• Authors:
    • Cerri, C. C.
    • Bernoux, M.
    • Cerri, C. E. P.
    • Frazao, L. A.
    • Raucci, G. S.
    • Nunes Carvalho, J. L.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 183
  • Issue: January
  • Year: 2014
  • Summary: The objective of this study was to quantify the soil greenhouse gas (GHG) balance after the conversion of native vegetation (NV) to pasture and agricultural land and the conversion of agriculture to crop-pasture rotation (CPR) by evaluating changes in C stocks and N2O and CH4 fluxes. Soil sampling was carried out in March 2007 and April 2009 and GHG fluxes were sampled nine times between April 2007 and March 2009. The conversion of NV to pasture and agriculture decreased soil C stocks, with loss rates ranging from 0.25 to 0.64 Mg C ha(-1) yr(-1), respectively. The implementation of CPR in,agriculture areas increased soil C stocks by 0.60 Mg ha(-1) yr(-1). N2O emissions were higher in CPR and lower in NV. Emission of 1.03 kg CH4-C ha(-1) yr(-1) was observed in pasture, while in other areas consumption of CH4 was observed. The net GHG emission from the soil, including all GHG expressed in C-equivalent, indicated that the conversion of NV to pasture and agricultural land results in emissions of 0.54 and 0.72 Mg C ha(-1) yr(-1), respectively. In contrast, the adoption of CPR in areas under crop succession was a sink of 0.36 Mg ha(-1) yr(-1). Among the evaluated land use changes, only the implementation of CPR proved to be a good strategy to mitigate soil GHG emissions in Brazilian Cerrado. (C) 2013 Elsevier B.V. All rights reserved.
  • 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:
    • Calderón, F.
    • Moore-Kucera, J.
    • Fultz, L. M.
    • Acosta-Martínez, V.
  • Source: Soil Science Society of America Journal
  • Volume: 78
  • Issue: 6
  • Year: 2014
  • Summary: The relationship between soil organic C (SOC) content and its composition as impacted by management is not well understood and may influence longterm storage of SOC. To better understand the potential for SOC storage in specific aggregate pools (e.g., physically protected intra-aggregate C), a wetsieving aggregate fractionation method was coupled with Fourier-transform mid-infrared (MidIR) spectroscopy to determine the composition of waterstable (macroaggregates, microaggregates, and silt + clay) and intra-aggregate (particulate organic matter [POM], microaggregates, and silt + clay) fractions under an integrated crop-livestock (ICL) system and continuous cotton (Gossypium hirsutum L.) production. These agroecosystems were located in the semiarid Texas High Plains on a clay loam soil. The ICL system included a paddock of grazed WW-B. Dahl Old World bluestem [Bothriochloa bladhii (Retz) S.T. Blake] and a no-till crop rotation of wheat (Triticum aestivum L.)-fallow-rye (Secale cereale L.)-cotton for livestock grazing and cotton production. Distance-based redundancy analysis (dbRDA) of the MidIR spectra distinguished the intra-aggregate POM from the other fractions. The intraaggregate POM fraction was correlated with increased pseudo-absorbance (PA) in regions associated with carboxylates, phenolic C-O, aliphatic C-H, and quartz, while macro- and microaggregates demonstrated higher PA at 1570 and 1700 to 1765cm-1. Differences attributed to management were identifiable in intra-aggregate POM and both silt + clay fractions. Within the intra-aggregate POM, dbRDA showed that bluestem was characterized by higher PA at 2800 to 3000 and 3300 to 3450 cm-1 relative to the rest of the rotations. In the silt + clay fractions, more labile functional groups were found following rye and cotton planting.
  • Authors:
    • Watts, D. B.
    • Wood, C. W.
    • Howe, J. A.
    • Gamble, A. V.
    • Van Santen, E.
  • Source: Soil Science Society of America Journal
  • Volume: 78
  • Issue: 6
  • Year: 2014
  • Summary: A frequently used cropping system in the southeastern Coastal Plain is an annual rotation of cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) under conventional tillage (CT). The traditional peanut-cotton rotation (TR) often results in erosion and loss of soil organic carbon (SOC). Incorporation of bahiagrass (Paspalum notatum Fluegge) into the peanut- cotton rotation for 2 yr (also called a sod-based rotation or SBR) has been suggested for improving SOC, particularly in conjunction with conservation tillage practices. To determine the effect of the SBR on carbon sequestration, SOC and its isotopic composition were evaluated on established (>10 yr) crop rotation systems. Cropping systems evaluated included (i) TR under CT, (ii) TR under strip tillage (ST), (iii) SBR under CT, (iv) SBR under ST, and (v) SBR under ST with cattle grazing. Total SOC, bahiagrass-derived SOC, and potential C mineralization increased in the top 10 cm of soil, indicating the potential for ST to improve soil fertility in SBR systems. Grazing bahiagrass decreased SOC in the 5 to 10 cm depth, but this effect was not observed for the subsequent peanut crop and did not appear to have a long-term negative effect on SOC storage. The SBR did not show consistent improvements in total SOC compared with the TR. A 3-yr comparison of SOC concentration revealed C increases in SBR and TR systems, indicating that other conservation practices (e.g., winter cover cropping) are the primary contributors to SOC storage for Coastal Plain soils evaluated in this study. Isotopic analysis of mineralized CO2 indicated bahiagrass-derived SOC may be preferred over C3 crop-derived SOC for degradation.
  • Authors:
    • Reardon-Smith, K.
    • Mushtaq, S.
    • Maraseni, T. N.
  • Source: JOURNAL OF WATER AND CLIMATE CHANGE
  • Volume: 5
  • Issue: 3
  • Year: 2014
  • Summary: While the prevailing rationale for new irrigation technology adoption is improved water use efficiency, this study evaluated trade-offs between water savings, greenhouse gas (GHG) emissions and economic gain associated with the conversion of a furrow irrigation system to a sprinkler irrigation (lateral-move) system on a cotton farm in eastern Australia. Trade-offs were evident when conversion to the pressurised sprinkler irrigation system was evaluated in terms of fuel and energy-related emission; the adoption of the new system saved water but increased GHG emissions. However, when we considered changes in farm machinery and input uses as a result of the conversion, we found an overall reduction in GHG emissions. Overall, the GHG modelling indicated that higher total quantities of GHGs were emitted from the furrow irrigation (4,453 kg CO 2e/ha) than from the sprinkler irrigation (3,347 kg CO 2e/ha) farming system. Water efficiency modelling indicated that, on average, water savings of 18% are possible, while economic modelling indicated that the conversion of irrigation technology is a viable option. Even at a carbon price of AUD$30/tCO 2e, investment in the sprinkler technology was an economically feasible option due to significant water savings and increased yield.
  • Authors:
    • Mcleod, M.
    • Schwenke, G.
    • Wilson, B. R.
    • Cowie, A.
    • Tighe, M.
    • Rabbi, S. M. F.
    • Badgery, W.
    • Baldock, J.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: This project aimed to identify land uses and soil management practices that have significant associations with soil organic carbon (SOC) stocks (0-0.3 m) in New South Wales (NSW), Australia. The work presented in this paper is based on a one-off survey targeting key land uses and management practices of eastern NSW. Because of the nature of the work, the land uses and management combinations surveyed in different soils and climatic conditions were significantly unbalanced, and separately analyzing associations after breaking the dataset into different land uses may lead to significant increases in Type errors. Therefore, redundancy analysis (RDA) was undertaken to explore the association between explanatory variables (i.e., land uses, soil management, soil properties and environmental variables) and the variation in stocks (mass per unit area) of particulate organic carbon (POC), humic organic carbon (HOC) and resistant organic carbon (ROC) across 780 sites in eastern NSW, south eastern Australia. Results indicated that soil properties, land uses, soil management and environmental variables together could explain 52% of total variation in stocks of the SOC fractions. Specifically soil properties and environmental variables explained 42.8%, whereas land uses and management practices together explained 9.2% of the total variation in SOC fractions. A forward selection RDA was also undertaken considering soil properties and environmental variables as covariates to assess the statistical significance of land uses and management practices on stocks of POC, HOC and ROC. We found that pasture had significant positive associations on stocks of carbon fractions. Among the soil properties and environmental variables rainfall, longitude and elevation had a significant positive influence while pH and bulk density had a significantly negative influence on the HOC, POC and ROC stocks. Using a novel multivariate technique, the current work identified the land uses and soil management that had significant impact on carbon stocks in soil after accounting for influences soil properties and environmental variables.
  • Authors:
    • Burmester, C. H.
    • Balkcom, K. S.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 2
  • Year: 2014
  • Summary: Alabama wheat ( Triticum aestivum L.) farmers are changing management practices, which include using higher N fertilizer rates and planting wheat with no-tillage or other conservation tillage systems to maximize yields. Experiments were conducted to (i) determine the level of tillage necessary to optimize wheat yields across different regions of Alabama and (ii) determine if N requirements change across tillage systems and regions in Alabama at four locations resulting in 9 site-year comparisons. Each experiment consisted of a split-plot design with tillage as the main plot and 12 N fertilizer treatments as subplots, replicated four times to compare Zadoks' Growth Stage (GS)-30 tiller densities, tiller N concentrations, tiller biomass, GS-31 wheat biomass, biomass N concentration, wheat yields, and grain crude protein. Nitrogen treatments consisted of different rates across fall, GS-30, and GS-31 application times. Tillage systems had no effect on tiller density, tiller N concentration, or tiller biomass, but fall N increased tiller density 15% and tiller biomass 34% across Coastal Plain locations. Non-inversion tillage increased wheat yields 13% on Coastal Plain soils compared to conventional tillage. Fall N increased wheat yields 10%, and N applied at GS-30 improved yields 18% compared to delaying application until GS-31, indicating application of fall N and applying total N by GS-30 was imperative for successful wheat production on Coastal Plain soils. Neither tillage system nor N applications affected wheat production extensively across the Limestone Valley. Non-inversion tillage or no-tillage with current recommended N practices can be successfully used in Alabama wheat production.
  • Authors:
    • Escobar,N.
    • Ribal,F. J.
    • Clemente,G.
    • Sanjuan,N.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector
  • Year: 2014
  • Summary: Imported biodiesel has accounted for a large share of the total amount consumed in Spain, the main supplier of which was Argentina at least until anti-dumping duties on biodiesel imports from this origin were approved by the European Commission in November 2013. A consequential LCA is carried out in the present study to compare this pathway, which was the prevailing one until almost 2014, with the alternative of using domestic biodiesel from Used Cooking Oil (UCO). System expansion is performed in order to take the indirect functions of both systems into account, functions arising from interactions between co-products (protein meals) in the animal feed market. The marginal suppliers of these co-products in the international market are identified and emissions from direct and indirect Land Use Change (LUC) are calculated. When they are not considered, imported soybean biodiesel leads to lower GHG emissions, due to the carbon uptake by biomass. However, when global LUC is taken into account, UCO biodiesel generates a much lower impact, because it causes a contraction in the area diverted to biofuel feedstock production in other parts of the world. The results underline the importance of considering emissions from LUC when comparing biodiesel alternatives and, thus, interactions in the global market must be addressed.
  • Authors:
    • Attavanich,Witsanu
    • McCarl,Bruce A.
  • Source: Climatic Change
  • Volume: 124
  • Issue: 4
  • Year: 2014
  • Summary: This paper analyzes the impact of climate, crop production technology, and atmospheric carbon dioxide (CO2) on current and future crop yields. The analysis of crop yields endeavors to advance the literature by estimating the effect of atmospheric CO2 on observed crop yields. This is done using an econometric model estimated over pooled historical data for 1950-2009 and data from the free air CO2 enrichment experiments. The main econometric findings are: 1) Yields of C3 crops (soybeans, cotton, and wheat) directly respond to the elevated CO2, while yields of C4 crops (corn and sorghum) do not, but they are found to indirectly benefit from elevated CO2 in times and places of drought stress; 2) The effect of technological progress on mean yields is non-linear; 3) Ignoring atmospheric CO2 in an econometric model of crop yield likely leads to overestimates of the pure effects of technological progress on crop yields of about 51, 15, 17, 9, and 1 % of observed yield gain for cotton, soybeans, wheat, corn and sorghum, respectively; 4) Average climate conditions and climate variability contribute in a statistically significant way to average crop yields and their variability; and 5) The effect of CO2 fertilization generally outweighs the effect of climate change on mean crop yields in many regions resulting in an increase of 7-22, 4-47, 5-26, 65-96, and 3-35 % for yields of corn, sorghum, soybeans, cotton, and wheat, respectively.
  • Authors:
    • Abella, S. R.
    • Engel, E. C.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 77
  • Issue: 5
  • Year: 2013
  • Summary: Fire is a major process in many ecosystems. Knowledge of fire effects on soils is fundamental to making informed land management decisions to meet objectives such as ecological restoration and promoting C sequestration. We assessed 30, 0 to 5 cm soil properties in interspaces (between shrubs) on 32 wildfires, each paired with their own unburned area and ranging in time since fire (TSF) from 2 to 29 yr, in the Mojave Desert. We analyzed relationships of soil properties to burn status (burned or unburned), TSF, and plant community type (blackbrush, Coleogyne ramosissima Torr., and creosote bush, Larrea tridentata [Sessé & Moc. ex DC] Coville, representing predominant Mojave Desert communities). Organic C and total N were two key properties significantly related to fire, being 25 and 44% greater in burned than unburned areas. Few soil properties exhibited a burn x TSF interaction, indicating that fire presence/absence alone was important. Coleogyne communities displayed greater overall difference between burned and unburned soils than did Larrea communities. Results suggest that: (i) burned areas had significantly greater soil C and total N than unburned areas across communities on this desert landscape, (ii) burned and unburned soils overall were more different in Coleogyne than in Larrea communities, and (iii) TSF was not strongly related to soil properties. © Soil Science Society of America, All rights reserved.