• Authors:
    • Grassini, P.
    • Gayler, S.
    • Sanctis, G. de
    • Deryng, D.
    • Corbeels, M.
    • Conijn, S.
    • Boogaard, H.
    • Biernath, C.
    • Basso, B.
    • Baron, C.
    • Adam, M.
    • Ruane, A. C.
    • Rosenzweig, C.
    • Jones, J. W.
    • Lizaso, J.
    • Boote, K.
    • Durand, J. L.
    • Brisson, N.
    • Bassu, S.
    • Hatfield, J.
    • Hoek, S.
    • Izaurralde, C.
    • Jongschaap, R.
    • Kemanian, A. R.
    • Kersebaum, K. C.
    • Kim, S. H. (et al)
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 7
  • Year: 2014
  • Summary: Potential consequences of climate change on crop production can be studied using mechanistic crop simulation models. While a broad variety of maize simulation models exist, it is not known whether different models diverge on grain yield responses to changes in climatic factors, or whether they agree in their general trends related to phenology, growth, and yield. With the goal of analyzing the sensitivity of simulated yields to changes in temperature and atmospheric carbon dioxide concentrations [CO 2], we present the largest maize crop model intercomparison to date, including 23 different models. These models were evaluated for four locations representing a wide range of maize production conditions in the world: Lusignan (France), Ames (USA), Rio Verde (Brazil) and Morogoro (Tanzania). While individual models differed considerably in absolute yield simulation at the four sites, an ensemble of a minimum number of models was able to simulate absolute yields accurately at the four sites even with low data for calibration, thus suggesting that using an ensemble of models has merit. Temperature increase had strong negative influence on modeled yield response of roughly -0.5 Mg ha -1 per °C. Doubling [CO 2] from 360 to 720 mol mol -1 increased grain yield by 7.5% on average across models and the sites. That would therefore make temperature the main factor altering maize yields at the end of this century. Furthermore, there was a large uncertainty in the yield response to [CO 2] among models. Model responses to temperature and [CO 2] did not differ whether models were simulated with low calibration information or, simulated with high level of calibration information.
  • Authors:
    • Cihacek, L. J.
    • DeSutter, T. M.
    • Rahman, S.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 1
  • Year: 2014
  • Summary: The 11 major electricity-generating coal combustion stations in the northern Great Plains have the potential to produce almost 1 million Mg of flue gas desulfurization gypsum (FGDG) annually, which is a very attractive fertilizer (Ca and S) and amendment for sodic and acid soils. The potential environmental impacts of applying FGDG to soils in this region have not been fully investigated. The objectives of this research were to determine the influence of FGDG on soil chemical characteristics and to determine the impact that FGDG has on hard red spring wheat ( Triticum aestivum L.) yields and element analysis of the grain. Flue gas desulfurization gypsum and commercial gypsum were applied at rates of 0, 2.24, 11.2, and 22.4 Mg ha -1 to two soils in southwestern North Dakota in the spring of 2007. Soil and grain chemistries were monitored for two growing seasons. Wheat grain yields and elemental analysis of the grain were generally not affected by the gypsum treatments, indicating that the gypsum products did not negatively affect plant productivity. In addition, soil elemental analysis was similar across the treatments at both sites in both years. The results from this study indicate that its application to soil at rates used for sodic soil remediation (Mg ha -1) did not negatively affect the chemistries of either the soils or the wheat evaluated in this study compared with a commercial gypsum product or control soils.
  • Authors:
    • Druschke, C. G.
    • Secchi, S.
  • Source: Journal of Soil and Water Conservation
  • Volume: 69
  • Issue: 2
  • Year: 2014
  • Summary: Female agricultural land ownership and operatorship are on the rise in Iowa and across the nation, but little research exists that explores agricultural conservation outreach to women and gendered differences in conservation knowledge and attitudes. The authors surveyed all agricultural landowners and operators in the Clear Creek Watershed in eastern Iowa about conservation knowledge and attitudes, as well as preferred sources of information about conservation. Clear Creek is a high-visibility watershed for conservation outreach for several reasons, including its long-standing watershed stakeholder council and its connection to the impaired Iowa River. Analysis of the survey results demonstrated that female respondents had significantly lower levels of knowledge about best management practices and significantly more positive attitudes towards conservation and collaboration than men. Meanwhile, women looked to the same sources for conservation information as male respondents, including neighbors, friends, and conservation agencies like the Natural Resources Conservation Service, Cooperative Extension, and the Farm Service Agency. These gendered results have significant consequences for the future of agricultural conservation practice and policy and for the subsequent health of the nation's soils and waterways. While lacking in knowledge about specific conservation practices, female respondents valued conservation practices, looked to government agencies for information about conservation, and expressed interest in collaborating with government entities for conservation on their land. Agricultural conservation practitioners can use these findings to tailor outreach efforts that will more effectively reach the nation's female landowners and operators.
  • Authors:
    • Liu, X.
    • Vidon, P.
    • Jacinthe, P. A.
    • Fisher, K.
    • Baker, M. E.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 1
  • Year: 2014
  • Summary: Riparian buffers are important nitrate (NO 3-) sinks in agricultural watersheds, but limited information is available regarding the intensity and control of nitrous oxide (N 2O) emission from these buffers. This study monitored (December 2009-May 2011) N 2O fluxes at two agricultural riparian buffers in the White River watershed in Indiana to assess the impact of land use and hydrogeomorphologic (HGM) attributes on emission. The study sites included a riparian forest in a glacial outwash/alluvium setting (White River [WR]) and a grassed riparian buffer in tile-drained till plains (Leary Weber Ditch [LWD]). Adjacent corn ( Zea mays L.) fields were monitored for land use assessment. Analysis of variance identified season, land use (riparian buffer vs. crop field), and site geomorphology as major drivers of N 2O fluxes. Strong relationships between N mineralization and N 2O fluxes were found at both sites, but relationships with other nutrient cycling indicators (C/N ratio, dissolved organic C, microbial biomass C) were detected only at LWD. Nitrous oxide emission showed strong seasonal variability; the largest N 2O peaks occurred in late spring/early summer as a result of flooding at the WR riparian buffer (up to 27.8 mg N 2O-N m -2 d -1) and N fertilizer application to crop fields. Annual N 2O emission (kg N 2O-N ha -1) was higher in the crop fields (WR: 7.82; LWD: 6.37) than in the riparian areas. A significant difference ( P<0.02) in annual N 2O emission between the riparian buffers was detected (4.32 vs. 1.03 kg N 2O-N ha -1 at WR and LWD, respectively), and this difference was attributed to site geomorphology and flooding (WR is flood prone; no flooding occurred at tile-drained LWD). The study results demonstrate the significance of landscape geomorphology and land-stream connection (i.e., flood potential) as drivers of N 2O emission in riparian buffers and therefore argue that an HGM-based approach should be especially suitable for determination of regional N 2O budget in riparian ecosystems.
  • Authors:
    • Grosso, S. J. del
    • Blaylock, A. D.
    • Snyder, C. S.
    • Halvorson, A. D.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 2
  • Year: 2014
  • Summary: Enhanced-efficiency N fertilizers (EENFs) have potential for mitigating N 2O emissions from N-fertilized cropping systems. Stabilized EENFs contain nitrification and/or urease inhibitors. Slow-release EENFs contain N components that are slowly released with variable release rates. Controlled-release EENFs release N at more predictable rates. The effectiveness of several EENFs in reducing soil N 2O emissions from a clay loam soil under irrigated, corn ( Zea mays L.)-based production systems in Colorado (2002-2012) was investigated. A controlled-release, polymer-coated urea, ESN, reduced N 2O emissions by 42% compared with urea and 14% compared with urea-NH 4NO 3 solution (UAN) in no-till and strip-till environments, but had no effect in a conventional tillage environment. A stabilized urea source, SuperU, reduced N 2O emissions by 46% compared with urea and 21% compared with UAN. A stabilized UAN source, UAN+AgrotainPlus, reduced N 2O emissions by 61% compared with urea and 41% compared with UAN alone. A slow-release UAN source, UAN+Nfusion, reduced N 2O emissions by 57% compared with urea and 28% compared with UAN. Urea-NH 4NO 3 reduced N 2O emissions by 35% compared with urea. A linear increase in N 2O emissions with increasing N rate was observed for untreated urea and UAN. Developers of management protocols to reduce N 2O emissions from irrigated cropping systems in semiarid areas can use this information to estimate reductions in N 2O emissions when EENFs are used. Policymakers can use this information to help determine financial credits needed to encourage producers to use these technologies in their crop production systems.
  • Authors:
    • Koo, W. W.
    • Jiang, Y.
  • Source: Journal of Soil and Water Conservation
  • Volume: 69
  • Issue: 3
  • Year: 2014
  • Summary: The objective of this study was to develop an understanding of producer preferences for land-based biological carbon (C) sequestration in agriculture. We conducted a mail survey in a US production region to elicit farmers' willingness to participate in different C credit programs in a hypothetical greenhouse gas mitigation market. We used the survey data to calibrate a behavior model in a benefit-cost framework that characterizes farmers' decisions about C program participation in relation to preferences and the attributes of both C programs and production. Our empirical analysis suggested that.(1) producers would respond to the market incentive for C sequestration; (2) producer responses might be limited, particularly at low C prices; and (3) producers might perceive differentially a cost for C sequestration, depending on individual preferences, production attributes, and specific practices to be adopted. A policy simulation of producer behavior with agricultural census data estimated the potential C offset supply in the study area.
  • Authors:
    • Dick, W. A.
    • Ladwig, K.
    • Tian, Y. Q.
    • Guo, X. L.
    • Chen, L. M.
    • Kost, D.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 1
  • Year: 2014
  • Summary: Gypsum (CaSO 4.2H 2O) is a quality source of Ca and S and has various beneficial uses that can improve agricultural production. This study was conducted to compare rates of flue gas desulfurization (FGD) gypsum and commercially available agricultural (i.e., mined) gypsum as soil amendments on soils typical of eastern Ohio or western Pennsylvania. Two field experiments were conducted, one involving a mixed grass hay field and the other corn ( Zea mays L.). Gypsum was applied once at rates of 0.2, 2.0, and 20 Mg ha -1 and a seventh treatment was a zero rate control. Corn grain yields response to gypsum was mixed with significant differences between low and high gypsum rates in 2010 but not between gypsum and no gypsum treatments. In the hay study, the low and intermediate gypsum rates generally did not result in any significant changes compared with the control treatment. At the high rate of 20 Mg ha -1, the following results were observed for the hay study: (i) both gypsums generally increased Ca, S, and soluble salts (electrical conductivity) in the topsoil and subsoil, when compared with the control; (ii) the FGD gypsum decreased Mg in soil when compared with all other treatments, and mined gypsum decreased Mg when compared with the control; and (iii) there were few effects on soil concentrations of trace elements, including Hg. Also at the high application rate, hay yield for the first cutting (May) in 2009 and 2010 was significantly less for mined and FGD gypsum compared with the control, but increased yields in subsequent cutting resulted in no significant treatment differences in total annual hay yield for 2008, 2009, or 2010 or cumulative yield for 2008 to 2010. Overall, for the hay study, the absence of significant soil chemical effects for the intermediate gypsum rate and the decrease in soil Mg concentrations for the high gypsum rate indicate that an application rate of approximately 2.0 Mg ha -1 would be optimal for this soil.
  • Authors:
    • Olsen, D.
    • Harner, L.
    • Merrill, S.
    • Tanaka, D.
    • Sanderson, M.
    • Nichols, K.
    • Hendrickson, J.
    • Archer, D.
    • Liebig, M.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 4
  • Year: 2014
  • Authors:
    • Lokhande, S.
    • Reddy, K. R.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 4
  • Year: 2014
  • Summary: Quantitative functional relationships between temperature and fiber quality are needed to improve predictive capability of cotton ( Gossypium hirsutum L.) models. An experiment was conducted by varying day/night temperatures, 22/14, 26/18, 30/22, and 34/26°C, imposed at flowering. Upland cotton cultivar, TM-1, was seeded in the soil bins using fine sand as the rooting medium and allowed to grow under optimum water and nutrients. Flowers and bolls were tagged daily to estimate the boll maturation period. Plant height and node numbers were recorded from emergence to 21 d after treatment. Stem, leaf, boll dry weights, and boll numbers were recorded at maturity. Measured fiber quality parameters were regressed against temperature to develop mathematical functions for modeling. The optimum temperature for biomass was between 18.1 and 21.5°C and biomass declined by 10% at 25.5°C and 19% at 29.5°C. More bolls were produced at 25.5°C, but declined sharply at 29.5°C. Reproductive potential, boll mass per unit total weight, peaked at 25.5°C and was lower by 21% at 18.1°C and 53% at 29.5°C. Fiber micronaire and uniformity increased with temperature up to 26°C and declined at higher temperature, while fiber strength increased linearly with temperature. Fiber length increased linearly from 18 to 22°C, and declined at higher temperatures. Fiber micronaire was more responsive to changes in temperature followed by strength, length, and uniformity. The functional relationships between temperature and fiber properties will be useful to optimize management decisions such as planting dates and to develop fiber submodel under optimal water and nutrient conditions.
  • Authors:
    • Venterea, R. T.
    • Maharjan, B.
    • Rosen, C.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 2
  • Year: 2014
  • Summary: Irrigation and N fertilizer management are important factors affecting crop yield, N fertilizer recovery efficiency, and N losses as nitrous oxide (N 2O) and nitrate (NO 3-). Split application of conventional urea (split-U) and/or one-time application of products designed to perform as enhanced-efficiency N fertilizers may mitigate N losses. The objective of this study was to compare the effects of controlled-release polymer-coated urea (PCU), stabilized urea with urease and nitrification inhibitors (IU) and split-U on direct soil-to-atmosphere N 2O emissions, NO 3- leaching, and yield for fully irrigated and minimum-irrigated corn in loamy sand. Indirect N 2O emissions due to NO 3- leaching were estimated using published emission factors (EF 5). Split-U increased yield and N uptake compared with preplant-applied PCU or IU and decreased NO 3- leaching compared with PCU. Direct N 2O emissions were significantly less with IU or split-U than with PCU, and there was a trend for greater emissions with split-U than with IU ( P=0.08). Irrigation significantly increased NO 3- leaching during the growing season but had no significant effect on direct N 2O emissions. After accounting for significantly increased yields with irrigation, however, N losses expressed on a yield basis did not differ and in some cases decreased with irrigation. Post-harvest soil N and soil-water NO 3- in spring showed the potential for greater N leaching in minimum-irrigated than fully irrigated plots. Indirect emissions due to NO 3- leaching were estimated to be 79 to 117% of direct emissions using the default value of EF 5, thus signifying the potential importance of indirect emissions in evaluating management effects on N 2O emissions.