Effects Of Nitrification Inhibitor DMPP On Soil Nitrate Leaching And Vegetable Production

In this study, we used soil column to study the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate and potassium leaching in two soils. Effects of compound fertilizer (ENTEC^?, 12-12-17) with nitrification inhibitor DMPP on vegetable and fruit were also discussed. Results were shown as follows:1. Effects of DMPP on nitrate and potassium leaching in the sandy soil and clay soil were investigated by using the soil column. Results showed that DMPP can reduce soil nitrate leaching significantly. In the sandy soil soil, compared with urea and ASN, urea+DMPP and ASN+DMPP reduced the accumulative nitrate leached 15.48 mg, 51.42 mg, and by 51.29%, 55.32%, respectively;In the clay soil, compared with urea and ASN, urea+DMPP and ASN+DMPP reduced the accumulative nitrate leached 10.55 mg, 7.26 mg, and by 64.88%, 19.70%, respectively. As for (NH₄⁺+NO₃^-)-N, urea+DMPP and ASN+DMPP reduced 17.96%, 48.17% in the sandy soil and 31.07%, 15.21% in the clay soil, respectively. DMPP supplementation also resulted in potassium leached from soil, but the difference was not significant except the treatment ASN and ASN+DMPP in the sandy soil soil. At the completion of leachate experiment, different soil depths in the DMPP-amended soil led to the maintenance of relatively high levels of NH₄⁺-N and low levels of NO₃^--N in soil, and nitrification was slower. Above results indicate that DMPP is a good nitrification inhibitor, but the efficiency of DMPP seemed better in the sandy soil than in the clay soil and lasted longer.2. Effects of ENTEC on growth, nutritional quality of celery (Apium graveolens L.) and soil nitrogen were investigated in field experiment. Results showed that basal dressing of ENTEC increased celery yield, decreased nitrate content, but also increased Vc, amino acid, N and P content, and hence improved nutritional quality. Basal dressing of ENTEC at rate of 67.5 kg·hm^-2(N) and 54.0 kg·hm^-2(N) increased yield by 5.78%, 10.14%, respectively, so ENTEC should basal dressing for celery. ENTEC also had higher nitrogen residual amount after harvested, so it was a recommendable fertilization management for vegetable.3. Effects of reducing level and apply times of ENTEC on yield and quality of eggplant (Solanum melongena L.) were investigated in field experiment. Results showed that compared with conventional urea treatment, applying ENTEC two times could increase eggplant yield significantly, reducing the level of ENTEC (N) by 20% did not decreased eggplant yield significantly. Applied ENTEC with less level can reduce nitrate of eggplant significantly, while with less times had no effect on it. Effects of applying ENTEC with less level and with less times on soluble sugar and amino acid of eggplant had different results during the growth stage, the reasons need further study, In addition, no differences were found on N> P and K content when ENTEC was applied.4. Effects of ENTEC on yield and nutritional quality of watermelon (Citrullus lanatus M.) and cucumber (Cucumis sativus L.) were investigated in field experiment. Results showed that compared with the same dosage of conventional compound fertilizer treatment, ENTEC not only increased watermelon yield significantly by 6.50% (Zhemi 1 hao), 44.55%(Zhemi 2 hao) and cucumber (Jinchu 4 hao) yield by 8.40%, decreased nitrate content by 2.42%(Zhemi 1 hao), 10.70%(Zhemi 2 hao) and cucumber(Jinchu 4 hao) by 27.44%, but also increased soluble sugar or solid, Vc, amino acid and N content, hence improved nutritional quality. And it was better when applied in Zhemi 2 hao than in Zhemi 1 hao.