• Authors:
    • Frisvold, G. B.
    • Konyar, K.
  • Source: Journal of Contemporary Water Research & Education
  • Volume: 151
  • Issue: 1
  • Year: 2013
  • Summary: This study examines how the proposed American Clean Energy and Security Act (H.R. 2454) would affect U.S. agriculture with special reference to water resources. The bill's cap and trade provisions for greenhouse gases would significantly raise fertilizer, irrigation pumping, and other energy-related costs. By 2030, it would reduce U.S. irrigation water use by >11 percent and fertilizer use by >18 percent with positive implications for water conservation and quality. Carbon offset provisions create financial incentives for farmers to sequester carbon by planting trees on cropland, reducing agricultural production and raising prices. Because sequestration potential differs by region, most of the estimated 51 million acres of converted cropland would be in the Corn Belt and Mississippi Delta. Afforestation would reduce Delta water use further, but increase water use in other regions compared to cap and trade alone. Compared to a no-policy baseline, irrigation water use declines 10 percent nationally, but increases in the Southern Plains. H.R. 2454 may have significant water conservation effects in some regions, but increase competition for water in others. By reducing fertilizer use and dramatically altering land use patterns in parts of the Mississippi Basin, it may also provide unexpected water quality benefits. Unintended water use and quality consequences of climate policies merit further research.
  • Authors:
    • Tani, H.
    • Wang, H.
    • Li, J.
    • Wang, X.
    • Guo, M.
  • Source: International Journal of Remote Sensing
  • Volume: 34
  • Issue: 12
  • Year: 2013
  • Summary: Measurements of land-cover changes suggest that such shifts may alter atmospheric concentrations of greenhouse gases (GHGs). However, owing to the lack of large-scale GHG data, a quantitative description of the relationships between land-cover changes and GHG concentrations does not exist on a regional scale. The Greenhouse Gases Observing Satellite (GOSAT) launched by Japan on 23 January 2009 can be of use in investigating this issue. In this study, we first calculated the monthly average GHG concentrations in East Asia from April 2009 to October 2011 and found that CO2 concentration displays a seasonal cycle, but that the CH4 seasonal trend is unclear. To understand the relationship between land cover and GHG concentrations, we used GHG data from GOSAT, normalized difference vegetation index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and land-cover data from EAS-GlobCover (2009) to analyse the correlation coefficients between land cover and GHG concentrations. We observed that vegetation may generally be considered as a source of, but not a sink for, CO2 and CH4, either on a yearly scale or during the growing season. With respect to the relationships between land-cover types and GHG concentrations, we conclude that on a yearly scale, land-cover types are not closely correlated with GHG concentrations. During the growing season, croplands and scrublands are negatively correlated with XCO2 (the ratio of the total number of CO2 molecules to that of dry air molecules), and forest, grasslands and bare areas are positively correlated with XCO2. Forest and croplands can be viewed as CH4 sources, while scrublands and grasslands can be thought of as CH4 sinks.
  • Authors:
    • Wang, Y.-H.
    • Chen, B.-L.
    • Qiang, Z.-Y.
    • Dai, Y.-J.
    • Zhou, Z.-G.
    • He, X.-Y.
  • Source: Chinese Journal of Applied Ecology OR Ying yong sheng tai xue bao = The journal of applied ecology / Zhongguo sheng tai xue xue hui, Zhongguo ke xue yuan Shenyang ying yong sheng tai yan jiu suo zhu ban
  • Volume: 24
  • Issue: 12
  • Year: 2013
  • Summary: To study the effect of temperature increase in boll period (13-Jul. to 24-Aug.) on cotton yield and fiber quality under the global warming background, a pot experiment with cotton cultivar Simian 3 was carried out in half-open-top greenhouse in Pailou experiment station (32 degrees 02' N, 118 degrees 50' E) of Nanjing Agricultural University in 2010 and 2011. The results indicated that when the temperature was increased by 2-3 degrees C (with an average daily temperature of 31.1 to 35.2 degrees C), the biomass declined by 10%, while the cotton yield declined by 30%-40%. The fiber quality also changed significantly with the relative indices responding differently. The micronaire value and fiber strength increased, the fiber length reduced while the fiber uniformity and elongation rate changed little. The plant photosynthesis capability, the biomass accumulation and the ability of carbohydrates transferring to sink organs all deceased. The soluble amino acids, soluble sugar, sucrose and C/N decreased significantly, while the starch content increased significantly. The allocation in vegetative organs was increased while that in reproductive organs was reduced, which in turn declined the economical index. The lower fruit branches were affected little under increased temperature condition while the middle, upper and top branches were affected greatly. The results indicated that, under the 2-3 degrees C warmer condition, the cotton plants experienced the high temperature stress, both the photosynthesis ability and the carbohydrates transportation from-source to sink were decreased, leading to the decline of cotton yield.
  • Authors:
    • Huang, B.-X.
    • Christie, P.
    • Oenema, O.
    • Gao, B.
    • Ju, X.-T.
    • Su, F.
    • Hu, X.-K.
    • Jiang, R.-F.
    • Zhang, F.-S.
  • Source: Environmental Pollution
  • Volume: 176
  • Year: 2013
  • Summary: Here, we report on a two-years field experiment aimed at the quantification of the emissions of nitrous oxide (N2O) and methane (CH4) from the dominant wheat maize double cropping system in North China Plain. The experiment had 6 different fertilization strategies, including a control treatment, recommended fertilization, with and without straw and manure applications, and nitrification inhibitor and slow release urea. Application of N fertilizer slightly decreased CH4 uptake by soil. Direct N2O emissions derived from recommended urea application was 0.39% of the annual urea-N input. Both straw and manure had relatively low N2O emissions factors. Slow release urea had a relatively high emission factor. Addition of nitrification inhibitor reduced N2O emission by 55%. We conclude that use of nitrification inhibitors is a promising strategy for N2O mitigation for the intensive wheat maize double cropping systems.
  • Authors:
    • Li, C.
    • Yang, Y.
    • Li, H.
    • Shen, S.
    • Chen, S.
    • Cui, H.
    • Hu, Z.
  • Source: Water, Air, & Soil Pollution
  • Volume: 224
  • Issue: 1
  • Year: 2013
  • Summary: Field experiments were conducted in the 2008-2009 soybean and winter wheat-growing seasons to assess soil respiration (SR) and nitrous oxide (N2O) emission as affected by enhanced UV-B radiation and straw incorporation. The SR rate was measured using a soil CO2 flux system; the N2O flux was measured using a static chamber-gas chromatograph technique. The results showed that in the soybean and winter wheat-growing seasons, enhanced UV-B radiation significantly decreased the SR rates and that straw incorporation increased the SR rates compared to the control treatment. The combined treatment of UV-B and straw incorporation had no obvious influence on the SR rates. Enhanced UV-B radiation, straw incorporation, and the combination treatment increased the temperature sensitivity of SR in the soybean-growing season. The study also showed that N2O emissions were reduced by enhanced UV-B radiation and that straw incorporation had no significant effects on the mean N2O emission fluxes in the soybean and winter wheat-growing seasons. Our findings suggest that enhanced UV-B radiation may lead to a decrease in SR and in N2O emissions, straw incorporation may increase SR, and the combined treatment may have no significant influence on SR and N2O emissions from soybean-winter wheat rotation systems.
  • Authors:
    • Jat, M. L.
    • Jat, H. S.
    • Saharawat, Y. S.
    • Kumar, A.
    • Sharma, P. C.
    • Singh, M.
    • Kumar, V.
    • Gathala, M. K.
    • Humphreys, E.
    • Sharma, D. K.
    • Ladha, J. K.
    • Sharma, S.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 177
  • Year: 2013
  • Summary: Increasing scarcity of resources (labour, water, and energy) and cost of production, along with climate variability, are major challenges for the sustainability of rice-wheat system in the northwesten Indo-Gangetic Plains (IGP). We hypothesized that adopting the principles of conservation agriculture together with best crop management practices would improve system productivity and overall efficiency, resulting in a higher profitability. To test this hypothesis, we evaluated the performance of four cropping system scenarios (treatments), which were designed to be adapted to current and future drivers of agricultural changes. The treatments including farmers practices varied in tillage and crop establishment methods, residue management, crop sequence, and crop management. Zero-tillage direct-seeded rice (ZT-DSR) with residue retention and best management practices provided equivalent or higher yield and 30-50% lower irrigation water use than those of farmer-managed puddled transplanted rice (CT-TPR). Overall, net economic returns increased up to 79% with a net reduction in production cost of up to US$ 55 ha -1 in ZT-DSR than CT-TPR. Substituting rice with ZT maize was equally profitable but with 88-95% less irrigation water use. Avoiding puddling in rice and dry tillage in maize with residue retention increased yield (by 0.5-1.2 t ha -1) and net economic returns of the succeeding wheat crop. Inclusion of mungbean in the rotation further increased system productivity and economic returns. In summary, our initial results of 2-year field study showed positive effects of CA-based improved management practices on yield and system efficiencies with greater benefits in the second year. There is a need of longer term monitoring to quantify cumulative effects of various interventions and to eventually make recommendations for wider dissemination.
  • Authors:
    • Taliaferro, C. M.
    • Kakani, V. G.
    • Zhang, H.
    • Wu, Y. Q.
    • Makaju, S. O.
    • Anderson, M. P.
  • Source: Agronomy Journal
  • Volume: 105
  • Issue: 2
  • Year: 2013
  • Summary: The maximum biomass yield of switchgrass ( Panicum virgatum L.) usually is achieved with one seasonal autumn harvest. However, information is limited on the influences of winter harvesting on annual biomass yield and on quality parameters impacting conversion into bioethanol. Accordingly, the objectives of this study were to assess: (i) yield of standing field cured biomass at monthly intervals through winter, (ii) year-round elemental composition of biomass, and (iii) associated year-round soil nutrient status. An unfertilized 'Kanlow' switchgrass planting established in 1998 was used for this study conducted from November 2007 to October 2010. The experimental treatment was monthly harvest from November to the following March and year-round monthly sampling of biomass (except April) and soil for chemical analyses. The 3-yr mean dry matter yield of winter harvests was 5.94Mg ha -1, ranging from 3.88 Mg ha -1 in the winter of 2007-2008 to 7.55 Mg ha -1 in 2009-2010. Monthly biomass yield differences were significant in Years 1 and 3 but not in Year 2. Concentrations of biomass elements and soil nutrients changed with various degrees over the 3 yr. Concentrations of ash, cell wall components, and mineral nutrients, except P, K, and S, did not change appreciably across winter months. Early winter harvests resulted in less yield loss compared to late winter harvests. These findings will be valuable in harvest management for switchgrass biomass production.
  • Authors:
    • Pijanowski, B. C.
    • Plourde, J. D.
    • Pekin, B. K.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 165
  • Year: 2013
  • Summary: While crop rotation patterns can be complex with multiple crops rotated over several years, the most common rotation practice in the Central United States is biannual rotation between corn and soybeans. We analyzed the changes in crop rotation patterns from 2003 to 2010 using the Cropland Data Layer (CDL), which provides remotely sensed land cover layers for agricultural crops in the Central United States. The accuracy of the CDL was validated by comparing the total acreage for a state or county present in the CDL with the total planted crop acreage available from the National Agricultural Statistics Service. The data layers were combined into two time periods 2003-2006 and 2007-2010, and specific rotation patterns were determined for every location in the study area. The combinations resulted in unique sequences such as single, double, triple and quadruple, the latter of which is equivalent to the same crop class present all four years at a particular location. Corn and soybeans were analyzed to determine the amount of area used for production as well as the amount of change between unique crop rotation sequences. While the total area under production of major crops in the second half of our study period increased only slightly, the extent to which major crops (e.g., corn and soybeans) were grown in continuous cropping sequences increased significantly. For example, the amount of land impacted by corn in the first time period increased by only 2% in the second time period. However, the amount of corn grown in quadruple sequence doubled from the first half to the second half of our study period. We conclude that, although crop rotation patterns are very complex in this region, involving considerable amount of non-cropland, the footprint of major crops such as corn have moved toward monoculture cropping practices in the last decade.
  • Authors:
    • Payero, J.
    • Rowlings, D. W.
    • Grace, P. R.
    • Scheer, C.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 95
  • Issue: 1
  • Year: 2013
  • Summary: Irrigation is known to stimulate soil microbial carbon and nitrogen turnover and potentially the emissions of nitrous oxide (N2O) and carbon dioxide (CO2). We conducted a study to evaluate the effect of three different irrigation intensities on soil N2O and CO2 fluxes and to determine if irrigation management can be used to mitigate N2O emissions from irrigated cotton on black vertisols in South-Eastern Queensland, Australia. Fluxes were measured over the entire 2009/2010 cotton growing season with a fully automated chamber system that measured emissions on a sub-daily basis. Irrigation intensity had a significant effect on CO2 emission. More frequent irrigation stimulated soil respiration and seasonal CO2 fluxes ranged from 2.7 to 4.1 Mg-C ha(-1) for the treatments with the lowest and highest irrigation frequency, respectively. N2O emission happened episodic with highest emissions when heavy rainfall or irrigation coincided with elevated soil mineral N levels and seasonal emissions ranged from 0.80 to 1.07 kg N2O-N ha(-1) for the different treatments. Emission factors (EF = proportion of N fertilizer emitted as N2O) over the cotton cropping season, uncorrected for background emissions, ranged from 0.40 to 0.53 % of total N applied for the different treatments. There was no significant effect of the different irrigation treatments on soil N2O fluxes because highest emission happened in all treatments following heavy rainfall caused by a series of summer thunderstorms which overrode the effect of the irrigation treatment. However, higher irrigation intensity increased the cotton yield and therefore reduced the N2O intensity (N2O emission per lint yield) of this cropping system. Our data suggest that there is only limited scope to reduce absolute N2O emissions by different irrigation intensities in irrigated cotton systems with summer dominated rainfall. However, the significant impact of the irrigation treatments on the N2O intensity clearly shows that irrigation can easily be used to optimize the N2O intensity of such a system.
  • Authors:
    • Brown, D. G.
    • Sylvester, K. M.
    • Deane, G. D.
    • Kornak, R. N.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 168
  • Year: 2013
  • Summary: This paper examines drivers of land-cover change in the U.S. Great Plains in the last half of the twentieth century. Its central aim is to evaluate the dynamics of grassland preservation and conversion, across the region, and to identify areas of grassland that were never plowed during the period. The research compares land-cover data from 400 sample areas, selected from and nested within 50 counties, to aggregate data from the agricultural and population censuses. The spatially explicit land-cover data were interpreted from aerial photographs taken at three time points (1950s, 1970s and 2000s). Sample areas were chosen using a stratified random design based on the Public Land Survey grid with in the target counties, in several clusters across the region. We modeled the sequences and magnitudes of changes in the interpreted air photo data in a multi-level panel model that included soil quality and slope of sample areas and agricultural activities and employment reported in the U.S. Censuses of Agriculture and Population. We conclude that land retirement programs and production subsidies have worked at cross purposes, destabilizing micro-level patterns of land use in recent decades, increasing levels of switching between cropland and grassland and reducing the size of remaining areas of native grassland in the U.S. Great Plains.