Affiliation:
1. Rubber Research Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
2. College of Ecology and Environment, Hainan University, Haikou 570228, China
3. College of Tropical Crops, Hainan University, Haikou 570228, China
4. Sanya Tropical Ecosystem Carbon Source and Sink Field Scientific Observation and Research Station, Sanya 572022, China
Abstract
Overuse of chemical nitrogen (N) fertilizers leads to N leaching and soil degradation. Replacing chemical N fertilizers with organic fertilizers can enhance soil nutrition, reduce N loss, and improve soil productivity. However, the effects of combining organic and chemical fertilizers on soil N components and N transformation remain unclear. A 12-year field study included four treatments: no fertilizer (CK), chemical fertilizer alone (CF), 50% chemical N fertilizer combined with co-composted organic fertilizer (CFM), and composted (CFMC) organic fertilizer. The results showed that CFM and CFMC significantly enhanced SOC, TN, LFON, DON, NH4+-N, and MIN levels compared to CF. The CFM and CFMC treatments enhanced the soil N supply capacity and N pool stability by increasing the N mineralization potential (N0) and decreasing the N0/TN ratio. The CFM and CFMC treatments decreased net N ammonification rates by 108.03%–139.83% and 0.44%–64.91% and net mineralization rates by 60.60%–66.30% and 1.74%–30.38%, respectively. Changes in N transformation have been attributed to increased soil pH, enzyme activity, and substrate availability. These findings suggest that partial organic fertilizer substitution, particularly with co-composted organic fertilizers, is a viable strategy for enhancing soil fertility, improving soil N supply and stability, and reducing N loss in rubber plantations.
Funder
National Natural Science Foundation of China
Earmarked Fund for China Agriculture Research System
Postdoctoral research grants of Hainan Province