• Authors:
    • Thierfelder, C.
    • Aune, J. B.
    • Ngwira, A. R.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 143
  • Year: 2014
  • Summary: Adoption of conservation agriculture (CA) is increasingly being promoted as a way of adapting agricultural systems to increasing climate variability, especially for areas such as southern Africa where rainfall is projected to decrease. The DSSAT crop simulation models can be a valuable tool in evaluating the effects of CA which are viable both economically and environmentally. Our objectives were: (1) to evaluate the ability of DSSAT to predict continuous maize (Zea mays L.) yield for conventional tillage (CT) and CA systems as well as maize yield for a CA maize-cowpea (Vigna unguiculata) rotation on an Oxic rhodustalf (2) to use DSSAT to project weather effect of climate change on yield, economic returns and risk in CT and CA systems. The DSSAT model was calibrated using data from 2007-2008 season and validated against independent data sets of yield of 2008-2009 to 2011-2012 seasons. Simulations of maize yields were conducted on projected future weather data from 2010 to 2030 that was generated by RegCM4 using the A1B scenario. The DSSAT model calibration and validation showed that it could be used for decision-making to choose specific CA practices especially for no-till and crop residue retention. Long term simulations showed that maize-cowpea rotation gave 451kgha-1 and 1.62kgmm-1 rain more maize grain yield and rain water productivity, respectively compared with CT. On the other hand, CT (3131-5023kgha-1) showed larger variation in yield than both CA systems (3863kgha-1 and 4905kgha-1). CT and CA systems gave 50% and 10% cumulative probability of obtaining yield below the minimum acceptable limit of 4000kgha-1 respectively suggesting that CA has lower probability of low yield than CT, thus could be preferred by risk-averse farmers in uncertain climatic conditions. Using similar reasoning, Mean-Gini Dominance analysis showed the dominancy of maize-cowpea rotation and indicated it as the most efficient management system. This study therefore suggests that CA, especially when all three principles are practiced by smallholders in the medium altitude of Lilongwe and similar areas, has the potential to adapt the maize based systems to climate change. Use of DSSAT simulation of the effects of CA was successful for no-till and crop residue retention, but poor for crop rotation. Refinement of crop rotation algorithm in DSSAT is recommended.
  • Authors:
    • Zhu, X. D.
    • Zhuang, Q. L.
    • Qin, Z. C.
  • Source: GLOBAL CHANGE BIOLOGY BIOENERGY
  • Volume: 6
  • Issue: 6
  • Year: 2014
  • Summary: Biofuel made from conventional (e.g., maize (Zea mays L.)) and cellulosic crops (e.g., switchgrass (Panicum virgatum L.) and Miscanthus (Miscanthus * giganteus)) provides alternative energy to fossil fuels and has been considered to mitigate greenhouse gas emissions. To estimate the large-scale carbon and nitrogen dynamics of these biofuel ecosystems, process-based models are needed. Here, we developed an agroecosystem model (AgTEM) based on the Terrestrial Ecosystem Model for these ecosystems. The model was incorporated with biogeochemical and ecophysiological processes including crop phenology, biomass allocation, nitrification, and denitrification, as well as agronomic management of irrigation and fertilization. It was used to estimate crop yield, biomass, net carbon exchange, and nitrous oxide emissions at an ecosystem level. The model was first parameterized for maize, switchgrass, and Miscanthus ecosystems and then validated with field observation data. We found that AgTEM well reproduces the annual net primary production and nitrous oxide fluxes of most sites, with over 85% of total variation explained by the model. Local sensitivity analysis indicated that the model sensitivity varies among different ecosystems. Net primary production of maize is sensitive to temperature, precipitation, cloudiness, fertilizer, and irrigation and less sensitive to atmospheric CO 2 concentrations. In contrast, the net primary production of switchgrass and Miscanthus is most sensitive to temperature among all factors. Nitrous oxide fluxes are sensitive to management in maize ecosystems, and sensitive to climate factors in cellulosic ecosystems. The developed model should help advance our understanding of carbon and nitrogen dynamics of these biofuel ecosystems at both site and regional levels.
  • Authors:
    • De Prager, M. S.
    • Rodrígues, B. A. S.
    • Reyes, O. E. S.
  • 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 ammoniaoxidizing bacteria, total porosity filled with water (TPW), temperature, flow of greenhouse gases: methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O), 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 CO2 was significantly lower in T1, in contrast to the CH4 and N2O 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:
    • Lauzon, J.
    • Deen, B.
    • Wagner-Riddle, C.
    • Roy, A. K.
    • Bruulsema, T.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 4
  • Year: 2014
  • Summary: Nitrous oxide (N 2O) emissions resulting from application of nitrogen (N) fertilizer contribute to the greenhouse gas footprint of corn production. In eastern Canada, corn is a major crop with most N fertilizer applied pre- or at planting. This timing of application results in a lack of synchrony of soil N supply and crop N demand. Matching the amount and timing of application to crop uptake has been suggested as a mitigation measure to reduce N losses, and is an integral part of the 4R Nutrient Stewardship program. This study examined the effect of timing, rate and history of urea-ammonium nitrate application on N 2O emissions in corn in 2011 and 2012 at Elora, ON, Canada. Treatments were three N rates (30, 145 and 218 kg N ha -1); two timings (N injected in mid-row at planting and at the 8th leaf stage, V8); two histories (short-term: applying N rate treatments on plots that had received 145 kg N ha -1 in the previous year, and long-term: applying the same N rate to a given plot over the duration of the trial). N 2O emissions were measured using static chambers. History of N application did not have an effect on N 2O emissions or grain yield. In both years, cumulative N 2O emissions during the growing season and corn yields increased significantly with increasing N application rates. In 2011, cumulative N 2O emissions were significantly lower when N was applied as side-dress at V8 (0.88 kg N ha -1) compared with planting (2.12 kg N ha -1), with no significant impact on corn grain yield (average 9.1 Mg ha -1). In contrast, in 2012, limited rainfall reduced both N 2O emissions and corn grain yield, and neither N 2O emission (average 0.17 kg N ha -1) nor grain yield (average 6.7 Mg ha -1) was affected by timing of N application. Applying N as side-dress at V8 instead of at planting and using the recommended N rate were shown to be effective N 2O emission mitigation practices without affecting corn yield during a typical wet spring in Ontario.
  • Authors:
    • Wight, J. P.
    • Hons, F. M.
    • Storlien, J. O.
    • Heilman, J. L.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 5
  • Year: 2014
  • Summary: Modern bioenergy feedstocks, such as bioenergy sorghum [Sorghum bicolor (L.) Moench], are being developed to supply future cellulosic biofuel demands. How these cropping systems impact greenhouse gas (GHG) emission of CO2and N2O from the soil is unknown and field research is necessary to elucidate the effects of agronomic management practices on soil trace gas emissions. We studied the effects of N fertilization (0 vs. 280 kg urea-N ha-1), residue management (0 vs. 50% of sorghum biomass returned), crop sequence (corn [Zea mays L.]-sorghum vs. sorghum-sorghum), and their interactions on CO2and N2O emissions from bioenergy production scenarios on a Weswood (finesilty, mixed, superactive, thermic Udifluventic Haplustept) silty clay loam soil in central Texas. Gas fluxes were measured approximately weekly throughout the 2010 and 2011 growing season and at a reduced rate during the fallow season with a photoacoustic gas analyzer integrated with a static chamber. Overall, CO2and N2O fluxes were relatively higher than those observed by others in the United States despite drought conditions throughout much of 2010 and 2011. Highest emissions of both gases were observed during the growing season, often following a precipitation-irrigation event and shortly after N fertilization. Residue return increased cumulative CO2emissions each year, probably due to increased heterotrophic microbial activity. Nitrogen addition significantly increased cumulative emissions of N2O both years but only impacted cumulative CO2emissions in 2011. While crop rotation impacted biomass yield, it had no significant effect on cumulative CO2or N2O emissions. Additional research is needed to identify the optimal N and residue application rates that provide high yields with minimal soil GHG emissions and aid in sustaining long-term soil quality.
  • Authors:
    • Qiao, X.
    • Liang, Z.
    • Rasaily, R. G.
    • Sarker, K. K.
    • He, J.
    • Li, H.
    • Lu, C.
    • Wang, Q.
    • Li, H.
    • Mchugh, A. D. J.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 137
  • Year: 2014
  • Summary: Soil sodicity and salinization are two major issues concerning agricultural production in Northern China and the affected areas are expanding at a rate of 1-1.5. Mha/year. The effects of two treatments, i.e. no-tillage with subsoiling and straw cover (NTSC) and conventional tillage with ploughing and straw removal (CTSR), on soil physical and chemical properties and yields were compared from 1999 to 2011. The results showed that NTSC reduced soil bulk density in the 0-30. cm soil layer, but more importantly the treatment increased total porosity by 20.9%, water stable aggregates and pore size class distribution. The enhance soil structure and improved infiltration in NTSC treatments contributed to reducing soil salinity by 20.3%-73.4% when compared with CTSR. Soil organic matter was significantly greater to 30. cm in NTSC, while total soil nitrogen was lower than CTSR treatments; however, available P was significantly higher in the 0-5. cm soil surface. During the first 3 years, there was no difference in spring maize yield between NTSC and CTSR, but yield significantly increased in NTSC compared with CTSR during the remaining years due to reduced salinity stress and increased soil health. In conclusion, NTSC soil management practices appear to be a more sustainable approach to farming than conventional methods that utilize intensive tillage and crop residue removal.
  • Authors:
    • Wang, Q.
    • Wang, Y.
    • Wang, Q.
    • Liu, J.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 143
  • Year: 2014
  • Summary: Labile soil organic carbon pools are widely regarded as valuable indicators of changes in soil C sequestration pools and dynamics induced by different soil management practices. The objective of this study was to evaluate how a new conservational agricultural management (NCAM), which has been proved to be an effective pattern to increase corn yield, affects soil organic C (SOC) and labile SOC pools after a 9-year experiment in Northeast China. Narrow-wide row (1.70m wide row and 0.30m narrow row, corn is sowed in the narrow row with two lines), no-till, residue retention, change of ridge direction, and fallow are adopted for NCAM. Soil under conventional agricultural management (CAM) was also studied to be as a comparison. Soil samples were taken from 0-20 to 20-40cm depths. The results showed that no significant difference was found for SOC between the two managements for both depths, indicating that SOC is a too gross measurement. Soil labile organic C fractions: microbial biomass C, hot-water extractable organic C and permanganate oxidizable C (KMnO4-C) contents were significantly higher under NCAM compared to CAM for both depths, reflecting the build-up of labile C pools under NCAM. In addition, of the three C fractions, KMnO4-C was the most sensitive indicator of changes in SOC induced by different agricultural management regimes. Our results implied that the application of NCAM is important to soil C sequestration and improving soil quality.
  • Authors:
    • Liang, L.
    • Jia, Z.
    • Wang, X.
  • Source: JOURNAL OF SOIL AND WATER CONSERVATION
  • Volume: 69
  • Issue: 5
  • Year: 2014
  • Summary: Field experiments were conducted from 2008 to 2010 in the Weibei Highlands of China to study the effects of straw incorporation on soil moisture, evapotranspiration (ET), and rainfall-use efficiency (RUE) of maize (Zea mays L.) under semiarid conditions in dark loessial soil. The straw application rates were at low straw ([LS] 4.5 t ha(-1)), medium straw ([MS] 9 t ha(-1)), and high straw ([HS] 13.5 t ha(-1)) rates combined with fixed levels of chemical fertilizers compared with only chemical fertilizers. Straw incorporation significantly increased surface soil moisture at the grain filling stage of maize and significantly improved RUE in the whole growth period of maize. Evapotransipiration at the ten leaf collar to tasseling and the grain filling to maturity stages of maize were significantly increased by straw incorporation. However, ET at the tasseling to grain filling stage of maize was significantly reduced by straw incorporation. Medium straw and HS treatments significantly improved surface soil moisture at the tasseling stage of maize and RUE at the five leaf collar to maturity stage of maize. Increasing straw application rates significantly reduced ET at the grain filling to maturity stage of maize. With increasing experimental years, LS treatment significantly improved surface soil moisture at the five leaf collar to tasseling stage of maize and RUE at the five and ten leaf collar stage of maize, MS treatment significantly increased surface soil moisture at the five and ten leaf collar stages of maize, and HS treatment significantly reduced ET at the sowing to five leaf collar stage of maize. We conclude that a reasonable combination application of straw and chemical fertilizers could make full use of surface soil moisture, inhibit soil evaporation, reduce the ineffective evaporation of crop, and increase RUE at a different growth period of maize and grain yield. In this experiment, the optimum straw application rate for improving RUE and grain yield was MS treatment.
  • Authors:
    • Lv, Y. Z.
    • Huang, F.
    • Zhao, N.
    • Yang, Z. C.
  • Source: SOIL & TILLAGE RESEARCH
  • Year: 2014
  • Summary: The aim of the study is to analyze the effects of different fertilization of organic and inorganic fertilizers on soil organic carbon (SOC) sequestration and crop yields after a 22 years long-term field experiment. The crop yields and SOC were investigated from 1981 to 2003 in Dry-Land Farming Research Institute of Hebei Academy of Agricultural and Forestry Sciences, Hebei Province, China. The dominant cropping systems are winter wheat-summer corn rotation. There were totally sixteen treatments applied to both wheat and corn seasons: inorganic fertilizers as main plots and corn stalks as subplots and the main plots and subplots all have four levels. The results revealed: after 22 years, mixed application of inorganic fertilizers and crop residuals, the SOC and crop yields substantially increased. Higher fertilizer application rates resulted in greater crop yields improvement. In 2002-2003, wheat and corn for the highest fertilizer inputs had the highest yield level, 6400 kg ha-1 and 8600 kg ha-1, respectively. However, the SOC decreased as the excessive inorganic fertilizer input and increased with the rising application of corn stalks. The treatment of the second-highest inorganic fertilizer and the highest corn stalks had the highest SOC concentration (8.64 g C kg-1). Pearson correlation analysis shows that corn and winter wheat yields and the mineralization amount of SOC have significant correlation with SOC at p < 0.05 level.
  • Authors:
    • Zhou, D. W.
    • Diabate, B.
    • Shen, X. J.
    • Zheng, W.
    • Li, G. D.
    • Jia, H.T.
    • Li, Q.
    • Yu, P.J.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 5
  • Year: 2014
  • Summary: The accurate estimation of soil C stock is important for understanding the global C cycles. Particularly in arid regions, quantification of soil inorganic carbon (SIC) is required in addition to the more frequently reported soil organic carbon (SOC). We analyzed SOC, SIC, soil bulk density (BD), electrical conductivity (EC) and pH of alkali-saline soils at a 0- to 100-cm depth in a cultivation chronosequence that consisted of a meadow steppe site and four cropped sites with maize ( Zea mays L.) for 1, 7, 17, and 24 yr in Songnen Plain, Northeast China to quantify SOC and SIC dynamics. Results showed that SOC stock in 0 to 100 cm soil was 92.3, 83.7, 80.9, 78.2, and 76.9 Mg C ha -1 for Steppe, Crop-1Y, Crop-7Y, Crop-17Y, and Crop-24Y, respectively, decreased at a rate of 3.63 Mg C ha -1 yr -1. In contrast, SIC stock, ranging from 159.0 to 179.4 Mg C ha -1 increased at a rate of 0.53 Mg C ha -1 yr -1 in 0- to 100-cm depth. The soil total carbon (STC) stock increased at a rate of 0.46 Mg C ha -1 yr -1 following land use conversion, peaked in the seventh year of cultivation and then declined at a rate of 0.89 Mg C ha -1 yr -1. The SOC concentrations were negatively correlated with BD, EC, and pH, but SIC concentrations were positively correlated with soil BD, EC, and pH. The findings underline the importance of including SIC in the soil C estimates while considering deep soil profile and longer cultivation period.