• Authors:
    • Yuan, W.
    • Xia, J.
    • Zhang, H.
    • Chen, J.
    • Xiao, J.
    • Dong, W.
    • Cai, W.
    • Chen, Y.
    • Liu, D.
  • Source: LANDSCAPE ECOLOGY
  • Volume: 29
  • Issue: 10
  • Year: 2014
  • Summary: Forests play an important role in regulating atmospheric carbon dioxide concentration and mitigating the greenhouse effect. The Grain to Green Program (GGP) is one of the largest ecological programs in China, and it aims at converting croplands on steep slopes to forests. However, the magnitude and distribution of carbon sequestration induced by GGP remain unknown. In this study, we estimated the changes in carbon fluxes and stocks caused by forests converted from croplands under the GGP using a process-based ecosystem model (i.e., IBIS). Our results showed that the converted areas from croplands to forests under the GGP program could sequester 110.45 Tg C by 2020, and 524.36 Tg C by the end of this century. The sequestration capacity showed substantial spatial variations with large sequestration in southern China. The economic benefits of carbon sequestration from the GGP were also estimated according to the current carbon price. The estimated economic benefits ranged from $8.84 to $44.20 billion from 2000 through 2100, which may exceed the current total investment ($38.99 billion) on the program. As the GGP program continues and forests grow, the impact of this program will be even larger in the future, making a more considerable contribution to China’s carbon sink over the upcoming decades.
  • Authors:
    • Duan, W. X.
    • Cheng, D. J.
    • Bu, Q. G.
    • Li, Zizhong
    • Lu, X. J.
    • Sun, Z. H.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: The Corn Belt of Northeast China is the most important corn production area in China, accounting for 30% of the total corn production. However, seasonal drought conditions limit local corn production. Field experiments were conducted in 2011 and 2012 in Lishu county (Jilin Province, China) to study the effects of ridge and furrow rainfall harvesting and mulching on corn yields, evapotranspiration (ET), and water use efficiency (WUE) in black and aeolian sandy soils. The treatments included flat planting bed (FB), plastic-mulched ridges with bare furrows (RFB), and plastic-mulched ridges with straw-mulched furrows (RFM). For both soil types, the RFB and RFM treatments improved soil water conditions in the root zone. However, adding straw mulch did not consistently improve soil water content. In the black soil, the RFB treatment did not affect crop yield but increased WUE by 13% relative to the FB treatment in 2011. Furthermore, yield and WUE decreased by 30 and 24%, respectively, in 2012. In the aeolian sandy soil, the RFB treatment increased yield and WUE by 26 and 25%, respectively, relative to the FB treatment in 2011. However, the RFB treatment had no effect on yield or WUE in 2012. For both soil types, the RFM treatment did not significantly affect yield or WUE relative to the RFB treatment during 2011 or 2012. Therefore, the RFB treatment should only be used in aeolian sandy soils to achieve higher corn yields and WUEs and not be recommended for black soils when the soil water is sufficient.
  • Authors:
    • Rotter, R. P.
    • Zhang, Z.
    • Zhang, S.
    • Tao, F. L.
  • Source: GLOBAL CHANGE BIOLOGY
  • Volume: 20
  • Issue: 12
  • Year: 2014
  • Summary: Maize phenology observations at 112 national agro-meteorological experiment stations across China spanning the years 1981-2009 were used to investigate the spatiotemporal changes of maize phenology, as well as the relations to temperature change and cultivar shift. The greater scope of the dataset allows us to estimate the effects of temperature change and cultivar shift on maize phenology more precisely. We found that maize sowing date advanced significantly at 26.0% of stations mainly for spring maize in northwestern, southwestern and northeastern China, although delayed significantly at 8.0% of stations mainly in northeastern China and the North China Plain (NCP). Maize maturity date delayed significantly at 36.6% of stations mainly in the northeastern China and the NCP. As a result, duration of maize whole growing period (GPw) was prolonged significantly at 41.1% of stations, although mean temperature ( Tmean) during GPw increased at 72.3% of stations, significantly at 19.6% of stations, and Tmean was negatively correlated with the duration of GPw at 92.9% of stations and significantly at 42.9% of stations. Once disentangling the effects of temperature change and cultivar shift with an approach based on accumulated thermal development unit, we found that increase in temperature advanced heading date and maturity date and reduced the duration of GPw at 81.3%, 82.1% and 83.9% of stations on average by 3.2, 6.0 and 3.5 days/decade, respectively. By contrast, cultivar shift delayed heading date and maturity date and prolonged the duration of GPw at 75.0%, 94.6% and 92.9% of stations on average by 1.5, 6.5 and 6.5 days/decade, respectively. Our results suggest that maize production is adapting to ongoing climate change by shift of sowing date and adoption of cultivars with longer growing period. The spatiotemporal changes of maize phenology presented here can further guide the development of adaptation options for maize production in near future.
  • Authors:
    • Zhang, F. S.
    • Yue, S. C.
    • Cui, Z. L.
    • Chen, X. P.
    • Wang, G. L.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: A thorough understanding of reactive N (Nr) losses from N fertilization applications and the factors that influence it is necessary to better evaluate various Nr losses mitigation scenarios and improve N management practices. The objectives of this study were to develop empirical models to calculate Nr losses using meta-analysis and to evaluate trade-offs among grain yield, N recovery efficiency (RE N), and Nr loss intensity for in-season N management for intensive summer maize ( Zea mays L.) production in China. A meta-analysis with 55 studies and 170 observations suggested that both N 2O emissions and N leaching increased exponentially with the N application rate or N surplus, while NH 3 volatilization increased linearly with the N application rate. According to regression curves, models based on the N rate (N-R) and N surplus (N-S) were used to estimate Nr losses. Because the N-R did not account for large variations in RE N or grain yield across farmers' fields for difference competence in N management, estimated Nr losses were a little higher than those estimated by the N-S, especially for high-yield, high-RE N systems. Across 162 on-farm experimental sites, an in-season root-zone N management strategy with a 39% lower N application rate and 6% higher grain yield increased the RE N by 98% (from 16% to 31%) and reduced Nr loss intensity (based on the N-S) by 45% (from 13.6 to 7.5 kg N Mg -1) compared to farmers' typical N practices. In conclusion, the reconciliation of food security with greater environmental protection for the future can be driven by improved agronomic management to increase grain yield as well as RE N, rather than by solely focusing on optimizing the N application rate.
  • Authors:
    • Zhao, C.
    • Yin, G. D.
    • Zhang, X. P.
    • Peng, L. Q.
    • Wang, X. H.
    • Piao, S. L.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 196
  • Year: 2014
  • Summary: Northeast China (NEC), the most productive maize growing area in China, has experienced pronounced climate change. However, the impacts of historical climate changes on maize production and their spatial variations remain uncertain. In this study, we used yield statistics at prefecture scale over the past three decades, along with contemporary climate data, to explore the yield-climate relationship and its spatial variations. At the regional scale, maximum and minimum temperature changes had opposite impacts on maize yield, which increased by 10.07.7% in response to a 1°C increase in growing season mean daily minimum temperature ( Tmin), but decreased by 13.47.1% in response to a 1°C increase in growing season mean daily maximum temperature ( Tmax). Variations in precipitation seemed to have small impacts on the maize yield variations (-0.95.2%/100 mm). However, these responses of maize yield to climate variations were subject to large spatial differences in terms of both the sign and the magnitude. ~30% of the prefectures showed a positive response of maize yield to rising Tmax, which was in contrast to the negative response at the regional scale. Our results further indicate that the spatial variations in the yield response to climate change can be partly explained by variations in local climate conditions. The growing season mean temperature was significantly correlated with the response of maize yield to Tmax ( R=-0.67, P<0.01), which changes from positive to negative when the growing season mean temperature exceeds 17.90.2°C. Precipitation became the dominant climatic factor driving maize yield variations when growing season precipitation was lower than ~400 mm, but had a weaker influence than temperature over most of the study area. We conclude that, although NEC is a region spanning only more than one millions of kilometer squares, the divergence of the yield response to climatic variations highlights the need to analyze the yield-climate relationship at fine spatial scales.
  • Authors:
    • Barnett, J.
    • Webber, M.
    • Xu, H.
    • Wu, X.
    • Chen, J.
    • Wei, T.
    • Finlayson, B.
    • Chen, Z.
    • Li, M.
    • Wang, M.
  • Source: Estuarine, Coastal and Shelf Science
  • Year: 2014
  • Summary: The densely-populated mega-city of Shanghai relies increasingly on freshwater from the Changjiang estuary (70% now). However, this strategy is facing potential threats due to extensive water diversion in the lower Changjiang basin and future sea-level rise. Given this, the present study evaluates the ability of Shanghai to source its water from the estuary, especially in the dry season. Flow 0.45 for 20-65, 75-90 and 120-128 days (in 2020, 2030, and 2040, respectively), for extreme low-flow conditions. These periods exceed the present 68-day maximum freshwater storage in Qingcaosha reservoir, which is meant to secure freshwater for Shanghai in the future. Urgently countermeasures are needed to secure the Shanghai's water in the future. © 2014 Elsevier Ltd. All rights reserved.
  • Authors:
    • Jin, D. S.
    • Lu, C. D.
    • Zhang, Q.
    • Gao, C. H.
    • Li, J. H.
  • Source: Meteorological and Environmental Research
  • Volume: 5
  • Issue: 4
  • Year: 2014
  • Summary: Taking a three-year fertilization trial in mine reclamation soil from Shanxi Province, China as an example, the effects of different fertilization treatments on soil carbon storage and carbon fixation by corn were studied in this paper. Four treatments were designed in the experiment, including fertilizer (F), organic manure (M), half organic manure plus half fertilizer (FM) and control (CK). The results showed that fertilization had certain roles in increasing organic carbon storage of mine reclamation soil, and the application of single or combined organic and inorganic fertilizers had the most remarkable influence. Meanwhile, the treatment of single or combined organic and inorganic fertilizers could improve the carbon fixation capacity of corn prominently, and increased soil organic matter input. Thus, the application of organic manure or combined organic and inorganic fertilizer has great contribution to enhancing soil carbon sink and sustainable development of agriculture. However, the combined application of organic and inorganic fertilizer is the best choice for agricultural field based on economic consideration.
  • Authors:
    • Ziadi, N.
    • Zhang, J.
    • Qin, S.
    • Xiang, J.
    • Ding, W.
    • Fan, J.
  • Source: Geoderma
  • Volume: 230-231
  • Year: 2014
  • Summary: Understanding the balance between soil organic carbon (SOC) accumulation and depletion under different fertilization regimes is important for improving soil quality and crop productivity and for mitigating climate change. A long-term field experiment established in 1989 was used to monitor the influence of organic and inorganic fertilizers on the SOC stock in a soil depth of 0-60 cm under an intensive wheat-maize cropping system in the North China Plain. The study involved seven treatments with four replicates: CM, compost; HCM, half compost nitrogen (N) plus half fertilizer N; NPK, fertilizer N, phosphorus (P), and potassium (K); NP, fertilizer N and P; NK, fertilizer N and K; PK, fertilizer P and K; and CK, control without fertilization. Soil samples were collected and analyzed for SOC content in the 0-20 cm layer each year and in the 20-40 cm and 40-60 cm layers every five years. The SOC stock in the 0-60 cm depth displayed a net decrease over 20 years under treatments without fertilizer P or N, and in contrast, increased by proportions ranging from 3.7% to 31.1% under the addition of compost and fertilizer N and P. The stabilization rate of exogenous organic carbon (C) into SOC was only 1.5% in NPK-treated soil but amounted to 8.7% to 14.1% in compost-amended soils (CM and HCM). The total quantities of sequestered SOC were linearly related (P < 0.01) to cumulative C inputs to the soil, and a critical input amount of 2.04 Mg C ha(-1) yr(-1) was found to be required to maintain the SOC stock level (zero change due to cropping). However, the organic C sequestration rate in the 0-60 cm depth decreased from 0.41 to 0.29 Mg C ha(-1) yr(-1) for HCM and from 0.90 to 0.29 Mg C ha(-1) yr(-1) for CM from the period of 1989-1994 to the period of 2004-.2009, indicating that the SOC stock was getting to saturation after the long-term application of compost. The estimated SOC saturation level in the 0-60 cm depth for CM was 61.31 Mg C ha(-1), which was 1.52 and 1.14 times the levels for NPK and HCM, respectively. These results show that SOC sequestration in the North China Plain may mainly depend on the application of organic fertilizer. Furthermore, the SOC sequestration potential in the 0-20 cm layer accounted for 40.3% to 44.6% of the total amount in the 0-60 cm depth for NPK, HCM, and CM, indicating that the SOC sequestration potential would be underestimated using topsoil only and that improving the depth distribution may be a practical way to achieve C sequestration. (C) 2014 Elsevier B.V. All rights reserved.
  • Authors:
    • He, W.
    • Liu, S.
    • Gu, R.
    • Yu, J.
    • Yan, C.
    • Teclemariam, S.
    • Liu, E.
    • Liu, Q.
  • Source: Geoderma
  • Volume: 213
  • Year: 2014
  • Summary: The influence of different tillage practices on soil organic carbon levels is more significant under long-term tillage compared to short-term tillage. Despite the great interest in the effect of no-tillage (NT) management practice on carbon sequestration, the long-term effect of NT practice on soil organic carbon and its fractions in northern China remain unclear. We evaluated the long-term effects (after 17 years) of NT and conventional tillage (CT) practices on soil organic carbon and its fractions at different depths ranging from 0 to 60 cm using a cinnamon soil in Shanxi, China. A randomised block design with three replications was used to evaluate both the tillage and its effects on the yield performance of winter wheat (Triticum aestivum L.). After 17 years, the soil organic carbon (SOC) concentration in the NT soil was greater than that of the CT soil, but only in the layer that was located between 0 and 10 cm. There was a significant accumulation of SOC (0-60 cm) in the NT soil (50.2 Mg C ha(-1)) compared to that observed in the CT soil (46.3 Mg C ha(-1)). The particulate organic matter C (POM-C), dissolved organic C (DOC), and microbial biomass C (MBC) levels in the 0-5 cm layer under NT treatment were 155%, 232%, and 63% greater, respectively, compared to the CT treatment. The POM-C, DOC, and MBC in the 5-10 cm layer under NT treatment were 67%, 123%, and 63% greater, respectively, compared to the CT treatment. Below 10 cm, the labile carbon observed in the NT treatment did not differ from that of the CT treatment. Significantly positive correlations were observed between the SOC and the labile organic C fractions. Moreover, the winter wheat (T. aestivum L) yield increased 28.9% in the NT treatment compared to the CT treatment. The data show that NT is an effective and sustainable management practice that improves carbon sequestration and increases soil fertility, resulting in higher winter wheat yields in the rainfed dryland farming areas of northern China. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Liu, H.
    • Huang, S.
    • Yang, X.
    • Zhang, W.
    • Wang, J.
    • Xu, M.
    • Wang, X.
  • Source: Plant and Soil
  • Volume: 380
  • Issue: 1-2
  • Year: 2014
  • Summary: Soil inorganic carbon (SIC), primarily calcium carbonate, is a major reservoir of carbon in arid lands. This study was designed to test the hypothesis that carbonate might be enhanced in arid cropland, in association with soil fertility improvement via organic amendments. We obtained two sets (65 each) of archived soil samples collected in the early and late 2000's from three long-term experiment sites under wheat-corn cropping with various fertilization treatments in northern China. Soil organic (SOC), SIC and their Stable C-13 compositions were determined over the range 0-100 cm. All sites showed an overall increase of SIC content in soil profiles over time. Particularly, fertilizations led to large SIC accumulation with a range of 101-202 g C m(-2) y(-1) in the 0-100 cm. Accumulation of pedogenic carbonate under fertilization varied from 60 to 179 g C m(-2) y(-1) in the 0-100 cm. Organic amendments significantly enhanced carbonate accumulation, in particular in the subsoil. More carbon was sequestrated in the form of carbonate than as SOC in the arid cropland in northern China. Increasing SOC stock through long-term straw incorporation and manure application in the arid and semi-arid regions also enhanced carbonate accumulation in soil profiles.