Effect of long-term addition of lantana biomass on crop yields and N uptake in rice-wheat cropping in Himalayan acid Alfisols

To study the long-term effect of lantana (Lantana camara L.) addition and N application on crop yields and N uptake in rice-wheat cropping, an experim ent was conducted in the wet season (July-November) of 1988-95 with four le vels of lantana (0, 10, 20, and 30 t ha(-1) on fresh weight basis) and thre e levels of N at Palampur, India. Lantana biomass was added only to rice 10 to 15 days before transplanting and (or) puddling each year. The levels of N were 45, 67.5, and 90 kg ha(-1) to rice (i.e,, 50, 75, and 100% of recom mended dose). The order of these three N levels was reversed during wheat t o 120, 90, and 60 kg ha(-1) (i.e., 100, 75, and 50% of the recommended dose ). The yield and N uptake by both rice and wheat increased significantly wi th the additions of lantana and N. The average increase in yield over the c ontrol was about 11, 18, and 22% in rice and 11, 21, and 29% in wheat with the addition of 10, 20, and 30 t ha(-1) lantana, respectively. Similarly, t he increase in rice yield was about 7 and 14%, and in wheat, 10 and 12% wit h 75 and 100% of the recommended N over its 50% recommended dose. The corre lation studies revealed that NH4-N in rice and NO3-N in wheat were the most important N fractions contributing to N nutrition of rice and wheat, respe ctively, and that amino acid N was the next in importance in both the crops .