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| Effects of reducing chemical fertilizer combined with Chinese milk vetch on soil carbon and nitrogen in paddy fields |
| Received:December 10, 2019 |
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| KeyWord:Chinese milk vetch;double cropping rice;yield;active organic carbon;active organic nitrogen |
| Author Name | Affiliation | E-mail | | CHENG Hui-dan | Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China
Long Ping Branch, Graduate School of Hunan University, Changsha 410125, China | | | LU Yan-hong | Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China
Scientific Observing and Experimental Station of Arable Land Conservation(Hunan), Ministry of Agriculture and Rural Affairs, Changsha 410125, China | | | NIE Jun | Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China
Scientific Observing and Experimental Station of Arable Land Conservation(Hunan), Ministry of Agriculture and Rural Affairs, Changsha 410125, China | | | ZHU Qi-dong | Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China
Scientific Observing and Experimental Station of Arable Land Conservation(Hunan), Ministry of Agriculture and Rural Affairs, Changsha 410125, China | | | NIE Xin | Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China
Long Ping Branch, Graduate School of Hunan University, Changsha 410125, China | | | CAO Wei-dong | Agricultural Resource and Agricultural Division Institute of Chinese Academy of Agricultural Sciences, Beijing 100081, China | | | GAO Ya-jie | Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China
Scientific Observing and Experimental Station of Arable Land Conservation(Hunan), Ministry of Agriculture and Rural Affairs, Changsha 410125, China | | | LIAO Yu-lin | Soil and Fertilizer Institute of Hunan Province, Changsha 410125, China
Long Ping Branch, Graduate School of Hunan University, Changsha 410125, China
Scientific Observing and Experimental Station of Arable Land Conservation(Hunan), Ministry of Agriculture and Rural Affairs, Changsha 410125, China | ylliao2006@126.com |
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| Abstract: |
| An eleven-year field experiment was conducted to investigate the effects of different incorporation rates of Chinese milk vetch on grain yields, active organic carbon(DOC+MBC), and nitrogen(DON+MBN)under a chemical fertilizer application saving rate. Another aim was to explore a suitable application rate and the effect of the substitution of chemical fertilizer by Chinese milk vetch. The field experiments included seven treatments:CK(no application of Chinese milk vetch and chemical fertilizer), GM22.5(only Chinese milk vetch application 22.5 t·hm-2), 100%CF(conventional fertilizer), and Chinese milk vetch application of 15, 22.5, 30 t·hm-2, and 37.5 t·hm-2 under a 40% reduced chemical fertilizer(60%CF)application. Soil samples were collected after a harvest of late rice in 2018 to analyze soil microbial biomass carbon(MBC), nitrogen(MBN), dissolved organic carbon(DOC), and dissolved organic nitrogen(DON). The following results were obtained:The incorporation of Chinese milk vetch with a 40% reduction of chemical fertilizer either maintained or increased the grain yields of early rice and double-rice compared with conventional fertilizer application. The grain yields of early rice and double-rice system increased by increasing the amount of Chinese milk vetch incorporation. The grain yield of late rice increased by increasing the amount of Chinese milk vetch incorporation when the amount was within 15~30 t·hm-2. However, the incorporation of Chinese milk vetch over 30 t·hm-2 showed negative effects on crop production. Except for the Chinese milk vetch application of 15 t·hm-2, there were no significant differences in the grain yield of late rice between conventional fertilization and the treatments that were combined with Chinese milk vetch. Compared to conventional fertilization, the incorporation of Chinese milk vetch with chemical fertilizer increased the concentrations of soil MBC, MBN, DOC, and DON; these were increased with the increasing amount of Chinese milk vetch incorporation within 15~22.5 t·hm-2. However, they showed a decreasing trend when the incorporation amount was over 22.5 t·hm-2. The ratio of MBC to SOC and MBN to TN increased first and then decreased with the increased amount of Chinese milk vetch. The ratio of MBC to SOC and MBN to TN was highest under 60%CF + GM22.5 and 60%CF + GM30 treatments, respectively. Both the ratios of DOC to SOC and DON to TN were highest under a 60%CF+GM15 treatment. The concentrations of MBC, MBN, DOC, DON, DOC+MBC, and DON+MBN, were positively correlated with SOC and TN(P<0.01). The grain yields of early rice, late rice, and double-rice had significantly positive correlations with the active organic carbon and nitrogen concentrations(P<0.01). In southern rice-producing areas with similar climate conditions, soil types, and planting systems with this experiment, the optimal application rate of Chinese milk vetch was 22.5~30 t·hm-2 with a 40% reduced chemical fertilization due to its beneficial effect in maintaining grain yield and soil fertility. |
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