Enhanced Efficiency Phosphorus Fertilizers

C. J. Seely, B. G. Hopkins, S. J. Kobza
Brigham Young University
Phosphorus (P) Introduction
  • Essential plant nutrient
  • Makes up about 1/4 of global fertilizer sales
  • Essential to feed the world’s population of ~8 billion
  • Use efficiency is very low
  • Remaining unused fertilizer in the soil has the potential to run off and contaminate surface water--leading to eutrophication
  • P Enhanced Efficiency Fertilizers (P EEF) have potential to supply plant needs by increasing uptake efficiency and minimizing runoff to surface water. 
    • Many EEF chemistries available (Fig. 1)
Fig. 1. Categories of P EEFs
Weeks, J.J., Jr. and G.M. Hettiarachchi. 2019. A Review of the Latest in Phosphorus Fertilizer Technology: Possibilities and Pragmatism. J. Environ. Qual., 48: 1300-1313. Available at: https://doi.org/10.2134/jeq2019.02.0067
Figs. 2-6. Examples of yield data for P EEFs
Fig. 2.
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Fig. 6. 
Kobza, S.J. and B.G. Hopkins. 2020. Enhanced efficiency phosphorus fertilizers. (Poster presentation.) In Proceedings of the Great Plains Soil Fertility Conference (GPSFC); 10-11 Mar. 2020; Denver, CO.  Monticello, IL: Great Soil Fertility Conference. 18:190-195. Available at: https://greatplainssoilfertility.org/files/FINAL2020GPSFCProceedings.pdf
Results and Discussion

Potato yield results for two sites with three P rates [0 (control), 75, and 100% of full recommended rate] applied with various blends of struvite (Crystal Green)/monoammonium phosphate (MAP) [eg. 100% 0/100 = 100% P rate with 0% struvite and 100% MAP or 75% 50/50 = 75% P rate with 50% struvite and 50% MAP]. Bars of each type sharing at least one of the same letter over the top of the bar are not statistically different from one another. (Fig. 2) 

Yield increase across 503 field sites for P treated with a maleic itaconic copolymer (AVAIL) relative to untreated fertilizer for soil test categories ranging from extremely low (1) to extremely high (14) [graph on left] and combined for all data and parsed for just sites with a high probability of response with low soil test P (STP), extreme acid/alkaline pH, and with low P rates [graph on right; bars with different letters indicate significant difference]. (Figs. 3-4.)
An organic acid based P EEF (Carbond P, CB-P), has increased solubility relative to monoammonium phosphate (MAP) and ammonium polyphosphate (APP) [graph on left; * = significance at P = 0.05 and ** = 0.01 with NS = not significant], resulting in increased P uptake and yields in several species [graph on right; all bars are highly significant]. (Figs. 5-6.)
Using EEF P fertilizers could solve economic and environmental problems relating to P fertilizer. Three examples of P EEF show positive increases in yield (average of 5% across all types and sites). Studies have had promising results, showing increased yield and P uptake efficiency when applied correctly. These products can be effective if costs are not exorbitant.