• Authors:
    • Brookes,G.
    • Barfoot,P.
  • Source: GM Crops & Food
  • Volume: 7
  • Issue: 2
  • Year: 2015
  • Summary: This paper updates previous assessments of how crop biotechnology has changed the environmental impact of 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 since their first widespread commercial use in the mid 1990s. The adoption of GM insect resistant and herbicide tolerant technology has reduced pesticide spraying by 553 million kg (-8.6%) 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 19.1%. The technology has also facilitated important cuts in fuel use and tillage changes, resulting in a significant reduction in the release of greenhouse gas emissions from the GM cropping area. In 2013, this was equivalent to removing 12.4 million cars from the roads.
  • Authors:
    • Brunetto, G.
    • Tassinari, A.
    • Vidal, R. F.
    • Lourenzi, C. R.
    • Lorensini, F.
    • Ferreira, P. A.
    • Ceretta, C. A.
    • Conti, L.
  • Source: Brazilian Journal of Soil Science
  • Volume: 39
  • Issue: 3
  • Year: 2015
  • Summary: The application of pig slurry rates and plant cultivation can modify the soil phosphorus (P) content and distribution of chemical species in solution. The purpose of this study was to evaluate the total P, available P and P in solution, and the distribution of chemical P species in solution, in a soil under longstanding pig slurry applications and crop cultivation. The study was carried out in soil columns with undisturbed structure, collected in an experiment conducted for eight years in the experimental unit of the Universidade Federal de Santa Maria (UFSM), Santa Maria (RS). The soil was an Argissolo Vermelho distrofico arenico (Typic Hapludalf), subjected to applications of 0, 20, 40, and 80 m(3) ha(-1) pig slurry. Soil samples were collected from the layers 0-5, 5-10, 10-20, 20-30, 30-40, and 40-60 cm, before and after black oat and maize grown in a greenhouse, for the determination of available P, total P and P in the soil solution. In the solution, the concentration of the major cations, anions, dissolved organic carbon (DOC), and pH were determined. The distribution of chemical P species was determined by software Visual Minteq. The 21 pig slurry applications increased the total P content in the soil to a depth of 40 cm, and the P extracted by Mehlich-1 and from the solution to a depth of 30 cm. Successive applications of pig slurry changed the balance between the solid and liquid phases in the surface soil layers, increasing the proportion of the total amount of P present in the soil solution, aside from changing the chemical species in the solution, reducing the percentage complexed with Al and increasing the one complexed with Ca and Mg in the layers 0-5 and 5-10 cm. Black oat and maize cultivation increased pH in the solution, thereby increasing the proportion of HPO42- and reducing H2PO4- species.
  • Authors:
    • Meyer-Aurich, A.
    • Kern, J.
    • Ammon, C.
    • Andert, J.
    • Dicke, C.
    • Kaupenjohann, M.
  • Source: Science Article
  • Volume: 524
  • Year: 2015
  • Summary: Field studies that have investigated the effects of char materials on the emission of nitrous oxide (N2O) are still scarce. Therefore, we conducted a field trial with bio- and hydrochars and measured N2O emissions for one whole year. It was hypothesised that the incorporation of chars reduces the emissions of N2O. Chars were produced by pyrolysis and hydrothermal carbonisation (HTC) using either maize silage or wood residues as feedstock. In addition, after production chars were post-treated with digestate in order to accelerate the ageing process of the chars. Chars and digestate were applied to the soil to raise the C content. Emissions of N2O were measured weekly and soil samples for inorganic nitrogen (N) and soil water-content were taken once a month. Additionally, the abundance of functional marker genes from denitrification (nosZ) was determined in October 2012 and in June 2013. The treatment with pure digestate emitted the most N2O compared to the control and char treatments. However, this was significant only in one case. There were no great differences between the char treatments due to high spatial variability and gene abundance of nosZ did not differ between treatments. Overall, emissions of N2O were relatively low. This was attributed to the heterogeneous distribution of the chars and the sandy soils that did not favour the production of N2O. To conclude, the emissions of N2O were mainly influenced by temperature and precipitation and to a minor extent by the type of char and post-treatment. (C) 2015 Elsevier B.V. All rights reserved.
  • Authors:
    • Dold,Christian
    • Becker,Mathias
  • Source: Journal of Plant Nutrition and Soil Science
  • Volume: 178
  • Issue: 4
  • Year: 2015
  • Summary: Lake Naivasha is a freshwater lake in the East African Rift Valley. With continued lake level declines between 1980 and 2011, the newly exposed land areas were gradually taken for agricultural use. The resulting chronosequences allow for an analysis of the effects of land use duration on nutrient dynamics and agricultural production. Transects representing land use durations of 0-30 (cropland) and 15-30 years (pasture) were established on soils formed on alluvial deposits and lacustrine sediments. We assessed changes in topsoil nitrogen (N) stocks (t ha(-1)), ammonium mineralization potential (N-supplying capacity), and plant-available P with increasing durations of land use. An additional greenhouse experiment studied the responses of kikuyu grass (Cenchrus clandestinus) and maize (Zea mays) in potted topsoil collected from differnt land-use types and chronosequence positions. With increasing duration of land use we noted a significant decline (P < 5%) in soil N contents under both pasture and cropland uses, following a model of exponential decay. The N stocks decreased at 84kgha(-1) a(-1) and a decay rate constant of 0.019a(-1) in pasture soil within 15 years, and at 75kgha(-1) a(-1) with a decay rate-constant of 0.013 a(-1) in cropland soil within 30 years. While the ammonium-N mineralization potential also decreased with land use duration, the trends were significant only in lacustrine pasture soils. Plant-available P did not show any trends that were related to the duration of land use. Kikuyu grass and maize accumulated less dry matter and N as the duration of use increased. This biomass accumulation was significantly related to soil N. A continued mineralization of soil organic matter has possibly contributed to the observed soil N depletion over time. The continuous agricultural use of the littoral wetland zone of Lake Naivasha is likely to entail declining production potentials for both pastures and food crops.
  • Authors:
    • Eleto Torres,Carlos M. M.
    • Kohmann,Marta M.
    • Fraisse,Clyde W.
  • Source: Agricultural Systems
  • Volume: 137
  • Year: 2015
  • Summary: Agriculture is an important source of greenhouse gases (GHG), especially from crop production practices and enteric fermentation by ruminant livestock. Improved production practices in agriculture and increase in terrestrial carbon sinks are alternatives for mitigating GHG emissions in agriculture. The objective of this study was to estimate GHG emissions from hypothetical farm enterprise combinations in the southeastern United States with a mix of cropland and livestock production and estimate the area of forest plantation necessary to offset these emissions. Four different farm enterprise combinations (Cotton; Maize; Peanut; Wheat + Livestock + Forest) with different production practices were considered in the study resulting in different emission scenarios. We assumed typical production practices of farm operations in the region with 100 ha of cropland area and a herd of 50 cows. GHG emissions were calculated regarding production, storage and transportation of agrochemicals (pre-farm) and farm activities such as fertilization, machinery operation and irrigation (on-farm). Simulated total farm GHG emissions for the different farm enterprise combinations and production practices ranged from 348.8 t CO(2)e year(-1) to 765.6 t CO(2)e year(-1). The estimated forest area required to neutralize these emissions ranged from 19 ha to 40 ha. In general, enterprise combinations with more intense production practices that include the use of irrigation resulted in higher total emissions but lower emissions per unit of commodity produced. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Fumagalli,Mattia
  • Source: Italian Journal of Agrometeorology
  • Volume: 20
  • Issue: 1
  • Year: 2015
  • Summary: Intensive maize production in Lombardy region (northern Italy) is widespread and requires big amounts of input, especially nitrogen (N), thus leading to potential environmental risks. Starting from farm survey data the current work aims to evaluate how alternative N management options for reducing losses can be effective in climate change mitigation. Under current management (ACT) of typical continuous maize cropping systems across the region, the greenhouse gases (GHG) emissions from the production of inorganic fertilisers and from direct and indirect N2O released after N application accounted for, on average, 67% of the total GHG emissions. The adoption of the best N management plans (FERT scenario), reduced GHG emissions and C-footprint (expressed per unit of agricultural product) by 27 and 26%, respectively. Furthermore, the double cropping system (two crops harvested in 12 months - ROT scenario) strongly increased GHG emissions in comparison with the only cultivation of a summer crop. However, the high productivity of this system, led to a C-footprint lower than the ACT one and still higher than the FERT one. The current work highlights the opportunities for carbon mitigation offered by changes on field N management, without significantly impact the yield.
  • Authors:
    • Hao,B.
    • Xue,Q.
    • Marek,T. H.
    • Jessup,K. E.
    • Becker,J.
    • Hou,X.
    • Xu,W.
    • Bynum,E. D.
    • Bean,B. W.
    • Colaizzi,P. D.
    • Howell,T. A.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Drought is an important factor limiting corn ( Zea mays L.) yields in the Texas High Plains, and adoption of drought-tolerant (DT) hybrids could be a management tool under water shortage. We conducted a 3-yr field study to investigate yield, evapotranspiration (ET), and water use efficiency (WUE) in DT hybrids. One conventional (33D49) and 4 DT hybrids (P1151HR, P1324HR, P1498HR, and P1564HR) were grown at three water regimes (I 100, I 75, and I 50, referring to 100, 75, and 50% ET requirement) and three planting densities (PD) (5.9, 7.4, and 8.4 plants m -2). Yield (13.56 Mg ha -1) and ET (719 mm) were the greatest at I 100 but WUE (2.1 kg m -3) was the greatest at I 75. Although DT hybrids did not always have greater yield and WUE than 33D49 at I 100, hybrids P1151HR and P1564HR consistently had greater yield and WUE than 33D49 at I 75 and I 50. Compared to 33D49, P1151HR and P1564HR had 8.6 to 12.1% and 19.1% greater yield at I 75 and I 50, respectively. Correspondingly, WUE was 9.8 to 11.7% and 20.0% greater at I 75 and I 50, respectively. Greater PD resulted in greater yield and WUE at I 100 and I 75 but PD did not affect yield and WUE at I 50. Yield and WUE in greater PD (8.4 plants m -2) were 6.3 to 8.3% greater than those in smaller PD (5.9 plants m -2). The results of this study demonstrated that proper selection of DT hybrids can increase corn yield and WUE under water-limited conditions.
  • Authors:
    • Hou,Yong
    • Ma,Lin
    • Sardi,Katalin
    • Sisak,Istvan
    • Ma,Wenqi
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: Nitrogen (N) emissions from food production can cause serious environmental problems. Mitigation strategies require insights of N cycles in this complex system. A substance flow analysis for N in the Hungary food production and processing chain over the period 1961-2010 was conducted. Our results show that the history of the total N input and output for the Hungary food chain consists of four distinct periods: 1961-1974 a rapid increase; 1974-1988 a steady increase; 1988-1992 a sharp decrease; 1992-2010 a period of large annual variations. The total N input to the food chain largely depended on N fertilizer input (on average 83 % of total input). Nitrogen losses were the largest outflows, particularly via ammonia emissions and denitrification from agricultural systems. The N use efficiency (NUE) for crop production sharply decreased from 1961 to 1974, but went up since the late 1980s. The NUE of animal production increased from 11 % in 1961 to 20 % in 2010. The N cost of food production in Hungary largely varied from 3 to 10 kg kg(-1) during 1961-2010, which was related to changes in fertilizer use and human dietary preferences. Increased dependence of crop yield on weather was observed since the early 1990s where large decrease in N fertilizer use occurred. The observed weather-dependence has resulted in large yearly variations in crop yields, the NUE of crop production and also the food N cost, which may pose a threat to food security of Hungary.
  • Authors:
    • Li,Na
    • Ning,Tangyuan
    • Cui,Zhengyong
    • Tian,Shenzhong
    • Li,Zengjia
    • Lal,Rattan
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 102
  • Issue: 3
  • Year: 2015
  • Summary: Fertilizer application and tillage practices play an important role in agricultural production, whereas excess N input could create considerable N2O emissions. However, it is unclear whether urea types under subsoiling or rotary tillage have effects on yield and N2O emissions in maize field. We investigated the effects on N2O emissions and maize (Zea mays L.) yield of tillage (rotary tillage [R] alone and rotary tillage following subsoiling [S]) and two types of urea (polymer-coated urea [P] and conventional urea [C]) applications, respectively, at the sowing [0] and V6 [6] stages in a clay loam soil. N2O emissions varied from 1 to 11 kg N2O-N ha(-1). Compared with S soil, the R soils produced greater N2O emissions. Compared with conventional urea, polymer-coated urea increased maize production and fertilizer-induced N2O emission, but had no significant effect on yield scaled N2O emission. The increase of N2O emission was mainly related to water-filled pore space affected by tillage and soil nitrate and ammonium N concentrations affected by urea types. Polymer-coated urea topdressing at the V6 stage in S soils was better for producing a higher yield with lower N2O emission. The results indicate that R soils had more significant N2O emission than S soils during a wet climate; and polymer-coated urea can increase grain yield with a slight higher N2O emissions, whereas changing the application stage can decrease the cumulative N2O emissions without reducing the yield.
  • Authors:
    • Nash,R.
    • Motavalli,P.
    • Nelson,K.
    • Kremer,R.
  • Source: Journal of Soil and Water Conservation
  • Volume: 70
  • Issue: 4
  • Year: 2015
  • Summary: Gaseous nitrogen (N) loss from denitrification and ammonia (NH3) volatilization from poorly drained soils in corn (Zea mays L.) production can be significant, diminish production, and lead farmers to apply a high rate of N. Nitrous oxide (N2O), a greenhouse gas that is emitted during denitrification, has a high global warming potential that contributes to climate change. Reducing gaseous N loss from poorly drained soils through drainage and N management in corn production is essential to minimizing the environmental impact and maintaining high yields. The objective of the study Was to determine how subsurface tile drainage and applications of polymer-coated urea (PCU) affect soil N2O emissions and N fertilizer-induced NH3 volatilization loss from a claypan soil. Drainage water management treatments consisted of conventional subsurface tile drainage, managed subsurface tile drainage, and no-drainage in combination with N fertilizer source (noncoated urea [NCU] and PCU). Subsurface drainage treatments did not significantly (p <= 0.05) affect cumulative soil N2O emissions and NH3 volatilization loss compared to no-drainage. Averaged over 2010 to 2013, cumulative soil N2O emissions from PCU was 2% of applied N, and NCU was 4% of applied N. Yield-scaled soil N2O emissions were reduced 53% with PCU compared to NCU. The percentage fertilizer loss from NH3 volatilization was significantly (p <= 0.05) reduced from 2.8% with NCU to 0.8% with PCU. These results suggest that use of PCU may assist in reducing cumulative losses of N2O and NH3 from poorly drained claypan soils, but drainage systems operating under this study's environmental conditions did not affect gaseous N losses.