tray to grow toward the center of the tub.
Consistent with disclosed embodiments, there is also described a method of hydroponically growing plants. In an embodiment, the method comprises planting a plurality of seeds in growth media, where the growth media are contained in plurality of trays that are configured to float on top of a tub and to provide access for the crops to the water mixture when floating. As mentioned, the tub comprises a lip around the top circumference and containing a mixture of water and nutrient solution. The method further comprises germinating the seeds to produce trays with germinated seeds and transferring the trays with germinated seeds to the top of the tub. The trays are then floated on top of the tub until they are allowing the tray to drop closer to the tub as the water level in the tub decreases. As the water level decreasing from evaporation and as a result of being taken up by the growing plants, the tray moves down to sit on the lip of the tub such that a portion of the roots remained exposed to air and a portion of the roots in contact with the mixture of water and nutrient solution. The method comprises at least one aeration steps that causes a turbulent flow of the water mixture to impinge on the roots of the plant that are in contact with the mixture of water and nutrient solution.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate some disclosed embodiments and, together with the description, serve to explain the disclosed embodiments. The particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the present disclosure. The description taken with the drawings makes apparent to those skilled in the art how embodiments of the present disclosure may be practiced.
The following disclosure generally describes components, systems and methods to significantly reduce infection by pythium and other root pathogens in Deep Water Culture (DWC) spinach production. In one embodiment, there is described a container for hydroponically growing plants, comprising: a top tray that floats in water configured to sit on a bottom tub containing water and nutrients. The top tray described herein comprises a plurality of openings completely therethrough for holding soil and germinating seeds in the soil and water, the plurality of openings having a profile that allow the roots of the growing plant to extend into the bottom tub as the roots search for water and nutrients. In an embodiment, the tub is configured to hold a mixture of water and nutrient solution for the growing plants, the tub comprising a lip around the top circumference and at least one air diffuser for causing a turbulent flow of the water mixture that is contact with the roots of the growing plants.
The top tray and the tub are configured to allow the top tray to float on the water in the tub for a few days while the young roots of the germinating seeds need full immersion in water. As the plants and evaporation consumes water the floating tray drops into the tub until it seats on a ledge. Once seated on ledge the tray in now in a position that will allow the plants to be commercially harvested in a typical cutting system, that cuts the plants much like a hedge trimmer. As the water level continues to drop, the roots continue to grow in length in search of water and nutrients causing the upper layers of the roots to be exposed to air. The roots that are in contact with the water are exposed to a very aggressive flow of bubbles generated by the bubblers. Success has been achieved by maintaining a water level in the tub, but it is not necessary and does not provide the advantages of allowing the water level to drop and roots to be exposed to air.
In particular, the disclosed tubs, systems, and methods allow roots of growing plants to continue to grow into the water by taking advantage of a dropping water level, that leads to several advantages. These advantages include (a) keeping the bursting bubbles and turbulence closer to the root tips as they continue to grow; (b) introducing an air gap that allows mature roots to have maximum access to fresh air and oxygen and less exposure to pathogens while still being able to get nutrients and water from their tips; having less weight to move and reduced splashing at harvest since the water level drops; having less water to filter after the trays are harvested; and resulting in a drier substrate which reduces pest, plant, and human pathogen growth close to the stems of plants.
In some embodiments, the tubs are relatively small, typically less than 20 square feet, or even less than 15 square feet, and the water and nutrients in the tubs are completely isolated from other tubs and water handling systems to prevent cross contamination of pathogens. The tubs can easily be completely sterilized as often as each growth cycle if needed. The tubs are designed to be mechanically combined in a system that can be mechanized and efficiently operated at large scale such as a 10-acre greenhouse.
Consistent with disclosed embodiments, there is also described a method of hydroponically growing plants. In an embodiment, the method comprises planting a plurality of seeds in growth media, where the growth media are contained in plurality of trays that are configured to float on top of a tub and to provide access for the crops to the water mixture when floating. As mentioned, the tub comprises a lip around the top circumference and containing a mixture of water and nutrient solution. The method further comprises germinating the seeds to produce trays with germinated seeds and transferring the trays with germinated seeds to the top of the tub. The trays are then floated on top of the tub until they are allowing the tray to drop closer to the tub as the water level in the tub decreases. As the water level decreasing as a result of being taken up by the growing plants, the tray moves down to sit on the lip of the tub such that a portion of the roots remained exposed to air and a portion of the roots in contact with the mixture of water and nutrient solution. The method comprises at least one aeration steps that causes a turbulent flow of the water mixture to impinge on the roots of the plant that are in contact with the mixture of water and nutrient solution.
There is described a fully quarantined, meaning that each tray is sitting in an isolated tub of Nutrient Solution (NS) which is typically less than 20 square feet, such as 15 square feet in size and yet can be combined with other tubs in such a way that a large greenhouse (10 acres as an example) can be fully mechanized and commercially efficient. In one embodiment, there is described herein methods of growing spinach, other leafy greens, or vegetables (all to be called “plants” for the purposes of this document) in very small batches where the water source is isolated from other batches so that disease cannot spread to their roots from other plants.
The isolation prevents the movement of water between the tubs and mitigates the transfer of plant pathogens. It may offer some other plant-health advantages in addition to labor saving and food-safety advantages; and (2) it employs unusually large aerators and high airflow capacity to constantly cover plant roots in a rising cascade of bubbles that wash away exudates and prevent Pythium spore germination while rapidly agitating the plant roots.
In some embodiments, the disclosed tubs, systems, and methods to sterilize trays more effectively are directed to overcoming one or more of the problems set forth above and/or other problems of the prior art. In particular, the disclosed tubs, systems, and methods allow roots of growing plants to continue to grow into the water by taking advantage of a dropping water level, that leads to several advantages. In some embodiments, these advantages include (a) keeping the bursting bubbles and turbulence closer to the root tips as they continue to grow; (b) introducing an air gap that allows mature roots to have maximum access to fresh air and oxygen while still being able to get nutrients and water from their tips; having less weight to move and reduced splashing at harvest since the water level drops; having less water to filter after the trays are harvested; and resulting in a drier substrate which reduces pest, plant, and human pathogen growth close to the stems of plants.
This concept of reducing infection by Pythium and other root pathogens through vigorous bubbling of the roots was developed through understanding how pythium infection occurs on a microbiological level in wet conditions. It has been discovered that germinating spores of pythium species release swimming agents of infection that attack plant roots. These motile zoospores are attracted to root exudates of young plants. Spinach produces an unusually large quantity of these exudates, which is part of the reason it is especially vulnerable to infection. To address this problem, the present disclosure provides for intense bubbling in the disclosed system. This mechanism serves to wash away root exudates from the root surface while their constant movement prevents the motile pythium zoospores from attaching on root tips to germinate. By preventing infection by root pathogens, vigor and yield of hydroponically grown spinach is increased substantially allowing for significantly higher yields (kg/m2/year) than offered by other growing systems with improved consistency.
In one embodiment, the fully quarantined mobile tub spinach system described herein employs an unusually large aeration capacity. For example, in one embodiment of the present disclosure, a spinach system disclosed herein targets air flow of 25 L/min through an 8 inch air diffuser in a 20 gal reservoir. Various diffusers may be used with the understanding that they have a high capacity for air flow. In some embodiments, the disclosed method comprises pumping large amounts of dissolved oxygen in order to bubble a nutrient solution specific for the leafy greens to be grown.
In an embodiment, the amount of aeration used in the disclosed process is larger than 3 L/min per 20 gal, with the dissolved oxygen being impact directly on the roots of each growing plant. This is not possible in current systems that use large growing ponds. In some embodiments, it has been discovered that bubbling their NS in the amounts and at the locations (right at the root surface) described herein causes vigorous aeration and prevents infection by root pathogens. Therefore, the disclosed systems and methods have shown an increase in yield of the harvested plant. It has been shown that high-intensity bubbling in the disclosed moving tub system is effective at mitigating and preventing infection by pythium spp. and other root pathogens in hydroponically grown plants, such as spinach.
In some embodiments, it has been demonstrated that even in the presence of pythium propagules in the NS, spinach can be grown healthily with the disclosed Tub Spinach System providing vigorous aeration. In one embodiment, it was shown that it was possible to grow high-yielding, healthy crop in the same water for several cycles without discharging it while only replacing the water the plants use to keep the reservoirs full.
More generally, in some embodiments the fully-quarantine Mobile Tub System (MTS) and method of using the same according to the present disclosure starts with seeds that are sown in described seedling trays. Seeding depth, water content of the soilless mix, germination temperature/duration, and soil compaction are controlled such that: (a) seed coats are removed from emerging seedlings at over 95%; (b) homogeneous emergence of seedlings; (c) Roots protrude from the bottoms of trays before planting into tub system. This ensures root tips, the most vulnerable part of the juvenile seedlings, is immersed in the bubbling cascade immediately and the root tip does not spend time in water-logged soil where it can be quickly infected. The Inventors have found that the success of the system starts with seed trays.
In some embodiments, there is described a seed tray configured to contain and germinate plants. The seed tray described herein is configured to sit and float on an aqueous solution that is contained in a tub, wherein the seed tray has a top surface and a bottom surface with a plurality of openings completely through the top surface and the bottom surface.
In some embodiments, the seed trays have a rectangular shape that is 450-550 mm wide, such as 475-500 mm wide. In some embodiments, the seed trays are 700-800 mm long, such as 725-775 mm long. In some embodiments, the seed trays are 50-60 mm thick, such as 52-58 mm thick. In some embodiments, the seed trays have 400-450 openings, such as 410-430 openings, or even 415-420 opening, and can grow from 500-1200 plants, such as 600-800 plants.
In some embodiments, the plurality of openings 110 are configured to hold soil and germinate seeds in the soil. In some embodiments, each opening 110 has a volume ranging from 8-10 ml, such as 9 ml.
With reference to
The plurality of openings 110 further include a second region, which is a transition region having sidewalls that further taper to a more narrowed end region 122. In some embodiments, the sidewalls of the transition region have a taper angle of 26-28 degrees relative to a vertical plane drawn through the center of the openings.
The plurality of openings 110 further include a third region, which is an end region having straight sidewalls with a bottom opening for plant roots to grow through the bottom surface and contact the aqueous solution that is contained in a tub 124.
In some embodiments, the plurality of openings have an oval shape 118 on the top surface of the seed tray 100 and a round shape on the bottom surface 126. In some embodiments, the oval shape on the top surface 118 of seed tray 100 has as its longest axis a diameter of 18-20 mm, such as from 18.5-19.5 mm. In some embodiments, the round shape 126 on the bottom surface of seed tray 100 has a diameter of 8-10 mm.
In some embodiments, the top surface of seed trays 100 includes a border around the edge that is free of openings 105. In some embodiments, the border 105 has a size at least as wide as the longest axis of the oval shaped openings 118.
In some embodiments, the top surface of seed trays 100 includes a plurality of tabs 107 that are located on the border 105. The plurality of tabs 107 are configured to allow seed trays to be stacked on each other without the bottom surface of a top seed tray touching the top surface of a bottom seed tray stacked on top of it.
In some embodiments, there is described a seed tray configured to contain and germinate plants. In some embodiments, the seed tray comprises expanded polystyrene (EPS) and configured to sit and float on an aqueous solution that is contained in a tub.
In some embodiments, the seed tray has a top surface and a bottom surface with 400 to 450 oval-shaped openings completely through the top surface and ending at a circular shaped opening at the bottom surface. In some embodiments, the oval-shaped openings are configured to hold soil and germinate seeds in the soil, and comprise at least three regions: a top region, a transition region and a bottom region.
In some embodiments, the top region has top, oval-shaped openings having as its longest axis a diameter of 18-20 mm and tapered sidewalls having a taper angle of 2 to 4 degrees relative to a vertical plane drawn through the center of the openings, wherein the top region has a concaved shape bottom leading into a transition region.
In some embodiments, the transition region with tapered sidewalls having a taper angle of 26 to 28 degrees relative to a vertical plane drawn through the center of the openings that lead to a more narrowed end region.
In some embodiments, the end region has straight sidewalls with a bottom opening having a round shape and a diameter of 8-10 mm that allow plant roots to extend down through the bottom surface and contact the aqueous solution that is contained in a tub.
With reference to
In some embodiments, the tub includes a bottom closed portion 220 having a rectangular shape smaller in size than the top portion 210. The bottom closed portion 220 may comprise at least one attachment mechanism 230 for removably attaching the tub 200 to a frame. With reference to
In some embodiments, the air diffuser 240 creates an amount of aeration larger than 3 L/min per 20 gal. For example, in some embodiments, the air diffuser creates an amount of aeration of 25 L/min through an 8-inch air diffuser in a 20 gal reservoir.
In some embodiments, the sidewalls of the tub taper 225 from the top portion 210 to the bottom closed portion 220, wherein the tapered sidewalls 225 are configured to allow the roots hanging from the seed tray to grow toward the center of the tub and be impacted by the turbulent flow of the aqueous mixture located in the tub 200. In some embodiments, a majority of the roots hanging from the seed tray that grow toward the center of the tub are contacted with the amount of aeration.
In some embodiments, the lip around the internal circumference of the top portion 210 is configured to receive a seed tray may have a thickness from 50-60 mm. In some embodiments, the lip around the internal circumference of the top portion 210 includes a ledge 255 for resting the seed tray when the amount of aqueous mixture in the tub is not enough to float the seed tray.
With reference to
In contrast to the unfilled tub 620 shown in
With reference to
Consistent with the present disclosure, and with reference to
In some embodiments, the system is based on a process that typically starts with a cleaned and sanitized seed trays 1205 that are used in seeding. Step (A) In some embodiments, a seeding machine may be used to automate the process of planting seeds or seedlings in step (A). Non-limiting embodiments of the seed trays that can be used in the disclosed system are more fully shown and described in
As described herein, seeds are typically sown in trays, flats, or seedling beds filled with a growing medium, such as nutrient-rich soil. In some embodiments, seed trays for hydroponics can be made of durable and food-safe materials, such as plastic or Styrofoam. These materials are lightweight, easy to clean, and resistant to water and nutrient solutions. In some embodiments, the seed trays come in various sizes and shapes, and are typically rectangular or square.
In some embodiments, as shown in
The size and configuration of a particular tray will vary depending on the type of crop grown in the tray. For small plants naturally the cells will be closer together for larger plants they will be spaced further apart etc. The following particulars of sizes of trays are for a crop or cultivar of kale and is provided for illustrative purposes, other crops or cultivar would call for different configurations size but such changes would not depart from the concepts of the invention as those skilled in the art will appreciate once they understand to concepts of the invention and they would be able to adapt the tray to the particular crop without departing from the concepts of the invention. In the example of tray may be 25½ inches on its longitudinal axis 12½ on it short or latitudinal axis, 2 17/64 inch thick. Each of the oval cells is 13/16th of inch on the major axis of the top of the oval cell and the minor axis of the oval at the top of cell is 11/16th of an inch. Trays can be made of expanded polystyrene or any other similar light weight formable and buoyant material. In the prior art the floating tray or was simply a matrix of cells that covered the entire tray.
After seeding, the seeds are germinated in Step (B) by placing the seed trays 1210 into a germination chamber. In some embodiments, the seed trays are stacked inside the germination chamber with two or more trays stacked on top of each other. To allow the trays to be stacked without suppressing or damaging germinating plants, each tray includes at least one protrusion configured to provide a space between trays when stacked. In some embodiments, each tray includes at multiple protrusions located around the edges of the seed trays, such as at the corners of the trays.
The germination chamber used in step B, also known as a seed germination chamber or seedling incubator, is a specialized environment designed to facilitate the germination of seeds and the early growth of seedlings in hydroponic and traditional agriculture systems. It provides controlled conditions such as temperature, humidity, and sometimes light to optimize the germination process.
In some embodiments, the germination chamber maintains a consistent and controlled temperature, typically in the range of 70-85° F. (21-29° C.), which is optimal for seed germination. This temperature control helps speed up the germination process and ensures uniformity. The germination chamber may also maintain high humidity to prevent desiccation of the seeds. This is often achieved using misting systems or humidifiers.
In some embodiments, the germination chamber may be equipped with adjustable lighting systems to provide a consistent light source for seedlings. Additionally or alternatively, germination chambers may be placed in a separate growth area with appropriate lighting once germination occurs.
Adequate air circulation prevents the buildup of humidity and to ensure that the air around the seeds remains fresh and oxygen-rich. Small fans or ventilation systems may be included.
After the germination step (B) is complete, resulting in growth trays comprising sprouted seedlings, the trays 1205 are removed from the germination chamber 1215 and floated on top of the tubs 1220. Step (C) Consistent with some embodiments, the tubs have been cleaned and sanitized, and filled with a nutrient rich solution.
In some embodiments, the tubs 1220 with the sprouted seedlings trays 1215 may be placed on a table Step D. In some embodiments, the table contains one or more ports for receiving compressed air. In some embodiments, the one or more ports may be connected directly to the bottom of the tub to ensure a turbulent flow of are impinges the roots of the growing plant. In some embodiments, the one or more ports are connected to a hub that allows the compressed air to be distributed to multiple tubs simultaneously.
In some embodiments, as shown in step D, the table may be movable to allow it to be relocated, such as into or around a greenhouse. For example, in one embodiment the table may be moved, such as rolled, into a greenhouse where the plants will grow to maturity, typically in 11 to 16 days for spinach, such as 12 to 15 days, or 12 to 14 days. Step (D) In some embodiments, the tubs themselves may be configured to move independently of the other tubs.
To assist with seedling development and promote vegetative growth, lighting and environmental conditions may be adjusted, which typically includes more hours of light per day. In addition, the nutrient solution is monitored and may be adjusted to provide essential macro and micronutrients.
Once the plant has grown to maturity, it is ready for the harvesting 1225. Step (E). In some embodiments, harvesting is performed using a harvest machine. These machines are particularly valuable in large-scale commercial hydroponic operations where efficiency, speed, and precision are essential. In some embodiments, harvest machines are equipped with mechanisms to efficiently and gently handle the harvested crops. These mechanisms can include conveyor belts, robotic arms, or cutting blades, depending on the crop. One of the primary benefits of harvest machines is their ability to significantly increase the speed and efficiency of the harvesting process. They can harvest large quantities of crops in a short amount of time, reducing labor costs and increasing productivity. Another benefit of the disclosed system is the ability to move the entire table, with the mature plant contained in the disclosed tubs, through a harvest machine without having to remove the plant from the tub, or the tub from the table. This allows the harvesting step to be both efficient and economical.
After harvesting, the harvested plant is moved to cold storage 1230. The seed trays are then removed from the tub. Step F. Any remaining Nutrient Solution is removed from the tub. Step J. In some embodiments, the used Nutrient Solution may be filtered and re-used. For example, in some embodiments, the Nutrient Solution is filtered using basic mechanical filtering, such as with a 5 micron filter to eliminate spores. In some embodiments, the filtered Nutrient Solution may then be further cleaned such as with one or more methods including chemical sterilization, ozone treatment, or UV radiation.
In some embodiments, both the tubs and the seed trays are thoroughly cleaned and sterilized in preparation of the next growth cycle. For example, once the remaining NS is dumped to be filtered (Step J), the dirty tub 1235 is cleaned and sanitized, as are the tables and any other elements used during the growth cycle. Step K, resulting in cleaned and sanitized tubs 1240 to be filled with fresh NS and reused. Step L.
Similarly, after separating the trays from the tub after harvesting (Step F), any remaining stems and roots are cut from the growing substrate 1250 to leave the dirty trays 1245 which are washed and sanitized. In some embodiments, the washing step may include washing the trays with water (and/or desired solution) and cleaning the trays with a chemical cleaner. Step (G) In one embodiment, there is described a washing tray table filled with a chemical cleaner. The trays may be submerged in the chemical cleaner. Trays can be first washed with water (or other solution) prior to chemical cleaning (i.e. washing trays with chemical cleaners). After trays have been used at least once, dirt, debris, film, or other build up may accumulate on the tray. “On the tray,” in this context, means on any part of the tray, including but not limited to the top, bottom, sides, and on the inside and outside of the tray cells. Examples of build-up may include excess plant matter, growth media, algae growth, slime, residue, or other films or matter that may accumulate on the tray while used in the hydroponic system. The purpose of this washing is to remove any dirt, debris, film, or other build up on the trays. It may be done with water alone or with water and soap solutions, for example. Removing build-up enables the subsequent steps to sterilize the trays more effectively. The trays may be power washer, rinsed, soaked, submerged, sprayed, and/or scrubbed. In one embodiment, the trays are power washed using a high-power sprayer.
In some embodiments, after water washing, the trays are then washed using chemical cleaners. In this step, trays are submerged into, coated with, filled with, covered with, rinsed with, and/or surrounded by chemical cleaners. Chemical cleaners may be in a liquid, semiliquid, vaporized, or gas state. Chemical cleans can include, for example, soaps, alcohols, detergents, acids, or bases depending on the type of tray and matter to be removed from tray. Further examples may include hydrogen peroxides, bleaches (sodium hypochlorite), quaternary ammonium solutions, low foaming alkaline detergents, peracetic acid, or combinations thereof. The chemical cleaner may be diluted as necessary to ensure safety for people, plants, and trays. For example, chemical cleaners should not be so corrosive that they melt or damage the tray, making the tray unusable in a hydroponic system.
In some embodiments, low foaming alkaline detergent, such as Master MHW, is beneficial because it is formulated to emulsify dirt, oils, and organic materials such as biofilm, without producing excessive foam from the high agitation of automatic washers. A quaternary ammonium compound, such as Kleengrow, may also be used to wash trays either alone or alongside Master MHW, because it offers long lasting and effective broad-spectrum microbial control. Quaternary ammonium compounds' mode of action is membrane disruption by denaturing proteins, which makes the compounds ideal for removing biofilms for long-lasting microbial control. The positively charged chemistry attacks negatively charged pests found on trays. Contrary to other chemicals, the performance is not impaired by pH changes or exposure to light or temperatures used to maintain plant growth. Because quaternary ammonium compounds are very stable the use of Kleengrow leaves approximately a 30-day residual on all propagation trays. The use of Sanidate 5.0, a hydrogen peroxide and peracetic acid-based sanitizer, can also be used to wash trays and remove biofilm; however, the solution is much less stable compared to the use of a quaternary ammonium compound sanitizer, and the cleaning solutions degrades quickly.
In some embodiments, the seed trays are first rinsed with a chemical cleaner and then submerged into a bath of a chemical cleaner. In one example, rinsed with a quaternary ammonium sanitizer spray, and then submerged in a high concentration quaternary ammonium solution for under 1 minute. The trays may be submerged into a high concentration quaternary ammonium solution, or other chemical cleaner, less than 10 minutes. The amount of time will depend on the type of cleaner being used, the concentration of the cleaner, and the make-up of the tray. If the cleaner is particularly tray-friendly (meaning it will not damage the tray), then the tray may be left in the cleaner for longer periods of time (overnight for example).
In another embodiment, trays are cleaned with Master MHW, a low foaming alkaline detergent, and Kleengrow, a quaternary ammonium compound solution. Master MHW may be diluted at approximately 1 oz to approximately 3 oz per gallon of water. Kleengrow may be diluted at approximately 0.25 to approximately 0.50 oz per gallon of water, which correlates to approximately 150 to approximately 300 ppm quaternary ammonium compound. Preferably, tray washing uses solutions at approximately 200 ppm quaternary ammonium compound. A concentration of any higher than approximately 300 ppm would not be considered appropriate for treating the trays when the sanitizing solution is not rinsed off before planting. Anything higher than 300 ppm could leave behind excess residue that would negatively impact propagation. A concentration of less than approximately 150 would not be effective in breaking down bacterial biofilms.
The trays may be optionally rinsed off with water after chemical cleaning to ensure no harmful chemicals impact the growth systems and plants. Water may be filtered, sterilized, deuterated, distilled, and/or tap.
In some embodiments, the washed trays are thoroughly dried to near zero moisture 1255, prior to being reused for the next growth cycle. In some embodiments, the total moisture content may be less than about 5%, such as less than 4%, 3%, 2% or even less than 1%. Percent moisture may be determined using moisture content readers, spectrology, or through comparing the tray weight before and after washing. If weight is used to determine percent moisture, the trays may be measured individually or in groups. The trays may also be randomly sampled and tested.
The desired moisture content may also be determined and evaluated through physical inspection of the trays, such as whether the tray is dry to the touch or has no beads or pools of water. A tray that is dry to the touch or that has no beads or pools of water will have a percent moisture that is high enough to enable pathogen killing in the dielectric step but low enough to prevent tray damage.
The features and advantages of the tubs, methods of growing and systems used for growing disclosed herein are illustrated by the following example, which is not to be construed as limiting the scope of the present disclosure in any way.
In contrast to the mobile tub system illustrated in
As described herein, seeds are typically sown in trays, flats, or seedling beds filled with a growing medium, such as nutrient-rich soil. In some embodiments, seed trays for hydroponics can be made of durable and food-safe materials, such as plastic or Styrofoam. These materials are lightweight, easy to clean, and resistant to water and nutrient solutions. In some embodiments, the seed trays come in various sizes and shapes, and are typically rectangular or square.
After seeding, the seeds are germinated in Step (B) by placing the seed trays 1310 into a germination chamber, as previously described.
After the germination step (B) is complete, resulting in growth trays comprising sprouted seedlings, the trays 1315 are removed from the germination chamber and floated in ponds in which water and nutrients have been added 1320. The sprouted seedlings trays are floated in these ponds for 12-30 days, depending on the plant.
Once the plant has grown to maturity, it is ready for the harvesting 1325 and Step E. In some embodiments, harvesting is performed using a harvest machine. After harvesting 1230, the harvested plant is moved to cold storage 1235. After harvesting, any remaining stems and roots are cut from the growing substrate to leave the dirty trays 1245 which are washed, sanitized and dried to a desired moisture level 1250, prior to being reused for the next growth cycle.
In one embodiment, the tub has a connection hose that allows it to be connected to a source of air that feeds a bubbler that is fitted into the bottom of the tub. The bubbler is sized to fit the specially designed tub so that the bubbles emitted generate turbulence throughout the root system of the leafy greens. This turbulence is an important part of the disclosed process. Without being bound by theory, the turbulence caused by the bubbler is expected to prevent bacteria and disease from attaching to the root system. The turbulence caused by the bubbler is also expected to help in removing extrudates that are emitted from the roots and are the food source of bacteria and disease. For at least these reasons, the bubblers run for most of the growth process, and in some embodiments, constantly throughout the growth process.
In other embodiments, there is disclosed other growing methods that speed up the growth cycle of the plant to reduce the time that disease has to develop. For example, in an embodiment, supplemental lighting is used to speed up the growth process. Similarly, nutrient levels in the water sources are carefully balanced to optimize growth of the plant. In addition, temperatures of the water and air above the plants are controlled to achieve optimum growth characteristics.
After the growth period (which in some cases is as low as 14 days), the plants are harvested and the tubs and rafts are completely sanitized. Plants being grown in isolated batches, with constant bubbling, and complete sanitations after every growth cycle is described herein. In one embodiment, the disclosed tubs are arranged in special racks that allow two or more tubs to be connected. In one example, there could be 6 to 12 tubs in one rack. Reference is made to
The system described herein enables the movement of the racks throughout the life cycle of plant growth. In one embodiment, a plurality of tubs, such as in groups of 5-15, such as 6-12 or 5-12 sit on a platform that has a common air-line and drain. This platform is referred to as a “row”. Rows can be conveyed throughout the greenhouse on rails with pneumatic lifts. As shown in
In some embodiments, the disclosed invention comprising a moving tub system with distributed air is best appreciated by contrasting it to currently available commercial growing systems. For crops like leafy greens and herbs, it is ideal to have a centralized area for seedling/germination and for harvest/packaging and other inter-crop cycle activities—this is commonly referred to as the “headhouse”. That means that the plants themselves must move from the “headhouse” to the greenhouse where they'll grow to maturity before returning to the “headhouse” to be processed.
Once plants go into the greenhouse to grow, they need light, air, and water. The greenhouse structure provides for the air and light plants need. But there are several different strategies growers use to deliver water to their plants. These include (1) overhead irrigation by moving booms and/or fixed misters; (2) drip line/tube and/or emitters where water is delivered to plants through distributed lines at low flow rates through pressure compensated emitters. This is typically used for plants that will remain stationary for a long time, such as cucumbers, strawberries, and tomatoes as well as cannabis. This method requires significant labor in setting up drip tube/emitters and they frequently need to be flushed to avoid buildup/clogging; (3) Flood and drain systems, which is commonly used for longer cycle ornamental plants when implemented on the greenhouse floor; (4) NFT troughs, in which water is trickled through a gutter—intermittently or continuously through low flow tubes that run throughout the greenhouse; and (5) Deep water culture (DWC) ponds, in which large ponds filled with recirculating nutrient solution both convey the plants in floating trays and provide them nutrient water as they grow. These systems are difficult to clean and since water-borne root pathogens can move freely throughout the pond, they are non-ideal for sensitive root crops. In addition, ponds are costly to shut down if a breakout of infection occurs and complete cleaning is required.
The Fully-Quarantined Mobile Tub System described herein is different from the aforementioned systems in the fundamental way that it does not rely on the movement of water to irrigate the plants throughout the crop cycle. Instead of pumping fertilized nutrient solution throughout the greenhouse, there is described herein a system for conveying only low-pressure air throughout the greenhouse to deliver turbulence to the nutrient solution in the root zone. In some embodiments, the airlines in the disclosed system contain a constantly fast flowing stream of warm, dry air and because of this they are not a suitable environment for pathogen growth to flourish. This stands in stark contrast to the plumbing systems of other systems that are ambient temperature, wet, and contain all the nutrients necessary for the growth of algae and other microbes within the irrigation lines and adjacent to them.
In the inventive system, once the tubs are filled at the beginning of the crop cycle, no water will enter the tub and none will leave except by way of evaporation and biomass accumulation. After filling, the tub, attached to a rolling table with other self-contained tubs, is then sent into the greenhouse with all the water it needs to reach maturity. This fundamental difference makes it a much more robust method for mitigating spread of water-borne pathogens. It has also been discovered that the vigorous agitation accomplished with the large air-diffuser and high air-flow rate provide additional protection against root infection and promotes vigorous growth. The disclosed design and configuration thus achieves important benefits for growing leafy greens and herbs, especially for mechanical harvest.
The system described herein comprises tables that are significantly heavier than traditional horticulture techniques used to grow plotted plants. Traditional, “Dutch rolling tables” are versatile table and rail systems that are popular for growing potted plants. Unlike the described Fully-Quarantined Mobile Tub System, Dutch rolling tables used a watering system with drip or overhead booms as well as herbs in ebb and flow setups.
The system described herein that comprises tables that are significantly heavier than traditional horticulture techniques can efficiently move larger loads, such as the described tubs, on large tables from the processing areas down conveyors and into greenhouse bays using pneumatic cylinders to change to the perpendicular direction. In some embodiments, the described tables can be configured to feed the grown plants through a harvesting machine.
In some embodiments, tables used in the present disclosure may be fabricated from aluminum extrusions. In some embodiments, the frame has two aluminum pieces, such as 4×2″ pieces, that run the length of the table which are connected by cross members on both the top and bottom of the tray. This edge allows the table to roll on the conveyor the runs perpendicular to the greenhouse bays.
In some embodiments, on the underside of the table there may be 3 cross members that are both structural and are also the locations of the wheel mounts. In some embodiments, there may be two types of wheels on the bottom of the tables: guide wheels and drive wheels. The guide wheels grip the rail from the side to keep the table moving straight, and the drive wheels just roll on top of the rail. The middle cross member has two drive wheels while the cross members on each side have two guide wheels. Thus, in some embodiments, each table may have 6 wheels (2 guide, 4 drive) on its cross members. These wheels allow the table to roll on the rails within a greenhouse bay.
The top of the table may contain two (2) lighter gauge cross members (rungs) to support each tub. In some embodiments, these rungs have holes drilled to match those of the tubs so that the tub can be bolted to the table rungs with a watertight connection.
In some embodiments, the table contains an integrated air manifold pipe. For example, in some embodiments, there is an air manifold located between the wheel cross members and rungs. In some embodiments, this manifold may be constructed of ¾″ Schedule 80 PVC pipe, and this pipe runs the length of the table. For each tub, the ¾″ pipe is tapped and a hose barb is inserted. A small diameter (¼″ ID) hose connects the barb at each tub to the diffuser in the bottom of the tub.
In some embodiments, at one end of the table manifold, there is a removable cap that allows the manifold to be cleaned out/cleared. At the other end of the manifold, there is a connection to attach the manifold to the air mainline.
In some embodiments, the table contains an integrated air manifold pipe. In some the integrated air manifold pipe may be attached to an air main. For example, the air main line may be a 2″ Schedule 80 PVC pipe fed from a single blower. A 3.5 HP blower could be used to supply air to up to 25 tables at once so that a single 200 ft greenhouse bay may have 3 or more blowers to feed 60-70 tables (600-700 tubs). For each table in the bay, the air main is tapped and a longer ¾″ hose attaches the table to the air main via a threaded connection. The table with the air manifold was configured to deliver air to each tub's diffuser. In some embodiments, the manifold is located under each table with a connection to the air main to connect an entire table to the airline with one connection.
In some embodiments, the above-described table is used in conjunction with the tray and tub described herein, which allowed the tub that contained a large diffuser and configured a lip portion to hold tray in place.
In some embodiments, there is described a system in which the disclosed table is configured to be fed through a harvester without handling trays. More generally, the system includes one or more tables configured in a row, that are constructed from aluminum onto which the tubs are bolted. The air manifold is located underneath the table that feeds each tub's diffuser, which is screwed into the bottom of each tub. As stated, the air manifold can be connected to the air “main” that feeds each row of tables i.e. one (dis)connection each time a table is relocated. In the disclosed system, the tables have 2-4 sets of wheels underneath them so that they can roll on rails down the bay of a greenhouse. In some embodiments, at the ends of the bays, conveyor wheels grip the tables on their undersides to move them in the perpendicular direction. As a result of the design of the tub and the ending position of the trays within the tubs, at harvest the entire row is conveyed through the harvesting machine with the trays.
The features and advantages of the present invention are more fully shown by the following examples which are provided for purposes of illustration and are not to be construed as limiting the invention in any way.
The purpose of this example was to investigate whether growth rate and severity of pythium infection in spinach grown in deep water culture would be affected by the source water the plants were grown in. This was performed to determine the cause of different growth rates in different independent production reservoirs (ponds), which was attributed at least some of this variability in plant performance to differences in starting concentrations of pythium spores/other pathogenic or potentially symbiotic microbes in the reservoirs. It was believed that tubs filled from the best performing reservoirs and tap water (which was assumed to be free from spores) would be most productive (in terms of fresh weight produced), primarily because the plants would be less infected by pythium due to a lower starting concentration of spores.
Methodology: After germination is complete, trays are taken from the stacked carts and placed in their tubs. Each tray goes into its own tub. It's possible the trays are misted from above at this point as well. The tub profile allows the tray to float when the water level is above the upper level of the tub. As the water level drops, the tray will drop until it sits on the lip of the lip about 3″ below the maximum water level of the tub.
Cleaned and sanitized insulated tubs were filled with water according to the table below. Fresh fertilizer and acid were added to tub 5, which had been filled with fresh well water, so that it matched the pH and nutrient profile of our production reservoir water. A 9″ air diffuser was placed at the bottom of each tub to provide aeration and vigorous turbulence to the water in the tubs, which we have previously observed helps stave off infection. Air diffusers were fed by a ¾ HP compressor. The tubs were not actively cooled throughout the growth cycle. Four of the tubs were under HPS (high-pressure sodium) lamps, and the remaining two were grown under an LED light fixture. This light was supplemental on top of the natural light the plants received inside the greenhouse. After setting the tubs up, a tray of spinach that had been sown in a new EPS tray and allowed to germinate for 5 days was placed in each tub.
After planting into the tubs, grow out continued for 14 days. No additions of fertilizer or corrections to pH were made during this time. At maturity, the trays were harvested and weights were recorded. Photos of the canopy and the roots were taken and observations of plant health were made. The amount of aeration and turbulence in each tub was also noted as can be seen in the “Bubbler Status” column.
Several important observations were made as a result of this experiment. Even when vigorously bubbling compressed air in the tubs, the heat gain is manageable. This is important because the research we've designed our system around suggests that keeping root zone temperature below 20° C. is ideal for slowing the growth of pythium and increasing the time it needs to reproduce, helping to mitigate infection. The fact that the warmest tubs were only 21° C. at the conclusion of the experiment strongly suggests that this heat gain can be overcome with our existing water cooling capacity and we can keep our production reservoirs comfortably within our ideal range of 18-20° C.
As noted in the far-right column of the table, the diffuser in tub 2 became fouled throughout the course of the experiment (with algae/mineral deposits). This resulted in lower levels of aeration and turbulence in this tub as can be seen in the photos comparing tubs 2 and 3 below. Unsurprisingly, tub 2 is the tub where the pythium infection was observed to be most severe.
In addition, the air diffuser in tub 2 was also slightly off center. As a result, the morphology of the roots on different sides of the tub were quite different. This contrast supports the position that vigorous turbulence does indeed have an effect on the course of infection and a lack of vigorous bubbles/turbulence will lead to faster developing infection and more severe symptoms, even in a very local area, which manifests in shorter, less vigorous roots with more lateral branching.
While it does appear that source water has some effect on yield, it did not appear to be the most important factor in terms of plant health or overall productivity. Given that tub 5, which was filled with fresh water and fertilizer at the outset, was only middle of the pack in terms of yield in this trial, it certainly calls into question our assumptions that the fresh water tub had no pythium in it and/or that the performance in a tub would be related to our perceived starting concentration of spores in that water source. And given tub 2, which had water from our best performing reservoir, still became infected with low bubbles, it seems bubbling/turbulence is a more important variable.
This suggests that pythium may inevitably be present in our reservoirs at some concentration even when filled with fresh water. Despite our best efforts, pythium may be introduced to clean reservoirs through airborne spores, reusable EPS trays, or spread by fungus gnats flying between infected and healthy plants, just to name a few possible avenues. It's possible that even a very low initial concentration of spores inadvertently introduced can quickly multiply given the right circumstances in a reservoir to reach a critical threshold where it begins to do damage.
Additionally, the morphology of the roots in the freshwater tub more closely resembled the infected portion of tub 2 than any other tray. The roots in the best performing trays were consistently long and taproot-like. Less healthy roots were shorter and had more lateral branching, suggesting that root morphology can be used as an indicator of plant health.
Spinach grown over high bubbles can reach harvestable size in as little as 12 days and be nearly as productive (in grams fresh weight per day) as lettuce varieties.
At harvest, rows are conveyed to a mechanical harvester on rails that cuts the sellable leaves. After this point the remaining root and stem material are removed and the trays and tubs are prepared to be re-seeded. Trays are washed and then subject to more disinfection through use of chemicals sanitizers, microwave, desiccation. Remaining water in the tubs is emptied to go to filtration. Tubs are washed and disinfected before being refilled with fresh or filtered and reused NS.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
This application claims the benefit of priority to U.S. Provisional Application No. 63/500,427, filed May 5, 2023, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63500427 | May 2023 | US |
