Replacing chemical fertilizers with organic alternatives: A comparison of performance of Phosphate Rich Organic Manure and Di Ammonium Phosphate on mustard

Abstract

Combining rock phosphate with natural organics facilitates the release of phosphorus (P) from the mineral in a form that
is easily available to plants. Replacing chemical fertilizers with such organic alternative is expected to improve soil
organic matter content and increase agricultural soil sustainability. Phosphorus release rate from rock phosphate in
presence of organic matter containing tobacco waste is observed to be better than or at par with that due to activity of
P solubilizing bacteria. A field experiment was conducted to study the production and nutrient cluster of Indian mustard
influenced by the organic source of P - Phosphate Rich Organic Manure (PROM) and the chemical fertilizer Diammonium
Phosphate (DAP). Phosphorous release rate from rock phosphate by bacterial activity is compared with that by organic
acids present in tobacco to see higher release of P by the later. Results indicated clear possibility for partially replacing
chemical phosphatic fertilizers with organic alternatives. Using rock phosphate composted with organic manure turns
out to be an excellent alternative for chemical phosphatic fertilizers. Higher yield parameters are obtained with PROM
and DAP in combination as P source for mustard crop. A combination of PROM as source of 66% of P requirement and
DAP as source of the rest of the P requirement gave best results in the efficacy studies, indicating possibilities in
replacement of chemical fertilizers with organic alternatives and hence reducing consumption of rock phosphate mineral
for production of chemical fertilizers.