Abstract

                                Field experiments were conducted in low lands at Tamil Nadu Rice Research Institute, Aduthurai, Tamil Nadu for two years (1985-87) to study the change in soil nutrient status due to the rice based cropping systems in Cauvery delta zone. The inclusion of legume in the cropping systems resulted in higher soil nitrogen (+95.2 kg ha) and higher phosphorus uptake (13.4 per cent increase). As that of legume, cotton in the systems too resulted in higher soil available nitrogen ( +117.1 kg ha¹) which might be because of lesser uptake by cotton crop or higher addition of residues by cotton or both. The systems rice-rice-cotton andrice-cotton-cotton second flush possessing cotton as components crop found to leave more phosphorus into the soil because of mining/pumping of phosphorus from deeper soil zone with its deep root system. The systems involving pulses left higher potassium in the soil because of comparatively lesser uptake of potassium by these component crops.

Key words : Rice Cropping System, Cauvery Delta, Tamil Nadu.