• Authors:
    • Lehrsch, G. A.
    • Lentz, R. D.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 3
  • Year: 2014
  • Summary: Little is known about inorganic fertilizer or manure effects on organic C (OC) and inorganic C (IC) losses from a furrow irrigated field, particularly in the context of other system C gains or losses. In 2003 and 2004, we measured dissolved organic and inorganic C (DOC, DIC) and particulate OC and IC (POC, PIC) concentrations in irrigation inflow, runoff, and percolation waters (six to seven irrigations per year); C inputs from soil amendments and crop biomass; harvested C; and gaseous C emissions from field plots cropped to silage corn (Zea mays L.) in southern Idaho. Annual treatments included: manure treatment (M) 13 (Year 1) and 34 (Year 2) Mg ha-1 stockpiled dairy manure; inorganic fertilizer treatment (F) 78 (Year 1) and 195 (Year 2) kg N ha-1 inorganic N fertilizer; or no amendment treatment (NA) as a control. The mean annual total C input was 15.7, 10.8, and 10.4 Mg ha-1 for M, F, and NA, respectively, while total C outputs for the three treatments were similar, averaging 12.2 Mg ha-1. Manure plots ended each growing season with a mean net gain of 3.3 Mg C ha-1 (a positive net C flux) vs. a net loss for F and NA (-1.6 and -1.5 Mg C ha-1, respectively). The C added to M was ∼1.5 × that added to F or NA, yet relative to F, M increased gaseous C emissions only 1.18×, increased runoff DOC losses only 1.04×, decreased particulate runoff total C 19%, and decreased percolate DOC 32%. Increased C gas emissions from manure (relative to fertilizer) were less when silage was removed than when retained (1.18× vs. 2× reported in other studies). This suggests a means by which manure applications to corn crops can be managed to minimize C emissions. Amendments had both direct and indirect influences on individual C components, e.g., the losses of DIC and POC in runoff and DOC in percolation water, producing temporally complex outcomes, which may depend on environmental conditions external to the field. © Soil Science Society of America.
  • Authors:
    • Zhu, X. D.
    • Zhuang, Q. L.
    • Qin, Z. C.
  • Source: GLOBAL CHANGE BIOLOGY BIOENERGY
  • Volume: 6
  • Issue: 6
  • Year: 2014
  • Summary: Biofuel made from conventional (e.g., maize (Zea mays L.)) and cellulosic crops (e.g., switchgrass (Panicum virgatum L.) and Miscanthus (Miscanthus * giganteus)) provides alternative energy to fossil fuels and has been considered to mitigate greenhouse gas emissions. To estimate the large-scale carbon and nitrogen dynamics of these biofuel ecosystems, process-based models are needed. Here, we developed an agroecosystem model (AgTEM) based on the Terrestrial Ecosystem Model for these ecosystems. The model was incorporated with biogeochemical and ecophysiological processes including crop phenology, biomass allocation, nitrification, and denitrification, as well as agronomic management of irrigation and fertilization. It was used to estimate crop yield, biomass, net carbon exchange, and nitrous oxide emissions at an ecosystem level. The model was first parameterized for maize, switchgrass, and Miscanthus ecosystems and then validated with field observation data. We found that AgTEM well reproduces the annual net primary production and nitrous oxide fluxes of most sites, with over 85% of total variation explained by the model. Local sensitivity analysis indicated that the model sensitivity varies among different ecosystems. Net primary production of maize is sensitive to temperature, precipitation, cloudiness, fertilizer, and irrigation and less sensitive to atmospheric CO 2 concentrations. In contrast, the net primary production of switchgrass and Miscanthus is most sensitive to temperature among all factors. Nitrous oxide fluxes are sensitive to management in maize ecosystems, and sensitive to climate factors in cellulosic ecosystems. The developed model should help advance our understanding of carbon and nitrogen dynamics of these biofuel ecosystems at both site and regional levels.
  • Authors:
    • Caesar-TonThat, T.
    • Stevens, W. B.
    • Sainju, U. M.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 3
  • Year: 2014
  • Summary: Management practices are needed to reduce soil C losses from croplands converted from Conservation Reserve Program (CRP) grassland. We evaluated the effects of irrigation, tillage, cropping system, and N fertilization on surface residue and soil organic C (SOC) at the 0- to 85-cm depth in relation to crop yields in a sandy loam soil from 2005 to 2011 in croplands converted from CRP in western North Dakota. Treatments were two irrigation practices (irrigated vs. nonirrigated) as the main plot and six cropping systems [CRP, conventional till malt barley (Hordeum vulgare L.) with N fertilizer (CTBN), conventional till malt barley without N fertilizer (CTBO), no-till malt barley- pea (Pisum sativum L.) with N fertilizer (NTB-P), no-till malt barley with N fertilizer (NTBN), and no-till malt barley without N fertilizer (NTBO)] as the split plot arranged in a randomized complete block with three replications. Soil surface residue amount and C content were greater in CRP and NTBN than the other cropping systems. At 0 to 5 cm, SOC was greater in irrigated CRP, but at 0 to 85 cm it was greater in nonirrigated NTBN than most other treatments. At 0 to 20 cm, SOC increased by 0.26 to 1.21 Mg C ha-1 yr-1 in NTB-P and CRP but decreased by 0.02 to 0.68 Mg C ha-1 yr-1 in other cropping systems. Surface residue C and SOC at 0 to 10 cm were related to annualized crop grain yield (R2 = 0.45-0.77, P x≤ 0.12, n = 10). Because of positive C sequestration rate and favorable crop yields, NTB-P may be used as a superior management option to reduce soil C losses and sustain yields in croplands converted from CRP in the northern Great Plains.
  • Authors:
    • Caesar-Tonthat, T.
    • Stevens, W. B.
    • Sainju, U. M.
    • Montagne, C.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 5
  • Year: 2014
  • Summary: Management practices are needed to reduce N losses from croplands converted from Conservation Reserve Program (CRP). We evaluated the effects of irrigation, tillage, cropping system, and N fertilization on surface residue N, soil total nitrogen (STN), NH 4-N, and NO 3-N at the 0- to 85-cm depth in a sandy loam from 2005 to 2011 in croplands converted from CRP in western North Dakota. Treatments were two irrigation practices (irrigated vs. non-irrigated) and six cropping systems (CRP, conventional till malt barley [ Hordeum vulgaris L.] with nitrogen fertilizer [CTBN], conventional till malt barley without nitrogen fertilizer [CTBO], no-till malt barley-pea ( Pisum sativum L.) with nitrogen fertilizer [NTB-P], no-till malt barley with nitrogen fertilizer [NTBN], and no-till malt barley without nitrogen fertilizer [NTBO]). Surface residue N was greater in non-irrigated CRP than irrigated and non-irrigated CTBN, CTBO, and NTBO and non-irrigated NTB-P. Soil total N at 0 to 10 cm was greater in irrigated CRP, but at 0 to 85 cm was greater in non-irrigated NTBN than irrigated CRP, CTBN, CTBO, and NTBO and non-irrigated NTB-P. Soil NH 4-N content at 0 to 20 cm was also greater in irrigated CRP than irrigated and non-irrigated CTBO, NTB-P, and NTBO. Soil NO 3-N at 0 to 85 cm was greater in NTB-P than CRP, CTBO, and NTBO. Because of increased soil N sequestration and NO 3-N level, irrigated NTB-P may be used to reduce soil N losses and optimize N availability compared to other treatments in croplands converted from CRP.
  • Authors:
    • Yeluripati, J. B.
    • Wilson, B. R.
    • Smith, P.
    • Hulugalle, N. R.
    • Senapati, N.
    • Daniel, H.
    • Ghosh, S.
    • Lockwood, P.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 143
  • Year: 2014
  • Summary: The performance of the Rothamsted Carbon Model (RothC) in simulating soil carbon (SOC) storage in cotton based cropping systems under different tillage management practices on an irrigated Vertisol in semi-arid, subtropics was evaluated using data from a long-term (1994-2012) cotton cropping systems experiment near Narrabri in north-western New South Wales, Australia. The experimental treatments were continuous cotton/conventional tillage (CC/CT), continuous cotton/minimum tillage (CC/MT), and cotton-wheat (Triticum aestivum L.) rotation/minimum tillage (CW/MT). Soil carbon (C) input was calculated by published functions that relate crop yield to soil C input. Measured values showed a loss in SOC of 34%, 24% and 31% of the initial SOC storages within 19 years (1994-2012) under CC/CT, CC/MT, and CW/MT, respectively. RothC satisfactorily simulated the dynamics of SOC in cotton based cropping systems under minimum tillage (CC/MT and CW/MT), whereas the model performance was poor under intensive conventional tillage (CC/CT). The model RothC overestimated SOC storage in cotton cropping under conventional intensive tillage management system. This over estimation could not be attributed to the overestimation of soil C inputs, or errors in initial quantification of SOC pools for model initialization, or the ratio of incoming decomposable plant materials to resistant plant materials. Among other different factors affecting SOC dynamics and its modelling under intensive tillage in tropics and sub-tropics, we conclude that factors for tillage and soil erosion might be needed when modelling SOC dynamics using RothC under intensive tillage management system in the tropics and the sub-tropics.
  • Authors:
    • Wight, J. P.
    • Hons, F. M.
    • Storlien, J. O.
    • Heilman, J. L.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 5
  • Year: 2014
  • Summary: Modern bioenergy feedstocks, such as bioenergy sorghum [Sorghum bicolor (L.) Moench], are being developed to supply future cellulosic biofuel demands. How these cropping systems impact greenhouse gas (GHG) emission of CO2and N2O from the soil is unknown and field research is necessary to elucidate the effects of agronomic management practices on soil trace gas emissions. We studied the effects of N fertilization (0 vs. 280 kg urea-N ha-1), residue management (0 vs. 50% of sorghum biomass returned), crop sequence (corn [Zea mays L.]-sorghum vs. sorghum-sorghum), and their interactions on CO2and N2O emissions from bioenergy production scenarios on a Weswood (finesilty, mixed, superactive, thermic Udifluventic Haplustept) silty clay loam soil in central Texas. Gas fluxes were measured approximately weekly throughout the 2010 and 2011 growing season and at a reduced rate during the fallow season with a photoacoustic gas analyzer integrated with a static chamber. Overall, CO2and N2O fluxes were relatively higher than those observed by others in the United States despite drought conditions throughout much of 2010 and 2011. Highest emissions of both gases were observed during the growing season, often following a precipitation-irrigation event and shortly after N fertilization. Residue return increased cumulative CO2emissions each year, probably due to increased heterotrophic microbial activity. Nitrogen addition significantly increased cumulative emissions of N2O both years but only impacted cumulative CO2emissions in 2011. While crop rotation impacted biomass yield, it had no significant effect on cumulative CO2or N2O emissions. Additional research is needed to identify the optimal N and residue application rates that provide high yields with minimal soil GHG emissions and aid in sustaining long-term soil quality.
  • Authors:
    • Caesar-Tonthat, T.
    • Stevens, W. B.
    • Sainju, U. M.
    • Liebig, M. A.
    • Wang, J.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 3
  • Year: 2014
  • Summary: Little information exists about how global warming potential (GWP) is affected by management practices in agroecosystems. We evaluated the effects of irrigation, tillage, crop rotation, and N fertilization on net GWP and greenhouse gas intensity (GHGI or GWP per unit crop yield) calculated by soil respiration (GWP R and GHGI R) and organic C (SOC) (GWP C and GHGI C) methods after accounting for CO 2 emissions from all sources (irrigation, farm operations, N fertilization, and greenhouse gas [GHG] fluxes) and sinks (crop residue and SOC) in a Lihen sandy loam from 2008 to 2011 in western North Dakota. Treatments were two irrigation practices (irrigated vs. nonirrigated) and five cropping systems (conventional-till malt barley [ Hordeum vulgaris L.] with N fertilizer [CTBN], conventional-till malt barley with no N fertilizer [CTBO], no-till malt barley-pea [ Pisum sativum L.] with N fertilizer [NTB-P], no-till malt barley with N fertilizer, and no-till malt barley with no N fertilizer [NTBO]). While CO 2 equivalents were greater with irrigation, tillage, and N fertilization than without, N 2O and CH 4 fluxes were 2 to 218 kg CO 2 eq. ha -1 greater in nonirrigated NTBN and irrigated CTBN than in other treatments. Previous year's crop residue and C sequestration rate were 202 to 9316 kg CO 2 eq. ha -1 greater in irrigated NTB-P than in other treatments. Compared with other treatments, GWP R and GWP C were 160 to 9052 kg CO 2 eq. ha -1 lower in irrigated and nonirrigated NTB-P. Similarly, GHGI R and GHGI C were lower in nonirrigated NTB-P than in other treatments. Regardless of irrigation practices, NTB-P may lower net GHG emissions more than other treatments in the northern Great Plains.
  • Authors:
    • Liebig, M. A.
    • Caesar-TonThat, T.
    • Stevens, W. B.
    • Sainju, U. M.
    • Wang, J.
  • Source: Journal of Environmental Quality
  • Volume: 43
  • Issue: 3
  • Year: 2014
  • Summary: Little information exists about how global warming potential (GWP) is affected by management practices in agroecosystems. We evaluated the effects of irrigation, tillage, crop rotation, and N fertilization on net GWP and greenhouse gas intensity (GHGI or GWP per unit crop yield) calculated by soil respiration (GWP(R) and GHGI(R)) and organic C (SOC) (GWP(C) and GHGI(C)) methods after accounting for CO2 emissions from all sources (irrigation, farm operations, N fertilization, and greenhouse gas [GHG] fluxes) and sinks (crop residue and SOC) in a Lihen sandy loam from 2008 to 2011 in western North Dakota. Treatments were two irrigation practices (irrigated vs. nonirrigated) and five cropping systems (conventional-till malt barley [Hordeum vulgaris L.] with N fertilizer [CTBN], conventional-till malt barley with no N fertilizer [CTBO], no-till malt barley-pea [Pisum sativum L.] with N fertilizer [NTB-P], no-till malt barley with N fertilizer, and no-till malt barley with no N fertilizer [NTBO]). While CO2 equivalents were greater with irrigation, tillage, and N fertilization than without, N2O and CH4 fluxes were 2 to 218 kg CO2 eq. ha(-1) greater in nonirrigated NTBN and irrigated CTBN than in other treatments. Previous year's crop residue and C sequestration rate were 202 to 9316 kg CO2 eq. ha(-1) greater in irrigated NTB-P than in other treatments. Compared with other treatments, GWP(R) and GWP(C) were 160 to 9052 kg CO2 eq. ha(-1) lower in irrigated and nonirrigated NTB-P. Similarly, GHGI(R) and GHGI(C) were lower in nonirrigated NTB-P than in other treatments. Regardless of irrigation practices, NTB-P may lower net GHG emissions more than other treatments in the northern Great Plains.
  • Authors:
    • Gabriel, J. L.
    • Quemada, M.
    • Garcia-Marco, S.
    • Sanz-Cobena, A.
    • Almendros, P.
    • Vallejo, A.
  • Source: Science of The Total Environment
  • Volume: 466
  • Year: 2014
  • Summary: This study evaluates the effect of planting three cover crops (CCs) (barley, Hordeum vulgare L.; vetch, Vicia villosa L.; rape, Brassica napus L) on the direct emission of N2O, CO2 and CH4 in the intercrop period and the impact of incorporating these CCs on the emission of greenhouse gas (GHG) from the forthcoming irrigated maize (Zea mays L.) crop. Vetch and barley were the CCs with the highest N2O and CO2 losses (75 and 47% increase compared with the control, respectively) in the fallow period. In all cases, fluxes of N2O were increased through N fertilization and the incorporation of barley and rape residues (40 and 17% increase, respectively). The combination of a high C:N ratio with the addition of an external source of mineral N increased the fluxes of N2O compared with -Ba and -Rp. The direct emissions of N2O were lower than expected for a fertilized crop (0.10% emission factor, EF) compared with other studies and the IPCC EF. These results are believed to be associated with a decreased NO pool due to highly denitrifying conditions and increased drainage. The fluxes of CO2 were in the range of other fertilized crops (i.e., 1118.71-1736.52 kg CO2-C ha(-1)). The incorporation of CC residues enhanced soil respiration in the range of 21-28% for barley and rape although no significant differences between treatments were detected. Negative CH4 fluxes were measured and displayed an overall sink effect for all incorporated CC (mean values of -0.12 and -0.10 kg CH4-C ha(-1) for plots with and without incorporated CCs, respectively). (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Skaracis, G. N.
    • Mariolis, N. A.
    • Vlachos, C. E.
  • Source: The Journal of Agricultural Science
  • Volume: 152
  • Issue: 2
  • Year: 2014
  • Summary: Sunflower (Helianthus annuus L.) and rapeseed (Brassica napus L.) are considered as the most suitable crops for biodiesel production in the Mediterranean basin. Soybean (Glycine max L.) could also be used, under certain conditions. In Greece, the farming practice adopted in each region varies significantly, leading to significant differences in the levels of emitted greenhouse gases (GHG). Greenhouse gas emissions were estimated during the cultivation phase as grams of carbon dioxide equivalents (g CO 2e) per megajoule (MJ), followed by emission savings (%) estimation when fossil fuels are replaced by biodiesel. Crop and region comparisons provided important information towards promoting sustainability. Overall, sunflower demonstrated the lowest average emissions, 53.8 g CO 2e/MJ, followed by rapeseed and soybean. Furthermore, rapeseed achieved the lowest emission saving level required by European legislation in most cases studied, with an average value of 37%. Irrigation and nitrogen fertilization were the operations mostly contributing to the total quantity of GHG emissions. More specifically, the highest GHG emissions were found for soybean irrigation (34%) and rapeseed nitrogen fertilization (68%).