Macronutrients (N, K, Ca, Mg, P, and S) and Micronutrients (Fe, B, Mn, Zn, Cu, Mo, Co, and Ni) are crucial to a plant's growth, development, disease resistance and various metabolic pathways such as photosynthesis. Plant available micronutrient insufficiencies are due to traditional farming methods that have exhausted the soil and to the micronutrient metals existing as water insoluble salts and complexes. Many of the water insoluble forms in the soil involve a metal cation and boron, sulfur, or phosphorous based anions. A deficiency in micronutrients results in poor plant growth and development and thus in diminished yields (Mortvedt 1990). Plant requirements for many of the micronutrients can be as low as parts/million in the plant tissue. It is known that increasing the plant available micronutrient metal ions by addition of complexed metal ions to the soil or to plant foliage or by freeing up micronutrients, bound in the soil as an insoluble salts or complexes, in a plant absorbable form can help to significantly alleviate soil deficiencies and assist in development, growth, and disease resistance of the plants.
Phosphorous is second to nitrogen as the most limiting macronutrient. In the case of phosphorus fertilizer, 40% of landscape soil is considered to contain inadequate levels of phosphorus for woody plant growth. Moreover, most of the phosphorus in the soil is largely inaccessible as it exists in a form that is not soluble in water and thus is not readily available to plants. In some cases, only 0.01% of the total soil phosphorus is in the form of a water soluble ion, the only form which can be absorbed by the plant. Adequate and accessible soil phosphorus is essential for optimal crop yields. Phosphorus enables a plant to store and transfer energy, promotes root, flower and fruit development, and allows early maturity. Phosphorus is also involved in many processes critical to plant development such as photosynthesis where plants utilize organic phosphorous compounds when converting sunlight to energy. Without enough phosphorus present in the soil, plants cannot grow sufficient root structure, which is key to the plant's ability to absorb water and nutrients from the soil. Moreover, woody plants, without sufficient root structure cannot maintain an equilibrium between roots and shoots, which is key to surviving drought, windy weather, and/or pests. Many of the nutrients required by plants are locked into salts and complexes that are water insoluble and therefore not plant available. To overcome these challenges, the agriculture industry has turned to chelates and anionic based polymers to form water soluble complexes with metal cations such as the micronutrients Ca, Mg, Mn, Fe, Cu, Co Ni, Zn, and Mo resulting in freeing up bound macronutrients such as phosphorous. The current delivery system technology of the chelates and polymer based products is water. Water is not only an excellent solubilizing/dispersing medium for chelates and [P(OA)]s, but can solvate a high load of water soluble metal salts. However, the use of water soluble metal salts can form insoluble complexes with chemistries that allow them to be available in the soil but unavailable to the plant.
Coating a fertilizer with water based products can result in severe clumping of the fertilizer granules during blending, or gelling of the [P(OA)]s due to high electrolyte content caused by the fertilizer granule dissolving into the water. Clumping has a negative impact on its effectiveness to complex with metal cations, and/or it requires a drying step for seed coatings to prevent pre-mature sprouting or the growth of mold and mildew, which ultimately destroys the seeds. The use of aqueous based systems also has a deleterious impact on the urease inhibitor NBPT. The agricultural industry needs a technology that is able to easily, safely, evenly, and economically coat fertilizer granules and seeds with non-aqueous, liquid formulations that contain [P(OA)]s that can form water soluble metal cation complexes and free up bound macronutrients such as phosphorous.