Effect of balanced fertilization on vegetables

Favored for its warm weather year round, Hainan Island has become one of the most important vegetable production bases in China. Vegetable production is a lucrative business, second only to fruit production in Hainan Province, and has gained considerable momentum in recent years. The region has become a critical supplier of summer varieties in the winter season and has satisfied the keen demands of northern China. This motivates farmers to obtain high yields by every possible means, including high input of fertilizers. Without concrete research and science-based technology and related guidance in fertilization, common farm practice often results in a reduction in vegetable yield and quality and increased cost and environment risk.

The objective of this study was to investigate the effect of different fertilizer treatments on yield and quality of three chili pepper varieties (i.e., pickle, vegetable, and spicy) and develop best fertilizer management practices.

Soil testing indicated that N, P, K, and magnesium (Mg) were limiting chili pepper production. These results were further verified through field trials. In 2007, experiments consisted of six treatments, including the optimal treatment (OPT) with 300-150-300-90 kg N-P₂O₅-K₂O-MgO/ha, OPT-N, OPT-P, OPT-K, and OPT-Mg. Chili yields varied considerably among treatments, but the OPT treatment produced the highest chili yields (i.e., 15.1 t/ha for the pickle chili, 37.9 t/ha for the spicy chili, and 29.5 t/ha for the vegetable chili). The most yield-limiting nutrient was N as yield was reduced by 2.7 t/ha (17.6%) for the pickle chili, by 14.9 t/ha (39.3%) for the spicy chili, and by 11.4 t/ha (36.3%) for the vegetable chili. Pickle chili yields were reduced by only 5 to 6% under the - P, - K, or - Mg treatments. Similarly, spicy chili yields were reduced by 16.3%, 10.4%, and 14.3%; and vegetable chili yields were reduced by 10.1%, 21.5%, and 3.3% under the treatments omitting P, K, or Mg. The OPT enhanced vitamin C content in all three varieties. The results further revealed that the three chili peppers had very low N recovery rates, ranging from 18% to 23%. Management to increase N use efficiency by chili peppers needs further in-depth study. Hainan-BFDP-06