• Authors:
    • Lai, X. J.
    • Jiang, J. H.
    • Gemmer, M.
    • Tao, H.
    • Zhang, Z. X.
  • Source: CLIMATIC CHANGE
  • Volume: 111
  • Issue: 3-4
  • Year: 2012
  • Summary: The projected changes of precipitation and temperature in the Yangtze River Basin in the 20th Century from 20 models of the CMIP3 (phase 3 of the Coupled Model Inter-comparison Project) dataset are analyzed based on the observed precipitation and temperature data of 147 meteorological stations in the Yangtze River Basin. The results show that all models tend to underestimate the annual mean temperature over the Yangtze River Basin, and to overestimate the annual mean precipitation. The temporal changes of simulated annual mean precipitation and temperature are broadly comparable with the observations, but with large variability among the results of the models. Most of the models can reproduce maximum precipitation during the monsoon season, while all models tend to underestimate the mean temperature of each month over the Yangtze River Basin. The Taylor diagram shows that the differences between modeled and observed temperature are relatively smaller as compared to differences in precipitation. For a detailed investigation of regional characteristics of climate change in the Yangtze River Basin during 2011-2050, the multi-model ensembles produced by an upgraded REA method are carried out for more reliable projections. The projected precipitation and temperature show large spatial variability in the Yangtze River Basin. Mean precipitation will increase under the A1B and B1 scenarios and decrease under the A2 scenario, with linear trends ranging from -21 to 28.5 mm/decade. Increasing mean temperature can be found in all scenarios with linear trends ranging from 0.15 to 0.48 degrees C/decade. Grids in the head region of the Jingshajiang catchment show distinct increasing trends for all scenarios. Some physical processes associated with precipitation are not well represented in the models.
  • Authors:
    • Zhang, F. S.
    • Yang, X. G.
    • Wang, E. L.
    • Wang, J.
    • Yin, H.
  • Source: CLIMATIC CHANGE
  • Volume: 113
  • Issue: 3-4
  • Year: 2012
  • Summary: In the North China Plain, the grain yield of irrigated wheat-maize cropping system has been steadily increasing in the past decades under a significant warming climate. This paper combined regional and field data with modeling to analyze the changes in the climate in the last 40 years, and to investigate the influence of changes in crop varieties and management options to crop yield. In particular, we examined the impact of a planned adaptation strategy to climate change -"Double-Delay" technology, i.e., delay both the sowing time of wheat and the harvesting time of maize, on both wheat and maize yield. The results show that improved crop varieties and management options not only compensated some negative impact of reduced crop growth period on crop yield due to the increase in temperature, they have contributed significantly to crop yield increase. The increase in temperature before over-wintering stage enabled late sowing of winter wheat and late harvesting of maize, leading to overall 4-6% increase in total grain yield of the wheat-maize system. Increased use of farming machines and minimum tillage technology also shortened the time for field preparation from harvest time of summer maize to sowing time of winter wheat, which facilitated the later harvest of summer maize.
  • Authors:
    • Zhang, S. L.
    • Sun, B. H.
    • Ren, W. D.
    • Yang, X. Y.
  • Source: GEODERMA
  • Volume: 177
  • Year: 2012
  • Summary: Labile soil organic carbon pools are valuable indicators of soil quality, early changes in soil total organic carbon (TOC) stocks, and (hence) changes in soil carbon sequestration pools and dynamics induced by changes in soil management practices. To improve the management of loess soils in China, we have examined effects of soil and nutrient management treatments applied in a 20-year experiment on TOC and the following fractions: particulate organic carbon (POC), light fraction organic carbon (LFOC), microbial biomass carbon (MBC) and permanganate oxidizable carbon (KMnO4 C). The soil management regimes were cropland abandonment (Abandonment), bare fallow without vegetation (Fallow) and a wheat-maize cropping system (Cropping). Cropping was combined with the following nutrient management treatments: control (CM, no nutrient input), nitrogen only (N), nitrogen and potassium (NK), phosphorus and potassium (PM), NP, NPK, straw plus NPK (SNPK) and two levels of manure (M, 13.7 and 20.6 t ha(-1)) plus NPK (M1NPK and M2NPK). After 20 years, the Fallow treatment resulted in significantly lower TOC by 22% and labile C fractions by 29%-43% except MBC than Cropping, while Abandonment markedly increased all labile C fractions by 43%-64% except POC relative to Cropping, but the Abandonment and Cropping regimes resulted in similar TOC contents (10.75 g kg(-1) and 10.16 g kg(-1), respectively). Of the four C fractions, LFOC and KMnO4 C were the most sensitive indicators of changes in TOC induced by the soil management regimes. Under Cropping, TOC contents were similar in NP, NPK and SNPK plots, and significantly higher than those in CM plots (by 34%, 32% and 45%, respectively). Manure addition further enhanced TOC contents, which were highest following the M2NPK treatment (13.88 g kg(-1)). Labile C fractions were also significantly higher following the treatments including organic amendment than following applications solely of chemical fertilizers, except that the SNPK, NP and NPK treatments resulted in similar LFOC contents. Application solely of chemical fertilizers had no significant effects on LFOC and KMnO4 C fractions compared with CM. Nevertheless, application of NP or NPK significantly increased contents of POC and MBC relative to CM (by 115% and 90% or 31% and 53%, respectively). Thus, LFOC and KMnO4 C fractions were not sensitive indicators of changes in TOC induced by mineral nutrient management practices under current conditions. Overall, given the minor differences between the effects of the NP and NPK treatments, application of manure and NP appears to be the most suitable management practice for improving TOC sequestration in the loess soil. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Xing, S. H.
    • Wang, S. H.
    • Xu, S. X.
    • Shi, X. Z.
    • Yu, D. S.
    • Zhang, L. M.
    • Zhao, Y. C.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 121
  • Year: 2012
  • Summary: Regional soil organic carbon (SOC) modeling is the dominant approach for regional and global carbon cycling assessment, but the models are often applied to regions with high heterogeneity that are not adequately represented by the spatially limited soil data. This study used version 9.1 of the denitrification-decomposition (DNDC) model with the most detailed soil database for the paddy region of China. The database is a 1:50,000 record derived from 1107 paddy soil profiles with 52,034 polygons. The simulations suggested that the 2.3Mha of paddy soils in the Tai-Lake region had a net sequestration of about 1.48TgC from 1982 to 2000, with the annual SOC change ranging from -45 to 92kgCha -1y -1. In general, paddy soils in the Tai-Lake region were a weak sink of atmospheric CO 2. Highest SOC loss (-201kgCha -1y -1) was associated with the gleyed paddy soil subgroup. Highest SOC sequestration (205kgCha -1y -1) was associated with the submergenic paddy soil subgroup. On a regional basis, model simulations indicated a C loss in the polder region (-39kgCha -1y -1), but this was offset by increases in the alluvial plain (104kgCha -1y -1), low mountainous and hilly region (87kgCha -1y -1), and Tai-Lake Plain (7kgCha -1y -1). At the administrative scale, SOC of most counties in Zhejiang Province decreased, while it increased in Jiangsu Province and Shanghai City. Overall, the SOC change in the Tai-Lake region was strongly influenced by paddy subgroup, sub-region, and administrative area, because of the high variability in soil properties. This emphasizes that the use of detailed soil data sets with high-resolution digital soil maps and robust soil profile data essential for creating accurate models of the soil carbon cycle.
  • Authors:
    • Liang, W.
    • Chen, L.
    • Wei, K.
    • Zhang, X.
    • Li, Q.
    • Zhang, S.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 124
  • Year: 2012
  • Summary: Tillage strongly affects the process of soil aggregate stabilization, which involves a variety of binding mechanisms interacting at a range of spatial scales. To understand how binding mechanisms interact to promote soil aggregation, the impacts of three tillage systems (no tillage (NT), ridge tillage (RT) and conventional tillage (CT)) on soil aggregate binding agents (i.e., organic carbon (SOC), microbial biomass and glomalin-related soil proteins (GRSPs)) and aggregation were studied in the black soil of Northeast China. Compared with CT, RT increased all the aggregate-associated SOC, and NT only increased the SOC in the microaggregates. However, the contents of microbial biomass and GRSPs within bulk soil and different aggregate fractions were higher in NT and RT than in CT. Among the four aggregate fractions, greater values of SOC, microbial biomass and easily extractable GRSP (EEGRSP) were found in microaggregates and macroaggregates, respectively; while the total GRSP (TGRSP) was distributed equally among aggregate fractions. Structural equation modelling revealed that SOC, microbial biomass, and GRSPs accounted for 79% of the variation in soil aggregation. Soil organic carbon influenced aggregate stability indirectly through the effects on MBC and MBN. Microbial biomass and glomalin were more important driving factors for aggregate stability in the RT and NT systems. Our results suggest that conservation tillage (RT and NT) is beneficial for soil structure due to its positive effects on aggregation processes in black soil region of Northeast China.
  • Authors:
    • Yao, J.
    • Mahmood, Q.
    • He, M.
    • Tian, G.
    • Wu, X.
    • Pan, D.
  • Source: Journal of Food, Agriculture & Environment
  • Volume: 10
  • Issue: 3-4
  • Year: 2012
  • Summary: A better comprehension of carbon dynamics during agricultural production requires an understanding of the CO2 and CH4 fluxes from an agro-ecosystem after fertilisation. The dynamics of CO2 and CH4 fluxes for plant-soil ecosystems in a ventilated transparent greenhouse were evaluated after a pig manure compost or inorganic fertiliser application at the rate of 150 kg N ha(-1) during Brassica chinensis growth from seedling to maturity. Gas samples for the plant-soil ecosystems were collected using a static chamber approach, and the concentrations of CO2 and CH4 were determined using gas chromatography. The results showed that CO2 was fixed by the plant-soil ecosystem during Brassica chinensis growth after fertilisation and the CO2 and CH4 fluxes were not significantly different among the treatments compared with the control. The ecosystem uptake of CO2 increased with the soil temperature and the variation was in agreement with a first-order exponential curve. The temperature sensitivity of the CO2 efflux at the ecosystem level for the pig manure compost, inorganic fertiliser and control treatments were 7.97, 9.82 and 8.88, respectively. There was a positive correlation between the soil microbial biomass carbon and the CO2 uptake for both fertiliser treatments, whereas the CO2 uptake for the control treatment was increased by the soil microbial biomass nitrogen. The plant-soil ecosystems were minor CH4 sinks and sources, and the CH4 flux ranged from -5.56 to 4.23 mg CH4 m(-2)h(-1) for all of the treatments. The CH4 consumption for the pig manure compost and inorganic fertiliser treatments were negatively correlated with the soil microbial biomass nitrogen, whereas that for the control treatment showed a significant negative correlation with the soil nitrate-N. The results indicate that a plant-soil ecosystem could be a carbon sink, and that fertiliser application had no significant effects on either the CO2 or the CH4 uptake in a plant-soil ecosystem.
  • Authors:
    • Kuzyakov, Y.
    • Li, X.
    • Marschner, P.
    • Guo, J.
    • Fan, M.
    • Tian, J.
  • Source: European Journal of Soil Biology
  • Volume: 52
  • Issue: September–Octobe
  • Year: 2012
  • Summary: In the last three decades there has been a major shift in China's agriculture with the conversion from cereal fields to vegetable production, however little is known about the impact of this land use change on labile soil carbon and microbial community structure. We conducted a study to characterize dissolved organic carbon (DOC) and soil microbial community by comparing greenhouse vegetable fields with contrasting management intensity and adjacent cereal fields (wheat maize rotation) in Shouguang and Quzhou in North China. Compared with cereal fields, greenhouse vegetable cultivation increased soil organic carbon (SOC) and total nitrogen (TN), while it decreased the soil pH, particularly at the high-intensity site. The DOC concentration was significantly higher in greenhouse vegetable fields than in cereal fields, whereas DOC composition differed between greenhouse vegetable fields and cereal fields only at high management intensity. Chemical fractionation indicated that DOC from greenhouse vegetable fields with high management intensity was less decomposed than DOC from cereal fields, because the percentage of hydrophobic acid (HOA) as DOC was higher in vegetable fields. Vegetable production significantly changed the microbial community structure in comparison to cereal fields: high-intensity management increased total bacteria, G (+) bacteria and fungi, while low-intensity decreased fungi and increased bacteria-to-fungi ratio. The main factor affecting microbial community structure was soil pH in this study, accounting for 24% of the differences. (C) 2012 Elsevier Masson SAS. All rights reserved.
  • Authors:
    • Chi, S.
    • Li, Z.
    • Han, H.
    • Li, N.
    • Wang, B.
    • Zhao, H.
    • Ning, T.
    • Tian, S.
  • Source: Web Of Knowledge
  • Volume: 7
  • Issue: 12
  • Year: 2012
  • Summary: The objective of this study was to quantify soil methane (CH4) and nitrous oxide (N2O) emissions when converting from minimum and no-tillage systems to subsoiling (tilled soil to a depth of 40 cm to 45 cm) in the North China Plain. The relationships between CH4 and N2O flux and soil temperature, moisture, NH4+-N, organic carbon (SOC) and pH were investigated over 18 months using a split-plot design. The soil absorption of CH4 appeared to increase after conversion from no-tillage (NT) to subsoiling (NTS), from harrow tillage (HT) to subsoiling (HTS) and from rotary tillage (RT) to subsoiling (RTS). N2O emissions also increased after conversion. Furthermore, after conversion to subsoiling, the combined global warming potential (GWP) of CH4 and N2O increased by approximately 0.05 kg CO2 ha(-1) for HTS, 0.02 kg CO2 ha(-1) for RTS and 0.23 kg CO2 ha(-1) for NTS. Soil temperature, moisture, SOC, NH4+-N and pH also changed after conversion to subsoiling. These changes were correlated with CH4 uptake and N2O emissions. However, there was no significant correlation between N2O emissions and soil temperature in this study. The grain yields of wheat improved after conversion to subsoiling. Under HTS, RTS and NTS, the average grain yield was elevated by approximately 42.5%, 27.8% and 60.3% respectively. Our findings indicate that RTS and HTS would be ideal rotation tillage systems to balance GWP decreases and grain yield improvements in the North China Plain region. Citation: Tian S, Ning T, Zhao H, Wang B, Li N, et al. (2012) Response of CH4 and N2O Emissions and Wheat Yields to Tillage Method Changes in the North China Plain. PLoS ONE 7(12): e51206. doi:10.1371/journal.pone.0051206
  • Authors:
    • Wang, M.
    • Li, D.
    • Zhang, P.
    • Li, N.
    • Wan, Y.
  • Source: Agricultural Science & Technology
  • Volume: 13
  • Issue: 2
  • Year: 2012
  • Summary: Objective: To analyze the positioning of low-carbon agriculture development in local governments of China. Method: The emissions of green-house gas, the connotation and characteristics of low-carbon agriculture, and the necessity of developing low-carbon agriculture were analyzed, obtaining the positioning and measures for the development of low-carbon agriculture in local government. Result: Government plays a leading role in the development of low-carbon agriculture. The development of low-carbon agriculture can be promoted through the formulation of scientific low-carbon agricultural development plan, culturing new talents on low-carbon agriculture, promoting low-carbon agricultural technology, establishing low-carbon agricultural risk prevention mechanisms. Conclusion: Making economy, environment and resources coordinated with each other, leading by the concept of scientific development with the concept of sustainable development, is where the future of agricultural development in China lies.
  • Authors:
    • Xiong, Z.
    • Zhang, X.
    • Liu, Y.
    • Pan, X.
    • Wang, J.
  • Source: Plant and Soil
  • Volume: 360
  • Issue: 1-2
  • Year: 2012
  • Summary: Worldwide, there is an increasing interest in using biochar in agriculture to help mitigate global warming and improve crop productivity. The effects of biochar on greenhouse gas (GHG) emissions and rice and wheat yields were assessed using outdoor pot experiments in two different soils (upland soil vs. paddy soil) and an aerobic incubation experiment in the paddy soil. Biochar addition to the upland soil increased methane (CH4) emissions by 37 % during the rice season, while it had no effect on CH4 emissions during the wheat season. Biochar amendment decreased nitrous oxide (N2O) emissions up to 54 % and 53 % during the rice and wheat seasons, respectively, but had no effect on the ecosystem respiration in either crop season. In the aerobic incubation experiment, biochar addition significantly decreased N2O emissions and increased carbon dioxide (CO2) emissions from the paddy soil (P < 0.01) without urea nitrogen. Biochar addition increased grain yield and biomass if applied with nitrogen fertilizer. Averaged over the two soils, biochar amendments increased the production of rice and wheat by 12 % and 17 %, respectively, and these increases can be partly attributed to the increases in soil nitrate retention. Our results demonstrated that although biochar increased the global warming potential at high nitrogen fertilizer application, biochar incorporation significantly decreased N2O emissions while promoting crop production.