• Authors:
    • Woli,K. P.
    • Ruiz-Diaz,D. A.
    • Kaiser,D. E.
    • Mallarino,A. P.
    • Sawyer,J. E.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: An on-farm study was conducted in Iowa from 2004 to 2006 at 18 sites to evaluate corn ( Zea mays L.) grain yield (GY) and soil- and plant-test responses to poultry manure (PM) nutrient application at the field scale. A control and two target PM rates based on total N (PM-N) were applied in randomized field-length strips with three replications. Corn GY responded positively to PM applications. While N, P, and K plant and soil tests were related to PM nutrient rates, there was considerable variation, and relationships were probably influenced by the multiple applied nutrients. Soil-test P and soil-test K across sites increased linearly with increasing PM total P and K rates and with large increases from the high rates. This confirms high P and K crop availability. Grain yield responses to PM decreased linearly with increasing leaf chlorophyll meter (CM) and late spring soil NO 3-N test (LSNT) values but were not related to end-of-season lower corn stalk NO 3-N test values. No N test had a plateau relationship with GY, suggesting no excess N supply despite large PM-N rates. This confirms low first-year PM-N availability. The relationship between CM and LSNT indicated a critical LSNT value at 24 mg kg -1, similar to that from previous small-plot research. This field-scale study showed that PM is a valuable nutrient resource. However, due to PM multinutrient content and differences in availability, the nutrient causing GY and plant- or soil-test results often cannot be clearly identified and results need careful interpretation for reliable use.
  • Authors:
    • Heitman, J. L.
    • Sauer, T. J.
    • Kuang, X.
    • Xiao, X.
    • Horton, R.
  • Source: Journal
  • Volume: 79
  • Issue: 4
  • Year: 2015
  • Summary: Soil CO2 production rates and fluxes vary with time and depth. The shallow near-surface soil layer is important for myriad soil processes, yet knowledge of dynamic CO2 concentrations and fluxes in this complex zone is limited. We used a concentration gradient method (CGM) to determine CO2 production and effluxes with depth in shallow layers of a bare soil. The CO2 concentration was continuously measured at 13 depths in the 0- to 200-mm soil layer. For an 11-d period, 2% of the soil CO2 was produced below a depth of 175 mm, 8% was produced in the 50- to 175-mm soil layer, and 90% was produced in the 0- to 50-mm soil layer. Soil CO2 concentration showed similar diurnal patterns with temperature in deeper soil layers and out-of-phase diurnal patterns in surface soil layers. Soil CO2 flux from most of the soil layers can be described by an exponential function of soil temperature, with temperature sensitivity (Q10) ranging from 1.40 to 2.00 (1.62 ± 0.17). The temperature-normalized CO2 fluxes are related to soil water content with a positive linear relationship in surface soil layers and a negative relationship in deep soil layers. The CO2 fluxes from CGM and chamber methods had good agreement at multiple time scales, which showed that the CGM method was able to estimate near-surface soil CO2 fluxes and production. The contrasting patterns between surface and deep layers of soil CO2 concentration and fluxes suggest the necessity of intensive CO2 concentration measurements in the surface soil layer for accurate determination of soil-atmosphere CO2 flux when using the CGM. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA.
  • Authors:
    • Xie YaPing
    • Gan YanTai
    • Li Yang
    • Niu JunYi
    • Gao YuHong
    • An HuiHui
    • Li AiRong
  • Source: Plant and Soil
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Oilseed flax ( Linum usitatissimum L.) yields are primarily fertilizer-limited, especially by N supply in the semiarid regions of North China. This study was conducted to determine whether N accumulation, translocation and N use efficiency (NUE) could be manipulated through N. The effects of N on N translocation, oilseed flax yield, oil content and NUE were studied at Zhangjiakou, China. Plants were grown at 0, 45, 90, and 135 kg N ha -1 (designated as the control, low N, moderate N, and high N, respectively), in 2011 and 2012. We found that N accumulation in leaves and capsule pericarps reached the maximum at anthesis and kernel developmental stage, respectively, then decreased rapidly before maturity. Averaged over 2 yr, N translocation from leaves to the seeds increased by 43, 150, and 150% under low N, moderate N, and high N, respectively, compared to the control; similarly, N translocation in capsule pericarps increased by 43, 243, and 190%, respectively. We discovered that leaves contributed the largest proportion of the seed N (averaging 80% in both years), and secondarily by the capsule pericarp N, which contributed 12% (in 2011) and 9% (in 2012) of the seed N. The highest seed yields were 2270 kg ha -1 (in 2011) and 1903 kg ha -1 (in 2012) which were obtained with the moderate N. Oil content was not affected by N. Nitrogen use efficiency decreased with progressively higher rates of N. The results suggest the moderate-N supply was adequate for promoting N translocation, and increasing N harvest index, NUE, and the productivity of oilseed flax.
  • Authors:
    • Yan Jiao
    • Hou JianHua
    • Zhao JiangHong
    • Yang WenZhu
  • Source: Acta Agriculturae Scandinavica: Section B, Soil & Plant Science
  • Volume: 65
  • Issue: 6
  • Year: 2015
  • Summary: The effects of soil properties and cropland age on atmospheric nitrous oxide (N2O) emissions following the conversion of grassland to cropland in temperate grassland ecosystems are uncertain. In this study, N2O emissions were compared among grassland and cropland soils in the agro-pastoral ecotone of Inner Mongolia over three growing seasons. Four adjacent sites with different land-use histories were selected, including grassland and croplands cultivated for 5, 10, and 50 years after conversion. N2O flux measurements were obtained using a closed-chamber method and were performed continuously during vegetation periods. After the conversion of grassland to cropland, N2O emission initially decreased and thereafter increased in the study sites. The cumulative N2O emissions of the cropland soils 5 and 10 years in age were 10-50% less than those of the grassland, and the N2O emissions from the cropland soil 50 years in age were 10-30% greater than the grassland. When the seasonal emissions were correlated against single soil parameter, the key soil parameter that affected N2O emissions over the entire growing season was the soil moisture content. When the interactions among soil parameters were considered, the amount of N2O emissions could be quantitatively described by a linear combination of two soil variables, the soil ammonium nitrogen (NH4+-N) and moisture concentrations. This study demonstrates how the time of land use conversion from grassland to cropland can positively or negatively affect N2O emission.
  • Authors:
    • Yunusa,Isa A. M.
    • Blair,Graeme
    • Zerihun,Ayalsew
    • Yang,Shenjiao
    • Wilson,Susan C.
    • Young,Iain M.
  • Source: Acta Agriculturae Scandinavica, Section B — Soil & Plant Science
  • Volume: 131
  • Issue: 4
  • Year: 2015
  • Summary: Coal-fired power generation and agriculture account for more than half of global greenhouse gas emissions, but the coal fly ash (CFA) produced in the former can be a resource for reducing emissions from agriculture to minimise environmental footprints in both industries. Our aim in this study was to test how acidic and alkaline CFA addition could minimise loss of C and N from acidic soil, with or without added manure. We determined composition and structural characteristics of acidic and alkaline CFA for their capacity to adsorb organic carbon, but observed poor adsorption because of low concentrations of cenospheres and unburnt carbon as the primary absorbents in the ash. Addition of CFA had no impact on the loss of carbon or nitrogen from unmanured soil in which concentrations of these nutrients were low. Loss of carbon from manured soil was reduced by 36 % with alkaline ashes and by 3-fold with acidic ashes; while loss of N was 30-50 % lower with acidic ashes, but 28 % higher with alkaline ashes, compared with no ash treatment. The increases in C sparing with CFA addition were achieved not by direct C absorption but by restraining microbial population and respiration, and potentially emissions. Alkaline CFA increased soil pH and if used to substitute just 10 % of lime for ameliorating soil acidity would reduce CO2 emission associated with the mining of the lime and its eventual dissolution in soil by 2.66 Tg or 2.8 % of Australia's annual agricultural emissions. High concentrations of oxides of phosphorus, silicon, titanium and clay particles in acidic ashes, and oxides of cations in alkaline ashes, were associated with potential for promoting C storage and acidity amelioration in soil.
  • Authors:
    • Evans,Jason M.
    • Calabria,Jon
    • Borisova,Tatiana
    • Boellstorf,Diane E.
    • Sochacka,Nicki
    • Smolen,Michael D.
    • Mahler,Robert L.
    • Risse,L. Mark
  • Source: Climatic Change
  • Volume: 132
  • Issue: 2
  • Year: 2015
  • Summary: A growing body of research indicates that opinions about long-term climate change and other natural resource issues can be significantly affected by current weather conditions (e.g., outside air temperature) and other highly contingent environmental cues. Although increased severity and frequency of droughts is regarded as a likely consequence of anthropogenic climate change, little previous research has attempted to relate the experience of drought with public attitudes about water supply or water-related climate change issues. For this study, a large set (n = 3,163) of public survey data collected across nine states of the southern United States was spatio-temporally linked with records of short-term (similar to 12 weeks) and long-term (similar to 5 years) drought condition at the level of each respondent's zip code. Multivariate ordinal logistic regression models that included numerous other independent variables (environmental ideology, age, gender, education, community size, residency duration, and local annual precipitation) indicated highly significant interactions with long-term drought condition, but showed no significant effect from short-term drought condition. Conversely, attitudes about water-related climate change showed highly significant interactions with short-term drought, with weaker to no effects from long-term drought. While the finding of significant effects from short-term drought condition on opinions about future drought is broadly consistent with previous public opinion research on climate change, the finding of water supply attitudes being more responsive to longer term drought condition is, to our knowledge, a novel result. This study more generally demonstrates the methodological feasibility and applied importance of accounting for local drought condition when public opinion information is used to evaluate outreach programs for water conservation and climate change.
  • Authors:
    • Kaliyan,N.
    • Morey,R. V.
    • Tiffany,D. G.
  • Source: BioEnergy Research
  • Volume: 8
  • Issue: 3
  • Year: 2015
  • Summary: Supply logistics systems for corn (Zea mays L.) stover and switchgrass (Panicum virgatum L.) with two collection methods, round bales and rectangular bales, are developed. A location in the US Midwest is assumed with corn grown on highly productive crop land and switchgrass grown on less productive land. Bales (15 % moisture wet basis) are stored at local storage sites within 3.2 km (2 mi) of the field at harvest time. Biomass is transported to an end user within a 48 km (30 mi) throughout the year. Round bales are converted to bulk product [bulk density of 240 kg m−3 (15 lb ft−3)] by tub grinding followed by roll-press compacting before truck transport. Rectangular bales are delivered by truck without processing. Total delivered cost is $97.70 Mg−1 ($88.63 ton−1) for corn stover and $137.87 Mg−1 ($125.07 ton−1) for switchgrass when delivered as a bulk compacted product. Total delivered cost is $90.25 Mg−1 ($81.87 ton−1) for corn stover and $128.67 Mg−1 ($116.73 ton−1) for switchgrass when delivered as rectangular bales. Life-cycle fossil energy consumption is higher for delivering switchgrass (9.9 to 13.8 % of energy in dry matter) than for corn stover (5.8 to 9.5 % of energy in dry matter). Excluding any potential change in soil organic carbon (SOC), life-cycle greenhouse gas (GHG) emissions are 59.2 to 99.8 kg CO2e Mg−1 for delivering corn stover and 231.8 to 279.6 kg CO2e Mg−1 for delivering switchgrass. The effect of change in SOC on the life-cycle GHG emissions for corn stover and switchgrass is discussed. © 2015, Springer Science+Business Media New York.
  • Authors:
    • Mushtaq,S.
    • Maraseni,T. N.
    • Reardon-Smith,K.
    • Bundschuh,J.
    • Jackson,T.
  • Source: Journal of Cleaner Production
  • Volume: 103
  • Year: 2015
  • Summary: Robust understanding of possible trade-offs and synergies between climate change, energy and water sector policies is critical to achieving economically viable and environmentally sound agricultural production systems in a low-carbon water-constrained economy, in which greenhouse gas (GHG) emissions are penalized and water savings rewarded. Accurate assessment of the potential costs/benefits of investment decisions can help to optimize the economic efficiency of agricultural production while minimizing environmental impacts. This paper presents a novel integrated framework, based on carbon and water accounting, which enables analysis of potential trade-offs between water savings, energy consumption, GHG emissions and economic costs/benefits associated with the adoption of new water efficient irrigation technologies. The framework was applied to an irrigated lucerne cropping system in eastern Australia and compares the costs/benefits of old roll-line sprinkler irrigation systems against new pressurized systems. Positive synergies were found with the adoption of the new technology, which saved both water and energy use, reduced total GHG emissions and resulted in net economic returns across a range of carbon prices. The results of this study provide support for an integrated evidence-based approach to policy development and strategic decision-making and for the prioritization of investments on both economic and environmental grounds. (C) 2014 Elsevier Ltd. All rights reserved.
  • Authors:
    • Parton,W. J.
    • Gutmann,M. P.
    • Merchant,E. R.
    • Hartman,M. D.
    • Adler,P. R.
    • McNeal,F. M.
    • Lutz,S. M.
  • Source: Proceedings of the National Academy of Sciences of the United States
  • Volume: 112
  • Issue: 34
  • Year: 2015
  • Summary: The Great Plains region of the United States is an agricultural production center for the global market and, as such, an important source of greenhouse gas (GHG) emissions. This article uses historical agricultural census data and ecosystem models to estimate the magnitude of annual GHG fluxes from all agricultural sources (e.g., cropping, livestock raising, irrigation, fertilizer production, tractor use) in the Great Plains from 1870 to 2000. Here, we show that carbon (C) released during the plow-out of native grasslands was the largest source of GHG emissions before 1930, whereas livestock production, direct energy use, and soil nitrous oxide emissions are currently the largest sources. Climatic factors mediate these emissions, with cool and wet weather promoting C sequestration and hot and dry weather increasing GHG release. This analysis demonstrates the long-term ecosystem consequences of both historical and current agricultural activities, but also indicates that adoption of available alternative management practices could substantially mitigate agricultural GHG fluxes, ranging from a 34% reduction with a 25% adoption rate to as much as complete elimination with possible net sequestration of C when a greater proportion of farmers adopt new agricultural practices.
  • Authors:
    • Rosas,Francisco
    • Babcock,Bruce A.
    • Hayes,Dermot J.
  • Source: Climatic Change
  • Volume: 132
  • Issue: 2
  • Year: 2015
  • Summary: Farmers may choose to apply nitrogen fertilizer at a rate that exceeds the average ex post agronomically optimal rate when the yield response to nitrogen varies across growing seasons. Negative environmental consequences such as nitrous oxide (N2O) emissions and/or water pollution can result when all the applied nitrogen is not needed by the crop. Here we consider a nonlinear market instrument targeting farmers' nitrogen use, and by solving for the optimal nitrogen reduction using a model of expected utility of farm profits, we evaluate the induced N2O emission reductions that are consistent with the instrument introduced. The market instrument is nonlinear because of the expected nonlinear relationship between N2O and nitrogen application rates. Our simulations show that, in cases where farmers apply N at rates which exceed recommendations and the N2O response is likely to be non-linear, payments will induce participation in the program and will have a significant impact on both expected and actual N2O emissions without significantly harming expected or actual yields. Failure to consider this nonlinearity would deviate the attention away from N2O pollution because it would require large N reductions (and crop yields) to achieve equivalent N2O abatement.