Nutrient Management Strategies for Yunnan

IPNI-1999-CHN-YN13

30 Jan 2007

2006 Annual Interpretive Summary

Nutrient Management Strategies for Grain and Tobacco Systems in Yunnan, 2006

This project was initiated in 2001 to monitor the impact of different fertilizer treatments on crop yields in rice-broadbean and wheat-tobacco cropping systems. Songmin and Qujing counties were selected to track nutrient variability within typical farming regions in Yunnan, 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 from 2002 to 2004. In 2005, the proper fertilizer rates were verified and nutrient balances were determined for the two major cropping systems. In 2006, the objective was to continue verifying the fertilizer rates and to analyze the long-term effect of fertilizer treatment on crop yields.

For tobacco in Qujing, the balanced fertilization (BF) treatment using 135-190-240 kg N-P2O5-K2O/ha produced 1,380 kg/ha (64%), 446 kg/ha (21%), and 419 kg/ha (19%) more yield, and US$1,824/ha, US$379/ha, and US$79/ha more income, compared to the treatments omitting N, P, and K, respectively. In wheat, the BF treatment using 150-150-150 kg/ha produced 1,557 kg/ha (46%), 1,400 kg/ha (41%), and 1,257 kg/ha (37%) more grain than N, P, and K omission 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 2,068 kg/ha (15%), 1,542 kg/ha (11%), and 1,542 kg/ha (11%) higher than those produced without N, P, and K, respectively. Similarly, broadbean yields were 1,672 kg/ha (37%) and 1,535 kg/ha (34%) higher than yields produced without P and K. Fertilizer use efficiency was also significantly improved under the BF regimes.

In the wheat-tobacco cropping system, yields of both crops under all treatments have been declining since 2004. A fast decline in crop yields was observed for the N omission treatment, and this phenomenon is more subtle for the P and K omission treatments. In the rice-broadbean cropping system, crop yields have been maintained and may be slightly improving since 2004. Omission of N caused only a 3 to 7% yield reduction in broadbean from 2004 to 2006. It is possible that the rice-broadbean cropping system is beneficial to improving soil fertility while the wheat-tobacco cropping system is not. Yunnan-NMS-01