Building Available Phosphorus without soluble fertilizers

Nutrients should be available, but not soluble ~ William Albrecht

To develop regenerative farming systems, it is important that any soil amendments or fertilizers we add have a positive effect on both plant health and soil biology. It is not acceptable to have a positive effect for one, and a negative for the other.

Many soluble fertilizers are known to have pronounced negative effects on soil biology, particularly nitrogen and phosphorus.

One of the objectives of regenerative agronomy is to develop biological nutrient release to the point where limited or no additional fertilizers are needed to support the crop. A question is, how do you get to this point when your soils are very low in available nutrients to begin with?

In the case of phosphorus, a practice we have recommended for over a decade is to combine rock phosphate with manure before application. We generally observe approximately four times greater phosphorus response in soil and plant sap analysis as compared with an application of straight rock phosphate.

Soluble phosphorus applications are known to suppress mycorrhizal fungi colonization, phosphorus solubilizing bacteria, and phosphatase enzyme activity,  creating a continued dependence on soluble phosphorus applications. Biology has been replaced with spoon feeding chemistry.

New research just out reports that combinations of rock phosphate and manure increase phosphatase enzyme activity and organic matter1.

Increased plant availability, but not water solubility.

Which also means not leachable, and produces no water pollution. Perfect.

1. J. A. Omenda1* K. F. Ngetich1 M. N. Kiboi1 M. W. Mucheru-Muna2 D. N. Mugendi. Soil Organic Carbon and Acid Phosphatase Enzyme Activity Response to Phosphate Rock and Organic Inputs in Acidic Soils of Central Highlands of Kenya in Maize. International Journal of Plant & Soil Science 30, 1–13 (2019).