Effect of organic manures and inorganic fertilizers on productivity, nutrient uptake and soil fertility in rice (Oryza sativa)-wheat (Triticum aestivum) crop sequence in western Himalayas

A study was conducted in a western Himalayan soil for two years (1999–2001) in a randomized block design replicated thrice with five locally available sources of organic manures and three fertilizer levels in wheat (Triticum aestivum L. emend. Fiori and Paol) along with one absolute control, while rice (Oryza sativa L.) was grown with 100% of recommended NPK dose except control to study the residual effect of treatments of preceding wheat crop. Grain and straw yield as well as nutrient (NPK) uptake in both wheat and rice were significantly higher in plots receiving farm yard manure (FYM) @ 10 t ha⁻¹, followed by berseem (Trifolium alexandrinum L.) green manure ‘in-situ’ + FYM and mushroom spent compost + FYM, respectively during both the years due to higher residual fertility of respective organics. Productivity and NPK uptake both in wheat and rice also increased significantly with increase in fertilizer levels from 50 to 150% of recommended NPK dose. Integrated use of organics and inorganic fertilizers to wheat also resulted in consistent and significant improvement in grain yield of these crops during both the years with increase in fertilizer levels with significantly highest grain yield in wheat (4.89 t ha⁻¹) and rice (4.85 t ha⁻¹) in FYM supplied plots @ 10 t ha⁻¹ + 150% NPK dose. Application of organics and inorganic fertilizers also improved soil organic carbon, total N and available NPK content over initial status and over the years as studied at the end of first and second year of experimentation. The study revealed that integrated use of organic manures and inorganic fertilizers can play a key role in improving crop productivity, nutrient uptake and soil fertility in wheat-rice sequence besides substantial organic carbon and total N build up in wet temperate western Himalayan soils.