• Authors:
    • Liu, H.
    • Huang, S.
    • Yang, X.
    • Zhang, W.
    • Wang, J.
    • Xu, M.
    • Wang, X.
  • Source: Plant and Soil
  • Volume: 380
  • Issue: 1-2
  • Year: 2014
  • Summary: Soil inorganic carbon (SIC), primarily calcium carbonate, is a major reservoir of carbon in arid lands. This study was designed to test the hypothesis that carbonate might be enhanced in arid cropland, in association with soil fertility improvement via organic amendments. We obtained two sets (65 each) of archived soil samples collected in the early and late 2000's from three long-term experiment sites under wheat-corn cropping with various fertilization treatments in northern China. Soil organic (SOC), SIC and their Stable C-13 compositions were determined over the range 0-100 cm. All sites showed an overall increase of SIC content in soil profiles over time. Particularly, fertilizations led to large SIC accumulation with a range of 101-202 g C m(-2) y(-1) in the 0-100 cm. Accumulation of pedogenic carbonate under fertilization varied from 60 to 179 g C m(-2) y(-1) in the 0-100 cm. Organic amendments significantly enhanced carbonate accumulation, in particular in the subsoil. More carbon was sequestrated in the form of carbonate than as SOC in the arid cropland in northern China. Increasing SOC stock through long-term straw incorporation and manure application in the arid and semi-arid regions also enhanced carbonate accumulation in soil profiles.
  • Authors:
    • Zechmeister-Boltenstern, S.
    • Stahr, K.
    • Zehetner, F.
    • Wimmer, B.
    • Kitzler, B.
    • Rempt, F.
    • Watzinger, A.
    • Anders, E.
    • Soja, G.
  • Source: Agricultural and Food Science
  • Volume: 22
  • Issue: 4
  • Year: 2013
  • Summary: Biochar application is a promising strategy for sequestering carbon in agricultural soils and for improving degraded soils. Nonetheless, contradictory and unsettled issues remain. This study investigates whether biochar influences the soil microbial biomass and community structure using phospholipid fatty acid (PLFA) analysis. We monitored the effects of four different types of biochar on the soil microbial communities in three temperate soils of Austria over several months. A greenhouse experiment and two field experiments were conducted. The biochar application did not significantly increase or decrease the microbial biomass. Only the addition of vineyard pruning biochar pyrolysed at 400 degrees C caused microbial biomass to increase in the greenhouse experiment. The biochar treatments however caused shifts in microbial communities (visualized by principal component analysis). We concluded that the shifts in the microbial community structure are an indirect rather than a direct effect and depend on soil conditions and nutrient status.
  • Authors:
    • Barfoot, P.
    • Brookes, G.
  • Source: GM crops & food
  • Volume: 4
  • Issue: 2
  • Year: 2013
  • Summary: Given the increasing awareness and appreciation of issues such as global warming and the impact of mankind's activities such as agriculture on the global environment, this paper updates previous assessments of the environmental impact of an important and relatively new technology, crop biotechnology has had on global agriculture. It focuses on the environmental impacts associated with changes in pesticide use and greenhouse gas emissions arising from the use of GM crops. The adoption of the technology has reduced pesticide spraying by 474 million kg (-8.9%) and, as a result, decreased the environmental impact associated with herbicide and insecticide use on these crops [as measured by the indicator the Environmental Impact Quotient (EIQ)] by 18.1%. The technology has also facilitated a significant reduction in the release of greenhouse gas emissions from this cropping area, which, in 2011, was equivalent to removing 10.22 million cars from the roads.
  • Authors:
    • Kucharik, C. J.
    • Duran, B. E. L.
  • Source: Soil Science Society of America Journal
  • Volume: 77
  • Issue: 5
  • Year: 2013
  • Summary: Greenhouse gas emissions from soils are often measured using trace-gas flux chamber techniques without a standardized protocol, raising concerns about measurement accuracy and consistency. To address this, we compared measurements from non-steady-state non-through-flow (NTF) chambers with a non-steady-state through-flow (TF) chamber system in three bioenergy cropping systems located in Wisconsin. Additionally, we investigated the effects of the NTF flux calculation method and deployment time on flux measurements. In all cropping systems, when NTF chambers were deployed for 60 min and a linear regression (LR) flux calculation was used, soil CO2 and N2O fluxes were, on average, 18 and 12% lower, respectively, than fluxes measured with a 15-min deployment. Fluxes calculated with the HMR method, a hybrid of nonlinear and linear approaches, showed no deployment time effects for CO2 and N2O and produced 27 to 32% higher CO2 fluxes and 28 to 33% higher N2O fluxes in all crops than the LR approach with 60-min deployment. Across all crops, CO2 fluxes measured with the TF chamber system were higher by 24.4 to 84.9 mg CO2-C m(-2) h(-1) than fluxes measured with NTF chambers using either flux calculation method. These results suggest that NTF chamber deployment time should be shortened if the LR approach is used, although detection limits should be considered, and the HMR approach may be more appropriate when long deployment times are necessary. Significant differences in absolute flux values with different chamber types highlight the need for significant effort in determining the accuracy of methods or alternative flux measurement technologies.
  • Authors:
    • McDaniel, M. D.
    • Wickings, K.
    • Salam, D. S.
    • Grandy, A. S.
    • Culman, S. W.
    • Snapp, S. S.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 179
  • Year: 2013
  • Summary: Litter decomposition dynamics are influenced by soil nutrient status, yet the specific effects of soil nitrogen (N) on litter decomposition in agricultural systems are not well understood. We explored litter decomposition and related soil organic matter dynamics in no-till, corn-based Midwestern U.S. cropping systems receiving 0, 134, and 291 kg N ha -1 y -1. We found that total soil carbon (C) and N, light fraction organic matter, and permanganate oxidizable C were similar among treatments, but N fertilization at rates of 134 and 291 kg N ha -1 y -1 reduced potentially mineralizable C by as much as 37% and 58%, respectively, compared to the unfertilized treatment. Litter mass remaining after one year of field decomposition was greater with wheat litter (37%) than with corn litter (23%), but was not influenced by N fertilizer rate. In litter, N fertilization led to increases in the activities of two hydrolase enzymes involved in simple carbohydrate metabolism (beta-d-cellobiohydrolase and beta-1,4-glucosidase) and periodic increases in one related to N metabolism (beta-1,4-N-acetylglucosaminidase), but had no effects on enzymes regulating the breakdown of aromatic compounds (phenol oxidase), or on enzymes measured in the soil. N fertilization also decreased arthropod densities in decomposing litter. We found contrasting effects of N fertilizer on processes regulating decomposition, but altogether our results were consistent with a limited or nil role for N fertilization in accelerating litter and soil C turnover, and thus do not support N fertilization as a contributor to depletion of C stocks in agricultural soils.
  • Authors:
    • Gottschall, N.
    • Drury, C. F.
    • Gregorich, E. G.
    • Topp, E.
    • Sunohara, M. D.
    • Nangia, V.
    • Lapen, D. R.
  • Source: Journal of Environmental Management
  • Volume: 129
  • Year: 2013
  • Summary: Controlled tile drainage can boost crop yields and improve water quality, but it also has the potential to increase GHG emissions. This study compared in-situ chamber-based measures of soil CH4, N2O, and CO2 fluxes for silt loam soil under corn and soybean cropping with conventional tile drainage (UTD) and controlled tile drainage (LID). A semi-empirical model (NEMIS-NOE) was also used to predict soil N2O fluxes from soils using observed soil data. Observed N2O and CH4 fluxes between UTD and CID fields during the farming season were not significantly different at 0.05 level. Soils were primarily a sink for CH4 but in some cases a source (sources were associated exclusively with CTD). The average N2O fluxes measured ranged between 0.003 and 0.028 kg N ha(-1) day(-1). There were some significantly higher (p <= 0.05) CO2 fluxes associated with LID relative to UTD during some years of study. Correlation analyses indicated that the shallower the water table, the greater the CO2 fluxes. Higher corn plant C for CTD tended to offset estimated higher CTD CO2 C losses via soil respiration by similar to 100-300 kg C ha(-1). There were good fits between observed and predicted (NEMIS-NOE) N2O fluxes for corn (R-2 = 0.70) and soybean (R-2 = 0.53). Predicted N2O fluxes were higher for CID for approximately 70% of the paired-field study periods suggesting that soil physical factors, such as water-filled pore space, imposed by CTD have potentially strong impacts on net N fluxes. Model predictions of daily cumulative N2O fluxes for the agronomically-active study period for corn-CTD and corn-UTD, as a percentage of total N fertilizer applied, were 3.1% and 2.6%, respectively. For predicted N2O fluxes on basis of yield units, indices were 0.0005 and 0.0004 (kg N kg(-1) crop grain yield) for CTD and UTD corn fields, respectively, and 0.0011 and 0.0005 for CTD and UTD soybean fields, respectively.
  • Authors:
    • Ouyang, W.
    • Qi, S.
    • Hao, F.
    • Wang, X.
    • Shan, Y.
    • Chen, S.
  • Source: Ecological Modelling
  • Volume: 252
  • Year: 2013
  • Summary: Agricultural activity is a primary factor contributing to global warming. In higher latitude freeze zone, agricultural activities pose a more serious threat to global warming than other zones. The crop management practices of various land use types have direct impacts on soil organic carbon (SOC) and global warming potential (GWP). Crop variations and cultivation practices are two important factors affecting carbon sequestration and the exchange of greenhouse gases between soils and the atmosphere. This exchange has special characteristics in the freeze zone. In this paper, the impact of crop patterns and cultivation management (i.e., residue return rate, manure amendment, and chemical N fertiliser application) on SOC and GWP in an agricultural freeze zone was analysed. The Denitrification-Decomposition (DNDC) model was employed to predict the long-term dynamics of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) for diyland and paddy rice systems. The CO2-equivalent index was used to express the GWP response of N2O, CH4 and CO2. The simulated results indicated that the manure amendment and N fertiliser application can improve the SOC, increase crop production and enhance the GWP. The cultivation of returning residue to the soil is the win-win solution for SOC conservation and GWP control. It was found that paddy rice was preferable to dryland for sequestering atmospheric CO2 and mitigating global warming. This analysis also indicated that the DNDC model is a valid tool for predicting the consequences of SOC and GWP changes in cropland agroecosystems in the freeze zone. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Arbuckle,J. Gordon, Jr.
    • Morton,Lois Wright
    • Hobbs,Jon
  • Source: Climatic Change
  • Volume: 118
  • Issue: 3-4
  • Year: 2013
  • Summary: Agriculture is both vulnerable to climate change impacts and a significant source of greenhouse gases. Increasing agriculture's resilience and reducing its contribution to climate change are societal priorities. Survey data collected from Iowa farmers are analyzed to answer the related research questions: (1) do farmers support adaptation and mitigation actions, and (2) do beliefs and concerns about climate change influence those attitudes. Results indicate that farmers who were concerned about the impacts of climate change on agriculture and attributed it to human activities had more positive attitudes toward both adaptive and mitigative management strategies. Farmers who believed that climate change is not a problem because human ingenuity will enable adaptations and who did not believe climate change is occurring or believed it is a natural phenomenon-a substantial percentage of farmers-tended not to support mitigation.
  • Authors:
    • Smith,Lydia J.
    • Torn,Margaret S.
  • Source: Climatic Change
  • Volume: 118
  • Issue: 1
  • Year: 2013
  • Summary: Terrestrial biological atmospheric carbon dioxide removal (BCDR) through bioenergy with carbon capture and storage (BECS), afforestation/reforestation, and forest and soil management is a family of proposed climate change mitigation strategies. Very high sequestration potentials for these strategies have been reported, but there has been no systematic analysis of the potential ecological limits to and environmental impacts of implementation at the scale relevant to climate change mitigation. In this analysis, we identified site-specific aspects of land, water, nutrients, and habitat that will affect local project-scale carbon sequestration and ecological impacts. Using this framework, we estimated global-scale land and resource requirements for BCDR, implemented at a rate of 1 Pg C y(-1). We estimate that removing 1 Pg C y(-1) via tropical afforestation would require at least 7 x 10(6) ha y(-1) of land, 0.09 Tg y(-1) of nitrogen, and 0.2 Tg y(-1) of phosphorous, and would increase evapotranspiration from those lands by almost 50 %. Switchgrass BECS would require at least 2 x 10(8) ha of land (20 times U.S. area currently under bioethanol production) and 20 Tg y(-1) of nitrogen (20 % of global fertilizer nitrogen production), consuming 4 x 10(12) m(3) y(-1) of water. While BCDR promises some direct (climate) and ancillary (restoration, habitat protection) benefits, Pg C-scale implementation may be constrained by ecological factors, and may compromise the ultimate goals of climate change mitigation.
  • Authors:
    • Oztekin, M. E.
  • Source: Journal of Food, Agriculture and Environment
  • Volume: 10
  • Issue: 2 part 3
  • Year: 2012
  • Summary: Land use is an important global issue in terms of preserving the soils, agricultural crop production and farmers' economy as well as the other usage purposes. There are many useful approaches and tools for efficient determination of the land use types. In this study, distribution of different field crops and citrus orchards were monitored and determined for land use types (LUTs) using the low cost ASTER satellite images and GIS in Akarsu Irrigation District of Lower Seyhan Plain (9495 ha) in southern Turkey. Prior to parceling in the field, study area maps of 1:5000 scale were digitized by using ArcGIS software. The enhanced satellite images were overlaid onto the digitized parcel map for ground observations. The images were printed and checked for all crops of the fields. Commonly grown different field crops and orchards were mapped during the field work. A database for this research was established after an intensive field work. The crop types and their coordinates were determined and recorded during the field works. Five LUTs were identified in the study area, and corn and citrus were the most planted LUTs. Furthermore, suitability of soil series for LUTs was investigated; Canakci and Mursel soil series in the study area were found to be highly suitable for all LUTs. It was concluded that cost effective ASTER images could be potentially used for the determination of different crops and orchards which have different reflection values. However, the images must be obtained during the appropriate time period.