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Chen Z.-D.,China Agricultural University | Dikgwatlhe S.B.,China Agricultural University | Dikgwatlhe S.B.,Research Services Plant Production Systems Division | Xue J.-F.,China Agricultural University | And 3 more authors.
Journal of Cleaner Production | Year: 2014

Scientific regulation of carbon (C) flows under conservation tillage is of great significance for mitigating C emission to the atmosphere and increasing C sequestration potential in soils. The objective of this study was to assess tillage impacts on C cycle from a situ field experiment and identify potential tillage practices for C-smart technology in paddy soils of the Southern China. A field experiment was conducted during 2005-2011, including conventional tillage without residue retention (CT), conventional tillage with residue retention (CTS), rotary tillage with residue retention (RTS), and no-till with residue retention (NTS). We computed SOC concentrations, SOC stocks and C emissions from farm inputs with time, and results in values representing a change in net carbon flux under different tillage systems in a double rice (Oryza sativa L.) cropping system. The annual increase rates of SOC stocks were 452.6, 523.3, 1340.8, and 2385.4 kg ha-1 yr-1 from 2007 to 2011 under CT, CTS, RTS, and NTS, respectively. The annual C emissions under CT, CTS, RTS, and NTS were 1182.5, 1182.5, 1152.5, and 1139.2 kg C-eq ha-1 yr-1, respectively. Among the treatments, NTS treatment had the lowest net C flux with -1246.2 kg C-eq ha-1 yr-1. Taking CT as the baseline, the relative net C flux under RTS and NTS were -918.2 and -1976.1 kg C-eq ha-1 yr-1, respectively. This suggests that adoption of conservation tillage would be beneficial in the reduction of GHG emission and could be a good option for C-smart agriculture in double rice cropping regions. © 2014 Elsevier Ltd. All rights reserved.

Gao J.,Chinese Academy of Agricultural Sciences | Cao W.,Chinese Academy of Agricultural Sciences | Li D.,Chinese Academy of Agricultural Sciences | Xu M.,Chinese Academy of Agricultural Sciences | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Rotation cropping systems have important significance to soil fertility, productivity and ecological function in paddy field. We analyzed the long-term data from a field experiment started in 1982 to investigate the effects of rotation cropping of double-rice with various green manure on the dynamics of rice yield and the total and labile soil organic matter in Red Soil Experimental Station CAAS. Four rotation cropping systems were selected by three replicates, which were rotation of double rice with Chinese milk vetch (Astragalus sinicus L.), rape (Astragalus sinicus L.), ryegrass (lolium multiflorum) and winter fallow. Results showed that, during the duration from 1982 to 2008, the averaged annual rice yield were 10.8 t·hm -2·a -1, 10.2 t·hm -2·a -1 and 10.0 t·hm -2·a -1 for the rotation cropping systems with Chinese milk vetch (Astragalus sinicus L.), rape (Astragalus sinicus L.) and ryegrass (Lolium multiflorum) respectively. Compared with double-rice and winter-fallow cropping, rice yield was increased significantly by 27.2%, 20.5%, and 18.1% under the rotation cropping with Chinese milk vetch (Astragalus sinicus L.), rape (Astragalus sinicus L.) and ryegrass (lolium multiflorum) respectively. There was no significant difference among these rotation cropping systems with three kinds of green manure during the early period from 1982 to 1993, while the rice yield under the rotation with cultivating Chinese milk vetch was significantly higher than that under the other two kinds green manure rotations at the latter period from 1994 to 2008. Sustainability index of grain yield (SYI) was a reliable parameter on evaluate the productivity of sustainable cropping systems. Cultivating Chinese milk vetch could fix atmospheric nitrogen and improve soil fertility. The Sustainability index of grain yield (SYI) and potential of yield increased with cultivating Chinese milk vetch was the highest. Soil organic matter showed an increasing trend under the rotation cropping of double rice and green manure. The rotation of double rice with Chinese milk vetch had the highest annually increasing rate (0.31g/kg) of soil organic matter, while the rate was 0.28g/kg and 0.26g/kg for the rotation cropping with ryegrass and rape, respectively. The labile soil organic matter under the rotation with Chinese milk vetch was the highest of all the treatments. Total organic carbon, total nitrogen, soil microbial biomass carbon and nitrogen under the rotation with three kinds of green manure were significantly higher than that under the winter-fallow cropping systems. Compared with rape, ryegrass has strong fibrous root system which content high organic matter and crude protein. More carbon and nitrogen were cumulated in the soil under the rotation of double rice with Chinese milk vetch and ryegrass than that under the other two cropping systems. Additionally, the two rotation cropping systems of double-rice with ryegrass and Chinese milk vetch increased the microbial biomass carbon content and the ratio of microbial biomass carbon to total organic carbon (C mic-to-C org) significantly compared with the cropping of double-rice and rape or fallow. In conclusion, rotation cropping of double rice with green manure had significant effects on enhancing rice yield and promoting soil organic matter quantity and quality. Rice cropping with Chinese milk rotation vetch was recommendable for rice productivity and soil fertility.

Cui S.,China Agricultural University | Yin X.,China Agricultural University | Chen F.,China Agricultural University | Tang H.,Hunan Soil and Fertilizer Institute | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011

Tillage affects the nitrogen leakage by changing soil physical and chemical properties. The effects of tillage on soil permeability and nitrogen leakage were studied for increasing utilization efficiency of nitrogen in paddy field. Long-term field experiments were established from 2005 in a double rice cropping region, Ningxiang county, Hunan province of China. Treatments included no-tillage with straw returning(NT), rotary-tillage with straw returning (RT), conventional tillage with straw returning (CT) and conventional tillage without straw returning (CT0). Constant-head method was used to analyze soil hydraulic conductivity in the soil layer 0-80 cm. Results showed that there was an increase in soil hydraulic conductivity in NT, which was 63.14% and higher than that in CT. Higher leakage of NH4 +-N and NO3 --N (p<0.05) were found in NT than in other treatments. Straw returning enhanced the leakage of NO3 --N, especially in the period of early rice cultivation. The annual leakage of NH4 +-N was almost two times than that of NO3 --N among each treatment. Compared with other tillage treatments, NT could increase nitrogen leakage, and more attention should be focused on NH4 +-N leakage in long-term flooding paddy fields.

Zhu Q.-H.,CAS Institute of Subtropical Agriculture | Huang D.-Y.,CAS Institute of Subtropical Agriculture | Liu S.-L.,CAS Institute of Subtropical Agriculture | Zhou B.,CAS Institute of Subtropical Agriculture | And 3 more authors.
Journal of Soils and Sediments | Year: 2012

Purpose: Little is known of the effect of sepiolite on the transformation of Cd in anthropogenically contaminated paddy soil under different moisture conditions; therefore, we studied the effects of sepiolite and flooding on the extractability and fractionation of Cd in paddy soils. Materials and methods: The dynamics of soil Eh, pH, DTPA-extractable Cd, and different Cd soil fractions were studied in two typical paddy soils from south China that were spiked with 10 mg kg-1 Cd following amendment with sepiolite at 5 and 10 g kg-1 soil during a 30-day incubation period at 25°C, with either no flooding or continuous flooding conditions. Results and discussion: The addition of sepiolite at two rates of 5 and 10 g kg-1 soil resulted in an average reduction in soil Eh of 76 and 93 mV, increase in soil pH of 1.2 and 2.3 pH units, and decrease in DTPA-extractable Cd in soils of 1.43 and 2.53 mg kg-1 under continuous flooding conditions, respectively. Sepiolite addition resulted in a significant decrease in the exchangeable Cd in the soils, and a significant increase, in the carbonate-bound and Fe/Mn oxide-bound Cd in the soils under both moisture conditions. Cadmium was also immobilized by flooding and by interactions between sepiolite application and flooding; these effects were greater in sandy paddy soil than in clay paddy soil. Conclusions: The immobilization of Cd in typical paddy soils was related mainly to changes in Eh and pH caused by the addition of sepiolite and flooding. Sepiolite can be used in the remediation of Cd-contaminated paddy soils, especially in sandy paddy soils, and flooding enhances the stabilization of Cd in paddy soils by sepiolite. © 2011 Springer-Verlag.

Zhu Q.H.,CAS Institute of Subtropical Agriculture | Huang D.Y.,CAS Institute of Subtropical Agriculture | Liu S.L.,CAS Institute of Subtropical Agriculture | Luo Z.C.,Hunan Soil and Fertilizer Institute | And 5 more authors.
Plant, Soil and Environment | Year: 2013

The tolerance, accumulation and subcellular distribution characteristics of cadmium (Cd) in ramie (Boehmeria nivea L. Gaud.) were investigated using a 2-year field experiment. The results indicated that ramie has a certain extent of tolerance to soil Cd (≤ 20 mg/kg) contamination with no significant decrease in shoot biomass and fibre yield relative to control conditions. Although ramie did not hyperaccumulate Cd, it accumulated considerable amount of Cd in the aboveground parts (approximately 0.19 to 1.09 kg/ha annually). The Cd contents retained in ramie tissues were found in order of roots > stems > leaves. Further, regarding the subcellular distribution of Cd in ramie tissues, 80% of the total Cd was bound to the cell walls of the roots and stems, whereas in leaves the proportion of Cd stored in the cell wall fraction was around 60% and a lesser amount of Cd was stored in the soluble fraction (24.1-25.5%). Our collective results indicated that ramie adapts to Cd stress via the store of a large amount of Cd in cell walls, and suggested potential usefulness of ramie in the phytoremediation of Cd-contaminated farmlands.

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