• Authors:
    • Mangalassery,S.
    • Mooney,S. J.
    • Sparkes,D. L.
    • Fraser,W. T.
    • Sjoegersten,S.
  • Source: European Journal of Soil Biology
  • Volume: 68
  • Issue: 1
  • Year: 2015
  • Summary: Zero tillage management of agricultural soils has potential for enhancing soil carbon (C) storage and reducing greenhouse gas emissions. However, the mechanisms which control carbon (C) sequestration in soil in response to zero tillage are not well understood. The aim of this study was to investigate the links between zero tillage practices and the functioning of the soil microbial community with regards to C cycling, testing the hypothesis that zero tillage enhances biological functioning in soil with positive implications for C sequestration. Specifically, we determined microbial respiration rates, enzyme activities, carbon source utilization and the functional chemistry of the soil organic matter in temperate well drained soils that had been zero tilled for seven years against annually tilled soils. Zero tilled soils contained 9% more soil C, 30% higher microbial biomass C than tilled soil and an increased presence of aromatic functional groups indicating greater preservation of recalcitrant C. Greater CO2 emission and higher respirational quotients were observed from tilled soils compared to zero tilled soils while microbial biomass was 30% greater in zero tilled soils indicating a more efficient functioning of the microbial community under zero tillage practice. Furthermore, microbial enzyme activities of dehydrogenase, cellulase, xylanase, beta-glucosidase, phenol oxidase and peroxidase were higher in zero tilled soils. Considering zero tillage enhanced both microbial functioning and C storage in soil, we suggest that it offers significant promise to improve soil health and support mitigation measures against climate change. (C) 2015 Elsevier Masson SAS. All rights reserved.
  • Authors:
    • Wu,Yiping
    • Liu,Shuguang
    • Young,Claudia J.
    • Dahal,Devendra
    • Sohl,Terry L.
    • Davis,Brian
  • Source: Scientific Reports
  • Volume: 5
  • Year: 2015
  • Summary: Terrestrial carbon sequestration potential is widely considered as a realistic option for mitigating greenhouse gas emissions. However, this potential may be threatened by global changes including climate, land use, and management changes such as increased corn stover harvesting for rising production of cellulosic biofuel. Therefore, it is critical to investigate the dynamics of soil organic carbon (SOC) at regional or global scale. This study simulated the corn production and spatiotemporal changes of SOC in the U.S. Temperate Prairies, which covers over one-third of the U.S. corn acreage, using a biogeochemical model with multiple climate and land-use change projections. The corn production (either grain yield or stover biomass) could reach 88.7-104.7 TgC as of 2050, 70-101% increase when compared to the base year of 2010. A removal of 50% stover at the regional scale could be a reasonable cap in view of maintaining SOC content and soil fertility especially in the beginning years. The projected SOC dynamics indicated that the average carbon sequestration potential across the entire region may vary from 12.7 to 19.6 g C/m(2)/yr (i.e., 6.6-10.2 g TgC/yr). This study not only helps understand SOC dynamics but also provides decision support for sustainable biofuel development.
  • Authors:
    • Deng,Q.
    • Hui,D. F.
    • Wang,J. M.
    • Iwuozo,S.
    • Yu,C. L.
    • Jima,T.
    • Smart,D.
    • Reddy,C.
    • Dennis,S.
  • Source: Web Of Knowledge
  • Volume: 10
  • Issue: 4
  • Year: 2015
  • Summary: Background: A three-year field experiment was conducted to examine the responses of corn yield and soil nitrous oxide (N 2O) emission to various management practices in middle Tennessee. Methodology/Principal Findings: The management practices include no-tillage + regular applications of urea ammonium nitrate (NT-URAN); no-tillage + regular applications of URAN + denitrification inhibitor (NT-inhibitor); no-tillage + regular applications of URAN + biochar (NT-biochar); no-tillage + 20% applications of URAN + chicken litter (NT-litter), no-tillage + split applications of URAN (NT-split); and conventional tillage + regular applications of URAN as a control (CT-URAN). Fertilizer equivalent to 217 kg N ha -1 was applied to each of the experimental plots. Results showed that no-tillage (NT-URAN) significantly increased corn yield by 28% over the conventional tillage (CT-URAN) due to soil water conservation. The management practices significantly altered soil N 2O emission, with the highest in the CT-URAN (0.48 mg N 2O m -2 h -1) and the lowest in the NT-inhibitor (0.20 mg N 2O m -2 h -1) and NT-biochar (0.16 mg N 2O m -2 h -1) treatments. Significant exponential relationships between soil N 2O emission and water filled pore space were revealed in all treatments. However, variations in soil N 2O emission among the treatments were positively correlated with the moisture sensitivity of soil N 2O emission that likely reflects an interactive effect between soil properties and WFPS. Conclusion/Significance: Our results indicated that improved fertilizer and soil management have the potential to maintain highly productive corn yield while reducing greenhouse gas emissions.
  • Authors:
    • Elshout,P. M. F.
    • van Zelm,R.
    • Balkovic,J.
    • Obersteiner,M.
    • Schmid,E.
    • Skalsky,R.
    • van der Velde,M.
    • Huijbregts,M. A. J.
  • Source: Nature Climate Change
  • Volume: 5
  • Issue: 6
  • Year: 2015
  • Summary: A global increase in the demand for crop-based biofuels may be met by cropland expansion, and could require the sacrifice of natural vegetation. Such land transformation alters the carbon and nitrogen cycles of the original system, and causes significant greenhouse-gas emissions, which should be considered when assessing the global warming performance of crop-based biofuels. As an indicator of this performance we propose the use of greenhouse-gas payback time (GPBT), that is, the number of years it takes before the greenhouse-gas savings due to displacing fossil fuels with biofuels equal the initial losses of carbon and nitrogen stocks from the original ecosystem. Spatially explicit global GPBTs were derived for biofuel production systems using five different feedstocks (corn, rapeseed, soybean, sugarcane and winter wheat), cultivated under no-input and high-input farm management. Overall, GPBTs were found to range between 1 and 162 years (95% range, median: 19 years) with the longest GPBTs occurring in the tropics. Replacing no-input with high-input farming typically shortened the GPBTs by 45 to 79%. Location of crop cultivation was identified as the primary factor driving variation in GPBTs. This study underscores the importance of using spatially explicit impact assessments to guide biofuel policy.
  • Authors:
    • Fujisaki,K.
    • Perrin,A. S.
    • Desjardins,T.
    • Bernoux,M.
    • Balbino,L. C.
    • Brossard,M.
  • Source: Global Change BIology
  • Volume: 21
  • Issue: 7
  • Year: 2015
  • Summary: The impact of deforestation on soil organic carbon (SOC) stocks is important in the context of climate change and agricultural soil use. Trends of SOC stock changes after agroecosystem establishment vary according to the spatial scale considered, and factors explaining these trends may differ sometimes according to meta-analyses. We have reviewed the knowledge about changes in SOC stocks in Amazonia after the establishment of pasture or cropland, sought relationships between observed changes and soil, climatic variables and management practices, and synthesized the delta 13C measured in pastures. Our dataset consisted of 21 studies mostly synchronic, across 52 sites (Brazil, Colombia, French Guiana, Suriname), totalling 70 forest-agroecosystem comparisons. We found that pastures ( n=52, mean age=17.6 years) had slightly higher SOC stocks than forest (+6.83.1 %), whereas croplands ( n=18, mean age=8.7 years) had lower SOC stocks than forest (-8.52.9 %). Annual precipitation and SOC stocks under forest had no effect on the SOC changes in the agroecosystems. For croplands, we found a lower SOC loss than other meta-analyses, but the short time period after deforestation here could have reduced this loss. There was no clear effect of tillage on the SOC response. Management of pastures, whether they were degraded/nominal/improved, had no significant effect on SOC response. delta 13C measurements on 16 pasture chronosequences showed that decay of forest-derived SOC was variable, whereas pasture-derived SOC was less so and was characterized by an accumulation plateau of 20 Mg SOC ha -1 after 20 years. The large uncertainties in SOC response observed could be derived from the chronosequence approach, sensitive to natural soil variability and to human management practices. This study emphasizes the need for diachronic and long-term studies, associated with better knowledge of agroecosystem management.
  • Authors:
    • Kurganova,I.
    • Lopes de Gerenyu,V.
    • Kuzyakov,Y.
  • Source: Catena; ScienceDirect
  • Volume: 122
  • Year: 2015
  • Summary: Most land use changes (LUC) significantly affect the amount of carbon (C) sequestered in vegetation and soil, thereby, shifting the C balance in ecosystems. Disintegration of the USSR and the followed collapse of collective farming system have led to abandonment of more than 58millionha (Mha) of former croplands in Russia and Kazakhstan that comprise together about 90% of land area in the former USSR. This was the most widespread and abrupt LUC in the 20th century in the northern hemisphere. The spontaneous withdrawal of croplands in 1990s caused several benefits for environment including substantial C sequestration in post-agrogenic ecosystems. The new estimations of net ecosystem production (NEP) and changes in soil organic carbon stocks ({increment}SOC) in post-agrogenic ecosystems presented here are based on the uniform bio-climatic approach, and hereby, allow to update C balance of the former USSR. The total extra C sink in abandoned croplands in Russia (45.5Mha) and Kazakhstan (12.9Mha) is estimated to be 155±27MtCyr-1 and 31±2MtCyr-1, respectively. This additional C sink could cover about 18% of the global CO2 release due to deforestation and other land use changes or compensate annually about 36% and 49% of the current fossil fuel emissions in Russia and Kazakhstan, respectively. The extra C sink to the post-agrogenic ecosystems in Russia and Kazakhstan contributes possibly about 1/3 part to the total current C balance of the former USSR. Hence, the disintegration of the former USSR significantly affected national and global C budget over few decades after LUC. © 2015 Elsevier B.V.
  • Authors:
    • Antille,D. L.
    • Chamen,W. C. T.
    • Tullberg,J. N.
    • Lal,R.
  • Source: Transactions of the ASABE
  • Volume: 58
  • Issue: 3
  • Year: 2015
  • Summary: The drive toward adoption of conservation agriculture to reduce costs and increase production sustainably causes concern due to the potentially negative effects of increased soil compaction. Soil compaction reduces aeration, water infiltration, and saturated hydraulic conductivity and increases the risk of waterlogging. Controlled traffic farming (CTF) is a system in which: (1) all machinery has the same or modular working and track width so that field traffic can be confined to the least possible area of permanent traffic lanes, (2) all machinery is capable of precise guidance along those permanent traffic lanes, and (3) the layout of the permanent traffic lanes is designed to optimize surface drainage and logistics. Without CTF, varying equipment operating and track widths translate into random traffic patterns, which can cover up to 85% of the cultivated field area each time a crop is produced. Nitrous oxide (N2O) is the greatest contributor to agriculture's greenhouse gas (GHG) emissions from cropping, and research suggests that its production increases significantly under conditions of high (>60%) water-filled porosity when nitrate (mainly from fertilizer N) and carbon (usually from crop residues) are available. Self-amelioration of soils affected by compaction occurs slowly from the surface downward; however, the rate of amelioration decreases with increase in depth. Consequently, all soils in non-CTF systems in mechanized agriculture are prone to some degree of compaction, which compromises water infiltration, increases the frequency and duration of waterlogged conditions, reduces gaseous exchange between soil and the atmosphere, inhibits root penetration and exploitation of nutrients and water in the subsoil, and enhances N2O emissions. Adoption of CTF increases soil porosity in the range of 5% to 70%, water infiltration by a factor of 4, and saturated hydraulic conductivity by a factor of 2. The greater cropping opportunity and enhanced crop growth for given fertilizer and rainfall inputs offered by CTF, coupled with no-tillage, provide potential for enhanced soil carbon sequestration. Reduced need and intensity of tillage, where compaction is avoided, also helps protect soil organic matter in stable aggregates, which may otherwise be exposed and oxidized. There is both circumstantial and direct evidence to suggest that improved soil structural conditions and aeration offered by CTF can reduce N2O emissions by 20% to 50% compared with non-CTF. It is not compaction per se that increases the risk of N2O emissions but rather the increased risk of waterlogging and increase in water-filled pore space. There may be an elevated risk of GHG emissions from the relatively small area of permanent traffic lanes (typically <20% of total cultivated area) if these are not managed appropriately. Quantification of the benefits of compaction avoidance in terms of GHG emissions may be possible through the use of well-developed models. © 2015 American Society of Agricultural and Biological Engineers.
  • Authors:
    • Bagley,Justin E.
    • Miller,Jesse
    • Bernacchi,Carl J.
  • Source: Plant Cell Environment
  • Volume: 38
  • Issue: 9
  • Year: 2015
  • Summary: The potential impacts of climate change in the Midwest United States present unprecedented challenges to regional agriculture. In response to these challenges, a variety of climate-smart agricultural methodologies have been proposed to retain or improve crop yields, reduce agricultural greenhouse gas emissions, retain soil quality and increase climate resilience of agricultural systems. One component that is commonly neglected when assessing the environmental impacts of climate-smart agriculture is the biophysical impacts, where changes in ecosystem fluxes and storage of moisture and energy lead to perturbations in local climate and water availability. Using a combination of observational data and an agroecosystem model, a series of climate-smart agricultural scenarios were assessed to determine the biophysical impacts these techniques have in the Midwest United States. The first scenario extended the growing season for existing crops using future temperature and CO2 concentrations. The second scenario examined the biophysical impacts of no-till agriculture and the impacts of annually retaining crop debris. Finally, the third scenario evaluated the potential impacts that the adoption of perennial cultivars had on biophysical quantities. Each of these scenarios was found to have significant biophysical impacts. However, the timing and magnitude of the biophysical impacts differed between scenarios. This study assessed the biophysical impacts of several climate-smart agricultural practices in the Midwest United States. Specifically we investigated the biophysical impacts of adapting crops to extended growing season length, expanding no-till agriculture, and the adoption of perennial cultivars. We found that each of these practices had significant biophysical impacts, but the seasonality and extent of the impacts differed between scenarios.
  • Authors:
    • Buckley,Cathal
    • Wall,David P.
    • Moran,Brian
    • Murphy,Paul N. C.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: This study uses a national farm survey which is part of the European Union (EU) Farm Accountancy Data Network (FADN) to develop environmental sustainability indicators in the use of nitrogen (N) and phosphorus (P) across a range of farm systems in the Republic of Ireland. Farm level micro data were used to calculate all inputs and outputs of N and P that cross the farm gate and to derive balances (kg ha(-1)) and overall use efficiencies across 827 farms in 2012. The sample is populated weighted to represents 71,480 farms nationally. Results indicated an average N balance of 71.0 kg ha(-1) and use efficiency of 36.7 % across the nationally representative sample. Nitrogen balances were between two and four times higher across specialist dairy farms compared to livestock rearing and specialist tillage systems. Nitrogen use efficiency was generally lowest across milk producing systems compared to livestock rearing and tillage systems. Phosphorus balance and use efficiency averaged 4.7 kg ha(-1) and 79.6 % respectively across the sample. Specialist tillage and dairying farms had higher average P balances compared to other livestock based systems. The approach developed in this analysis will form the benchmark for temporal analysis across these indicators for future nutrient balance and efficiency trends and could assist other members of the EU FADN to develop similar nationally representative indicators.
  • Authors:
    • Gul,S.
    • Whalen,J. K.
    • Thomas,B. W.
    • Sachdeva,V.
    • Deng HongYuan
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 206
  • Year: 2015
  • Summary: Soil microbial communities are responsive to biochar amendments. As the residence time of biochar in soil is expected to be hundreds to thousands of years, the changes in microbial community structure and functions could persist for a long period of time. Given that biochar is being applied as a soil amendment in many parts of the world, the long-term consequences for soil microbial communities need to be considered. The objective of this review is to document how biochar creates new habitats and changes the soil environment for microorganisms, which may lead to changes in microbial abundance, community structure and activities. Our meta-analysis revealed that slow pyrolyzed biochars produced from various feedstocks at temperatures from 300°C to 600°C consistently increased some physico-chemical properties (i.e., pH, cation exchange capacity and aggregation) and microbial parameters (i.e., abundance and community structure of microorganisms) in a vast number of soils during short (≤90 days) laboratory incubations and longer (1-3 years) field studies. The biochar-mediated changes in soil physico-chemical and biological properties appeared to be a function of soil texture and biochar type based on its feedstock and production temperature, which determines key biochar characteristics such as surface area, porosity and pH. Biochars derived from manure or crop residue feedstocks tend to promote microbial abundance more than wood-derived biochars. Biochars derived from wood and other lignocellulosic-rich feedstocks tend to exhibit beneficial effects on soil microbial abundance later (≥60 days) than biochars from manure or crop residue feedstocks. Coarse textured soils tend to have less aggregation, lower microbial biomass and lower enzyme activities when amended with slow pyrolyzed biochars produced at high temperatures (>600°C), but these biochars did not affect the physico-chemical and biological properties of clayey soils. Further research is needed to evaluate the magnitude of biochar influence on soil microbial abundance and activities considering (1) the biochar particle size, surface area, porosity, nutrient content and pH, and (2) the soil organic matter (SOM) content and microbial abundance of the soil matrix. Once the microbial activities in the biochar-soil system are understood, they can be manipulated through organic and inorganic fertilizer applications to sustain or improve agricultural crop production.