• Authors:
    • Butterbach-Bahl, K.
    • Murphy, D. V.
    • Barton, L.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 167
  • Year: 2013
  • Summary: Semi-arid lands represent one fifth of the global land area but our understanding of greenhouse gas fluxes from these regions is poor. We investigated if inclusion of a grain legume and/or lime in a crop rotation altered greenhouse gas emissions from an acidic soil. Nitrous oxide (N 2O) and methane (CH 4) fluxes were measured from a rain-fed, cropped soil in a semi-arid region of Australia for two years on a sub-daily basis. The randomised-block design included two cropping rotations (lupin-wheat, wheat-wheat) by two liming treatments (0, 3.5 t ha -1) by three replicates. The lupin-wheat rotation only received N fertilizer during the wheat phase (20 kg N ha -1), while the wheat-wheat received 125 kg N ha -1 during the two year study. Fluxes were measured using soil chambers connected to a fully automated system that measured N 2O and CH 4 by gas chromatography. Nitrous oxide fluxes were low (-1.4 to 9.2 g N 2O-N ha -1 day -1), and less than those reported for arable soils in temperate climates. Including a grain legume in the cropping rotation did not enhance soil N 2O; total N 2O losses were approximately 0.1 kg N 2O-N ha -1 after two years for both lupin-wheat and wheat-wheat rotations when averaged across liming treatment. Liming decreased cumulative N 2O emissions from the wheat-wheat rotation by 30% by lowering the contribution of N 2O emissions following summer-autumn rainfall events, but had no effect on N 2O emissions from the lupin-wheat rotation. Daily CH 4 fluxes ranged from -14 to 5 g CH 4-C ha -1 day -1. Methane uptake after two years was lower from the wheat-wheat rotation (601 g CH 4-C ha -1) than from either lupin-wheat rotations (967 g CH 4-C ha -1), however liming the wheat-wheat rotation increased CH 4 uptake (1078 g CH 4-C ha -1) to a value similar to the lupin-wheat rotation. Liming provides a strategy for lowering on-farm greenhouse gas emissions from N fertilised soils in semi-arid environments via decreased N 2O fluxes and increased CH 4 uptake.
  • Authors:
    • Schoenau, J. J.
    • Alotaibi, K. D.
  • Source: Biology and Fertility of Soils
  • Volume: 49
  • Issue: 2
  • Year: 2013
  • Summary: Ethanol production results in distiller grain, and biodiesel produces glycerol as by-product. However, there is limited information on effects of their addition on evolution of N2O and CO2 from soils, yet it is important to enable our understanding of impacts of biofuel production on greenhouse gas budgets. The objective of this study was to evaluate the direct effects of adding wet distillers grain (WDG), thin stillage (TS), and glycerol at three rates on greenhouse gas emissions (N2O and CO2) and nutrient supply rates in a cultivated soil from the Canadian prairies. The WDG and TS application rates were: 100, 200, or 400 kg N ha(-1), whereas glycerol was applied at: 40, 400, or 4,000 kg C ha(-1) applied alone (G -aEuro parts per thousand N) or in a combination with 300 kg N ha(-1) (G + N). In addition, conventional amendments of urea (UR) and dehydrated alfalfa (DA) were added at the same rates of total N as the by-products for comparative purposes. The production of N2O and CO2 was measured over an incubation period of 10 days in incubation chambers and Plant Root Simulator (TM) resin membrane probes were used to measure nutrient (NH (4) (+) -N, NO (3) (-) -N, and PO (4) (-3) -P) supply rates in the soil during incubation. Per unit of N added, urea tended to result in the greatest N2O production, followed by wet distillers grain and thin stillage, with glycerol and dehydrated alfalfa resulting in the lowest N2O production. Cumulative N2O production increased with increasing the rate of N-containing amendments and was the highest at the high rate of UR treatment. Addition of urea with glycerol contributed to a higher rate of N2O emission, especially at the low rate of glycerol. The DA and WDG resulted in the greatest evolution of CO2 from the soil, with the thin stillage resulting in less CO2 evolved per unit of N added. Addition of N fertilizer along with glycerol enhanced microbial activity and decomposition. The amendments had significant impacts on release of available nutrient, with the UR treatments providing the highest NO (3) (-) -N supply rate. The TS treatments supplied the highest rate of NH (4) (+) -N, followed by WDG compared to the other amendments. The WDG treatments were able to provide the greatest supply of PO (4) (-3) -P supply in comparison to the other amendments. Microbial N immobilization was associated with glycerol treatments applied alone. This study showed that the investigated biofuel by-products can be suitable soil amendments as a result of their ability to supply nutrients and N2O emissions that did not exceed that of the conventional urea fertilizer.
  • Authors:
    • Wu, J.
    • Luo, Z. Z.
    • Wang, J.
    • Cai, L. Q.
    • Zhang, R. Z.
  • Source: Zhongguo Shengtai Nongye Xuebao / Chinese Journal of Eco-Agriculture
  • Volume: 21
  • Issue: 8
  • Year: 2013
  • Summary: This study analyzed the effects of different tillage conditions on greenhouse gas emissions of double sequence pea-wheat rotation fields during 2011. Three greenhouse gases (CO 2, N 2O and CH 4) emission were investigated under four tillage types [conventional tillage without straw mulching (T), no-tillage without straw mulching (NT), conventional tillage with straw mulching (TS) and no-tillage with straw mulching (NTS)]. The carbon dioxide analyzer and static chamber-gas chromatographic techniques were used to continuously measure and analyze the greenhouse gases fluxes. The results showed that double sequence pea-wheat rotation fields served not only as source of atmospheric CO 2, N 2O, but also as sink of atmospheric CH 4. Compared with T, NT retarded CO 2 emission. The three conservation tillage methods of NTS, NT and TS reduced N 2O emission but significantly increased CH 4 absorption. CO 2 and N 2O fluxes were significantly correlated with topsoil temperature ( R2=0.92** and 0.89**), soil temperature at the 5 cm soil depth ( R2=0.95** and 0.91**) and soil temperature at the 10 cm soil depth ( R2=0.77* and 0.62*). CH 4 fluxes were uncorrected with soil temperature at different soil depths. The correlation coefficients between CO 2 and soil water content, and CH 4 and soil water content at 0-5 cm soil layer were 0.69* and 0.72*, respectively. The correlation coefficient between CO 2 and soil water content at the 5-10 cm soil layer was 0.77* and that between CH 4, and soil water content at the 5-10 cm soil layer was 0.64*. CO 2, CH 4, fluxes were positively correlated with soil water content at the 10-30 cm soil layer. N 2O fluxes showed negative correlations with soil water content at different soil layers. The calculated global warming potential of the three greenhouse gases under the different tillage conditions showed that NT limited greenhouse gas flux, thereby reducing greenhouse effect.
  • Authors:
    • Heinemann, A. B.
    • Moreira, J. A. A.
    • Silveira, P. M. da
    • Machado, P. L. O. de A.
    • Costa, A. R. da
    • Leal, W. G. de O.
    • Madari, B. E.
    • Carvalho, M. T. de M.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 48
  • Issue: 5
  • Year: 2013
  • Summary: The objective of this work was to measure the fluxes of N2O‑N and NH3‑N throughout the growing season of irrigated common‑bean (Phaseolus vulgaris), as affected by mulching and mineral fertilization. Fluxes of N2O‑N and NH3‑N were evaluated in areas with or without Congo signal grass mulching (Urochloa ruziziensis) or mineral fertilization. Fluxes of N were also measured in a native Cerrado area, which served as reference. Total N2O‑N and NH3‑N emissions were positively related to the increasing concentrations of moisture, ammonium, and nitrate in the crop system, within 0.5 m soil depth. Carbon content in the substrate and microbial biomass within 0.1 m soil depth were favoured by Congo signal grass and related to higher emissions of N2O‑N, regardless of N fertilization. Emission factors (N losses from the applied mineral nitrogen) for N2O‑N (0.01-0.02%) and NH3‑N (0.3-0.6%) were lower than the default value recognized by the Intergovernmental Panel on Climate Change. Mulch of Congo signal grass benefits N2O‑N emission regardless of N fertilization.
  • Authors:
    • Alves Moreira, J. A.
    • da Silveira, P. M.
    • Oliveira de Almeida Machado, P. L.
    • da Costa, A. R.
    • de Oliveira Leal, W. G.
    • Madari, B. E.
    • de Melo Carvalho, M. T.
    • Heinemann, A. B.
  • Source: Pesquisa Agropecuária Brasileira
  • Volume: 48
  • Issue: 5
  • Year: 2013
  • Summary: The objective of this work was to measure the fluxes of N2O-N and NH3-N throughout the growing season of irrigated common-bean (Phaseolus vulgaris), as affected by mulching and mineral fertilization. Fluxes of N2O-N and NH3-N were evaluated in areas with or without Congo signal grass mulching (Urochloa ruziziensis) or mineral fertilization. Fluxes of N were also measured in a native Cerrado area, which served as reference. Total N2O-N and NH3-N emissions were positively related to the increasing concentrations of moisture, ammonium, and nitrate in the crop system, within 0.5 m soil depth. Carbon content in the substrate and microbial biomass within 0.1 m soil depth were favoured by Congo signal grass and related to higher emissions of N2O-N, regardless of N fertilization. Emission factors (N losses from the applied mineral nitrogen) for N2O-N (0.01-0.02%) and NH3-N (0.3-0.6%) were lower than the default value recognized by the Intergovernmental Panel on Climate Change. Mulch of Congo signal grass benefits N2O-N emission regardless of N fertilization.
  • Authors:
    • Norton, J. B.
    • Hurisso, T. T.
    • Norton, U.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 181
  • Year: 2013
  • Summary: Conversion of native prairie land for agricultural production has resulted in significant loss and redistribution of soil organic matter (SOM) in the soil profile ultimately leading to declining soil fertility in a low-productivity semiarid agroecosystem. Improved understanding of such losses can lead to development of sustainable land management practices that maintain soil fertility and enhance soil quality. This study was conducted to determine whether conservation practices impact soil profile carbon (C) and nitrogen (N) accumulation in central High Plains. Soil samples were taken at four-depth increments to 1.2 m in July of 2011 from five unfertilized fields under long-term management with varying degrees of soil disturbance: (1) historic wheat ( Triticum aestivum)-fallow (HT) - managed with tillage alone, (2) conventional wheat-fallow (CT) - input of herbicides for weed control and fewer tillage operation than historic wheat-fallow, (3) no-till wheat-fallow (NT) - not plowed since 2000 and herbicides used for weed control, (4) grass-legume mixture - established in 2005 as in the Conservation Reserve Program (CRP), and (5) native mixed grass prairie (NP) - representing a relatively undisturbed reference location. Cumulative soil organic C (SOC) was not significantly different among the three wheat-fallow systems when the whole profile (0-120 cm) was analyzed. However, SOC, dissolved organic C (DOC), and total soil N contents decreased in the direction NP > CRP ≥ NT > HT ≥ CT in the surface 0-30 cm depth. In the surface 0-30 cm depth, estimated annual SOC storage rate averaged 0.28 Mg C ha -1 year -1 since the cessation of tillage in 2000 and 0.58 Mg C ha -1 year -1 since the establishment of CRP grass-legume mixture in 2005. Cumulative soil inorganic C (SIC) accumulation ranged between 8.1 and 24.9 Mg ha -1and was greatest under wheat-fallow systems, particularly at deeper soil layers, relative to the perennial systems (NP and CRP). Results from this study suggest that repeated soil disturbance induced by cropping and fallow favored large accumulation of SIC which presence may result in decline in soil fertility and productivity; whereas conversion from tilled wheat-fallow to CRP grass-legume mixture offers great SOC storage potential relative to NT wheat-fallow practices.
  • Authors:
    • Miller, P. R.
    • O'Dea, J. K.
    • Jones, C. A.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 68
  • Issue: 4
  • Year: 2013
  • Summary: Replacing summer fallow practices with annual legumes as green manures (LGMs) may increase the sustainability of northern Great Plains wheat (Triticum aestivum L.) systems. Viability hinges on soil water use management and realizing biologically fixed nitrogen (N) benefits. Plot-scale research has shown that managing LGMs with first-flower stage termination and no-till practices conserves soil water and that rotational N benefits can increase wheat grain quality Nonetheless, farmer adoption of LGMs has been negligible. To better understand this practice and its regional adoption potential, we conducted a participatory on-farm assessment of no-till LGM versus summer fallow wheat rotations in north-central Montana. Soil water and nitrate (NO3) levels to 0.9 m (3 ft), potentially mineralizable N (PMN) to 0.3 m (1 ft), wheat yields, conservation potential, and producer adoption challenges were assessed at five farmer-managed, field-scale sites. Compared to fallow, LGM treatment diminished mean wheat yield by 6% (0.24 Mg ha(-1) [3.7 bu ac(-1)]), diminished grain protein by 9 g kg(-1) when wheat was fertilized with N (p = 0.01), and increased grain protein by 5 g kg(-1) when wheat was unfertilized (p = 0.08). Small soil water depletions in LGM treatments below fallow at wheat seeding (17%; 30 mm [1.2 in]) and near-record high rainfall during the wheat growing season (280 to 380 mm [11 to 14 in]) suggest that LGMs likely did not limit soil water available to wheat in this study. Soil NO3 levels following LGMs were 29% to 56% less than summer fallow at wheat seeding, and conversely, greater PMN was detected in LGM treatments at 3 of 5 sites. We theorize that N mineralization from LGMs was insubstantial by wheat seeding due to dry soil conditions and low LGM biomass N contributions, consequently affecting wheat yield potential due to limited early season soil N availability. LGMs increased average use efficiency of available N by 24% during the wheat year and increased total residue carbon (C) and N returned to soils by 260 and 26 kg ha(-1) (232 and 23 lb ac(-1)), respectively, after two years. Our results illustrated that farmers viably managed LGM soil water use with early termination and no-till practices but that LGM adoption may be hindered by a lack of immediate wheat yield or protein benefits from legume-N and seed costs for LGMs. Appropriate incentives, management strategies, and yield benefit expectations (short versus long term) should be fostered to increase the adoption potential of this N-economizing soil and water conservation strategy.
  • Authors:
    • Ghosh, P. K.
    • Hazra, K. K.
    • Venkatesh, M. S.
    • Praharaj, C. S.
    • Kumar, N.
  • Source: CANADIAN JOURNAL OF SOIL SCIENCE
  • Volume: 93
  • Issue: 1
  • Year: 2013
  • Summary: As an important component of crop diversification, pulses/legumes are known to improve soil quality through their unique characteristics of biological N 2 fixation, root exudates, leaf litter fall and deep root system. Changes in the soil organic carbon pool due to the inclusion of pulses in an upland maize-based cropping system were evaluated after seven cropping cycles. The results indicate that inclusion of pulses in an upland maize-based cropping system improved the total soil organic carbon content, being greater in surface soil (0-0.2 m) and declining with soil depth. Of the four carbon fractions of total soil organic carbon ( C frac1 - C frac4 ) measured in the upland maize-based system, the most labile C fraction ( C frac1 ) was dominant. Distribution of the carbon pool varied with depth and the size of the active carbon pool was larger than that of the passive carbon pool in the surface soil, whereas in the subsurface soil depth, the size of the passive carbon pool was larger than that of the active carbon pool. Maize-wheat-mungbean and pigeonpea-wheat systems resulted in significant increases ( P≤0.05), of 11 and 10%, respectively in total soil organic carbon, and 10 and 15% in soil microbial biomass carbon, respectively, as compared with a conventional maize-wheat system. Application of crop residues along with farmyard manure at 5 Mg ha -1 and biofertilizers resulted in greater amounts of carbon fractions and higher carbon management index than in the control and the recommended inorganic (NPKSZnB) treatment, particularly in the system where pulses were included. In plots receiving organic amendments, the variable cumulative carbon input had higher correlation with total organic carbon ( R2=0.997), active pool ( R2=0.934), passive pool ( R2=0.916) and soil microbial biomass carbon ( R2=0.664). Inclusion of pulses in the maize-based system and the organic nutrient management system sequestered more organic carbon and maintained better soil health in Inceptisols of the Indo-Gangetic plains of India.
  • Authors:
    • Armstrong, R.
    • Norton, R.
    • Chen, D.
    • Lam, S. K.
  • Source: Plant and Soil
  • Volume: 364
  • Issue: 1-2
  • Year: 2013
  • Summary: This study investigated the residual contribution of legume and fertilizer nitrogen (N) to a subsequent crop under the effect of elevated carbon dioxide concentration ([CO2]). Field pea (Pisum sativum L.) was labeled in situ with N-15 (by absorption of a N-15-labeled urea solution through cut tendrils) under ambient and elevated (700 mu mol mol(-1)) [CO2] in controlled environment glasshouse chambers. Barley (Hordeum vulgare L.) and its soil were also labeled under the same conditions by addition of N-15-enriched urea to the soil. Wheat (Triticum aestivum L.) was subsequently grown to physiological maturity on the soil containing either N-15-labeled field pea residues (including N-15-labeled rhizodeposits) or N-15-labeled barley plus fertilizer N-15 residues. Elevated [CO2] increased the total biomass of field pea (21 %) and N-fertilized barley (23 %), but did not significantly affect the biomass of unfertilized barley. Elevated [CO2] increased the C:N ratio of residues of field pea (18 %) and N-fertilized barley (19 %), but had no significant effect on that of unfertilized barley. Elevated [CO2] increased total biomass (11 %) and grain yield (40 %) of subsequent wheat crop regardless of rotation type in the first phase. Irrespective of [CO2], the grain yield and total N uptake by wheat following field pea were 24 % and 11 %, respectively, higher than those of the wheat following N-fertilized barley. The residual N contribution from field pea to wheat was 20 % under ambient [CO2], but dropped to 11 % under elevated [CO2], while that from fertilizer did not differ significantly between ambient [CO2] (4 %) and elevated [CO2] (5 %). The relative value of legume derived N to subsequent cereals may be reduced under elevated [CO2]. However, compared to N fertilizer application, legume incorporation will be more beneficial to grain yield and N supply to subsequent cereals under future (elevated [CO2]) climates.
  • Authors:
    • Oikawa,S.
    • Okada,M.
    • Hikosaka,K.
  • Source: Plant and Soil
  • Volume: 373
  • Issue: 1-2
  • Year: 2013
  • Summary: The effects of elevated CO2 on leaf area index (LAI) vary among studies. We hypothesized that the interactive effects of CO2 and nitrogen on leaf area loss have important roles in LAI regulation. We studied the leaf area production and loss using nodulating soybean and its non-nodulating isogenic line in CO2-controlled greenhouse systems. Leaf area production increased with elevated CO2 levels in the nodulating soybean stand and to a lesser extent in the non-nodulating line. Elevated CO2 levels accelerated leaf area loss only in nodulating plants. Consequently, both plants exhibited a similar stimulation of peak LAI with CO2 elevation. The accelerated leaf loss in nodulating plants may have been caused by newly produced leaves shading the lower leaves. The nodulating plants acquired N throughout the growth phase, whereas non-nodulating plants did not acquire N after flowering due to the depletion of soil N. N retranslocation to new organs and subsequent leaf loss were faster in non-nodulating plants compared with nodulating plants, irrespective of the CO2 levels. LAI regulation in soybean involved various factors, such as light availability within the canopy, N acquisition and N demands in new organs. These effects varied among the growth stages and CO2 levels.