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Zhang H.-L.,China Agricultural University | Bai X.-L.,China Agricultural University | Xue J.-F.,China Agricultural University | Chen Z.-D.,China Agricultural University | And 2 more authors.
PLoS ONE | Year: 2013

Understanding greenhouse gases (GHG) emissions is becoming increasingly important with the climate change. Most previous studies have focused on the assessment of soil organic carbon (SOC) sequestration potential and GHG emissions from agriculture. However, specific experiments assessing tillage impacts on GHG emission from double-cropped paddy fields in Southern China are relatively scarce. Therefore, the objective of this study was to assess the effects of tillage systems on methane (CH4) and nitrous oxide (N2O) emission in a double rice (Oryza sativa L.) cropping system. The experiment was established in 2005 in Hunan Province, China. Three tillage treatments were laid out in a randomized complete block design: conventional tillage (CT), rotary tillage (RT) and no-till (NT). Fluxes of CH4 from different tillage treatments followed a similar trend during the two years, with a single peak emission for the early rice season and a double peak emission for the late rice season. Compared with other treatments, NT significantly reduced CH4 emission among the rice growing seasons (P<0.05). However, much higher variations in N2O emission were observed across the rice growing seasons due to the vulnerability of N2O to external influences. The amount of CH4 emission in paddy fields was much higher relative to N2O emission. Conversion of CT to NT significantly reduced the cumulative CH4 emission for both rice seasons compared with other treatments (P<0.05). The mean value of global warming potentials (GWPs) of CH4 and N2O emissions over 100 years was in the order of NT Source


Liu X.,China Agricultural University | Xiao X.,Soil and Fertilizer Institute of Hunan Province | Yang G.,Soil and Fertilizer Institute of Hunan Province | Ren T.,China Agricultural University
Soil Science | Year: 2011

The soil-water retention curve (WRC), applied in hydrology, agronomy, and ecology, is an important soil parameter for assessing soil quality and soil functions. Agricultural practices influence WRC by modifying other soil properties, such as soil organic matter content and aggregation. In this study, we investigated the changes in WRC among aggregate fractions as related to fertilizer management in the 0-to 10-cm layer of a paddy soil. The long-term experiment was established in 1986 with five fertilizer treatments: no fertilizer, chemical fertilizer alone, rice residues plus chemical fertilizer, low manure rate plus chemical fertilizer, and high manure rate plus chemical fertilizer. The results demonstrated that at larger water suctions (pF >1.6), the shapes of WRC for different aggregate fractions were similar, but larger aggregates (>2 mm) retained more water than smaller ones (<2 mm). Intra-aggregate water retention capacity was closely related to the interaction of aggregate mineralogy and organic carbon content, as the larger aggregates had lower sand content and higher silt and organic carbon contents than the smaller ones. Under the intensive rice-rice-barley cropping system, joint application of organic materials and chemical fertilizer improved aggregate water retention capacity, but the change of aggregate water retention from chemical fertilizer alone was not significant. © 2011 by Lippincott Williams & Wilkins. Source


Yang Z.-P.,Soil and Fertilizer Institute of Hunan Province | Yang Z.-P.,Hunan Agricultural University | Xu M.-G.,Chinese Academy of Agricultural Sciences | Zheng S.-X.,Soil and Fertilizer Institute of Hunan Province | And 4 more authors.
Journal of Integrative Agriculture | Year: 2012

Soil physical properties are important indicators of the potential for agricultural production. Our objective was to evaluate the effects of long-term inputs of green manures on physical properties of a reddish paddy soil (Fe-Typic Hapli-Stagnic Anthrosols) under a double cropping system. The common cropping pattern before the study was early-late rice-fallow (winter). The field treatments included rice-rice-fallow (R-R-WF), rice-rice-rape (R-R-RP), rice-rice-Chinese milk vetch (R-R-MV), and rice-rice-ryegrass (R-R-RG). The rape, Chinese milk vetch and ryegrass were all incorporated as green manures 15 d before early rice transplanting during the following year. The soil bulk density in all green manure treatments was significantly reduced compared with the winter fallow treatment. Soil porosity with green manure applications was significantly higher than that under the winter fallow. The green manure treatments had higher 0.25-5 mm water stable aggregates and aggregates stabilities in the plow layer (0-15 cm depth) compared with the fallow treatment. The mean weight diameter (MWD) and normalized mean weight diameter (NMWD) of aggregates in the green manure treatment were larger than that with the winter fallow. Soil given green manure retained both a higher water holding capacity in the plow layer soil, and a larger volume of moisture at all matric potentials (-10, -33 and -100 kPa). We conclude that the management of double-rice fields in southern central China should be encouraged to use green manures along with chemical fertilizers to increase SOC content, improve soil physical properties and soil fertility. © 2012 Chinese Academy of Agricultural Sciences. Source


Zhang W.,Chinese Academy of Agricultural Sciences | Xu M.,Chinese Academy of Agricultural Sciences | Wang X.,Xinjiang Institute of Ecology and Geography | Wang X.,The Interdisciplinary Center | And 6 more authors.
Journal of Soils and Sediments | Year: 2012

Purpose: Although organic amendments have been recommended as one of the practices for crop production and soil carbon sequestration, little has been done to evaluate soil organic carbon (SOC) dynamics following long-term application of organic amendments. The objective of this research were to (1) assess the effect of long-term organic amendments on SOC dynamics in rice-based systems; (2) evaluate the relationship between soil carbon sequestration and carbon input based on various mineral and organic fertilization treatments. Materials and methods: A multi-sites analysis was conducted on four long-term experiments with double-rice (three sites) and rice-wheat (one site) cropping systems which started in the 1980s in Southern China. We selected three groups of treatments in common at each site: (1) control (no fertilizer), (2) mineral nitrogen-phosphorus with and without potassium (NPK/NP), and (3) the combined treatments of mineral NP/NPK with pig manure (M), green manure (G, Astragalus sinicus L.), rice straw (S), and/or their combinations. Harvestable crop biomass was annually recorded for all plots. SOC in topsoil was determined in 1-5 yearly intervals after rice harvest. Results and discussion: Analysis showed that organic amendments sustained or significantly increased carbon biomass, but had little effects on the coefficient of variance (CV) of the carbon biomass production compared with the mineral NPK/NP treatments. With additional carbon input, organic amendments increased SOC significantly by 7-45% after 25-28 years of fertilization compared with the mineral treatments. These combined treatments sequestered carbon at a rate from 0.20 to 0.48 t ha-1 year-1 under the double-rice and 0.70 to 0.88 t ha-1 year-1 under rice-wheat cropping system. The estimated annual SOC decomposition rate ranged from 0.15 to 0.82 t ha-1 at these studied sites. Our analyses revealed strong positive correlations between soil carbon sequestration and carbon input for all sites. Conclusions: We concluded that organic amendments applied as substitution and extra nutrients had significant effect on soil carbon sequestration and served as a carbon sink for the duration of the experiments. Paddy soil high in clay content had the potential to sequester more carbon. Soil carbon sequestration efficiency-declined with carbon input at some sites with loam soil texture, suggesting applying a large amount of organic amendments is not recommended as a sustainable agricultural management practice because of the high risk of non-point environment pollution. © 2012 Springer-Verlag. Source


Ji X.,Soil and Fertilizer Institute of Hunan Province | Liu S.,Soil and Fertilizer Institute of Hunan Province | Huang J.,Soil and Fertilizer Institute of Hunan Province | Bocharnikova E.,RAS Institute of Chemistry | Matichenkov V.,RAS Institute of Basic Biological Problems
Chemosphere | Year: 2016

The contamination of agricultural areas by heavy metals has a negative influence on food quality and human health. Various remediation techniques have been developed for the removal and/or immobilization of heavy metals (HM) in contaminated soils. Phytoremediation is innovative technology, which has advantages (low cost, easy monitoring, high selectivity) and limitations, including long time for procedure and negative impact of contaminants on used plants. Greenhouse investigations have shown that monosilicic acid can be used for regulation of the HM (Cd, Cr, Pb and Zn) mobility in the soil-plant system. If the concentration of monosilicic acid in soil was increased from 0 to 20 mg L-1 of Si in soil solution, the HM bioavailability was increased by 30-150%. However, the negative influence on the barley by HM was reduced under monosilicic acid application. If the concentration of monosilicic acid was increased more than 20 mg L-1, the HM mobility in the soil was decreased by 40-300% and heavy metal uptake by plants was reduced 2-3 times. The using of the monosilicic acid may increase the phytoremediation efficiency. However the technique adaptation will be necessary for phytoremediation on certain areas. © 2016 Elsevier Ltd. Source

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