Nutrient Management Strategies for Yunnan

Foodgrain production systems including rice, wheat, and broadbean continue to be the prominent staples in Yunnan, while tobacco production plays an important role in income generation for farmers and local governments. Songmin and Qujing counties were two representative grain and tobacco farming regions selected to track nutrient variability, collect fertilizer use information, and gather field trial data in order to develop rational fertilizer nutrient management systems. Soil deficiencies were determined by soil testing at project initiation and village maps of nutrient variability were formed in 2002/04. In 2005, the objective was to further verify prescribed fertilizer rates and determine nutrient balances for two major cropping systems.

In Qujing, treatments omitting nitrogen (N), phosphorus (P), and potassium (K) were compared to a balanced (BF) application of 135-190-240 kg N-P₂O₅-K₂O/ha for tobacco. The BF treatment produced 1,060 kg/ha (+62%), 980 kg/ha (+55%), and 970 kg/ha (+54%) more yield...and US$1,080/ha, US$131/ha, and US$529/ha more income than the - N, - P and - K treatments, respectively. Fertilizer use efficiency was also significantly improved under the BF regime. In wheat, BF of 150-150-150 kg/ha produced 2,460 kg/ha (+76%), 2,370 kg/ha (+72%), and 1,370 kg/ha (+32%) more grain than the - N, - P, and - K treatments, respectively. The best treatments at Songming were 120-135-240 kg/ha for rice and 60-195-135 kg/ha for broadbean. Rice yields were 3,010 kg/ha (+32%) and 3,190 kg/ha (+34%) higher than those produced without P and K, respectively. Similarly, broadbean yields were 1,660 kg/ha (+60%) and 1,920 kg/ha (+76%) higher than yields produced without P and K.

Evidence suggests that severe yield limitations found with site-specific nutrient recommendations can be addressed. Computer software was developed to construct fertilizer recommendations and to serve as a knowledge database for technicians and policymakers. These technologies continue to be extended through field days and training courses designed for both local leaders and farmers. Yunnan-NMS01