Effect of balanced fertilization on yield and quality of Chinese cabbage and lettuce in Chongqing


09 Jan 2009

2008 Annual Interpretive Summary

Effect of Balanced Fertilization on Yield and Quality within a Chinese Cabbage-Lettuce Crop Rotation in Chongqing, 2008

This project continues to study the effect of fertilization on yield and quality of consecutively planted Chinese cabbage and lettuce in the suburb region of Chongqing City. Project results will guide fertilizer application and nutrient management in this and similar areas under intensive vegetable cultivation. Both crops tested nine treatments combining two rates of N, P, and K, one rate of B, two types of manures (rapeseed meal and peat). The study also included an unfertilized control and a base NPK treatment of 225-75-150 kg N-P2O5-K2O/ha. Each vegetable was grown for three seasons during 2008. A single basal application was applied to cabbage due to its relatively short growing season, while three splits (25%, 50%, and 25%) were used for lettuce, including one basal application at transplanting and two top dressings.

Compared to the base NPK treatment, both cabbage and lettuce yields increased with further addition of 75 kg N/ha, 75 kg P2O5/ha, 75 kg K2O/ha, 0.9 kg B/ha, 2,250 kg peat/ha, and 2,250 kg rapeseed meal/ha. Cabbage yield was especially responsive to the large inputs of peat (+44%) or rapeseed meal (+52%). The cabbage quality response was somewhat different from previous years as the additional N, P, K, peat, or rapeseed meal slightly decreased amino acid, vitamin C, and sugar, but increased leaf nitrate. The pattern for lettuce yield responses in 2008 were of similar magnitude to those observed in cabbage. Compared to the base NPK treatment, all other treatments produced slightly lower lettuce tissue contents of amino acids, vitamin C, sugar, and nitrate. All nitrate contents were far below the critical risk level for lettuce.

No consistent year-to-year quality trends were observed among treatments for lettuce and Chinese cabbage. As a sign of poor soil quality, rapeseed meal appeared to be the most significant contributor to yield for both lettuce and Chinese cabbage, followed by peat. Besides their effect on crop yield and quality, these two amendments also significantly improved use efficiencies for N, P, and K. Chongqing-BFDP-SU06