Widespread deficiencies of sulfur, boron, and zinc in Indian semi-arid tropical soils: On-farm crop responses

On-farm studies were conducted during 2002 - 2004 to determine fertility status, including sulfur (S) and micronutrients, and crop response to fertilization on farmers' fields in the semi-arid zone of India. Nine hundred-twenty four soil samples taken from farmers' fields, spread in the three districts of Andhra Pradesh (India), were analyzed for soil chemical fertility parameters. Results showed that samples were low in organic carbon (C), total nitrogen (N), and low to moderate in extractable phosphorus (P), but adequate in available potassium (K). Analyses of soil samples for extractable S and micronutrients was most revealing and showed that 73 - 95% of the farmers' fields were deficient in S, 70 - 100% in boron (13), and 62 - 94% in zinc (Zn). On-farm trials conducted during three seasons (2002 - 2004) showed significant yield responses of maize, castor, groundnut, and mung bean to the applications of S, 13, and Zn. The yield responses were larger when S, Zn, and B were applied along with N and P. Applications of S, B and Zn also significantly increased the uptake of N, P, K, S, 13, and Zn in the crop biomass. Results show widespread deficiencies of S, 13, and Zn under dryland agricultural conditions; results also show that the nutrient deficiencies can be diagnosed by soil testing. It was concluded that the drylands in the semi-arid regions of India were not only thirsty (water shortage), but also hungry (nutrient deficiencies).