Nutrient Management Strategies for Yunnan

Qujing and Songmin counties provide good examples of the regional grain/tobacco farming system and were selected to systematically track nutrient variability, collect fertilizer use information, and produce field trial data in order to develop a rational fertilizer nutrient management system. Initial soil tests were taken in 2001, while village maps of nutrient variability were formed in 2002/03. In 2004, researchers continued to verify prescribed fertilizer rates and determine nutrient balances for two major cropping systems.

(i) Wheat-tobacco at Qujing: Though soil testing indicates both phosphorus (P) and potassium (K) contents were adequate, tobacco still required relatively high rates of P and K to achieve good yield and quality. The optimal fertilization rate of nitrogen (N), P, and K for tobacco was 135-190-300 kg N-P₂O₅-K₂O/ha using a 1:3 ratio of potassium chloride (KCl):potassium sulfate (K₂SO₄). The optimal rate for wheat was 150-150-225 kg/ha. Tobacco yield increased by 541 kg/ha (25%) compared to the - K treatment and by 787 kg/ha (40%) compared to the - P treatment. Balanced fertilization improved tobacco's intrinsic quality by reducing alkaloids and increasing total sugar and proteins. It also improved physical quality, bettering commercial quality. Similarly, wheat yield increased by 2,277 kg/ha (64%) compared to the - K treatment and by 2,415 kg/ha (71%) compared to the - P treatment.

(ii) Broadbean-rice at Songmin: The best treatments were achieved by applying 120-135-300 kg/ha for rice and 39-195-135 kg/ha for broad bean. Rice yield increased by 994 kg/ha (10%) compared to the - K treatment. Similarly, broad bean yield was increased by 782 kg/ha (18%) compared to the – K treatment and by 1,128 kg/ha (29%) compared to farmers' practice (135 kg P₂O₅/ha).

Computer software was developed to construct fertilizer recommendations and to serve as a knowledge base for technicians and policymakers. The technology is also being disseminated through field days and training courses for local leaders and farmers. Yunnan-NMS01