Response Of Vegetable Yield And Environment To Phosphorus Application In Two Vegetable Garden Soils In Wuhan

Based on the reviews of soil P accumulation and leaching, the effect of P application on the soil P accumulation, P removal of vegetables, the leaching characteristics of different P forms in leachate, P balance and P leaching risk were measured so as to scientifically guide the P application and provide the basis for the sustainable production and environmental protection of underground water of Wuhan vegetable garden. Undisturbed soil core lysimeters in field were chosen to be the experimental sites. The tested soils were two typical soil types (yellow brown soil and fluvo-aquic soil) from Wuhan surburbs, while vegetables of Chinese cabbage (Brassica chinensis L.), pepper (Capsicum annuum L.), amaranth (Amaranthus mangostanus L.), radish (Raphanus sativus L.) were planted seasonly. The main results were as follows.1. The P application enhanced both total P and Olsen-P content in topsoil, total P and Olsen-P content of fluvo-aquic soil were significantly higher than yellow brown soil's. Moreover, it was found that the co-treatment of P application 250 kg P₂O₅/(ha·a) with straw improved soil total P and Olsen-P content.2. The P application increased the yield of vegetables, and the increase rates were higher in yellow brown soil. The yield effect equation between yield of vegetables y (kg/ha) and P x (kg P₂O₅/ha) application were:Chinese cabbage: y=-0.5692x²+195.45x+1098.5 (yellow brown soil, R²=0.9516)y=-1.3049x²+289.28x+8870.3 (fluvo-aquic soil, R²=0.9750) pepper:y=-0.0764x²+31.613x+10686 (yellow brown soil, R²=0.9498)y=-0.8337x²+133.76x+59927 (fluvo-aquic soil, R²=0.8513) amaranth:y=-l .5184x²+320.3x+834.34 (yellow brown soil, R²=0.9937)y=-2.7203x²+303.04x+2735 (fluvo-aquic soil, R²=0.9984) radish:y=-0.9949x²+265.72x+53179 (yellow brown soil, R²=0.9232)y=-5.497x²+815.05x+74751 (fluvo-aquic soil, R²=0.9684) It was found that the co-treatment of P application 250 kg P₂O₅/(ha·a) with straw improved the yield of vegetables, and the increase rates were higher in yellow brown soil. Both P content and P accumulation of plants were increased with the increase the P application in every season vegetables. Statistically significant differences were observed between P application and CK on the sum of total P accumulation of four season vegetables in the two soil types, and the sum reached the maximum at the highest P application 375 kg P₂O₅/(ha·a).3. A similar trend was observed for all treatments on concentration and cumulative leaching loss of TP, TDP in leachate with seasons in the two soil types. It was found that annual average leaching concentration and annual cumulative leaching loss of TP, TDP were higher in yellow brown soil than that in fluvo-aquic soil for all treatments. The annual average leaching concentration and annual cumulative leaching loss of TP were elevated by P application 250 kg P₂O₅/(ha·a) co-treated with straw. The TDP was main form of P leaching in the two soil types, and no significant changes in proportion of different P forms were observed with the increase of P application. The rates of TDP in the two soil types were 48.49-62.99% and 60.64-84.52%.4. The surplus of P were exhibited in the two soil types while P were applied , and a higher surplus of P were found in yellow brown soil in all treatments. The highest apparent utilization of P in yellow brown soil reached the maximum in the treatment of 250 kg P₂O₅/(ha·a) and 125 kg P₂O₅/(ha·a) in fluvo-aquic soil. It was found that the co-treatment of P application 250 kg P₂O₅/(ha·a) with straw improved the apparent utilization of P.5. The critical value of leaching risk for yellow brown soil were 25.29 mg/kg of Olsen-P and 61.68 mg/kg for fluvo-aquic soil.6. In conclusion, the optimally recommend value for P application were 250 kg P₂O₅/(ha·a) in yellow brown soil and 125 kg P₂O₅/(ha·a) in fluvo-aquic soil. In the same P application condition, the vegetable yield was enhanced by properly reducing chemical P application and increasing organic P application. In addition, It is better to avoid the torrential rain when the P was applied in vegetable garden. And intensive irrigation should be prevented in agricultural management as well.