• Authors:
    • Stevenson, F. C.
    • Vanasse, A.
    • Legere, A.
  • Source: Agronomy Journal
  • Volume: 105
  • Issue: 3
  • Year: 2013
  • Summary: Combining low-input systems with conservation tillage may be feasible for field crops under northeastern conditions. This study compared the effects of herbicide-free (HF), organic (ORG), conventional (CONV), and herbicide-tolerant (GM) cropping systems applied to three 20 yr-old tillage treatments (MP, moldboard plow; CP, chisel plow; NT, no-till) on weed biomass and crop productivity in a 4-yr barley ( Hordeum vulgare L.)-red clover ( Trifolium pratense L.)-corn ( Zea mays L.)-soybean [ Glycine max (L.) Merr.] rotation. Barley yield (4.5 Mg ha -1), and red clover forage yield (two cuts: 5.3 Mg ha -1) were similar across treatments. With MP and CP tillage, silage corn yield for CONV and GM systems (15 Mg ha -1) was 25% greater than for HF and ORG (11 Mg ha -1), whereas HF-NT and ORG-NT systems produced no harvestable yield. Soybean yield for HF-MP and ORG-MP systems was similar to that for CONV and GM (2.4 Mg ha -1), whereas yield in for the HF and ORG systems with CP and NT was half or less than for other treatments. Some form of primary tillage (CP or MP) was needed in corn and soybean to achieve adequate weed control and yield in the ORG and HF systems. Midseason weed proportion of total biomass was greater in the HF and ORG systems with CP and NT, and provided good yield prediction in corn ( R2=0.74) and soybean ( R2=0.84). Nutrient availability appeared adequate in corn following N 2-fixing red clover but limiting in NT and CP for soybean following corn. Improving crop sequence, fertilization, and weed management will be key to the adoption of low-input systems using conservation tillage practices in cool, humid climates.
  • 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:
    • Mahanta, D.
    • Tuti, M. D.
    • Gupta, H. S.
    • Bhatt, J. C.
    • Bisht, J. K.
    • Pandey, S. C.
    • Bhattacharyya, R.
    • Mina, B. L.
    • Singh, R. D.
    • Chandra, S.
    • Srivastva, A. K.
    • Kundu, S.
  • Source: Agronomy Journal
  • Volume: 105
  • Issue: 1
  • Year: 2013
  • Summary: Carbon retention is a critical issue in arable farming of the Indian Himalayas. This study, conducted from 2001 through 2010 on a sandy clay loam soil, evaluated the effect of tillage alterations (conventional tillage [CT] and zero tillage [ZT]) and selected irrigation treatments (I1: pre-sowing, I2: pre-sowing + active tillering or crown root initiation, I3: pre-sowing + active tillering or crown root initiation + panicle initiation or flowering, and I4: pre-sowing + active tillering or crown root initiation + panicle initiation or flowering + grain filling), applied at the critical growth stages to rice ( Oryza sativa L.) and wheat ( Triticum aestivum L.) on soil organic C (SOC) retention and its pools, soil aggregation, and aggregate-associated C contents in the 0- to 30-cm soil layer. Results indicate that the plots under ZT had nearly 17 and 14% higher total SOC and particulate organic C contents compared with CT (~9.8 and 3.6 g kg -1 soil) in the 0- to 5-cm soil layer after 9 yr of cropping, despite similar mean aboveground biomass yields of both crops on both CT and ZT plots. Tillage had no effect on C pools in the subsurface layers. Irrigation had positive impact on SOC content in the 0- to 5- and 5- to 15-cm layers. Although the labile pools of SOC were positively affected by ZT, the recalcitrant pool was not. Plots under ZT and I4 also had higher large and small macroaggregates and macroaggregate-associated SOC. Thus, adoption of ZT is the better management option for soil C improvement than CT, and irrigation generally enhances the positive impacts.
  • Authors:
    • Campbell, C. A.
    • Desjardins, R. L.
    • Smith, W. N.
    • McConkey, B. G.
    • Shrestha, B. M.
    • Grant, B. B.
    • Miller, P. R.
  • Source: Canadian Journal of Soil Science
  • Volume: 93
  • Issue: 1
  • Year: 2013
  • Summary: There is uncertainty about how crop rotation and tillage affect soil organic C (SOC) on the Canadian prairies. We compared SOC amount and change (SOC) for one continuous crop and four 3-yr fallow-containing crop rotations under no-tillage (NT), and two fallow-containing crop rotations under minimum-tillage (MT), from 1995 to 2005 in semiarid southwestern Saskatchewan. After 11 yr, SOC (0- to 15-cm depth) was 0.2 Mg C ha -1 higher under continuous crop compared with fallow-containing systems. There were no significant differences in SOC and SOC among fallow-containing rotations or between MT and NT. Total C inputs were weakly ( R2=0.18) but significantly ( P<0.05) correlated to SOC, which changed by0.33 Mg C ha -1 for each Mg ha -1 C input above or below 2.4 Mg C ha -1 yr -1. Carbon inputs were typically less than this amount and SOC generally decreased over the experiment. Simulations of SOC with the Century model were consistent with our observations regarding SOC per unit of C input. There was slight loss of SOC for the above-average precipitation regime during the study. Simulations also supported our finding that SOC differences between crop mix and tillage systems may require several decades to become distinguishable in this semiarid climate with small and variable C inputs.
  • Authors:
    • Zhang, X-C.
    • Zheng, Z-Q.
    • Lu, Z.-Y.
    • Lu, C.-Y.
    • Sivelli,A.
    • Li, H.-W.
    • Wang, Q-J.
    • He, J
    • Li, H.
  • Source: Soil Science
  • Volume: 178
  • Issue: 1
  • Year: 2013
  • Summary: Traditional tillage (TT) in the North China Plain has maintained grain productivity in the past 50 years. Nonetheless, it has also been a major contributor to global greenhouse gas emissions, biodiversity and soil fertility loss, soil degradation, and even desertification. Permanent raised beds (PRB) have been proposed as a viable solution to achieve sustainable farming in this plain. The effects on soil chemical properties of the PRB treatment and two other treatments, namely, no-tillage and TT treatments, were measured between 2005 and 2011 in the annual double cropping regions of the North China Plain. The soil properties significantly ( P1.35) were significantly ( P<0.05) higher than those under no-tillage and TT. In the cropping zone of PRB, the bulk density was significantly reduced by 14.4%, whereas soil organic carbon, total nitrogen, phosphorus, and potassium and available nitrogen, phosphorus, and potassium in the 0- to 10-cm soil layer were significantly increased by 24.8%, 78.8%, 121.9%, 81.8%, 46.2%, 7.0%, 2.9%, respectively, in comparison with those of TT treatments. Winter wheat and summer maize yields in PRB also underwent a slight increase. Permanent raised beds seem to be an improvement on current farming systems in the North China Plain and valuable for the sustainability of farming in this region.
  • Authors:
    • Hulugalle, N. R.
  • Source: Crop and Pasture Science
  • Volume: 64
  • Issue: 8
  • Year: 2013
  • Summary: Partial mitigation of global warming caused by accelerated emissions of greenhouse gases such as carbon dioxide may be possible by storing atmospheric carbon in soils. Carbon storage is influenced by processes and properties that affect soil aggregation, such as clay and silt concentrations and mineralogy, intensity and frequency of wet/dry cycles, and microbial activity. Microbial activity, in turn, is influenced by factors such as temperature, nutrient and water availability, and residue quality. The objective of this study was to assess the influence of average annual maximum temperature on soil carbon storage in Vertosols under cotton-based farming systems. This paper reports a re-evaluation of results obtained from a series of experiments on cotton-farming systems conducted in eastern Australia between 1993 and 2010. The experimental sites were in the Macquarie and Namoi Valleys of New South Wales, and the Darling Downs and Central Highlands of Queensland. Average soil organic carbon storage in the 0-0.6m depth was highest in a Black Vertosol in Central Queensland and lowest in a Grey Vertosol that was irrigated with treated sewage effluent at Narrabri. At other sites, average values were generally comparable and ranged from 65 to 85 t C/ha. Climatic parameters such as ambient maximum temperature, T-max, and rainfall at rainfed sites (but not irrigated sites) were also related to soil organic carbon storage. At most sites, variations in carbon storage with average ambient maximum temperature were described by Gaussian models or bell-shaped curves, which are characteristic of microbial decomposition. Carbon storage occurred at peak rates only for a very limited temperature range at any one site, with these temperatures increasing with decreasing distance from the equator. The exception was a site near Narrabri that was irrigated with treated sewage effluent, where the relationship between soil organic carbon and T-max was linear. The decrease or absence of change in soil carbon storage with time reported in many Australian studies of annual cropping systems may be due to carbon storage occurring within a limited temperature range, whereas intra-seasonal average maximum temperatures can range widely. Further research needs to be conducted under field conditions to confirm these observations.
  • Authors:
    • Zhao, J.-S.
    • Hu, R.-G.
    • Iqbal, J.
    • Lin, S.
  • Source: Pedosphere
  • Volume: 23
  • Issue: 5
  • Year: 2013
  • Summary: To compare the CH4 oxidation potential among different land uses and seasons, and to observe its response to monsoon precipitation pattern and carbon and nitrogen parameters, a one-year study was conducted for different land uses (vegetable field, tilled and non-tilled orchard, upland crops and pine forest) in central subtropical China. Results showed significant differences in CH4 oxidation potential among different land uses (ranging from -3.08 to 0.36 kg CH4 ha(-1) year(-1)). Upland with corn-peanut-sweet potato rotation showed the highest CH4 emission, while pine forest showed the highest CH4 oxidation potential among all land uses. Non-tilled citrus orchard (-0.72 +/- 0.08 kg CH4 ha(-1) year(-1)) absorbed two times more CH4 than tilled citrus orchard.(-0.38 +/- 0.06 kg CH4 ha(-1) year(-1)). Irrespective of different vegetation, inorganic N fertilizer application significantly influenced CH4 fluxes across the sites (R-2 = 0.86, P = 0.002). Water-filled pore space, soil microbial biomass carbon, and dissolved nitrogen showed significant effects across different land uses (31% to 38% of variability) in one linear regression model. However, their cumulative interaction was significant for pine forest only, which might be attributed to undisturbed microbial communities legitimately responding to other variables, leading to net CH4 oxidation in the soil. These results suggested that i) natural soil condition tended to create win-win situation for CH4 oxidation, and agricultural activities could disrupt the oxidation potentials of the soils; and ii) specific management practices including but not limiting to efficient fertilizer application and utilization, water use efficiency, and less soil disruption might be required to increase the CH4 uptake from the soil.
  • Authors:
    • Wander, M. M.
    • Dunn, J. B.
    • Mueller, S.
    • Kwon, H.-Y.
  • Source: Biomass and Bioenergy
  • Volume: 55
  • Issue: August
  • Year: 2013
  • Summary: Current estimates of life cycle greenhouse gas emissions of biofuels produced in the US can be improved by refining soil C emission factors (EF; C emissions per land area per year) for direct land use change associated with different biofuel feedstock scenarios. We developed a modeling framework to estimate these EFs at the state-level by utilizing remote sensing data, national statistics databases, and a surrogate model for CENTURY's soil organic C dynamics submodel (SCSOC). We estimated the forward change in soil C concentration within the 0-30 cm depth and computed the associated EFs for the 2011 to 2040 period for croplands, grasslands or pasture/hay, croplands/conservation reserve, and forests that were suited to produce any of four possible biofuel feedstock systems [corn (Zea Mays L)-corn, corn-corn with stover harvest, switchgrass (Panicum virgatum L), and miscanthus (Miscanthus x giganteus Greef et Deuter)]. Our results predict smaller losses or even modest gains in sequestration for corn based systems, particularly on existing croplands, than previous efforts and support assertions that production of perennial grasses will lead to negative emissions in most situations and that conversion of forest or established grasslands to biofuel production would likely produce net emissions. The proposed framework and use of the SCSOC provide transparency and relative simplicity that permit users to easily modify model inputs to inform biofuel feedstock production targets set forth by policy. (C) 2013 Elsevier Ltd. All rights reserved.
  • Authors:
    • Lal, R.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 28
  • Issue: 2
  • Year: 2013
  • Summary: Ecosystem functions and services provided by soils depend on land use and management. The objective of this article is to review and synthesize relevant information on the impacts of no-till (NT) management of croplands on ecosystem functions and services. Sustainable management of soil through NT involves: (i) replacing what is removed, (ii) restoring what has been degraded, and (iii) minimizing on-site and off-site effects. Despite its merits, NT is adopted on merely similar to 9% of the 1.5 billion ha of global arable land area. Soil's ecosystem services depend on the natural capital (soil organic matter and clay contents, soil depth and water retention capacity) and its management. Soil management in various agro-ecosystems to enhance food production has some trade-offs/disservices (i. e., decline in biodiversity, accelerated erosion and non-point source pollution), which must be minimized by further developing agricultural complexity to mimic natural ecosystems. However, adoption of NT accentuates many ecosystem services: carbon sequestration, biodiversity, elemental cycling, and resilience to natural and anthropogenic perturbations, all of which can affect food security. Links exist among diverse ecosystem services, such that managing one can adversely impact others. For example, increasing agronomic production can reduce biodiversity and deplete soil organic carbon (SOC), harvesting crop residues for cellulosic ethanol can reduce SOC, etc. Undervaluing ecosystem services can jeopardize finite soil resources and aggravate disservices. Adoption of recommended management practices can be promoted through payments for ecosystem services by a market-based approach so that risks of disservices and negative costs can be reduced either through direct economic incentives or as performance payments.
  • Authors:
    • Osborne, S. L.
    • Lehman, R. M.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 170
  • Issue: April
  • Year: 2013
  • Summary: We determined soil surface fluxes of greenhouse gases (carbon dioxide, nitrous oxide, methane) from no-till, dryland corn (Zea mays L.) in eastern South Dakota and tested the effect of rotation on greenhouse gas fluxes from corn. The corn was grown within a randomized, complete block study that included both a 2-year (corn-soybean) rotation and a 4-year (corn-field peas-winter wheat-soybean) rotation with plots containing the corn phase present in every year, 2007-2010. Annual carbon dioxide (CO2) fluxes were between 1500 and 4000 kg CO2-C ha(-1) during the four-year study. Annual nitrous oxide (N2O) fluxes ranged from 0.8 to 1.5 kg N2O-N ha(-1) with peak fluxes during spring thaw and following fertilization. Net methane (CH4) fluxes in 2007 were close to zero, while fluxes for 2008-2010 were between 0.9 and 1.6 kg CH4-C ha(-1). Methane fluxes increased with consistently escalating values of soil moisture over the four-year period demonstrating that soils which previously exhibited neutral or negative CH4 flux may become net CH4 producers in response to multiyear climatic trends. No significant differences in gas fluxes from corn due to treatment (2-year vs. 4-year rotation) were observed. Mean net annual soil surface gas fluxes from corn calculated over four years for both treatments were 2.4 Mg CO2-C ha(-1), 1.2 kg N2O-N ha(-1), and 0.9 kg CH4-C ha(-1). Annual global warming potentials (GWP) as CO2 equivalents were 572 kg ha(-1) and 30 kg ha(-1) for N2O and CH4, respectively. Measurements of soil carbon showed that the 4-yr rotation accrued 596 kg C ha(-1) yr(-1) in the top 30 cm of soil which would be more than sufficient (2.19 Mg CO2 eq ha(-1) yr(-1)) to offset the annual GWP of the nitrous and methane emissions from corn. In contrast, the 2-year rotation lost 120 kg C ha(-1) yr(-1) from the top 30 cm of soil resulting in corn being a net producer of greenhouse gases and associated GWP. Published by Elsevier B.V.