Long-term combined application of manure and NPK fertilizers influenced nitrogen retention and stabilization of organic C in Loess soil
2012
Liang, Bin | Yang, Xueyun | He, Xinhua | Murphy, Daniel V. | Zhou, Jianbin
AIMS: Our aims were to: (1) compare the immobilization of NH 4 + -N by clay minerals and microbial biomass in soils with different fertilization history and (2) evaluate the effects of available C and N addition on the stabilization of soil organic carbon (SOC) in anthropogenic Lou soils. METHODS: Here we used three soil treatments, i.e., (a) no fertilizer (NF), (b) inorganic NPK fertilizers (F), and (c) manure plus inorganic NPK fertilizers (MF) from an 18-year old field trial located in the south Loess Plateau, China. Two short-term incubation experiments were used to assess the impact of adding available nitrogen (NH 4 + -N) and C (glucose) on NH 4 + fixation by clay minerals, and the decomposition of SOC in these soils. RESULTS: The NH 4 + fixed by clay minerals in the MF soils (3.8% of added N) was significantly (P < 0.05) lower than that in the NF, and F soils (14.1%, and 9.5% of added N). The decomposition rate of SOC in the MF soil (3.3%) during the incubation was significantly (P < 0.05) lower than in the NF, and F soils (4.4%, and 4.2%). Addition of NH 4 + -N significantly (P < 0.05) increased the decomposition of SOC in different soil treatments, and the MF soil also had lower decomposition rate than the NF, and F soils. CONCLUSION: We concluded that long-term combined application of manure and NPK fertilizers reduces the NH 4 + fixation by clay minerals and improves the stabilization of organic C in soil.
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