Potato Yield and Quality for a Citrate Soluble Phosphorus Fertilizer Product.

Phosphorus solubility in soil is a serious detriment for plants obtaining high percentages of the essential nutrient from fertilizers. Crystal Green is a relatively new fertilizer product which does not dissolve in water, but which is citrate soluble. The claimed mode of action is that the phosphorus remains in the fertilizer granule until roots come into close proximity, at which time the acidic root exudates begin solubilizing the phosphorus for plant uptake. Lab trials were conducted to verify the mode of action and were largely proven to be correct. The Crystal Green granules did not solubilize in water, but did solubilize in the presence of root exudates. In addition, the phosphorus remained 353% more soluble than monoammonium phosphate (MAP; 11-52-0), which had dissolved in water, precipitated, and was then exposed to root exudates under identical conditions. Additionally, three years of phosphorus fertilizer trials were conducted on potato (Solanum tuberosum L.). Crystal Green was compared to monoammonium phosphate (MAP; 11-52-0) at similar rates and balanced nitrogen levels. US No. 1 tuber yields increased by 3.1 Mg ha-1 with the primary factor for the increase being attributed to an increase in large size tubers. Overall yields were not impacted and there were no significant impacts on any other tuber quality factor, including internal and external defects and specific gravity.