1. Field of the Invention
The present invention relates to systems and methods for providing fertilizer to plants, and, more specifically, for providing fertilizer via low-flow irrigation systems.
2. Description of Related Art
It has been found during the use of low-flow systems, such as are typical with porous membranes, that most commercial fertilizers, even though water soluble, often fall out of solution, or “settle out.” When this happens, the amount of fertilizer available for plant use decreases in proceeding farther and farther from the fertilizer injection point.
In the case of systems using porous membranes, such as taught in commonly owned U.S. Pat. Nos. 7,198,431, 7,712,253, and 7,748,930, it may be that, as a plant pulls fertilizer from the porous membrane, the fertilizer concentration inside the membrane decreases, thereby decreasing the amount of fertilizer available to plants downstream.
Such a phenomenon is not an issue with high-flow, as the flowing fluid (water and fertilizer) carries the nutrients to the plant along with the water. However, with the systems such as the low-flow porous membrane system, this flow rate can be down to a level of extraction at the rates at which plants absorb water and fertilizer.
In testing the feeding system and method of the above-referenced '431 patent and '827 and '863 publications, a decrease in fertilizer concentration was noted. With tomato plants placed along a 100-ft membrane 1 in. in diameter, plant growth was seen to decrease at a distance of approximately 50 ft downstream of the fertilizer injection point, with continuing decrease further downstream. In recent tests, with the current pull rates of nutrition and water, it has been found that it takes approximately 30 days for water and/or nutrient to pass from the membrane feed inlet to the opposite end of the membrane. While this time is a function of environmental and biological factors, it serves as a demonstration of how substantially low the flow rates can be.
The present invention is directed to a system and method for increasing an efficacy of a fertigation system, wherein the fertigation system comprises a low-flow system including a tubing-based delivery apparatus.
The fertigation system of the present invention comprises a circulation pump positioned in-line in a closed-loop, low-flow tubing delivery array. The circulation pump acts to substantially equalize a concentration of a substance such as a nutrient in fluid within the tubing, thereby effectively preventing a concentration gradient from being established by upstream plants receiving preferential exposure to higher concentrations of the substance relative to downstream plants. The circulation pump should preferably be configured not to substantially raise a fluid pressure within the tubing.
A description of the preferred embodiments of the present invention will now be presented with reference to
A first embodiment of a fertigation system 10 is illustrated in
A proximal end 18 of the return tubing 16 is connected to an inlet 19 of a pump 20, such as, for example, a peristaltic-type pump, although this is not intended as a limitation on the invention. The pump 20 should preferably have the attribute of adding no substantial additional pressure to circulating fluid within the tubing lumen 21.
An outlet 22 of the pump 20 can connected adjacent the tubing inlet 12, thereby providing circulation and substantial fertilizer concentration equalization within the tubing lumen 21.
A second embodiment of a fertigation system 30 is illustrated in
A proximal end 38 of the return tubing 36 is connected to an inlet 39 of a pump 40, such as, for example, a peristaltic-type pump, although this is not intended as a limitation on the invention. The pump 40 should preferably have the attribute of adding no substantial additional pressure to circulating fluid within the tubing lumen 41.
A difference between this embodiment 30 and that 10 discussed above comprises that an outlet 42 of the pump 40 is connected with the tubing inlet 32 at an acute angle 43 (
In a third embodiment 50 (
A proximal end 58 of the return tubing 56 is connected to an inlet 59 of a pump 60, such as, for example, a peristaltic-type pump, although this is not intended as a limitation on the invention.
A difference between this embodiment 50 and those 10,30 discussed above comprises that an outlet 62 of the pump 60 is in fluid communication with tubing 63 that leads back to a storage tank 64. Here the pump 60 can deliver a higher-pressure feed, as the effect of any agitation would be delivered to the storage tank 64 and not the irrigation tubing 53,56. Thus the pressure within lumina 65,66 of the tubing 53,56 is maintained at a substantially constant value determined at least in part by an elevation head of the storage tank 64.
In a fourth embodiment 70 (
A distal end 78 of the return tubing 76 is connected to an inlet 79 of a pump 80, such as, for example, a peristaltic-type pump, although this is not intended as a limitation on the invention.
As with embodiment 50 discussed above, an outlet 82 of the pump 80 is in fluid communication with tubing 83 that leads back to a storage tank 84.
As discussed above, the pumps 20,40,60,80 can comprise any type of pump usable in the target setting, although a peristaltic pump is believed to represent the best mode at the time of filing.
In use, the pump 20,40,60,80 can run continuously or can be triggered intermittently depending upon the pump displacement and the length of the run. To ensure the fertilizer is kept in solution, and the concentration is substantially consistent, at least one full fluid rotation is believed preferable to be completed every several hours, the cycle time preferably designed to maintain a substantially constant concentration and keep the fertilizer in solution. Since the pump is run under low pressure and at a flow rate large enough to just cycle the fluid, the pump could be powered by a small solar panel when placed remotely.
Additional embodiments and elements can include the use of filtration in the system to help extend membrane lifespan.
Tubing membranes can be made as a unitary element having parallel sealed channels, or they can be separate tubing elements. If together, the tubing elements could be separated by perforations to enable easy separation.
The present invention claims priority to provisional patent application Ser. No. 61/329,867, filed Apr. 30, 2010.
Number | Date | Country | |
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61329867 | Apr 2010 | US |