Effects Of Organic, Specially Grown And Conventiinal Farming Systems On Vegetable Yield, Quality And Soil Fertility In Nanjing Region

A field experiment was carried on to evaluate the effects of organic, specially grown and conventional farming systems on yield, quality, soil fertility and soil enzyme activity and contamination of heavy metals in an organic farm in Nanjing. Four vegetables were involved in the experiment under different farming systems. The results of the study showed that:Different farming systems significantly influenced vegetable yields, although the effect of farming on yield was depended on vegetable species. Organic farming system had the highest yield than the other two systems. Compared with the yield of conventional vegetables, the yield of organic kidney bean, cucumber, tomato and the soy beans increased by 11.39%,45.40%,4.22% and 9.13%, respectively. A very significant difference (P< 0.01) in yield was obtained between organic and conventional cucumber. The yields of specially grown cucumber and tomato were higher than those of conventional ones, whereas the yields of specially grown kidney bean and soy bean were lower than those of conventional ones. Since the first year of conversion from conventional to organic, there had been an obvious superiority in yield of organic vegetables in the paddy soil. It suggested that organic farming was appropriate in the paddy soil to produce organic vegetables.The effects of farming systems on quality of vegetables depended on vegetable species. There was no significant difference in contents of vitamin C, crude protein, soluble protein and soluble sugar among of the four vegetables. Although there was no significant difference in organic acid content of tomato between different farming systems, the ratio of sugar to acid for organic tomato, which increase the flavor of tomato, was significantly higher than that of the specially grown and conventional ones. The contents of nitrate in vegetables under organic and specially grown farming systems were lower than those under conventional system.Significant difference in soil fertility occurred between different farming systems. Results showed that organic matter, total nitrogen, available P and available K as well as soil enzyme activities were increased under organic and specially grown farming systems as compared with conventional farming systems. Activities of soil enzymes such as soil catalase. urease. invertase and acid phosphatise under organic farming were generally, values of enzymatic activity in the specially grown system fell in the range between those in organic and those in conventional farming system. Soil pH in organic farming system was increased and was nearing the range of optimum pH for vegetable crops. There was no significant difference in contamination of heavy metals.As a whole, soil fertility was significantly improved in the organic farming system after three years of conversion. And thus organic farming increased yield and quality of vegetables. For specially grown farming performed better in vegetable yield and soil fertility than conventional system, it could be a alternative for sustainable crop cultivation.