Relative Efficiency of Fertilization Practices to Improve Productivity and Phosphorus Balance in Rice-Wheat Cropping System

Abstract

To increase and sustain crop productivity by reducing agro-chemical inputs for economic and environmental reasons, a field study was conducted on an experimental farm of the Indian Agricultural Research Institute, New Delhi, India during 2009–2012. The efficiency of three nutrient regimes, i.e., organic fertilization (OF), integrated nutrient management (INM) practice, and recommended dose of chemical fertilizers (CF) was evaluated, relative to productivity and phosphorus balance in rice (Oryza sativa)-wheat (Triticum aestivum) cropping system, using a split plot design. The OF practice significantly increased the productivity of rice, whereas INM practice was more beneficial for wheat crop as far as the crop yield was concerned. The relative agronomic effectiveness (RAE) of OF practice in relation to CF was 39.62%, 16.98%, and 41.93%, respectively, in the first, second, and third year of rice crop cycle, whereas with INM practice, it was 61.76%, 23.68%, and 54.16%, respectively. The soil phosphorus (P) balance after three rice-wheat crop cycles was higher with CF than with INM and OF practices, indicating low P availability and higher P accumulation in soil receiving chemical fertilizers. Both OF and INM practices recorded higher P availability and no P accumulation in soil. We concluded that OF and INM practices could be employed as an alternative to CF practices for rice-wheat cropping system, but to reduce the P depletion from soil under these practices, a shift from conventional compost to phosphorus-enriched compost prepared by amending composting substrate with animal manure/rock phosphate and its bio-augmentation with P-mineralizing/solubilizing microorganisms is desired.

KEYWORDS:

• farm yard manure
• INM
• microbial inoculants
• phosphorus
• vermicompost