• Authors:
    • Chen, X.
    • Jia, S.
    • Liang, A.
    • McLaughlin, N. B.
    • Zhang, X.
    • Wei, S.
    • Chen, X.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 144
  • Year: 2014
  • Summary: The CO2 flux from soils is an important part of the global carbon (C) cycle, whose dependence on erosion is as yet largely unknown. We hypothesized that erosion affects CO2 flux from the soil surface because of its effects on soil temperature and soil moisture. The CO2 flux, soil temperature, and soil moisture were monitored on summit, shoulder-slope, back-slope, and toe-slope on a sloping corn field in the black soil zone in northeast China once a day for 47 days between August 3 and September 18. The average CO2 flux varied significantly with slope positions ranging from 2.5±0.29 (mean±standard deviation)μmolm-2s-1 at summit to 1.5±0.32μmolm-2s-1 at toe-slope in the initial 27 days, but no significant difference among slope positions was observed in the last 20 days. Soil moisture contributed largely to CO2 flux in the initial 27 days, and soil temperature became the most important factor affecting CO2 flux in the last 20 days. In our study, second-order and first order regressions were fit the best models to predict CO2 flux at various slope positions based, respectively, on soil moisture content and soil temperature, with respective R2 ranging from 0.532 to 0.661 and 0.234 to 0.448.
  • Authors:
    • Lv, Y. Z.
    • Huang, F.
    • Zhao, N.
    • Yang, Z. C.
  • Source: SOIL & TILLAGE RESEARCH
  • Year: 2014
  • Summary: The aim of the study is to analyze the effects of different fertilization of organic and inorganic fertilizers on soil organic carbon (SOC) sequestration and crop yields after a 22 years long-term field experiment. The crop yields and SOC were investigated from 1981 to 2003 in Dry-Land Farming Research Institute of Hebei Academy of Agricultural and Forestry Sciences, Hebei Province, China. The dominant cropping systems are winter wheat-summer corn rotation. There were totally sixteen treatments applied to both wheat and corn seasons: inorganic fertilizers as main plots and corn stalks as subplots and the main plots and subplots all have four levels. The results revealed: after 22 years, mixed application of inorganic fertilizers and crop residuals, the SOC and crop yields substantially increased. Higher fertilizer application rates resulted in greater crop yields improvement. In 2002-2003, wheat and corn for the highest fertilizer inputs had the highest yield level, 6400 kg ha-1 and 8600 kg ha-1, respectively. However, the SOC decreased as the excessive inorganic fertilizer input and increased with the rising application of corn stalks. The treatment of the second-highest inorganic fertilizer and the highest corn stalks had the highest SOC concentration (8.64 g C kg-1). Pearson correlation analysis shows that corn and winter wheat yields and the mineralization amount of SOC have significant correlation with SOC at p < 0.05 level.
  • Authors:
    • Zhou, D. W.
    • Diabate, B.
    • Shen, X. J.
    • Zheng, W.
    • Li, G. D.
    • Jia, H.T.
    • Li, Q.
    • Yu, P.J.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 5
  • Year: 2014
  • Summary: The accurate estimation of soil C stock is important for understanding the global C cycles. Particularly in arid regions, quantification of soil inorganic carbon (SIC) is required in addition to the more frequently reported soil organic carbon (SOC). We analyzed SOC, SIC, soil bulk density (BD), electrical conductivity (EC) and pH of alkali-saline soils at a 0- to 100-cm depth in a cultivation chronosequence that consisted of a meadow steppe site and four cropped sites with maize ( Zea mays L.) for 1, 7, 17, and 24 yr in Songnen Plain, Northeast China to quantify SOC and SIC dynamics. Results showed that SOC stock in 0 to 100 cm soil was 92.3, 83.7, 80.9, 78.2, and 76.9 Mg C ha -1 for Steppe, Crop-1Y, Crop-7Y, Crop-17Y, and Crop-24Y, respectively, decreased at a rate of 3.63 Mg C ha -1 yr -1. In contrast, SIC stock, ranging from 159.0 to 179.4 Mg C ha -1 increased at a rate of 0.53 Mg C ha -1 yr -1 in 0- to 100-cm depth. The soil total carbon (STC) stock increased at a rate of 0.46 Mg C ha -1 yr -1 following land use conversion, peaked in the seventh year of cultivation and then declined at a rate of 0.89 Mg C ha -1 yr -1. The SOC concentrations were negatively correlated with BD, EC, and pH, but SIC concentrations were positively correlated with soil BD, EC, and pH. The findings underline the importance of including SIC in the soil C estimates while considering deep soil profile and longer cultivation period.
  • Authors:
    • Pan, G.
    • Parton, W. J.
    • Ogle, S. M.
    • Cheng, K.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 3
  • Year: 2014
  • Summary: Understanding the potential for greenhouse gas (GHG) mitigation in agricultural lands is a critical challenge for climate change policy. This study uses the DAYCENT ecosystem model to predict GHG mitigation potentials associated with soil management in Chinese cropland systems. Application of ecosystem models, such as DAYCENT, requires the evaluation of model performance with data sets from experiments relevant to the climate and management of the study region. DAYCENT was evaluated with data from 350 cropland experiments in China, including measurements of nitrous oxide emissions (N2O), methane emissions (CH4), and soil organic carbon (SOC) stock changes. In general, the model was reasonably accurate with R2 values for model predictions vs. measurements ranging from 0.71 to 0.85. Modeling efficiency varied from 0.65 for SOC stock changes to 0.83 for crop yields. Mitigation potentials were estimated on a yield basis (Mg CO2-equivalent Mg−1Yield). The results demonstrate that the largest decrease in GHG emissions in rainfed systems are associated with combined effect of reducing mineral N fertilization, organic matter amendments and reduced-till coupled with straw return, estimated at 0.31 to 0.83 Mg CO2-equivalent Mg−1Yield. A mitigation potential of 0.08 to 0.36 Mg CO2-equivalent Mg−1Yield is possible by reducing N chemical fertilizer rates, along with intermittent flooding in paddy rice cropping systems.
  • Authors:
    • Zhang, F. S.
    • Chen, X. P.
    • Ma, W. Q.
    • Ye, Y. L.
    • Wu, L.
    • Cui, Z. L.
  • Source: Biogeosciences
  • Volume: 11
  • Issue: 8
  • Year: 2014
  • Summary: Although the concept of producing higher yields with reduced greenhouse gas (GHG) emissions is a goal that attracts increasing public and scientific attention, the tradeoff between high yields and GHG emissions in intensive agricultural production is not well understood. Here, we hypothesize that there exists a mechanistic relationship between wheat grain yield and GHG emission, and that could be transformed into better agronomic management. A total 33 sites of on-farm experiments were investigated to evaluate the relationship between grain yield and GHG emissions using two systems (conventional practice, CP; high-yielding systems, HY) of intensive winter wheat (Triticum aestivum L.) in China. Furthermore, we discussed the potential to produce higher yields with lower GHG emissions based on a survey of 2938 farmers. Compared to the CP system, grain yield was 39% (2352 kg ha(-1)) higher in the HY system, while GHG emissions increased by only 10%, and GHG emission intensity was reduced by 21%. The current intensive winter wheat system with farmers' practice had a median yield and maximum GHG emission rate of 6050 kg ha(-1) and 4783 kg CO2 eq ha(-1), respectively; however, this system can be transformed to maintain yields while reducing GHG emissions by 26% (6077 kg ha(-1), and 3555 kg CO2 eq ha(-1)). Further, the HY system was found to increase grain yield by 39% with a simultaneous reduction in GHG emissions by 18% (8429 kg ha(-1), and 3905 kg CO2 eq ha(-1), respectively). In the future, we suggest moving the trade-off relationships and calculations from grain yield and GHG emissions to new measures of productivity and environmental protection using innovative management technologies.
  • Authors:
    • BaoHai, W.
    • Ying, L.
  • Source: Journal of Agricultural Science and Technology (Beijing)
  • Volume: 16
  • Issue: 2
  • Year: 2014
  • Summary: Since entering into the 21st century, greenhouse gas emissions have led to the continued global warming. Low-carbon environment protection has been raised on the agenda. The development of low-carbon eco-agriculture has become an effective way to solve China's agricultural resources exhaustion, to curb environment deterioration, and to achieve the sustainable development of China's agriculture. In 2009, the Yellow River Delta Efficient Ecological Economic Zone rose to the national strategy. Low-carbon agriculture has become the theme for the development of modern agriculture in the Yellow River Delta. This paper analyzed the necessity for the Yellow River Delta to develop Low-Carbon Eco-agriculture. Combining with the status quo of natural resources and environment in this area, and the requirement for developing Low-Carbon agriculture, the paper put up 5 models suitable for the Yellow River Delta to develop Low-Carbon Eco-agriculture. At the same time, a series of suggestions were put forward based on these models.
  • Authors:
    • Ming-gang, X.
    • Qi-mei, L.
  • Source: Journal of Integrative Agriculture
  • Volume: 13
  • Issue: 3
  • Year: 2014
  • Authors:
    • Tang, X.
    • Hu, C.
    • Zhang, W.
    • Liu, X.
  • Source: Biogeosciences
  • Volume: 11
  • Issue: 6
  • Year: 2014
  • Summary: The objectives of this study were to investigate seasonal variation of greenhouse gas fluxes from soils on sites dominated by plantation (Robinia pseudoacacia, Punica granatum, and Ziziphus jujube) and natural regenerated forests (Vitex negundo var. heterophylla, Leptodermis oblonga, and Bothriochloa ischcemum), and to identify how tree species, litter exclusion, and soil properties (soil temperature, soil moisture, soil organic carbon, total N, soil bulk density, and soil pH) explained the temporal and spatial variation in soil greenhouse gas fluxes. Fluxes of greenhouse gases were measured using static chamber and gas chromatography techniques. Six static chambers were randomly installed in each tree species. Three chambers were randomly designated to measure the impacts of surface litter exclusion, and the remaining three were used as a control. Field measurements were conducted biweekly from May 2010 to April 2012. Soil CO2 emissions from all tree species were significantly affected by soil temperature, soil moisture, and their interaction. Driven by the seasonality of temperature and precipitation, soil CO2 emissions demonstrated a clear seasonal pattern, with fluxes significantly higher during the rainy season than during the dry season. Soil CH4 and N2O fluxes were not significantly correlated with soil temperature, soil moisture, or their interaction, and no significant seasonal differences were detected. Soil organic carbon and total N were significantly positively correlated with CO2 and N2O fluxes. Soil bulk density was significantly negatively correlated with CO2 and N2O fluxes. Soil pH was not correlated with CO2 and N2O emissions. Soil CH4 fluxes did not dis-play pronounced dependency on soil organic carbon, total N, soil bulk density, and soil pH. Removal of surface litter significantly decreased in CO2 emissions and CH4 uptakes. Soils in six tree species acted as sinks for atmospheric CH4. With the exception of Ziziphus jujube, soils in all tree species acted as sinks for atmospheric N2O. Tree species had a significant effect on CO2 and N2O releases but not on CH4 uptake. The lower net global warming potential in natural regenerated vegetation suggested that natural regenerated vegetation were more desirable plant species in reducing global warming.
  • Authors:
    • Andren, O.
    • Zhao, X.
    • Luo, Y.
  • Source: Acta Agriculturae Scandinavica Section B-Soil and Plant Science
  • Volume: 64
  • Issue: 3
  • Year: 2014
  • Summary: Soil organic carbon (SOC) is a major source/sink in atmospheric carbon balances. Farmland usually has a high potential for carbon dioxide (CO2) uptake from the atmosphere, but also for emission. Data from different areas are valuable for global SOC calculations and model development, and a survey of 108 agricultural fields in Lanzhou, China was performed. The fields were grouped by: cropping intensity (3 levels), cropping methodology (3), and crop species (10). Intensive cropping (two or more crops per year, typically vegetables), moderate (annuals in monoculture: wheat, maize, potato, melons), and extensive (orchards, lily [Lilium brownii] fields, fallow) were the intensity classes; and open field, greenhouse field, and sand-covered field (10-20 cm added on top of the topsoil) were the three methodologies. SOC concentration, pH, electrical conductivity, and soil bulk density were measured, and SOC mass (gm(-2) 0-20 cm depth) was calculated. SOC concentration was high in cauliflower, wheat, leaf vegetables, and fruit vegetables; moderate in potato, fallow (3-5 years), tree orchards, and melons; while low in lily and maize fields, and differences in SOC mass followed the same pattern. SOC concentration and mass were lowest in the extensive fields while moderate and intensive fields showed higher values. Soil bulk density in open fields was significantly lower than those in greenhouse and sand-covered fields. The climate-induced soil activity factor r(e_clim) was calculated, compared with European conditions, and was fairly similar to those in central Sweden. Other factors behind the measured results, such as the influence of initial SOC content, manure addition, crops, etc., are discussed.
  • Authors:
    • Christie, P.
    • Tian, C.
    • Li, K.
    • Wang, X.
    • Liu, H.
    • Liu, X.
    • Lv, J.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 98
  • Issue: 1
  • Year: 2014
  • Summary: A long-term fertilizer experiment investigating cotton-based cropping systems established in 1990 in central Asia was used to quantify the emissions of CO2, CH4 and N2O from April 2012 to April 2013 to better understand greenhouse gas (GHG) emissions and net global warming potential (GWP) in extremely arid croplands. The study involved five treatments: no fertilizer application as a control (CK), balanced fertilizer NPK (NPK), fertilizer NPK plus straw (NPKS), fertilizer NPK plus organic manure (NPKM), and high rates of fertilizer NPK and organic manure (NPKM+). The net ecosystem carbon balance was estimated by the changes in topsoil (0-20 cm) organic carbon (SOC) density over the 22-year period 1990-2012. Manure and fertilizer combination treatments (NPKM and NPKM+) significantly increased CO2 and slightly increased N2O emissions during and outside the cotton growing seasons. Neither NPK nor NPKS treatment increased SOC in spite of relatively low CO2, CH4 and N2O fluxes. Treatments involving manure application showed the lowest net annual GWP and GHG intensity (GHGI). However, overuse of manure and fertilizers (NPKM+) did not significantly increase cotton yield (5.3 t ha(-1)) but the net annual GWP (-4,535 kg CO2_eqv. ha(-1)) and GHGI (-0.86 kg CO2_eqv. kg(-1) grain yield of cotton) were significantly lower than in NPKM. NPKS and NPK slightly increased the net annual GWP compared with the control plots. Our study shows that a suitable rate of fertilizer NPK plus manure may be the optimum choice to increase soil carbon sequestration, maintain crop yields, and restrict net annual GWP and GHGI to relatively low levels in extremely arid regions.