US 5,632,799 AGranted

Dried particulate, hydrophilic gel as micronutrient delivery system

AssigneeTennessee Valley Authority

InventorsAllan D. Behel, Jr., John J. Mortvedt

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Abstract

The inclusion of certain organic hydroxy acids, most notably citric acid, in the iron sulfate formulations of at least one prior art hydrophilic polymer delivery system followed by drying and crushing the product into particles has been found to significantly improve the efficiency and ease of application of iron source fertilizer materials for iron-sensitive plants growing on iron-deficient soils for periods exceeding one year. The dried particles most preferably may be selectively metered into soil in or near the seed row as a band application at or prior to planting or spot placed in the root zone of growing plants in soil. The dry band absorbs soil moisture to provide a unique environment which restricts contact of soluble iron fertilizers with the soil and provides for complexation of iron in the formulation with organic hydroxy acids also contained in the formulation, thereby minimizing the extent of chemical reactions with the soil that reduce the availability of the applied iron to plant roots. A unique characteristic of the invention is the maintenance of iron in water soluble plant available form in soil outside the particles or band. Thus, root penetration and proliferation into and around the band also is greater than in the soil matrix, resulting in greater uptake efficiency of applied iron. The ease of precise application to soil, coupled with significantly enhanced crop response and utilization of iron contained in the product, offer considerable advantage over existing iron source fertilizer materials.

Claims11

Dependent claims

A process for providing substantial isolation of water-soluble iron source micronutrient juxtaposed plant growth media to thereby inhibit degradation of said micronutrient;

said micronutrient comprising iron sulfate and said process comprising the steps of:
(a) mixing predetermined amounts of aqueous media, iron sulfate, and at least one hydroxy acid selected from the group consisting of citric acid, lactic acid, malic acid, tartaric acid, and mixtures thereof to effect a solution containing by weight between about 1 percent to about 15 percent iron sulfate and between about 5 percent to about 20 percent of said at least one hydroxy acid;
(b) subsequently mixing, with at least a portion of the solution effected in step (a), supra, a predetermined amount of hydrophilic polymer sufficient to effect a resulting solution containing by weight from about 1 percent to about 15 percent of said polymer;
(c) providing sufficient agitation of the solution resulting in step (b), supra, to effect a phase change from a liquid to a gel and thereafter removing at least a portion of the resulting iron sulfate-hydroxy acid containing hydrogel to means for dehydration;
(d) maintaining the gel material introduced into the hydrating means in step (c), supra, for a time and at a temperature to remove therefrom sufficient moisture to effect a resulting friable, dried hydrogel;
(e) removing at least a portion of the resulting friable, dried hydrogel effected in step (d), supra, to comminuting and sizing means wherefrom is removed product material;
and
(f) subsequently applying at least a portion of said product material recovered in step (e), supra, to a situs comprising plant growth media whereby is provided effective isolation of said water-soluble iron source micronutrient from the deleterious effects of reaction with said plant growth media.

5 more elements

Dependencies are inferred from the claim text.