Residual Soil Fertility as Influenced by Diverse Rice-based Inter/Relay Cropping Systems

A field experimented was conducted to study different direct seeded rice-based inter/relay cropping systems and their effect on residual soil fertility at the University of Agriculture, Faisalabad for two consecutive years (1998-1999 & 1999-2000). The intercropping systems comprised rice alone, rice + maize, rice + sesbania, rice + mungbean, rice + ricebean, rice + cowpea and rice + pigeonpea while wheat, lentil and Egyptian clover were sown as relay crops on residual soil moisture just after the harvest of rice previously intercropped with forage legumes and non-legumes at zero tillage. The results revealed that among the three sets of rice based inter/relay cropping systems, the overall production level of total rice grain yield equivalent (TRGYE) was higher for rice-based Egyptian clover set followed by lentil oriented to the lowest for wheat oriented set. Production level of TRGYE was highest (10.95 t ha(-1)) for rice + maize - Egyptian clover inter/relay cropping system followed by rice + sesbania - Egyptian clover inter/relay cropping system (10.29 t ha(-1)) compared to lowest (6.48 t ha(-1)) for rice alone wheat cropping system. However, rest of the cropping systems gave TRGYE ranging between 7.18 to 10.17 t ha(-1). Regarding residual soil fertility, residual soil nitrogen was improved in all leguminous inter/relay cropping systems as compared to sole rice as well as non-legume inter/relay cropping systems. Similarly residual soil organic matter was also improved in all inter/relay cropping systems. However, Egyptian clover oriented inter/relay cropping systems increased more residual nitrogen and organic matter as compared to lentil oriented inter/relay cropping systems, while wheat oriented inter/relay cropping systems either decreased or did not add nitrogen and organic matter in the soil. Residual soil phosphorus and potassium were depleted in all inter/relay cropping systems compared with the initial soil analysis. Similarly, as compared to rice alone, all intercropping systems showed similar trend in both years. Since rice-based leguminous inter/relay cropping systems proved to be more remunerative and sustainable than wheat-oriented inter/relay cropping systems, so some leguminous crop like lentil and Egyptian clover should be added in rice-based cropping system in place of wheat to sustain the yield of component crops of the cropping system and maintain the fertility status of the soil for long duration. (C) 2011 Friends Science Publishers