Recent studies established the superiority of site-specific nutrient management (SSNM) over other crop fertilization options in terms of sustained high productivity and restoration of soil fertility. When it comes to conservation agriculture (CA), nutrient management strategies that are actually developed and validated for conventional agriculture are followed at present, as strategies specific for CA systems are not available. It is not clear whether the nutrient application rates, schedules and methods suitable for conventional crop establishment after repeated tillage, puddling etc. perform equally well under a modified soil environment. This is in fact a major knowledge gap that needs to be bridged-up through well-planned experiments. Logically, nutrient management under no-till systems with surface residue retention would not be the same as adopted for conventional systems. Hence, an IARI-CIMMYT-IPNI collaborative project was initiated to assess nutrient availability under differing crop establishment and residue retention scenarios and to develop SSNM strategies for optimizing productivity of rice-wheat and rice-maize systems.

Objectives

i) To study the effect of crop establishment methods on the changes in soil fertility status
ii) To evaluate different nutrient management options vis-à-vis SSNM with respect to soil nutrient mining and apparent balance sheets
iii) To assess the impact of soil manipulation owing to different crop establishment methods on the annual productivity and economic returns of rice-wheat and rice-maize systems

Technical Programme

In order to address the above objectives, field experiments on rice-wheat and rice-maize cropping systems will be conducted on cultivators’ fields under the aegis of Cereal Systems Initiative for South Asia (CSISA) Hubs at Punjab, Haryana, Eastern U.P. and Bihar. When selecting field locations in a village or block, emphasis will be laid on establishing the experiments within a relatively small geographical location that vary widely in soil texture, landscape, and other critical factors affecting the indigenous supply of N, P and K.The nutrient omission techniques will be used extensively for the assessment of nutrient dynamics across sites under differing crop establishment and residue retention scenarios.

Measurements proposed

1) Site characterization (pH, EC, organic C, soil texture)
2) Initial and post harvest soil analysis for available NPK.
3) Nutrient (Ca, Mg, and K) content of irrigation water
4) Approximate amount of irrigation water used
5) Yield and yield-attributes
6) Plant analysis for N, P and K, and total uptake by the crops
7) NDVI data at 15 to 120 days (at 15 days interval) after crop emergence (for Experiment 2 only).