Nutrient Cycling in Agroecosystems

, Volume 51, Issue 3, pp 193–200

Long term effects of inorganic fertilizer inputs on crop productivity in a rice-wheat cropping system

  • R.L. Yadav
  • D.S. Yadav
  • R.M. Singh
  • A. Kumar
Article

DOI: 10.1023/A:1009744719420

Cite this article as:
Yadav, R., Yadav, D., Singh, R. et al. Nutrient Cycling in Agroecosystems (1998) 51: 193. doi:10.1023/A:1009744719420

Abstract

Three levels of N (40,80,120 kg N ha-1) and P (0,17.5,35 kg P ha-1), and 2 levels of K (0,33 kg K ha-1) were tested for 19 years in rice and wheat crops of a rice-wheat cropping system in a fixed layout of 3×2×2 factorial partially confounded design along with one control and 3 replications. From this trial, data of 7 treatments, i.e. 0-0-0, 40-35-33, 80-35-33, 120-35-33, 120-0-0, 120-35-0 and 120-0-33 kg ha-1 N-P-K respectively were compared for yield trends, changes in response functions, soil organic -C and available N,P,K status. Soil organic - C decreased in unfertilized plots by 62% (over initial value of 0.45%) but increased by 44, 40 and 36% in plots receiving 120-35-33, 120-35-0 and 80-35-33 kg ha-1 N-P-K respectively. Available N was also greatest in these same three treatments. Available soil P increased by about 5 fold in 15 years in treatments supplied with fertilizer P, but no significant change was detected in treatments without P addition. Yields of rice and wheat exhibited linear declining trend in all treatments. The highest rate of decline (89 kg ha-1 year-1 in rice and 175 kg ha-1 year-1 in wheat), however, was found when 120 kg ha-1 N was applied alone. The least rate of decline of 20 kg ha-1 year-1 in rice and 58 kg ha-1 year-1 in wheat was observed when 40-35-33 kg ha-1 N-P-K respectively was applied to both the crops. At currently recommended levels of NPK (120-35-33 kg ha-1), the rate of decline in yields was 25 kg ha-1 year-1 for rice and 62 kg ha-1 year-1 for wheat. Possible causes of these yield declines are discussed.

cropping systems inorganic fertilizer nitrogen organic carbon phosphorus potassium rice-wheat 

Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • R.L. Yadav
  • D.S. Yadav
  • R.M. Singh
  • A. Kumar

There are no affiliations available