Reduced fertilizer rates enhanced yields of vegetables grown on fertilizers overdosed vegetable soils in Yunnan

IPNI-2008-CHN-YN11

03 Feb 2011

2010 Annual Interpretive Summary

Cucumber Yield, Nutrient Use Efficiency, Economic Returns, and Soil Phosphorus Forms as Affected by Fertilization and Irrigation Systems in Yunnan, 2010

Over-fertilization is a common problem in vegetable production in Yunnan. This fertilizer practice inevitably leads to a high input cost, low fertilizer use efficiency, enhanced nutrient losses to the environment, and often reduced crop yield and/or quality. Thus, the purpose of this study was to investigate possible mitigating effects of different fertilizer practices on cucumber, one of the most commonly grown vegetables, to understand optimal fertilizer rates for its production in the region. The experiment consisted of 26 fertilizer treatments involving different rates of N, P, and K, each receiving two types of irrigation (drip and traditional). Two forms of K, potassium chloride (KCl) and potassium sulfate (K2SO4) were used in the study to demonstrate to vegetable growers that KCl can be equally as affective at producing high vegetable yields and quality. Fertilizer rates included: 0, 150, 300, and 450 kg of N; 0, 90, 150, and 225 kg of P2O5; and 0, 195, 345, and 495 kg of K2O per hectare. The rates were split several times using a 10-day interval starting at seeding.

Results showed that drip irrigation could increase cucumber yield by 3,660 to 7,140 kg/ha (10 to 23%) and save water by 570 m3/ha (45%) compared to traditional irrigation. The optimal fertilizer treatment was determined to be 300-150-345 kg N-P2O5-K2O/ha under both irrigation systems. Under this treatment, net income was USD 11,797 for drip irrigation and USD 10,645 for traditional irrigation. The use efficiencies of N, P and K fertilizers under drip irrigation were all obviously higher than with traditional irrigation. Results further revealed that drip irrigation favored the maintenance of higher available soil P, as well as Fe-P and Al-P complexes, and organic P, while traditional irrigation enhanced the presence of calcium P complexes and occluded P. Drip irrigation enhanced P availability in the soil and resulted in higher P use efficiency by cucumber, implying that whenever possible, drip irrigation should be used in high output/input crop production systems to enhance productivity and nutrient use efficiency. Yunnan-BFDP-10