Nutrient Management Strategies for Yunnan

Initiated in 2000, this project’s objective is to track soil fertility variability and to collect information from field trials and fertilizer use surveys in a typical grain and grain-tobacco farming area in Yunnan. In 2001, the nutrient limiting factors to crop growth were determined through soil testing. In 2002, the village field map and nutrient variability maps were generated using geographic information system software. Field trials were conducted to verify the nutrient requirements and provide information on balanced fertilizer recommendations for compound fertilizer producers and farmers. The cropping systems are wheat-tobacco at Qujing and broadbean-rice at Songmin.

Results show that wheat yield increased with increasing rates of phosphorus (P) and/or potassium (K). The optimal fertilizer treatment for wheat at Qujing was 150-150-225 kg N-P₂O₅-K₂O/ha, which increased wheat yield by 2,010 kg/ha (44%) compared to the zero P treatment, and by 2,270 kg/ha (48%) compared to the zero K treatment. Addition of boron (B) increased wheat yield by 7%.

A 3 to 1 ratio of potassium sulfate (K₂SO₄) to potassium chloride (KCl) increased yield and farmer income compared to common farmer practice of applying only K₂SO₄ to tobacco. At Songmin, both broadbean and rice yields increased with increasing rates of P and K. Application of 30-135-135 kg/ha increased bean yield by 993 kg/ha (34%) compared to common farmer practice. Application of 120-130-300 kg/ha increased bean yield by 2,020 kg/ha (21%) compared to the zero K treatment.

This study verified the soil nutrient limiting factors in the two villages and offers scientific guidance for nutrient management in different cropping systems in the province. The results also indicate that there is a significant potential to improve production and farmers’ income. Yunnan-NMS PA