Effects of Organic Fertilizer Combined with Chemical Fertilizer on Nutrients, Enzyme Activities, and Rice Yield in Reclaimed Soil
Jing Ju, Qiang Gu, Hongwei Zhou, Huan Zhang, Wei Mao, Hongjian Yang, Wenhai Mi, Haitao Zhao
Abstract
A field experiment was conducted to explore the effects of combined application of organic and chemical fertilizers (organic-chemical fertilizers) on reclaimed soil fertility and rice yield. The experiment involved five treatments: no nitrogen (N) fertilizer (CK1), 100% chemical fertilizer N (CK2), 40% chicken manure N + 60% chemical fertilizer N (T1), 40% vermicompost N + 60% chemical fertilizer N (T2), 40% rapeseed meal fertilizer N + 60% chemical fertilizer N (T3). Organic-chemical fertilizers maintained or increased rice yield. Rice yields of T2 and T3 increased by 6.7% and 8.9%, respectively, as compared with CK2. T1 showed similar value of rice yield with CK2. Organic-chemical fertilizers application increased contents of soil organic C (SOC), total N (TN), alkali-hydrolyzable N (AN), NH4+-N, NO3–N, available phosphorus (AP), available potassium (AK) as well as CEC by 10.5%~15.9%, 8.9%~39.3%, 16.9%~74.5%, 38.1%~77.2%, 18.3%~136.5%, 27.7%~75.0%, 16.1%~24.7% and 7.2 ~ 26.0%. T3 had highest soil TN, AN, NH4+-N, NO3–N, CEC as well as T2 showed the highest contents of soil AP and AK. Organic-chemical fertilizers application increased soil sucrase (S-SC), urease (S-UE) and catalase (S-CAT) activities. The highest soil S-SC activity was detected in T3, and the highest soil S-UE and soil alkaline phosphatase (S-AKP) activities were observed in T2. Rice yield was positively related to SOC, TN, AN, NH4+-N, NO3–N, AP and AK as well as S-SC, S-UE and S-AKP activities. In conclusion, 40% organic N + 60% chemical N application could improve soil fertility and rice yield in reclaimed soils, with rapeseed meal fertilizer the most effective organic N source, followed by vermicompost and chicken manure.