• Authors:
    • Hu, K.
    • Wei, Y.
    • Wu, W.
    • Zheng, L.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 145
  • Year: 2015
  • Summary: Understanding the effects of straw return and regional factors on changes of soil organic matter (SOM) is helpful for improving soil quality and sustaining high crop productivity in intensive agro-ecosystems. This study focuses on the changes in SOM of agricultural soils in a high yielding area of Huantai County, northern China, for which data are available for 1982, 1996 and 2011. The spatio-temporal patterns of SOM, and the factors that influence them, were analyzed before and after widespread implementation of straw retention practices in large areas. The results showed that the average SOM contents in the cultivated layer were 13.24, 15.06 and 18.73gkg-1 in 1982, 1996 and 2011, respectively. The rate of increase in SOM contents during 1996-2011 was approximately twice that of 1982-1996. Semivariogram analysis results showed that the spatial correlation distances of SOM in 1982 and 1996 were 8.78km and 4.02km, respectively, while the pattern was a pure nugget effect in 2011, reflecting that the influence of human activities on SOM content increased over time. During 1982-1996 straw retention practices had not been implemented in large areas and the increase of average SOM content was relatively small, and even declined in some sub-regions. In contrast, the average SOM content of the entire county generally increased from 1996 to 2011 after straw return was implemented in large areas. The effects of topography on SOM distribution can be ignored because the county is relatively flat. From 1982 to 1996 regional factors such as soil type and soil texture had moderate impacts on SOM distribution. From 1996 to 2011 increased straw return resulted in substantially increased SOM, while the effects of soil type and soil texture were weakened. Straw return increased carbon sequestration in an intensive agro-ecosystem in this region and should be recommended as a long-term management practice to improve soil fertility and sustain high crop yields, as well as to store carbon and reduce greenhouse gas emissions. © 2014 Elsevier B.V.
  • Authors:
    • Shi, X.
    • Liu, Y.
    • Jin, W.
    • Zhang, M.
    • Zhang, H.
    • Yu, D.
    • Dong, L.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 145
  • Year: 2015
  • Summary: Given the positive effects of mediating the growth of greenhouse gases in the atmosphere, interest in soil carbon stock dynamics has greatly increased. Several questions still exist as to whether irrigation with sediment laden water benefits carbon sequestration in soil profiles. This case study documented how long-term irrigation with sediment laden water from the Yellow River affected soil carbon sequestration in the Ningxia Irrigation Zone, China. The study included eight durations of irrigation management (10, 20, 30, 50, 280, 1300, 2100, and 2200 years) and five soil types. Soil samples from 44 profiles were collected to a depth of 100. cm, divided into four layers (0-20, 20-30, 30-60, 60-100 cm), and analyzed for soil organic carbon (SOC). SOC stocks both of soil profiles (0-100 cm) and irrigation-silted soil (ISS) layer, were 28.2 Tg C and 24.1 Tg C, respectively. The ISS layer was formed by the overlapping actions of irrigation and tillage, manure addition, and sediment silting as a result of long-term irrigation from the sediment laden water of the Yellow River. Compared to non-irrigated and non-cultivated control soils of similar depths and thicknesses, SOC stocks of the ISS layer increased 16.9. Tg C, and accounted for 89.9% of a total increment of 18.8 Tg C in the 0-100 cm layer of irrigated cropland soils. A significant correlation was found between the SOC density increment of the ISS layer and the number of irrigation years. Long-term irrigation with sediment laden Yellow River water greatly influenced SOC stocks, especially in the ISS layer, which plays an important role in soil carbon sequestration.
  • Authors:
    • Zhang, X. X.
    • Hu, X. B.
    • Zhang, G. S.
    • Li, J.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 145
  • Year: 2015
  • Summary: Plastic mulch is widely used for vegetable cropping in the mid-Yunnan plateau, southwestern China. However, the effects of plastic mulch on soil physical properties are poorly understood. A field experiment was conducted to evaluate the effects of different plastic mulch patterns (narrow and wide plastic mulch) and rotations (broccoli-zucchini-winter wheat and broccoli-zucchini-fallow) on soil physical properties and soil organic carbon content in a vegetable production system at a research station in the region. The experiment comprised four treatments and laid out in the field using randomized complete block design replicated nine times. The soil (0-20cm) under wide plastic mulch retained more water than the soil narrow plastic mulch under the vegetable growing season over 3 consecutive severe drought years. Significant decline (11%) of surface soil (0-5cm) organic carbon was observed in 2012 compared with in 2010, but soil organic carbon and physical properties did not differ significantly between the two different plastic mulch patterns. The higher macro-porosity, aggregate stability, Ksat and lower bulk density in the plastic mulched ridges imply that the conversion from narrow-plastic-mulch to wide-plastic-mulch increases mulched area thereby conserving larger area soil structure in the croplands. Although increased catch crop stubble retention in the furrows apparently improved surface soil macro-porosity and saturated hydraulic conductivity, the autumn rotary cultivation in broccoli-zucchini-winter wheat rotation system has significantly decreased (5%) surface soil organic carbon. The results suggested that continued use of vegetable-cereal crop rotation system, even with stubble retention, may result in loss soil organic carbon. Further research that covers wetter years should be taken to assess effects of vegetable-cereal crop rotation pattern on soil physical properties in this region.
  • Authors:
    • Zhang, Q.
    • Hu, C.
    • Ren, T.
    • Du, Z.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 146
  • Issue: Pt. A
  • Year: 2015
  • Summary: Physical protection by soil aggregates is critical for building soil organic carbon (SOC) stock. The objective of this study was to identify SOC sequestrated in the microaggregate holding within macroaggregte (mM) fraction after shifting tillage systems in the North China Plain. Soil samples from 0-5. cm layer of a 6-yr field experiment (MP. -. R, moldboard plow without residue; MP. +. R, moldboard plow with residue; RT, rotary tillage with residue; NT, no-till with residue) were collected and separated into different water-stable aggregates. The macroaggregate (250-2000. µm) was further isolated into intra-aggregate particulate organic matter (iPOM) fractions by density flotation, dispersion and sieving. The results showed that the SOC concentration of fine iPOM (250f, 53-250. µm) was increased by 23% in RT and 39% in NT compared with MP. +. R, whereas the difference in the coarse iPOM (250c, >250. µm) was not observed. The ratio of 250f-250c (i.e., 250f/250c) followed the order of NT (2.12). ˜. RT (1.94). >. MP. +. R (1.50). ˜. MP. -. R (1.47), indicating the alternative tillage systems decreased the turnover rates of macroaggregates. Adoption of NT and RT improved the mM formation by 36% and 23% and mM associated C concentration by 38% and 31% as relative to MP. +. R system. Additionally, the soil C concentration and storage of the iPOM and silt plus clay fractions located within the microaggregate were higher under NT and RT than that of MP. +. R and MP. -. R systems. Thus applying NT and RT improved mM formation and soil C sequestered inside this fraction. We concluded that adoption of NT and RT enhanced SOC sequestration in the microaggregates of surface soil of the intensive agroecosystem of North China.
  • Authors:
    • Chen, Y.
    • Zhang, H.
    • Jiang, Q.
    • Guo, L.
    • Liu, Y.
  • Source: Soil and Tillage Research
  • Volume: 148
  • Year: 2015
  • Summary: Soil organic carbon density (SOCD) has strong spatial variability and dependency, and its impact factors vary with changes in scale and geographic location. With 272 topsoil samples (0-30cm) collected from Chahe Town in the Jianghan Plain, China, we (i) investigated the impacts of environmental variables and land cover types on the spatial distribution of SOCD; (ii) estimated the spatial distribution of SOCD by using global and local spatial interpolation models, including geographically weighted regression kriging (GWRK), regression kriging, geographically weighted regression (GWR), multiple linear regression (MLR), and ordinary kriging; and (iii) used mean absolute estimation error (MAEE), mean relative error (MRE), root mean square error (RMSE) and Pearson's correlation coefficients (r) to evaluate the performance of these models. SOCD was significantly correlated with elevation, normalized difference moisture index (NDMI), and the nearest distance to road (TRD) and residential area (p<0.05). The SOCD ranged from 0.33kgha-1 to 10.14kgha-1 for the topsoil in the study area. Most of the study area, especially the middle region, exhibited SOCD ranging from 4.3kgha-1 to 7.2kgha-1. The highest SOCD value was in wetland (5.45kgha-1) and the lowest was in unused land (4.18kgha-1). The effects of different environmental variables on SOCD can be revealed by the coefficients of GWR and MLR. The spatial distribution map of dominant variables can help us distinguish the essential environmental influence variables for SOCD in different geographical locations. GWRK outperformed the other models in terms of the lowest MAEE (0.984kgha-1), RMSE (1.665kgha-1), MRE (0.190), and high r (0.559) values. Thus, GWRK is a promising approach for mapping SOCD at a local scale.
  • Authors:
    • Jiang, Y. J.
    • Long, G. Q.
    • Sun, B.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 146
  • Issue: Pt. B
  • Year: 2015
  • Summary: Dissolved organic matter (DOM) plays an important role in soil biological activity and transport of pollutants and nutrients in soils, but very little information is available with regard to the long-term impact of agricultural management practices on the dynamics and fate of DOM in acidic soils. The seasonal and inter-annual variation of dissolved organic carbon (DOC) and nitrogen (DON) contents and leaching were investigated in an acidic clay soil (Ferric Acrisol) by a long-term field lysimeter experiment in subtropical China. The experiment was conducted from 2002 to 2010 with 4 fertilization treatments under maize monoculture: no manure (CK), low-rate manure with 150kgNha-1y-1 (LM), high-rate manure with 600kgNha-1y-1 (HM), and high-rate manure with 600kgNha-1y-1 and lime at 3000kg Ca(OH)2ha-13y-1 (HML). Manure application resulted in a seasonal variation of soil DOC and DON, and significant effects were observed by manure DOC, microbial biomass and soil water content. Soil DOC, which was mainly determined by soil organic matter and soil water content, increased yearly until the seventh year when it was stabilized. Manure application on acidic clay soil did not alter DOC leaching, whereas DON leaching clearly increased after three years of high manure application of 600kgNha-1y-1. The average annual DON leaching losses under long-term manure application had a range of 3.8-5.4kgha-1, accounting for 6-11% of total nitrogen leached. The addition of lime, combined with manure application, produced no impact on soil dynamics and leaching of DOC and DON, with the exception of increasing emission of CO2.
  • Authors:
    • Lin, E. D.
    • Ju, X. T.
    • de Perthuis, C.
    • Lin, Y. B.
    • Su, M.
    • Li, Y. C.
    • Guo, L. P.
    • Wang, W.
    • Moran, D.
  • Source: CLIMATIC CHANGE
  • Volume: 128
  • Issue: 1-2
  • Year: 2015
  • Summary: China faces significant challenges in reconciling food security goals with the objective of becoming a low-carbon economy. Agriculture accounts for approximately 11 % of China's national greenhouse gas (GHG) emissions with cereal production representing a large proportion (about 32 %) of agricultural emissions. Minimizing emissions per unit of product is a policy objective and we estimated the GHG intensities (GHGI) of rice, wheat and maize production in China from 1985 to 2010. Results show significant variations of GHGIs among Chinese provinces and regions. Relative to wheat and maize, GHGI of rice production is much higher owing to CH4 emissions, and is more closely related to yield levels. In general, the south and central has been the most carbon intensive region in rice production while the GHGI of wheat production is highest in north and northwest provinces. The southwest has been characterized by the highest maize GHGI but the lowest rice GHGI. Compared to the baseline scenario, a 2 % annual reduction in N inputs, combined with improved water management in rice paddies, would mitigate 17 % of total GHG emissions from cereal production in 2020 while sustaining the required yield increase to ensure food security. Better management practices will entail additional gains in soil organic carbon further decreasing GHGI. To realize the full mitigation potential while maximizing agriculture development, the design of appropriate policies should accommodate local conditions.
  • Authors:
    • Lv, Y. Z.
    • Huang, F.
    • Zhao, N.
    • Yang, Z. C.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 146
  • Issue: Pt. A
  • Year: 2015
  • 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, 6400kgha-1 and 8600kgha-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 (8.64gCkg-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:
    • Pan, J.
    • Li, K.
    • Wang, W.
    • Lin, E.
    • Ju, H.
    • Berry, P.
    • Hu, W.
    • Xiong, W.
    • Li, Y. C.
  • Source: CLIMATIC CHANGE
  • Volume: 128
  • Issue: 3-4
  • Year: 2015
  • Summary: Assessment of agricultural vulnerability to climate change is a prerequisite for developing effective adaptation options and strategies for the future. While assessment approaches vary across sectors and countries, there is a need to devise an effective method to assess agricultural vulnerability and provide information to policy-makers and stakeholders so that they can take appropriate adaptation actions. Agricultural vulnerability is analyzed as a function of exposure, sensitivity and adaptive capacity using a multi-indicator approach. Spatial and temporal assessment is undertaken through constructing maps of agricultural vulnerability in China. The results indicate that using multiple indicators is very practical for assessing agricultural vulnerability and that agricultural vulnerability is already significant in Guizhou, Guangxi and Yunnan provinces in China and will become more serious in the 2040s. It was also found that adaptive capacity was generally underdeveloped in poor regions, such as Guizhou, Yunnan and Gansu. We recommend that policy-makers increase investment in improving irrigation infrastructure and provide more opportunities for the education of farmers and stakeholders together with developing the economy in vulnerable areas.
  • Authors:
    • Lal, R.
    • Smith, P.
    • Meng, F. Q.
    • Wu, W. L.
    • Liao, Y.
  • Source: BIOGEOSCIENCES
  • Volume: 12
  • Issue: 5
  • Year: 2015
  • Summary: Agricultural intensification has contributed greatly to the sustained food supply of China's population of 1.3 billion over the 30-year period from 1982 to 2011. Intensification has several and widely recognized negative environmental impacts including depletion of water resources, pollution of water bodies, greenhouse gas emissions and soil acidification. However, there have been few studies over this period on the impacts of intensification on soil organic carbon (SOC) at the regional level. The present study was conducted in Huantai County, a typical intensive farming region in northern China, to analyze the temporal dynamics of SOC influenced by climate and farming practices. The results indicate that from 1982 to 2011, SOC content and density in the 0-20 cm layer of the cropland increased from 7.8 ± 1.6 to 11.0 ± 2.3 g kg-1 (41%) and from 21.4 ± 4.3 to 33.0 ± 7.0 Mg ha-1 (54%), respectively. The SOC stock (0-20 cm) of the farmland for the entire county increased from 0.75 to 1.2 Tg (59%). Correlation analysis revealed that incorporation of crop residues significantly increased SOC, while an increase in the mean annual temperature decreased the SOC level. Therefore, agricultural intensification has increased crop productivity and contributed to SOC sequestration in northern China. In the near future, more appropriate technologies and practices must be developed and implemented for a maintenance or enhancement of SOC in this region and elsewhere in northern China, which also reduce non-CO2 greenhouse gas emissions, since the climate benefit from the additional SOC storage is estimated to be smaller than the negative climate impacts of N2O from N fertilizer additions