Effect of improved fertilization on yields of watermelon and broadbean in Tibet

Tibet's balanced fertilization [nitrogen (N), phosphorus (P), and potassium (K) BF] research was initiated only a few years ago with wheat and highland barley, but the program has produced valuable information needed to guide rational fertilizer use in the region. Similar technology is lacking for the region's cash crops, the major source of farmers’ income. Currently, local farmers and even ag technicians do not know how to properly fertilize cash crops such as watermelon and broadbean. The result has been rather low crop yields and poor income streams. The objective of this study was to determine optimal fertilizer rates for these crops and provide guidance regarding proper fertilization techniques to farmers.

As a result of very low reliance on fertilizer inputs in this region, a rather low "improved" fertilization rate of 94-38-38 kg N-P₂O₅-K₂O/ha was applied to both crops in 2005. The treatment produced 1.2 t/ha (+42%) more broadbean than common farmer practice (FP), which omits K, and 938 kg/ha more yield (+32%) than the P omission treatment. Net income under the improved regime was US$208/ha and US$192/ha higher than the - K and - P treatments, respectively. In watermelon, the yield produced under improved fertilization was 11.4 t/ha (+49%) above the - K treatment and 9.3 t/ha (+36%) above the - P treatment. Net income was US$5,680/ha higher than the - K treatment and US$4,610/ha higher than the - P treatment.

It is apparent that both broadbean and watermelon yields can be further improved as application rates are adjusted upward in coming years. Tibet-03