Controlled release agrochemical delivery units, their manufacture and use

Abstract

Disclosed is an agrochemical delivery unit comprising an impermeable cell which is a cell made of material that is impermeable to water; an agrochemical within the impermeable cell; and a wick comprising a hydrogel, said wick having a portion located within the impermeable cell and a portion located outside of the impermeable cell. Also disclosed is an agrochemical delivery unit comprising (a) a cell comprising two or more cell wall segments wherein at least one segment is impermeable to water and at least one segment is permeable to water; and (ii) an agrochemical within the cell. The invention provides methods of making and using the units.

What is claimed is: 
     
         1 . An agrochemical delivery unit comprising:
 a) an impermeable cell which is a cell made of material that is impermeable to water;   b) an agrochemical within the impermeable cell; and   c) a wick comprising a hydrogel, said wick having a portion located within the impermeable cell and a portion located outside of the impermeable cell.   
     
     
         2 . The unit of  claim 1 , wherein one or more portions of the wick are outside of the impermeable cell. 
     
     
         3 . The unit of  claim 1  or  2 , wherein one or more portions of the wick are in contact with the agrochemical. 
     
     
         4 . The unit of any one of  claims 1 - 3 , wherein the agrochemical is released from the cell only through the wick. 
     
     
         5 . The unit of any one of  claims 1 - 4 , comprising two or more separate impermeable cells. 
     
     
         6 . The unit of any one of  claims 1 - 5 , comprising two or more agrochemicals in a single impermeable cell. 
     
     
         7 . The unit of any one of  claims 5 - 6 , wherein each of the two or more separate impermeable cells, independently, contains a different agrochemical or a different combination of agrochemicals. 
     
     
         8 . The unit of any one of  claims 1 - 7 , arranged so as to permit controlled release of the agrochemical through the wick from inside the impermeable cell to media outside of the impermeable cell. 
     
     
         9 . The unit of any one of  claims 1 - 8 , wherein the agrochemical is dry prior to use, or prior to use of the unit the agrochemical is a paste containing water, a solution, a concentrated solution, a saturated solution, or a dispersion. 
     
     
         10 . The unit of any one of  claims 1 - 9 , wherein the same wick is in contact with the agrochemical in each different impermeable cell, such that a different portion of the wick is in contact with the agrochemical of each impermeable cell. 
     
     
         11 . The unit of any one of  claims 1 - 10 , having only one wick. 
     
     
         12 . The unit of any one of  claims 1 - 11 , having 2-20 wicks. 
     
     
         13 . The unit of any one of  claims 1 - 12 , wherein the wick comprises a fiber material. 
     
     
         14 . The unit of any one of  claims 1 - 12 , wherein the wick comprises a polyethelene, polypropylene, fiber mesh, cotton or other cellulose fiber, ceramic, or glass-based fiber, poly lactic acid. 
     
     
         15 . The unit of any one of  claims 1 - 14 , wherein the wick comprises a porous material possessing capillary structure. 
     
     
         16 . The unit of any one of  claims 1 - 15 , wherein the wick comprises a micro-porous material or macro-porous material. 
     
     
         17 . The unit of any one of  claims 1 - 16 , wherein the wick comprises fiber having a density of about 10-100 mg/meter. 
     
     
         18 . The unit of any one of  claims 1 - 17 , wherein the wick comprises about 1-500 fibers. 
     
     
         19 . The unit of any one of  claims 1 - 18 , wherein the hydrogel of the wick comprises a super absorbent polymer (SAP). 
     
     
         20 . The unit of  claim 19 , wherein the SAP comprises a natural super absorbent polymer (SAP), a poly-sugar SAP, a semi-synthetic SAP, a fully-synthetic SAP, or any combination thereof. 
     
     
         21 . The unit of any one of  claims 1 - 20 , wherein the hydrogel of the wick comprises a synthetic hydrogel, a natural carbohydrate hydrogel, or a pectin or protein hydrogel, or any combination thereof. 
     
     
         22 . The unit of any one of  claims 1 - 21 , wherein the hydrogel of the wick comprises acrylamide, an acrylic derivative, or any combination thereof. 
     
     
         23 . The unit of any one of  claims 1 - 22 , wherein only a first portion of the wick comprises the hydrogel, preferably the first portion is outside of the cell, while a second portion of the wick does not comprise the hydrogel. 
     
     
         24 . The unit of any one of  claims 1 - 23 , wherein the wick comprises a different hydrogel at different portions of the wick. 
     
     
         25 . The unit of any one of  claims 1 - 24 , wherein the wick is saturated with or coated by the hydrogel. 
     
     
         26 . The unit of any one of  claims 1 - 25 , wherein the material of the cell comprises: (a) one or more of polyethylene, polypropylene, or polyester, (b) comprises one or more of a polylactic acid, a polyhydroxyalkanoate, a polyhydroxybutyrate, or a polyhydroxyvalerate, (c) a thermoplastic starch, cellulose acetate, or other cellulose-based material, or (d) polycaprolactone, polyglycolide, polydioxanone, or any combinations or copolymers thereof. 
     
     
         27 . The unit of any one of  claims 1 - 26 , wherein the material of the cell comprises poly vinyl alcohol. 
     
     
         28 . The unit of any one of  claims 1 - 27 , wherein the material of the cell is a heat-sealable material, a biodegradable material, or a water soluble material. 
     
     
         29 . The unit of any one of  claims 1 - 28 , wherein the cell comprises sheets each having a thickness of 10-100 micrometers. 
     
     
         30 . The unit of any one of  claims 1 - 29 , wherein each sheet comprises one or more layers. 
     
     
         31 . The unit of any one of  claims 1 - 30 , wherein (a) at least about 20% by weight of the agrochemical is released from the unit within 40 days when the unit is immersed in water at room temperature, (b) about 20%-80% by weight of the agrochemical is released from the unit within 40 days when the unit is immersed in water at room temperature, (c) less than 20% by weight of the agrochemical is released from the unit within 40 days when the unit is immersed in water at room temperature, or (d) less than 50% by weight of the agrochemical is released from the unit within 60 days when the unit is immersed in water at room temperature. 
     
     
         32 . The unit of any one of  claims 1 - 31 , wherein the agrochemical is released over a period of 1 month to 3 months or wherein the agrochemical is released over a period of a growing season of a crop. 
     
     
         33 . The unit of any one of  claims 1 - 32 , further comprising a water permeable cell comprising an agrochemical, which permeable cell does not have a wick, but instead releases the agrochemical by permeation through one or more cell walls, or further comprising an agrochemical layer outside of the unit which is capable of dissolving in the presence of water. 
     
     
         34 . The unit of any one of  claims 1 - 33 , comprising multiple impermeable cells, arranged such that the agrochemical from a cell is released at a different time period, and/or at a different rate than the release of agrochemical from another impermeable cell of the unit. 
     
     
         35 . The unit of  claim 34 , arranged so as to release a different agrochemical at a different time period during a growing season. 
     
     
         36 . The unit of any one of  claims 1 - 35 , wherein: (a) the cell has a capacity of about 1-20 g of the agrochemical, (b) the volume of the cell is about 0.5-20 cm 3 , (c) the dry weight of the unit is about 0.1 g to 20 g, (d) the unit is in the shape of a cylinder, sphere, polyhedron, cube, or disc, and/or (e) the unit is in the shape having a cross section of a triangle, rectangle, circle, or square. 
     
     
         37 . The unit of any one of  claims 1 - 36 , wherein the agrochemical comprises fertilizer comprising nitrogen, potassium, phosphate, microelements or any of a combination thereof, preferably the microelements are selected from copper and zinc. 
     
     
         38 . The unit of any one of  claims 1 - 37 , wherein the agrochemical comprises at least one of a fertilizer, pesticide, hormone, drug, chemical growth agents, enzyme, growth promoter, or microelement. 
     
     
         39 . The unit of any one of  claims 1 - 38 , further comprising a hydrogel partially or completely surrounding the unit, which hydrogel can optionally contain a further agrochemical. 
     
     
         40 . The unit of any one of  claims 1 - 38 , further comprising a root development zone partially or completely surrounding the unit, which root development zone can optionally contain a further agrochemical. 
     
     
         41 . The unit of  claim 39  or  40 , wherein the gel or root development zone partially surrounds the unit and partially or completely surrounds the wick. 
     
     
         42 . The unit of any one of  claims 39 - 41 , wherein the root development zone comprises a hydrogel, aerogel, or organogel. 
     
     
         43 . The unit of any one of  claims 1 - 42 , wherein each parameter of the wick can be adjusted to accomplish a desired release profile. 
     
     
         44 . The unit of  claim 43 , wherein the parameter of the wick is length, width, material, density, and/or number of the wick. 
     
     
         45 . The unit of  claim 43  or  44 , wherein the release profile of the one or more agrochemicals is adjusted only by the parameter of the wick. 
     
     
         46 . The unit of any one of  claims 43 - 45 , wherein the release profile of the one or more agrochemicals is not affected by the amount of the one or more agrochemical inside the cell. 
     
     
         47 . An agrochemical delivery unit comprising:
 a) a cell comprising two or more cell wall segments wherein at least one segment is impermeable to water and at least one segment is permeable to water; and   b) an agrochemical within the cell.   
     
     
         48 . The unit of  claim 47 , wherein the agrochemical is released from the cell only through the permeable segment of the cell. 
     
     
         49 . The unit of  claim 47  or  48 , wherein the unit comprises two or more cells and/or the unit comprises two or more agrochemicals. 
     
     
         50 . The unit of any one of  claims 47 - 49 , wherein the unit is arranged so as to permit controlled release of the agrochemical through the at least one permeable segment of the cell from inside the cell to media outside of the cell. 
     
     
         51 . The unit of any one of  claims 47 - 50 , wherein the agrochemical is dry prior to use, or prior to use of the unit the agrochemical is a paste containing water, a solution, a concentrated solution, a saturated solution, or a dispersion. 
     
     
         52 . The unit of any one of  claims 47 - 51 , wherein the cell comprises one permeable segment. 
     
     
         53 . The unit of any one of  claims 47 - 52 , wherein the permeable segment of the cell comprises micro-porous or macro-porous material. 
     
     
         54 . The unit of any one of  claims 47 - 53 , wherein the permeable segment comprises hydrogel. 
     
     
         55 . The unit of  claim 54 , wherein the hydrogel comprises a super absorbent polymer (SAP). 
     
     
         56 . The unit of  claim 55 , wherein the SAP comprises:
 a. a natural super absorbent polymer (SAP), a poly-sugar SAP, a semi-synthetic SAP, a fully synthetic SAP, or any combination thereof,   b. a synthetic hydrogel, a natural carbohydrate hydrogel, or a pectin or protein hydrogel, or any combination thereof, and/or   c. acrylamide, an acrylic derivative, or any combination thereof.   
     
     
         57 . The unit of any one of  claims 54 - 56 , wherein:
 a) the natural carbohydrate hydrogel comprises agar, cellulose, chitosan, starch, hyaluronic acid, a dextrine, a natural gum, a sulfated polysaccharide, or any combination thereof, and/or   b) the pectin or protein hydrogel comprises gelatin, a gelatin derivative, collagen, a collagen derivative, or any combination thereof.   
     
     
         58 . The unit of any one of  claims 47 - 57 , wherein the impermeable segment of the cell comprises:
 a) one or more of polyethylene, polypropylene, or polyester,   b) one or more of a polylactic acid, a polyhydroxyalkanoate, a polyhydroxybutyrate, or a polyhydroxyvalerate,   c) a thermoplastic starch, cellulose acetate, or other cellulose-based material, and/or   d) polycaprolactone, polyglycolide, polydioxanone, or any combinations or copolymers thereof.   
     
     
         59 . The unit of any one of  claims 47 - 58 , wherein:
 a) the agrochemical is released from the unit within 40 days when the unit is immersed in water at room temperature,   b) the agrochemical is released from the unit within 40 days when the unit is immersed in water at room temperature,   c) less than 20% by weight of the agrochemical is released from the unit within 40 days when the unit is immersed in water at room temperature,   d) less than 50% by weight of the agrochemical is released from the unit within 60 days when the unit is immersed in water at room temperature,   e) the agrochemical is released over a period of I month to 8 months, or   f) the agrochemical is released over a period a growing season of a crop.   
     
     
         60 . The unit of any one of  claims 47 - 59 , wherein the unit comprises multiple cells, arranged such that the agrochemical from a cell is released at a different time period, and/or at a different rate than the release of agrochemical from another cell of the unit. 
     
     
         61 . The unit of any one of  claims 47 - 60 , wherein each parameter of the at least one permeable segment can be adjusted to accomplish a desired release profile. 
     
     
         62 . The unit of  claim 61 , wherein the parameter of the at least one permeable segment is the dimension, material, number, or percentage of the permeable segment. 
     
     
         63 . The unit of  claim 61  or  62 , wherein the release profile of the one or more agrochemicals is adjusted only by the parameter of the permeable segment. 
     
     
         64 . The unit of any one of  claims 61 - 63 , wherein the release profile of the one or more agrochemicals is not affected by the amount of the one or more agrochemical inside the cell. 
     
     
         65 . The unit of any one of  claims 47 - 64 , wherein:
 a) the volume of the cell is about 0.5-20 cm 3 ,   b) cell comprises 1-20 g of the one agrochemical,   c) the dry weight of the unit is about 0.1 g to 20 g,   d) the unit has a capacity of about 1-10 g of the agrochemical, and/or   e) the unit is in the shape of a cylinder, sphere, polyhedron, cube, or disc and/or the unit is in the shape having a cross section of a triangle, rectangle, circle, or square.   
     
     
         66 . The unit of any one of  claims 47 - 65 , wherein: (a) the agrochemical comprises at least one of a fertilizer, pesticide, hormone, drug, chemical growth agents, enzyme, growth promoter, biostimulant or microelement, and/or (b) the unit further comprises gel partially or completely surrounding the unit, wherein the gel is preferably formulated to contain one or more agrochemicals which are the same or different than the agrochemicals inside the cell of the unit. 
     
     
         67 . An agrochemical delivery method comprising distributing a multitude of agrochemical delivery units of any one of  claims 1 - 66  to plant growth medium. 
     
     
         68 . The method of  claim 67 , wherein the units are added to the plant growth medium at one or more depths below the medium surface. 
     
     
         69 . The method of  claim 67  or  68 , wherein the units are added at a depth of 1-50 cm. 
     
     
         70 . The method of any one of  claims 67 - 69 , wherein units are added to the growth medium in a concentration of about 1-50, 5-50, or 10-30 units per square meter. 
     
     
         71 . A process for making the agrochemical delivery unit of any one of  claims 1 - 46 , comprising forming an impermeable cell comprising the agrochemical and the wick. 
     
     
         72 . A process of making an agrochemical delivery unit comprising: creating a cell by encapsulating an agrochemical into a non-permeable polymeric cell equipped with a wick positioned party within and partly outside the cell such that the agrochemical is released through the wick in a controlled manner after it is in contact with water. 
     
     
         73 . The process of  claim 71  or  72 , comprising encapsulation using an extruder that attaches a polymeric layer surrounding the agrochemical. 
     
     
         74 . The process of  claim 71  or  72 , comprising filling the agrochemical into a polymeric cell and sealing the cell together with a wick. 
     
     
         75 . The process of  claim 71  or  72 , wherein a hydrogel is polymerized around the cell. 
     
     
         76 . The process of  claim 71  or  72 , comprising encapsulating a first polymerization step and a second polymerization step. 
     
     
         77 . A process of making an agrochemical delivery unit comprising: (i) creating a cell comprising two or more cell wall segments wherein at least one segment is impermeable to water and at least one segment is permeable to water and (ii) encapsulating at least one agrochemical into the cell such that the at least one agrochemical is released through the at least one permeable segment of the cell in a controlled manner after it is in contact with water.