• Authors:
    • Verhulst, N.
    • Luna-Guido, M.
    • Navarro-Noya, Y. E.
    • Bello-Lopez, J. M.
    • Ramirez-Villanueva, D. A.
    • Govaerts, B.
    • Dendooven, L.
  • Source: APPLIED SOIL ECOLOGY
  • Volume: 90
  • Year: 2015
  • Summary: Agricultural practices affect the bacterial community structure in soil. It was hypothesized that agricultural practices would also affect the bacteria involved in the degradation of crop residue. Soil was sampled from four different agricultural practices, i.e. conventional agriculture on the flat or on beds, or conservation agriculture on the flat or on beds. Cultivating crops on the flat is done traditionally, but cultivating crops on beds was introduced so as to avoid water logging during the rainy season and its potential negative effect on yields. Soil from these four treatments was amended in the laboratory with maize residue (Zea mays L.) or its neutral detergent fibre (NDF) fraction, mostly consisting of (hemi) cellulose, and incubated aerobically for 14 days. Maize residue was applied to soil as it is left in the field in conservation agriculture and NDF was added to study which bacteria were favoured by application of (hemi) cellulose. Soil was incubated aerobically while the carbon mineralization and the bacterial population were monitored. On the one hand, the relative abundance of phylotypes belonging to bacterial groups that preferred low nutrient environments was higher in soil with conservation agriculture (e.g. Acidobacteria 17.6%, Planctomycetes 1.7% and Verrucomicrobia 1.5%) compared to conventional practices (Acidobacteria 11.8%, Planctomycetes 0.9% and Verrucomicrobia 0.4%). On the other hand, the relative abundance of phylotypes belonging to bacterial groups that preferred nutrient rich environments, such as Actinobacteria, showed an opposite trend. It was 11.9% in conservation agriculture and 16.2% in conventional practices. The relative abundance of Arthrobacter (Actinobacteria) and Bacillales more than doubled when maize residue was applied to soil compared to the unamended soil and that of Actinomycetales when maize or NDF was applied. Application of organic material reduced the relative abundance of a wide range of bacterial groups, e.g. Acidobacteria, Bacteroidetes, Planctomycetes and Verrucomicrobia. It was found that application of organic material favoured the same bacterial groups that were more abundant in the soil cultivated conventionally while it reduced those that were favoured in conservation agriculture.
  • Authors:
    • Sakamoto, A.
    • Kimoto, N.
    • Aoki, H.
    • Yoshioka, R.
    • Yoshioka, N.
    • Arai, H.
    • Shimada, S.
    • Sakata, R.
    • Melling, L.
    • Inubushi, K.
  • Source: SOIL SCIENCE AND PLANT NUTRITION
  • Volume: 61
  • Issue: 1
  • Year: 2015
  • Summary: Oil palm (Elaeis guineensis Jacq.) production in Indonesia and Malaysia is currently the focus of concern due to its potential impact on the environment via greenhouse gas emissions. Oil palm plantations have been reported to release large quantities of nitrous oxide (N 2O) into the atmosphere, which is most likely linked to nitrogen (N) fertilizer use. However, there are still limited studies comparing effects of the type of soil and N fertilizer on N 2O and carbon dioxide (CO 2) emissions. This study aimed to evaluate the effects of soil types and N fertilizer on N 2O and CO 2 emissions in oil palm plantations. N 2O and CO 2 emissions were measured for 15-16 months from 2010-2012 in Tunggal sandy loam soil, Indonesia, and in Simunjan sandy soil and Tatau peat soil, Malaysia. Within each site, treatments with coated fertilizer and conventional fertilizer, and unfertilized with and without tillage, were established. N 2O and CO 2 fluxes showed high variabilities with seasons, types of soil and fertilizer treatments. The mean of the N 2O fluxes from each treatment in the Simunjan sandy soil was the lowest among the three soils, ranging from 0.80 to 3.81 and 1.63 to 5.34 g N m -2 h -1 in the wet and dry seasons, respectively. The mean of the N 2O fluxes from each treatment in the Tunggal sandy loam soil ranged from 27.4 to 89.7 and 6.27 to 19.1 g N m -2 h -1 in the wet and dry seasons, respectively. The mean of the N 2O fluxes was found to be the highest among the three soils in each treatment of the Tatau peat soil, ranging from 131 to 523 and 66.1 to 606 g N m -2 h -1 in the wet and dry seasons, respectively. The N application rate of coated fertilizer was about half that of conventional fertilizer and was applied as deep placement. In the Tungal soil, coated fertilizer reduced N 2O emissions by 31 and 48% in wet and dry seasons, respectively, compared to the conventional fertilizer, and was similar to unfertilized treatment. However, N 2O emissions increased in Simunjan and Tatau soils during dry seasons. There was no significant difference between treatments. These results show that N 2O and CO 2 fluxes in the tropical oil palm plantations were significantly affected by the type of soil, but not always by fertilizer treatments.
  • Authors:
    • Al-Kaisi, M. M.
    • Tenesaca, C. G.
  • Source: APPLIED SOIL ECOLOGY
  • Volume: 89
  • Year: 2015
  • Summary: In-field management practices of corn cob and residue mix (CRM) as a feedstock source for ethanol production can have potential effects on soil greenhouse gas (GHG) emissions. The objective of this study was to investigate the effects of CRM piles, storage in-field, and subsequent removal on soil CO2 and N2O emissions. The study was conducted in 2010-2012 at the Iowa State University, Agronomy Research Farm located near Ames, Iowa (42.0 degrees'N; 93.8 degrees'W). The soil type at the site is Canisteo silty clay loam (fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls). The treatments for CRM consisted of control (no CRM applied and no residue removed after harvest), early spring complete removal (CR) of CRM after application of 7.5 cmdepth of CRM in the fall, 2.5 cm, and 7.5 cmdepth of CRM over two tillage systems of no-till (NT) and conventional tillage (CT) and three N rates (0, 180, and 270 kg N ha(-1)) of 32% liquid UAN (NH4NO3) in a randomized complete block design with split-split arrangements. The findings of the study suggest that soil CO2 and N2O emissions were affected by tillage, CRM treatments, and N rates. Most N2O and CO2 emissions peaks occurred as soil moisture or temperature increased with increase precipitation or air temperature. However, soil CO2 emissions were increased as the CRM amount increased. On the other hand, soil N2O emissions increased with high level of CRM as N rate increased. Also, it was observed that NT with 7.5 cm CRM produced higher CO2 emissions in drought condition as compared to CT. Additionally, no differences in N2O emissions were observed due to tillage system. In general, dry soil conditions caused a reduction in both CO2 and N2O emissions across all tillage, CRM treatments, and N rates.
  • Authors:
    • Stone, J. J.
    • Moriles-Miller, J.
    • Carlson, C. G.
    • Reicks, G.
    • Clay, D. E.
    • Clay, S. A.
  • Source: Journal of Environmental Quality
  • Volume: 44
  • Issue: 3
  • Year: 2015
  • Summary: Corn stover harvesting is a common practice in the western U.S. Corn Belt. This 5-yr study used isotopic source tracking to quantify the influence of two tillage systems, two corn ( Zea mays L.) surface residue removal rates, and two yield zones on soil organic C (SOC) gains and losses at three soil depths. Soil samples collected in 2008 and 2012 were used to determine 13C enrichment during SOC mineralization, the amount of initial SOC mineralized (SOC lost), and plant C retained in the soil (PCR incorp) and sequestered C (PCR incorp - SOC lost). The 30% residue soil cover after planting was achieved by the no-till and residue returned treatments and was not achieved by the chisel plow, residue removed treatment. In the 0- to 15-cm soil depth, the high yield zone had lower SOC loss (1.49 Mg ha -1) than the moderate yield zone (2.18 Mg ha -1), whereas in the 15- to 30-cm soil depth, SOC loss was higher in the 60% (1.38 Mg ha -1) than the 0% (0.82 Mg ha -1) residue removal treatment. When the 0- to 15- and 15- to 30-cm soil depths were combined, (i) 0.91 and 3.62 Mg SOC ha -1 were sequestered in the 60 and 0% residue removal treatments; (ii) 2.51 and 0.36 Mg SOC ha -1 were sequestered in the no-till and chisel plow treatments, and (iii) 1.16 and 1.65 Mg SOC ha -1 were sequestered in the moderate and high yield zone treatments, respectively. The surface treatments influenced C cycling in the 0- to 15- and 15- to 30-cm depths but did not influence SOC turnover in the 30- to 60-cm depth.
  • Authors:
    • Olesen, J. E.
    • Munkholm, L. J.
    • Hansen, E. M.
    • Melander, B.
  • Source: Agronomy Journal
  • Volume: 44
  • Issue: 3
  • Year: 2015
  • Summary: Crop management factors, such as tillage, rotation, and straw retention, need to be long-term to allow conclusions on effects on crop yields, nitrate leaching, and carbon sequestration. In 2002, two field experiments, each including four cash crop rotations, were established on soils with 9 and 15% clay, under temperate, coastal climate conditions. Direct drilling and harrowing to two different depths were compared to plowing with respect to yield, nitrate N leaching, and carbon sequestration. For comparison of yields across rotations, grain and seed dry matter yields for each crop were converted to grain equivalents (GE). Leaching was compared to yields by calculating yield-scaled leaching (YSL, g N kg -1 GE), and N balances were calculated as the N input in manure minus the N output in products removed from the fields. Direct drilling reduced yields, but no effect on leaching was found. Straw retention did not significantly increase yields, nor did it reduce leaching, while fodder radish ( Raphanus sativus L.) as a catch crop was capable of reducing nitrate leaching to a low level. Thus, YSL of winter wheat ( Triticum aestivum L.) was higher than for spring barley ( Hordeum vulgare L.) grown after fodder radish due to the efficient catch crop. Soil organic carbon (SOC) did not increase significantly after 7 yr of straw incorporation or noninversion tillage. There was no correlation between N balances calculated for each growing season and N leaching measured in the following percolation period.
  • Authors:
    • Zheng, X.
    • Wang, K.
    • Yao, Z.
    • Liu, C.
  • Source: Science Article
  • Volume: 203
  • Year: 2015
  • Summary: Global nitrogen fertilizer consumption is expected to continue to increase. To explore effective mitigation strategies, a deeper understanding of the responses of nitrogen use efficiency, nitric oxide (NO) emission and the NO direct emission factor (EF d) to increasing fertilization rates is needed. A gradient of fertilization rates (0, 135, 270, 430, 650 and 850 kg N ha -1 yr -1 in the form of urea, hereafter referred to as N0, N135, N270, N430, N650 and N850, respectively) was used to fully represent the nitrogen application levels in the wheat-maize rotational cropping system that has been widely adopted in China. The annual NO emissions ranged from 0.430.04 (N0) to 2.640.35 kg N ha -1 yr -1 (N850) and linearly increased with increasing fertilization rates ( P<0.01). The high pH and low carbon availability in the calcareous soil limited NO production; thus, low EF d values (0.26-0.36%) were observed. The partial factor productivity of applied nitrogen (PFP N) rapidly decreased with increasing fertilization rates; the relationship could be characterized by a rectangular hyperbolic function ( P<0.01). The expected trade-off between EF d and PFP N was not observed. The on-farm PFP N was only 333 kg grain kg -1 N (N430), highlighting the necessity of optimizing current management strategies. Based on a review of previous studies, a comprehensive optimized management strategy is recommended to obtain the maximum benefits for multiple goals of a wheat-maize cropping system. However, consecutive field observations and model studies are still needed to validate the long-term effects of this management strategy.
  • Authors:
    • McNamara, N.
    • Dondini, M.
    • Smith, P.
    • Davies, C.
    • Robertson, A.
  • Source: Journal
  • Volume: 7
  • Issue: 3
  • Year: 2015
  • Summary: The lignocellulosic perennial grass Miscanthus has received considerable attention as a potential bioenergy crop over the last 25years, but few commercial plantations exist globally. This is partly due to the uncertainty associated with claims that land-use change (LUC) to Miscanthus will result in both commercially viable yields and net increases in carbon (C) storage. To simulate what the effects may be after LUC to Miscanthus, six process-based models have been parameterized for Miscanthus and here we review how these models operate. This review provides an overview of the key Miscanthus soil organic matter models and then highlights what measurers can do to accelerate model development. Each model (WIMOVAC, BioCro, Agro-IBIS, DAYCENT, DNDC and ECOSSE) is capable of simulating biomass production and soil C dynamics based on specific site characteristics. Understanding the design of these models is important in model selection as well as being important for field researchers to collect the most relevant data to improve model performance. The rapid increase in models parameterized for Miscanthus is promising, but refinements and improvements are still required to ensure that model predictions are reliable and can be applied to spatial scales relevant for policy. Specific improvements, needed to ensure the models are applicable for a range of environmental conditions, come under two categories: (i) increased data generation and (ii) development of frameworks and databases to allow simulations of ranging scales. Research into nonfood bioenergy crops such as Miscanthus is relatively recent and this review highlights that there are still a number of knowledge gaps regarding Miscanthus specifically. For example, the low input requirements of Miscanthus make it particularly attractive as a bioenergy crop, but it is essential that we increase our understanding of the crop's nutrient remobilization and ability to host N-fixing organisms to derive the most accurate simulations.
  • Authors:
    • Singh, J. S.
  • Source: Agriculture Article
  • Volume: 203
  • Year: 2015
  • Summary: The indiscriminate application of synthetic chemicals in agriculture has deteriorated extremely the quality of environment due to loss of beneficial microbial communities. The world now has a real prospect to grow sustainably and eliminate acute food scarcity in the next generation. Achieving this will require eco-friendly and safe technology for restoration of degraded lands. Microbes form the vital living components of soils contributing ecosystem sustainability due to their cosmopolitan survival, massive efficient genetic pool, catabolic versatility and stress tolerance potential. It has been reported that direct application of modified microbes enhances the microbial diversity in the agro-ecosystems by breaking dormancy of inactive soil microbial pool. It is presumed that enhanced diversity of efficient microbial community compositions in degraded ecosystems establish a functional equilibrium, which help maintain sustainability. Undoubtedly therefore, microbes may play the role of chief ecological engineers in resolving the environmental problems as well as the innovative tool to reinstate the degraded ecosystems.
  • Authors:
    • Huang, S.
    • Pan, X.
    • Shi, Q.
    • Zeng, Y.
    • Sun, Y.
  • Source: Article
  • Volume: 153
  • Year: 2015
  • Summary: Runoff from farmland is of great importance to both agricultural and environmental sustainability. In the present study, a meta-analysis was conducted to quantify the effectiveness of no-tillage (NT) in reducing surface runoff and to explore the factors controlling the effectiveness. Results showed that overall, NT significantly reduced runoff by 21.9% and 27.2% compared to reduced tillage (RT) and conventional moldboard plow (MP), respectively. The effectiveness of NT in reducing runoff was higher under simulated than natural rainfall, particularly as compared to MP. The reduction in runoff under NT was significant and greatest for moderate slope gradients (5-10%) relative to both RT and MP, but without statistical significance for both gentle (10%) slope gradients. As compared to MP, the effectiveness of NT in reducing runoff decreased over time, whereas no such trend was found relative to RT. Compared to RT, NT significantly reduced runoff in soils with low clay content (<33% clay), while resulting in a slight but non-significant increase in runoff in soils with high clay content (=33% clay). The effectiveness of NT in reducing runoff compared to RT did not vary with tillage direction. Runoff was significantly reduced by NT with crop residue retention relative to RT, but not with residue removal. Our results conclude that NT needs to be adapted to specific environmental conditions and management practices for improved controls on runoff. © 2015.
  • Authors:
    • VandenBygaart, A. J.
    • Smith, W. N.
    • Campbell, C. A.
    • Grant, B. B.
    • Congreves, K. A.
    • Krobel, R.
    • Lemke, R. L.
    • Desjardins, R. L.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 3
  • Year: 2015
  • Summary: Agricultural management practices which promote soil organic carbon (SOC) sequestration can contribute to the long-term productivity of soils, thus research must quantify and predict SOC dynamics in response to crop management. Using long-term (1967-2009) data from 10 cropping systems on a Brown Chernozem (Aridic Haploboroll) in the Canadian semiarid prairies at Swift Current, Saskatchewan, we assessed the effect of fertilizer, cropping frequency, and crop type on SOC dynamics in the 0- to 15-cm depth. Three models: Campbell, introductory carbon balance model (ICBM), and DayCent were evaluated, all of which produced fairly accurate predictions of SOC content and sequestration rates ( R2 of 0.64-0.82); however, DayCent had the highest correlation and lowest errors of prediction and was deemed superior. Residue inputs of 0.87 to 1.13 Mg C ha -1 yr -1 maintained the SOC level, and SOC content was directly related to factors which increased C inputs. The SOC content and sequestration rates were lowest for wheat ( Triticum aestivum L.)-based rotations which were frequently fallowed and included flax ( Linum usitatissimum L.), but highest for systems which were frequently cropped, well-fertilized, and included rye ( Secale cereale L.) or pulse crops in rotation. For systems with high C input, DayCent projected SOC gains of 12 Mg C ha -1 from 2009 to 2100, indicating that the soil at Swift Current had not reached maximum C capacity. This study was the first to rigorously test and demonstrate the strength of the DayCent for simulating SOC under different cropping systems on the Canadian prairies.