Abstract:

A plot experiment with four treatments including control, conventional fertilization, reduced fertilization by 10%, optimized fertilization (OF, reduced fertilization by 50%, optimized ratio of nitrogen, phosphorus and potassium) was conducted in a perennial continuous planting vegetable field nearby Shenzhen City. The aim of this study is to explore the effects of chemical fertilizer reduction on vegetable growth and soil fertility. The experiment used leafy vegetables as the test vegetables and planted them continuously for 2 crops. The results showed that fertilization significantly increased the absorption of N, P, and K nutrients and yields of vegetables. The contribution rate of fertilizer to the increase in leaf vegetable yield ranged from 32.3% to 37.7%, and there was no significant difference in the contribution rate of fertilizer between different fertilizer treatments. Under the conventional fertilization mode, the fertilizer use efficiency of N, P and K nutrients in vegetables was 13.98%, 5.39%, and 31.95%, respectively. And optimized fertilization significantly improved the fertilizer efficiency of P and K fertilizers in vegetables by 1.87 times and 26.3%. Fertilization had no significant effect on soil pH and organic matter concentration. Conventional fertilization and reduced fertilization by 10% significantly increased soil available nitrogen by 12.27%-27.83%, available phosphorus by 26.49%-44.24%, and available potassium by 13.17%-35.30%. Compared with conventional fertilization, optimized fertilization significantly reduced the available phosphorus content of the soil by 19.96%-23.65%, and the available potassium content by 22.29%-23.23%. The comprehensive soil fertility index of each treatment ranges from 1.34 to 1.43, all of which belong to the level of II. No significant differences were observed for soil fertility index between different fertilization treatments under two consecutive short-term experiments. Overall, optimizing the fertilization amount in the perennial continuous vegetable field system, that is, reducing fertilizer application by 50% and optimizing the proportion of N, P and K nutrients input, can maintain soil fertility levels while ensuring that vegetable yield, and reduce the risk of non-point source pollution caused by the accumulation of available phosphorus in the soil.

Key words: nutrient ratio, index of fertility, soil fertility, fertilizer contribution rate, continuous cropping, vegetable field, fertilizer reduction, nutrient utilization rate, non-point source pollution