Abstract

On-farm experiments (24) were conducted in two seasons to assess the influence of sulfur impurity in triple-super phosphate (TSP) on wheat. The experiments were laid-out in completely randomized block design in triplicate. Nutrients investigated include: Nitrogen (N), sulfur (S) and phosphorus (P). The TSP is tested to contain about 2 to 6% sulfur as impurity. However, wheat did not show response to sulfur from TSP. Though, it was not statistically significant, however, there were always yield increments by certain percent due to S-TSP in eight out of 10 sites with increasing trends of yield curves. Overall, the effects of such nutrients incidentally supplied from concentrated fertilizers like TSP should not be overlooked, as the benefits could be expressed in quality attributes of crops. Indeed, this is vital in varietal specific nutrient requirement studies. Overall, the benefits of such small-dose of nutrients could be many-folds to small-holders if integrated with organic resources, thereby encouraging organic agriculture. But, wheat showed response to sulfur from gypsum (in 67%) and N from urea (100%) of sites. As depicted, the sharply-rising yield curves with applied nitrogen elucidate that nitrogen was the most limiting nutrient followed by S. Always rising yield response curves also show strong positive synergies between the applied nutrients. 

Key words: Nitrogen, micro-dosing, precision-farming, sulfur impurity, triple-super phosphate (TSP), wheat yield response.