• Authors:
    • Posner, J. L.
    • Hedtcke, J. L.
    • Kucharik, C. J.
    • Osterholz, W. R.
  • Source: JOURNAL OF ENVIRONMENTAL QUALITY
  • Volume: 43
  • Issue: 6
  • Year: 2014
  • Summary: Agriculture in the midwestern United States is a major anthropogenic source of nitrous oxide (N2O) and is both a source and sink for methane (CH4), but the degree to which cropping systems differ in emissions of these gases is not well understood. Our objectives were to determine if fluxes of N2O and CH4 varied among cropping systems and among crop phases within a cropping system. We compare N2O and CH4 fluxes over the 2010 and 2011 growing seasons from the six cropping systems at the Wisconsin Integrated Cropping Systems Trial (WICST), a 20-yr-old cropping systems experiment. The study is composed of three grain and three forage cropping systems spanning a spectrum of crop diversity and perenniality that model a wide range of realistic cropping systems that differ in management, crop rotation, and fertilizer regimes. Among the grain systems, cumulative growing season N2O emissions were greater for continuous corn (Zea mays L.) (3.7 kg N2O-N ha(-1)) than corn-soybean [Glycine max (L.) Merr.] (2.0 kg N2O-N ha(-1)) or organic corn-soybean-wheat (Triticum aestivum L.) (1.7 kg N2O-N ha(-1)). Among the forage systems, cumulative growing-season N2O emissions were greater for organic corn-alfalfa (Medicago sativa L.)-alfalfa (2.9 kg N2O-N ha(-1)) and conventional corn-alfalfa-alfalfa-alfalfa (2.5 kg N2O-N ha(-1)), and lower for rotational pasture (1.9 kg N2O-N ha(-1)). Application of mineral or organic N fertilizer was associated with elevated N2O emissions. Yield-scaled emissions (kg N2O-N Mg-1) did not differ by cropping system. Methane fluxes were highly variable and no effect of cropping system was observed. These results suggest that extended and diversified cropping systems could reduce area-scaled N2O emissions from agriculture, but none of the systems studied significantly reduced yield-scaled N2O emissions.
  • Authors:
    • Varvel, G. E.
    • Wienhold, B. J.
    • Jin, V. L.
    • Schmer, M. R.
    • Follett, R. F.
  • Source: Soil Science Society of America Journal
  • Volume: 78
  • Issue: 6
  • Year: 2014
  • Summary: Demand for corn (Zea mays L.) stover as forage or as a cellulosic biofuel has increased the importance of determining the effects of stover removal on biomass production and the soil resource. Our objectives were to evaluate grain yield, soil organic C (SOC), and total soil N (0-150 cm) in a 10-yr, irrigated, continuous corn study under conventional disk tillage (CT) and notill (NT) with variable corn stover removal rates (none, medium, and high). Natural abundance C isotope compositions ( d13C) were used to determine C additions by corn (C4-C) to the soil profile and to evaluate the retention of residual C3-C. After 10 yr of management treatments, mean grain yields were 7.5 to 8.6% higher for NT when stover was removed compared with no stover removal, while grain yields were similar for CT in all stover removal treatments. Turnover of SOC occurred as C3-C stocks were replaced by C4-C in the 0- to 120-cm soil profile. Total SOC and N stocks changed mainly in surface soils (0-30 cm), with no detectable cumulative changes at 0 to 150 cm. Specifically, SOC declined after 10 yr under CT at 0 to 15 cm and was affected by residue management at 15 to 30 cm. Total soil N was greater when no stover was removed (P = 0.0073) compared with high stover removal at 0 to 15 cm. Long-term NT ameliorated medium stover removal effects by maintaining near-surface SOC levels. Results support the need to evaluate SOC cycling processes below near-surface soil layers.
  • Authors:
    • Muehling, K. H.
    • Kage, H.
    • Herrmann, A.
    • Wienforth, B.
    • Chen, R.
    • Senbayram, M.
    • Dittert, K.
  • Source: BIOENERGY RESEARCH
  • Volume: 7
  • Issue: 4
  • Year: 2014
  • Summary: There is a growing concern that greenhouse gas (GHG) emissions during agricultural energy crop production might negate GHG emission savings which was not intended when promoting the use of renewable energy. Nitrous oxide (N2O) is a major GHG, and in addition, it is the most powerful ozone-depleting compound that is emitted by human activity. The use of N fertilizers and animal manures is the main anthropogenic source of N2O emissions. In spite of their high relevance, we still have limited understanding of the complex underlying microbial processes that consume or produce N2O and their interactions with soil types, fertilizers (rate and types), plants, and other environmental variables. In a 2-year field experiment, we compared two important biogas crops in two different agro-ecological regions of northern Germany for their productivity and GHG emissions, using the closed-chamber technique and high time-resolution sampling. Silage maize, which is currently the most widespread crop grown for biogas fermentation purposes in Germany, was compared with an alternative bioenergy crop at each site. The three forms of nitrogen fertilizers/manures were given: calcium ammonium nitrate, cattle/pig slurry, and biogas residue. The greatest N2O flux activity occurred in the period of May-July in all crops and at both sites. Flux patterns indicated pronounced effects of soil moisture-soil mineral-N interactions which were also seen as causation of the higher N2O fluxes in the bioenergy crop maize compared to the other tested energy crops. However, the N2O emission per unit methane production (specific N2O emission) was clearly lower in soils planted with maize due to significantly higher methane hectare yield of maize. Our data suggest a linear relationship between increasing N input and increases in N2O emission in both years at site with sandy loam texture where highest N2O fluxes were measured. At sandy loam site, the percentage of applied N being emitted as N2O was 1.9 and 1.1 % in soils cropped with maize and 0.9 and 0.8 % in soils cropped with wheat during the investigation period 2007-2008 and 2008-2009, respectively. In contrast, at site with sandy soil texture, the percentage of applied N emitted as N2O was only 0.6 and 0.7 % in maize soils and 0.4 and 0.3 % in grassland during 2007-2008 and 2008-2009 period, respectively. Higher daily and annual N2O emissions at the sandy loam site were attributed to the finer soil texture and higher denitrification activity. The present study provides a very good basis for the assessment of direct emissions of greenhouse gases from relevant biogas crops in North-West Europe.
  • Authors:
    • Sanclemente Reyes, O. E.
    • Sanchez de Prager, M.
    • Sosa Rodrigues, B. A.
  • Source: Acta Agronomica, Universidad Nacional de Colombia
  • Volume: 63
  • Issue: 4
  • Year: 2014
  • Summary: This study provided knowledge about the agro-ecosystem N dynamics mediated by the use of agroecological practices such as GM. GM is established as legume its symbiotic action with soil rhizobia and arbuscular mycorrhiza formation, allows the cycling of nitrogen and phosphorus, among others. This study aimed at evaluating the influence of GM in the nitrogen dynamics of a Typic Haplustert located in the municipality of Candelaria (Colombia). In completely randomized blocks design with six replications, the GM coming from the intercropping Mucuna pruriens var utilis - Zea mays L. var. ICA 305 was established as T1 treatment and the native arvense Rottboellia cochinchinensis L. as T2, during the second half of year 2011. During the stage of preflowering of M. pruriens the content of organic C (OC) was evaluated as well as total N (TN), nitrate, ammonium, number of copies of amoA gene of ammonia-oxidizing bacteria, total porosity filled with water (TPW), temperature, flow of greenhouse gases: methane (CH 4), carbon dioxide (CO 2) and nitrous oxide (N 2O), as well as the dry matter (DM) and the contents of C, N and P in plant tissues. Significantly higher concentrations (p<0.05) of CO, NT, ammonium and nitrate, were recorded in T2. The number of oxidizing bacteria of ammonium was significantly higher in T1 which coincided with the higher TPW and the lower soil temperature. The emission of atmospheric CO 2 was significantly lower in T1, in contrast to the CH 4 and N 2O which scored the highest values. At the end of the trial, the GM in T1 provided about 4 t MS/ha, 1668.3 kg C/ha, 78.7 kg N/ha and 11.0 kg P/ha, with social economic benefit of 9.2 t corn/ha.
  • Authors:
    • Rotter, R. P.
    • Zhang, Z.
    • Zhang, S.
    • Tao, F. L.
  • Source: GLOBAL CHANGE BIOLOGY
  • Volume: 20
  • Issue: 12
  • Year: 2014
  • Summary: Maize phenology observations at 112 national agro-meteorological experiment stations across China spanning the years 1981-2009 were used to investigate the spatiotemporal changes of maize phenology, as well as the relations to temperature change and cultivar shift. The greater scope of the dataset allows us to estimate the effects of temperature change and cultivar shift on maize phenology more precisely. We found that maize sowing date advanced significantly at 26.0% of stations mainly for spring maize in northwestern, southwestern and northeastern China, although delayed significantly at 8.0% of stations mainly in northeastern China and the North China Plain (NCP). Maize maturity date delayed significantly at 36.6% of stations mainly in the northeastern China and the NCP. As a result, duration of maize whole growing period (GPw) was prolonged significantly at 41.1% of stations, although mean temperature ( Tmean) during GPw increased at 72.3% of stations, significantly at 19.6% of stations, and Tmean was negatively correlated with the duration of GPw at 92.9% of stations and significantly at 42.9% of stations. Once disentangling the effects of temperature change and cultivar shift with an approach based on accumulated thermal development unit, we found that increase in temperature advanced heading date and maturity date and reduced the duration of GPw at 81.3%, 82.1% and 83.9% of stations on average by 3.2, 6.0 and 3.5 days/decade, respectively. By contrast, cultivar shift delayed heading date and maturity date and prolonged the duration of GPw at 75.0%, 94.6% and 92.9% of stations on average by 1.5, 6.5 and 6.5 days/decade, respectively. Our results suggest that maize production is adapting to ongoing climate change by shift of sowing date and adoption of cultivars with longer growing period. The spatiotemporal changes of maize phenology presented here can further guide the development of adaptation options for maize production in near future.
  • Authors:
    • Zhang, F. S.
    • Yue, S. C.
    • Cui, Z. L.
    • Chen, X. P.
    • Wang, G. L.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: A thorough understanding of reactive N (Nr) losses from N fertilization applications and the factors that influence it is necessary to better evaluate various Nr losses mitigation scenarios and improve N management practices. The objectives of this study were to develop empirical models to calculate Nr losses using meta-analysis and to evaluate trade-offs among grain yield, N recovery efficiency (RE N), and Nr loss intensity for in-season N management for intensive summer maize ( Zea mays L.) production in China. A meta-analysis with 55 studies and 170 observations suggested that both N 2O emissions and N leaching increased exponentially with the N application rate or N surplus, while NH 3 volatilization increased linearly with the N application rate. According to regression curves, models based on the N rate (N-R) and N surplus (N-S) were used to estimate Nr losses. Because the N-R did not account for large variations in RE N or grain yield across farmers' fields for difference competence in N management, estimated Nr losses were a little higher than those estimated by the N-S, especially for high-yield, high-RE N systems. Across 162 on-farm experimental sites, an in-season root-zone N management strategy with a 39% lower N application rate and 6% higher grain yield increased the RE N by 98% (from 16% to 31%) and reduced Nr loss intensity (based on the N-S) by 45% (from 13.6 to 7.5 kg N Mg -1) compared to farmers' typical N practices. In conclusion, the reconciliation of food security with greater environmental protection for the future can be driven by improved agronomic management to increase grain yield as well as RE N, rather than by solely focusing on optimizing the N application rate.
  • Authors:
    • Zhao, C.
    • Yin, G. D.
    • Zhang, X. P.
    • Peng, L. Q.
    • Wang, X. H.
    • Piao, S. L.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 196
  • Year: 2014
  • Summary: Northeast China (NEC), the most productive maize growing area in China, has experienced pronounced climate change. However, the impacts of historical climate changes on maize production and their spatial variations remain uncertain. In this study, we used yield statistics at prefecture scale over the past three decades, along with contemporary climate data, to explore the yield-climate relationship and its spatial variations. At the regional scale, maximum and minimum temperature changes had opposite impacts on maize yield, which increased by 10.07.7% in response to a 1°C increase in growing season mean daily minimum temperature ( Tmin), but decreased by 13.47.1% in response to a 1°C increase in growing season mean daily maximum temperature ( Tmax). Variations in precipitation seemed to have small impacts on the maize yield variations (-0.95.2%/100 mm). However, these responses of maize yield to climate variations were subject to large spatial differences in terms of both the sign and the magnitude. ~30% of the prefectures showed a positive response of maize yield to rising Tmax, which was in contrast to the negative response at the regional scale. Our results further indicate that the spatial variations in the yield response to climate change can be partly explained by variations in local climate conditions. The growing season mean temperature was significantly correlated with the response of maize yield to Tmax ( R=-0.67, P<0.01), which changes from positive to negative when the growing season mean temperature exceeds 17.90.2°C. Precipitation became the dominant climatic factor driving maize yield variations when growing season precipitation was lower than ~400 mm, but had a weaker influence than temperature over most of the study area. We conclude that, although NEC is a region spanning only more than one millions of kilometer squares, the divergence of the yield response to climatic variations highlights the need to analyze the yield-climate relationship at fine spatial scales.
  • Authors:
    • Hachigonta, S.
    • Crespo, O.
    • Zinyengere, N.
    • Tadross, M.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: Climate change impact assessments on agriculture in Southern Africa are mostly carried out at large spatial scales, risking missing out on local impacts and adaptation potential that reflect the range of multiple and unique bio-physical and agronomic conditions under which farmers in the region operate. This study investigated how climate change may affect yields of various major food crops in specific locations in the region; maize and sorghum (Mohale's Hoek - Lesotho and Big Bend - Swaziland), maize and groundnut (Lilongwe - Malawi). Using statistically downscaled climate projections from nine GCMs and the DSSAT crop model and simulating selected agronomic strategies practiced in each location, the study confirmed that impacts of climate change on crop yields in Southern Africa vary across locations and crops. Despite various uncertainties associated with such assessments, the results showed that crop yields were predominantly projected to decline in Big Bend (maize (-20%); sorghum (-16%)) and Lilongwe (maize (-5%); groundnut (-33%)). However, crop yields in Mohale's Hoek, located in a high altitude region historically prone to cold related crop yield losses were on average projected to increase (maize (+8%) and sorghum (+51%)). The geographical variation of yield projections highlights the importance of location specific climate change impact assessments. The exploration of local agronomic management alternatives revealed prospects for identifying locally relevant adaptation strategies, which cannot easily be captured at larger scales.
  • Authors:
    • Gericke, D.
    • Dittert, K.
    • Senbayram, M.
    • Kage, H.
    • Sieling, K.
    • Svoboda, N.
    • Wienforth, B.
    • Taube, F.
    • Claus, S.
    • Pacholski, A.
    • Herrmann, A.
  • Source: JOURNAL OF AGRICULTURAL SCIENCE
  • Volume: 152
  • Issue: S1
  • Year: 2014
  • Summary: A considerable expansion of biogas production in Germany, paralleled by a strong increase in maize acreage, has caused growing concern that greenhouse gas (GHG) emissions during crop substrate production might counteract the GHG emission saving potential. Based on a 2-year field trial, a GHG balance was conducted to evaluate the mitigation potential of regionally adapted cropping systems (continuous maize, maize-wheat-Italian ryegrass, perennial ryegrass ley), depending on nitrogen (N) level and N type. Considering the whole production chain, all cropping systems investigated contributed to the mitigation of GHG emissions (6.7-13.3 t CO2 eq/ha), with continuous maize revealing a carbon dioxide (CO2) saving potential of 55-61% compared with a fossil energy mix reference system. The current sustainability thresholds in terms of CO2 savings set by the EU Renewable Energy Directive could be met by all cropping systems (48-76%). Emissions from crop production had the largest impact on the mitigation effect (>= 50%) unless the biogas residue storage was not covered. The comparison of N fertilizer types showed less pronounced differences in GHG mitigation potential, whereas considerable site effects were observed.
  • Authors:
    • Wang, B.
    • Qin, X.
    • Wan, Y.
    • Li, Y.
    • Duan, Z.
  • Source: Transactions of the Chinese Society of Agricultural Engineering
  • Volume: 30
  • Issue: 24
  • Year: 2014
  • Summary: Maize production inevitably generates greenhouse gas (GHG) emissions which contribute to global warming. The greenhouse gas intensity (GHGI) of maize production was controlled by various management techniques. Fuel, fertilizer production, herbicide production, seed consumption, transportation, and on-farm energy consumption all result in GHG emissions. Life cycle assessment (LCA) methodology was adopted in this study to calculate GHG emissions under different fertilization treatments aiming at comprehensively evaluating the effects of different fertilization treatments on GHG emissions and selecting the options with both economic benefits and GHG mitigation. Four different fertilization treatments are: local traditional fertilization; urea treatment; sulfur coated urea; and urea added with dicyandiamide treatment. Static chamber and gas chromatography (GC) systems were used to continuously monitor N2O emissions from maize cropland. N2O emissions under different fertilization treatments were calculated. Data on the amount and type of fertilizer applied, energy consumption for the tillage, herbicide consumption, irrigation area and Diesel consumption, for tillage, electricity consumption for irrigation, and seed consumption were collected. Total GHG emissions from fertilizer production, energy consumption, seed production were estimated. GHG emission intensity based on grain yield and economic benefit were also calculated. The result showed that N2O emissions from fertilization, total GHG emission of the whole life cycle, emission intensities based on yield and output were all ranked as local traditional fertilization>urea treatment>urea added with dicyandiamide treatment>sulfur coated urea treatment. N2O emissions from the local traditional fertilization treatment was very significantly higher than that from the other three treatments (P0.05). Total GHG emissions from the treatments of local traditional fertilization, urea, sulfur coated urea, and urea added with dicyandiamide were 4.11, 2.71, 2.56, and 2.61 t/(hm2·a) respectively. Emission per unit of yield for the treatments of local traditional fertilization, urea, sulfur coated urea, and urea added with dicyandiamide were 364.1, 238.3, 216.6, and 223.4 kg/t maize, respectively. Emission per 10 000 yuan for the treatments of local traditional fertilization, urea, sulfur coated urea, and urea added with dicyandiamide were 2.19, 1.32, 1.15, and 1.18 t /10 000 yuan respectively. Compared with a traditional fertilization treatment, sulfur coated urea could reduce total GHG emissions, GHG emission per unit of yield and per 10 000 yuan net output by 37.8%, 40.5%, and 47.3% respectively, while the urea added with dicyandiamide treatment could reduce total GHG emissions, GHG emission per unit of yield, and per 10 000 yuan by 36.5%, 38.6%, and 45.9% respectively. Production of fertilizers, especially nitrogen fertilizer, makes the greatest contribution to total GHG emissions for maize cultivation, accounting for 42.4%-55.0% of the total GHG emissions from the four treatments, followed by fertilizer application, accounting for 20.8%-26.1% of the total GHG emissions from the four treatments. In order to ensure grain output and economic benefits, two fertilization treatments, sulfur coated urea treatment and urea added with dicyandiamide treatment, resulted in relatively low total emissions and emission intensity. They can be recommended as options to mitigate GHG emissions from maize production.