Studies on rice-based cropping systems.
In field experiments in Tamil Nadu rice was given 100 kg N + 22 kg P + 62 kg K/ha and grown in rotation with black gram [Vigna mungo], green gram [V. radiata], cowpeas, soyabeans or sesame and watergrass [Echinochloa pyramidalis] was given 90 kg N + 20 kg P + 37 kg K/ha and grown continuously. Grain yields of rice were 5.9, 5.8, 5.7, 5.5 and 5.6 t/ha when grown in rotation with V. mungo, V. radiata, cowpeas, soyabeans and sesame, resp. V. mungo, V. radiata, cowpeas, soyabeans and sesame gave seed yields of 0.7, 0.6, 0.4, 0.6 and 0.1 t, resp. E. pyramidalis produced 8.9 and 6.5 t forage/ha as 1st and 2nd crops, resp. Rice/V. mungo gave the highest net profit of $739/ha; E. pyramidalis/E. pyramidalis gave the lowest return of $140.