• Authors:
    • Hua,Keke
    • Zhu,Bo
    • Wang,Xiaoguo
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 103
  • Issue: 1
  • Year: 2015
  • Summary: Soil carbon dioxide (CO2) and methane (CH4) emissions, as well as runoff and leaching are major pathways of soil organic carbon (SOC) loss, which affect SOC sequestration in croplands. However, fluxes and relationships of the four pathways are still poorly understood. Static chamber-GC techniques were used to measure soil heterotrophic respiration rate and CH4 emission flux on hillslope upland of Regosol soil in Southwest China under traditional mineral fertilizer treatment from 2010 to 2012. Synchronously, SOC loss flux via overland flow, leaching and sediment was measured using free-drained lysimeters (8 m x 4 m). Average annual cumulative soil CO2 emission and CH4 uptake fluxes were 462.8 +/- A 52.2 and -1.1 +/- A 0.16 g cm(-2). Average annual cumulative dissolved organic carbon (DOC) loss fluxes via overland flow and leaching were 0.16 +/- A 0.03 and 0.92 +/- A 0.08 g cm(-2), respectively and organic C loss via sediment was 2.2 +/- A 0.3 g cm(-2). Relationship between DOC loss fluxes and soil heterotrophic respiration rates under natural rainfall events could be described by a significant exponential decay function (R = -0.63, P < 0.01). Moreover, a significantly negative correlation was also found between DOC loss flux and soil DOC content in topsoil at 15 cm depth (R = -0.75, P < 0.05). In conclusion, DOC loss decreases soil DOC content and is an underrated negative regulating factor of soil CO2 emission, especially in the regions where high DOC losses occur.
  • Authors:
    • Karasawa,Toshihiko
    • Takahashi,Shigeru
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 103
  • Issue: 1
  • Year: 2015
  • Summary: Field experiments were conducted to clarify whether the introduction of several cover crop species increases P uptake of the following wheat and soybean. Four summer cover crops (sorghum, buckwheat, groundnut and crotalaria) and four winter cover crops (oat, rye, vetch and lupin) were tested. Growth and P uptake of succeeding wheat were significantly increased by P fertilizer application and tended to be increased by sorghum, groundnut or crotalaria incorporation, whereas buckwheat did not show positive effects. Growth and P uptake of succeeding soybean were significantly increased by oat or vetch incorporation and tended to be increased by P fertilizer or other cover crop incorporation. These positive effects of cover crops were attributed to the large amount of P incorporation, increase in the P-solubilizing fungal population and/or biomass P in soil. Sorghum, oat, rye and vetch were thought to be suitable cover crops to accelerate P uptake of the following crops since a large amount of P would be incorporated. Sorghum, groundnut and lupin were thought to be suitable cover crops because they increased the indigenous P-solubilizing fungal population in soil. Soil biomass P correlated with P uptake of wheat. Incorporation of suitable cover crops as a P source and activation of indigenous soil microorganisms by the carbon supply were thought to have accelerated P uptake of the following wheat and soybean. It is therefore thought that introduction of suitable cover crops could be an effective means to reduce P fertilizer application for the following crops.
  • Authors:
    • Mu WeiSong
    • Yan ZhiYong
    • Gavrila,S. P.
    • Moga,L. M.
    • Feng JianYing
    • Jianu,I.
  • Source: Journal of Environmental Protection and Ecology
  • Volume: 16
  • Issue: 2
  • Year: 2015
  • Summary: (Will open in Google Docs) Greenhouse grape cultivation (GGC) has been an important part in grape production in China, and the ecological impact of the production system is vital for its sustainable development. This paper aims to evaluate the net carbon emissions and the overall impact on atmosphere of GGC and open-field grape cultivation (OGC) systems. A methodology of full carbon cycle analysis was adopted, and the net primary production, net ecosystem productivity and net carbon flux were chosen as the main indexes. The data were acquired through field investigations and chemical experiments. The results showed that both systems were the carbon source. The net carbon flux were 9.77 mg ha -1 year -1 and 1.17 mg ha -1 year -1. Compared to the OGC system, the GGC system is a bigger carbon source, however the carbon sink ability was improved and the NEP was increased by 2.18 mg ha -1 year -1. Minimisation the use of high carbon material in greenhouse building is a practical solution to reduction of carbon emission.
  • Authors:
    • Trebicki,P.
    • Nancarrow,N.
    • Cole,E.
    • Bosque-Perez,N. A.
    • Constable,F. E.
    • Freeman,A. J.
    • Rodoni,B.
    • Yen,A. L.
    • Luck,J. E.
    • Fitzgerald,G. J.
  • Source: Global Change Biology
  • Volume: 21
  • Issue: 9
  • Year: 2015
  • Summary: Current atmospheric CO 2 levels are about 400 mol mol -1 and are predicted to rise to 650 mol mol -1 later this century. Although the positive and negative impacts of CO 2 on plants are well documented, little is known about interactions with pests and diseases. If disease severity increases under future environmental conditions, then it becomes imperative to understand the impacts of pathogens on crop production in order to minimize crop losses and maximize food production. Barley yellow dwarf virus (BYDV) adversely affects the yield and quality of economically important crops including wheat, barley and oats. It is transmitted by numerous aphid species and causes a serious disease of cereal crops worldwide. This study examined the effects of ambient (aCO 2; 400 mol mol -1) and elevated CO 2 (eCO 2; 650 mol mol -1) on noninfected and BYDV-infected wheat. Using a RT-qPCR technique, we measured virus titre from aCO 2 and eCO 2 treatments. BYDV titre increased significantly by 36.8% in leaves of wheat grown under eCO 2 conditions compared to aCO 2. Plant growth parameters including height, tiller number, leaf area and biomass were generally higher in plants exposed to higher CO 2 levels but increased growth did not explain the increase in BYDV titre in these plants. High virus titre in plants has been shown to have a significant negative effect on plant yield and causes earlier and more pronounced symptom expression increasing the probability of virus spread by insects. The combination of these factors could negatively impact food production in Australia and worldwide under future climate conditions. This is the first quantitative evidence that BYDV titre increases in plants grown under elevated CO 2 levels.
  • Authors:
    • Yao ChunXue
    • Joseph,S.
    • Li LianQing
    • Pan GenXing
    • Lin Yun
    • Munroe,P.
    • Pace,B.
    • Taherymoosavi,S.
    • Zwieten,L. van
    • Thomas,T.
    • Nielsen,S.
    • Ye Jun
    • Donne,S.
  • Source: Pedosphere
  • Volume: 25
  • Issue: 5
  • Year: 2015
  • Summary: Utilization of biochar at high application rates can increase soil C and crop yields, decrease greenhouse gas emissions and reduce nutrient run-off from soils. However, the high application rate of 10 t ha -1 may not return a profit to the farmer due to the high cost of biochar. In this study biochar was modified through pre-treating the biomass and post-treating with phosphoric acid, minerals and different chemical fertilisers to study the effects of two new enhanced biochar fertilisers on the yield and quality of green pepper in a field experiment with 5 fertilisation treatments and 3 replications. The two new biochar fertilisers significantly ( P<<0.05) increased the yield of green pepper (11.33-11.47 t ha -1), compared with the conventional chemical fertiliser (9.72 t ha -1). The biochar fertiliser treatments improved the vitamin C content of green pepper from 236.99 to 278.28 mg kg -1, and also significantly ( P<0.05) reduced the nitrate content from 132.32 to 101.92 mg kg -1, compared with chemical fertiliser. This study indicated that, compared to the use of conventional chemical fertiliser, all of the biochar fertiliser treatments could significantly improve the yield and quality of green pepper.
  • Authors:
    • Navarro, J.
    • Li, J.
    • Nolan, M.
    • Crossman, N. D.
    • Bryan, B. A.
    • Connor, J. D.
  • Source: Primary Research Article
  • Volume: 21
  • Issue: 11
  • Year: 2015
  • Summary: Competition for land is increasing, and policy needs to ensure the efficient supply of multiple ecosystem services from land systems. We modelled the spatially explicit potential future supply of ecosystem services in Australia's intensive agricultural land in response to carbon markets under four global outlooks from 2013 to 2050. We assessed the productive efficiency of greenhouse gas emissions abatement, agricultural production, water resources, and biodiversity services and compared these to production possibility frontiers (PPFs). While interacting commodity markets and carbon markets produced efficient outcomes for agricultural production and emissions abatement, more efficient outcomes were possible for water resources and biodiversity services due to weak price signals. However, when only two objectives were considered as per typical efficiency assessments, efficiency improvements involved significant unintended trade-offs for the other objectives and incurred substantial opportunity costs. Considering multiple objectives simultaneously enabled the identification of land use arrangements that were efficient over multiple ecosystem services. Efficient land use arrangements could be selected that meet society's preferences for ecosystem service provision from land by adjusting the metric used to combine multiple services. To effectively manage competition for land via land use efficiency, market incentives are needed that effectively price multiple ecosystem services.
  • Authors:
    • Borghi, E.
    • Nascente, A. S.
    • Crusciol, C. A. C.
    • Soratto, R. P.
    • Martins, P. O.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 6
  • Year: 2015
  • Summary: In tropical regions with dry winters, low plant biomass accumulation during the period between spring-summer crop cultivations can negatively impact soil resources and make the no-till (NT) system unsustainable. Incorporating palisadegrass [ Urochloa brizantha (Hochst. Ex A. Rich.) R.D. Webster] [syn. Brachiaria brizantha (Hochst. Ex A. Rich) Stapf] in traditional grain production areas could improve soil quality for subsequent crops and lead to positive effects on grain yield. The objective of this study was to evaluate the effects of growing palisadegrass on soil fertility, plant nutrition, and grain yield of subsequent cash crops in a tropical region. The experiment was performed in southeastern Brazil in plots that were grown for two consecutive growing seasons (2002-2003 and 2003-2004) with either monocropped corn ( Zea mays L.) or corn intercropped with palisadegrass. An initial evaluation of soil fertility was performed in November 2004 when the land was either fallow (following monocropped corn) or covered by palisadegrass (intercropped areas). After the preceding treatments, the following crops were cultivated: soybean [ Glycine max (L.) Merr.] during the 2004-2005 and 2005-2006 spring-summer, white oat ( Avena sativa L.) during the 2005 and 2006 fall-winter, and corn during the 2006-2007 spring-summer. Intercropping palisadegrass with corn increased the soil fertility compared to monocropped corn. Soybean, white oat, and corn all had higher leaf macronutrient concentrations and grain yields in previously intercropped areas than in monocropped areas. Therefore, the periodic, short-term incorporation of a perennial forage grass, such as palisadegrass, as a cover crop is recommended to increase grain production and to improve the soil fertility of grain-production areas.
  • Authors:
    • Gao,H.
    • Shao,M.
  • Source: Soil and Tillage Research
  • Volume: 153
  • Year: 2015
  • Summary: Accurate simulation of the effects of temperature on soil water movement processes is lacking in the study of hydrothermal interactions in soil systems. Previous research has proposed some likely mechanisms (e.g., surface tension-viscous flow) to explain soil hydraulic properties in relation to temperature, but little research has focused on the temperature dependence of soil particles (e.g., thermal expansion). Using simulation analyses and experimental data, the effect of temperature on soil hydraulic properties was explored focusing on the thermal effect of water surficial properties and soil particle characteristics. Two temperature coefficients, λ, representing the thermal effect of water surficial properties and c, representing the thermal effect of soil particle characteristics are introduced into soil hydraulics formulae to represent temperature dependence. Results show that temperature-dependent changes in water surficial properties including kinematics viscosity, surface tension and water density effects on soil hydraulic properties. Changes in temperature also affect soil particles, soil porosity and the interactive surface between liquid and solid, especially in heavy loam with high clay content. Expected soil hydraulic properties were calculated at three temperatures in two soil types and then compared to corresponding experimental results. Comparison of predicted and experimental soil hydraulic properties revealed overall similarities with a few exceptions. This study represents an initial simulation study of the effects of temperature on soil hydraulic properties. © 2015.
  • Authors:
    • Baer, S. G.
    • Bello, N. M.
    • Knapp, M.
    • Morgan, T. J.
    • Bryant, J.
    • DeLaCruz, A.
    • Tetreault, H.
    • Olsen, J. T.
    • Johnson, L. C.
    • Maricle, B. R.
  • Source: Original Article
  • Volume: 8
  • Issue: 7
  • Year: 2015
  • Summary: Identifying suitable genetic stock for restoration often employs a best guess' approach. Without adaptive variation studies, restoration may be misguided. We test the extent to which climate in central US grasslands exerts selection pressure on a foundation grass big bluestem (Andropogon gerardii), widely used in restorations, and resulting in local adaptation. We seeded three regional ecotypes of A.gerardii in reciprocal transplant garden communities across 1150km precipitation gradient. We measured ecological responses over several timescales (instantaneous gas exchange, medium-term chlorophyll absorbance, and long-term responses of establishment and cover) in response to climate and biotic factors and tested if ecotypes could expand range. The ecotype from the driest region exhibited greatest cover under low rainfall, suggesting local adaptation under abiotic stress. Unexpectedly, no evidence for cover differences between ecotypes exists at mesic sites where establishment and cover of all ecotypes were low, perhaps due to strong biotic pressures. Expression of adaptive differences is strongly environment specific. Given observed adaptive variation, the most conservative restoration strategy would be to plant the local ecotype, especially in drier locations. With superior performance of the most xeric ecotype under dry conditions and predicted drought, this ecotype may migrate eastward, naturally or with assistance in restorations.
  • Authors:
    • Hu, W.
    • Cao, Y.
    • Xu, J.
    • Wang, Y.
    • Peng, Z.
    • Wang, H.
    • Han, X.
    • Xiong, W.
    • Lin, E.
    • Ju, H.
    • Huang, H.
    • Li, Y.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 209
  • Year: 2015
  • Summary: Drought is one of the major climatic disasters intimidating winter wheat production in the Huang-Huai-Hai (3H) Plain of China. The yield damage caused by drought tends to increase in the future, indicated by a pronounced uprising of drought events under RCP 8.5 scenario in terms of its affecting magnitude and area. This paper presents a modeling approach by using crop model DSSAT and hydrological indices to assess the vulnerability of winter wheat to future potential drought, based on an integrated assessment of exposure, sensitivity and adaptive capacity. Our results demonstrate that Beijing, Tianjin, Hebei and Shandong are more exposed and sensitive to potential drought than other regions in 3H. Traditional irrigation has the greater benefits in northern 3H Plain than southern regions, but is still insufficient to impede the yield loss due to potential drought. Under RCP 8.5 emission scenario and the period of 2010-2050, the worst drought effect is projected to occur around 2030. More than half of 3H plain are subject to high drought vulnerability. With increasing drought risks, we suggest immediate and appropriate adaptation actions to be taken before 2030s, especially in Shandong and Hebei, the most vulnerable provinces of 3H plain.