On-Farm Nutrient Balance Studies in the Dry Zone of Myanmar

Abstract

On-farm experiments to study soil fertility depletion—one of the biophysical factors limiting crop production—were conducted in six villages of central Myanmar during 1997 to 1999. Systematic socioeconomic surveys and analysis of socioeconomic and crop production factors aided the selection of farmers. Topsoil mineral nitrogen content at the start of the cropping season was high (10–25 mg N kg−1). Available phosphorous was around the threshold level for most crops, but exchangeable potassium was low. The predominant continuous cropping system of sole groundnut was on average positive for P (0.24 kg ha−1 y−1) and K (7.05 kg ha−1 y−1) and negative for N (−32.4 kg ha−1 y−1). A negative balance for N in the groundnut/pigeonpea (−58 kg ha−1 y−1) and mung bean/pigeonpea (−56 kg ha−1 y−1) intercropping systems was noted. The nutrient balances were positive in early sesame—late sesame (29 kg N ha−1 y−1, 8 kg P ha−1 y−1, 33 kg K ha−1 y−1) and early sesame/pigeonpea (8 kg N ha−1 y−1, 15 kg P h−1 y−1, 44 kg K ha−1 y−1) production systems while sole sorghum system resulted in positive balance for N (23.8 kg ha−1 y−1) and negative balance for K (−3.8 kg ha−1 y−1).