Reduced fertilizer rates enhanced yields of vegetables grown on fertilizers overdosed vegetable soils in Yunnan
IPNI-2008-CHN-YN11
15 Feb 2010
2009 Annual Interpretive Summary
Improved Nutrient Management to Reduce Run-off Losses from the Commercial Floral Production Surrounding Dianchi Lake in Yunnan, 2009
A huge commercial floral production base has developed around the Dianchi Lake over the past 10 years, and it has flourished due to good climate and geographic location. High profitability has stimulated the use of all crop inputs and has especially resulted in over-application of fertilizers. This is blamed, at least partially, for water eutrophication of the lake. This study investigated the effects of nine fertilizer treatments on growth and nutrient uptake of three rose cultivars (black, pink, and super) as well as nutrient loss through run-off. Treatments included a check (CK), farmers’ practice (FP) using N and P only, and selected combinations of four N rates (0, 187.5, 281, and 375 kg N/ha), four P rates (0, 112.5, 169, and 225 kg P2O5/ha), and 315 kg K2O/ha. All fertilizers were split three times between transplanting, floral initiation, and budding.
Rose flower numbers were significantly improved by reducing N and P rates, and with added K. The optimal treatment for all three rose cultivars was two-thirds of the current N and P rates used by farmers plus K (i.e., 187.5-112.5-375 kg/ha). This treatment increased black, pink, and super rose flower numbers by 5,780, 25,290, and 28,770/ha (8%, 19%, and 16%), respectively, when compared to FP. All the other treatments with reduced fertilizer rates had significantly fewer flower numbers. The total amount of nutrient uptake by the three roses followed the order of: super > black > pink for N; and super > pink > black for P. However, neither N nor P uptake by the three rose cultivars was closely correlated to fertilizer rate, which is a reflection of high initial soil N (available N >250 mg/kg) and P (available P >46 mg/kg) levels. Amounts of N or P detected in the effluent from the experiment fields were significantly increased under higher N or P rates. Furthermore, increased N rates also intensified P losses through leaching, but this did not hold true for the effect of increased P rates on N losses.
The results substantiated the hypothesis that floral fertilization in fields surrounding Dianchi Lake is excessive and should be rationalized to achieve better flower harvest, income, and environmental protection. Yunnan-BFDP-09