• Authors:
    • Pijanowski, B. C.
    • Plourde, J. D.
    • Pekin, B. K.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 165
  • Year: 2013
  • Summary: While crop rotation patterns can be complex with multiple crops rotated over several years, the most common rotation practice in the Central United States is biannual rotation between corn and soybeans. We analyzed the changes in crop rotation patterns from 2003 to 2010 using the Cropland Data Layer (CDL), which provides remotely sensed land cover layers for agricultural crops in the Central United States. The accuracy of the CDL was validated by comparing the total acreage for a state or county present in the CDL with the total planted crop acreage available from the National Agricultural Statistics Service. The data layers were combined into two time periods 2003-2006 and 2007-2010, and specific rotation patterns were determined for every location in the study area. The combinations resulted in unique sequences such as single, double, triple and quadruple, the latter of which is equivalent to the same crop class present all four years at a particular location. Corn and soybeans were analyzed to determine the amount of area used for production as well as the amount of change between unique crop rotation sequences. While the total area under production of major crops in the second half of our study period increased only slightly, the extent to which major crops (e.g., corn and soybeans) were grown in continuous cropping sequences increased significantly. For example, the amount of land impacted by corn in the first time period increased by only 2% in the second time period. However, the amount of corn grown in quadruple sequence doubled from the first half to the second half of our study period. We conclude that, although crop rotation patterns are very complex in this region, involving considerable amount of non-cropland, the footprint of major crops such as corn have moved toward monoculture cropping practices in the last decade.
  • Authors:
    • Uliasz, M.
    • Richardson, S.
    • Miles, N.
    • Davis, K. J.
    • Denning, A. S.
    • West, T. O.
    • Lauvaux, T.
    • Schuh, A. E.
    • Lokupitiya, E.
    • Cooley, D.
    • Andrews, A.
    • Ogle, S.
  • Source: Global Change Biology
  • Volume: 19
  • Issue: 5
  • Year: 2013
  • Summary: An intensive regional research campaign was conducted by the North American Carbon Program (NACP) in 2007 to study the carbon cycle of the highly productive agricultural regions of the Midwestern United States. Forty-five different associated projects were conducted across five US agencies over the course of nearly a decade involving hundreds of researchers. One of the primary objectives of the intensive campaign was to investigate the ability of atmospheric inversion techniques to use highly calibrated CO 2 mixing ratio data to estimate CO 2 flux over the major croplands of the United States by comparing the results to an inventory of CO 2 fluxes. Statistics from densely monitored crop production, consisting primarily of corn and soybeans, provided the backbone of a well studied bottom-up inventory flux estimate that was used to evaluate the atmospheric inversion results. Estimates were compared to the inventory from three different inversion systems, representing spatial scales varying from high resolution mesoscale (PSU), to continental (CSU) and global (CarbonTracker), coupled to different transport models and optimization techniques. The inversion-based mean CO 2-C sink estimates were generally slightly larger, 8-20% for PSU, 10-20% for CSU, and 21% for CarbonTracker, but statistically indistinguishable, from the inventory estimate of 135 TgC. While the comparisons show that the MCI region-wide C sink is robust across inversion system and spatial scale, only the continental and mesoscale inversions were able to reproduce the spatial patterns within the region. In general, the results demonstrate that inversions can recover CO 2 fluxes at sub-regional scales with a relatively high density of CO 2 observations and adequate information on atmospheric transport in the region.
  • Authors:
    • Wang, D. P.
    • Zheng, L.
    • Zhang, Z. H.
    • Meng, F. Q.
    • Wu, W. L.
    • Shi, Y. F.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 95
  • Issue: 2
  • Year: 2013
  • Summary: In the North China Plain, a field experiment was conducted to measure nitrous oxide (N2O) and methane (CH4) fluxes from a typical winter wheat-summer maize rotation system under five integrated agricultural management practices: conventional regime [excessive nitrogen (N) fertilization, flood irrigation, and rotary tillage before wheat sowing; CON], recommended regime 1 (balanced N fertilization, decreased irrigation, and deep plowing before wheat sowing; REC-1), recommended regime 2 (balanced N fertilization, decreased irrigation, and no tillage; REC-2), recommended regime 3 (controlled release N fertilizer, decreased irrigation, and no tillage; REC-3), and no N fertilizer (CK). Field measurements indicated that pulse emissions after N fertilization and irrigation contributed 19-49 % of annual N2O emissions. In contrast to CON (2.21 kg N2O-N ha(-1) year(-1)), the other treatments resulted in significant declines in cumulative N2O emissions, which ranged from 0.96 to 1.76 kg N2O-N ha(-1) year(-1), indicating that the recommended practices (e.g., balanced N fertilization, controlled release N fertilizer, and decreased irrigation) offered substantial benefits for both sustaining grain yield and reducing N2O emissions. Emission factors of N fertilizer were 0.21, 0.22, 0.23, and 0.37 % under CON, REC-1, REC-3, and REC-2, respectively. Emissions of N2O during the freeze-thaw cycle period and the winter freezing period accounted for 9.7 and 5.1 % of the annual N2O budget, respectively. Thus, we recommend that the monitoring frequency should be increased during the freeze-thaw cycle period to obtain a proper estimate of total emissions. Annual CH4 fluxes from the soil were low (-1.54 to -1.12 kg CH4-C ha(-1) year(-1)), and N fertilizer application had no obvious effects on CH4 uptake. Values of global warming potential were predominantly determined by N2O emissions, which were 411 kg CO2-eq ha(-1) year(-1) in the CK and 694-982 kg CO2-eq ha(-1) year(-1) in the N fertilization regimes. When comprehensively considering grain yield, global warming potential intensity values in REC-1, REC-2, and REC-3 were significantly lower than in CON. Meanwhile, grain yield increased slightly under REC-1 and REC-3 compared to CON. Generally, REC-1 and REC-3 are recommended as promising management regimes to attain the dual objectives of sustaining grain yield and reducing greenhouse gas emissions in the North China Plain.
  • Authors:
    • Anderson-Teixeira, K. J.
    • Masters, M. D.
    • Mitchell, C. A.
    • David, M. B.
    • Smith, C. M.
    • Bernacchi, C. J.
    • DeLucia, E. H.
  • Source: Journal of Environmental Quality
  • Volume: 42
  • Issue: 1
  • Year: 2013
  • Summary: Current biofuel feedstock crops such as corn lead to large environmental losses of N through nitrate leaching and N 2O emissions; second-generation cellulosic crops have the potential to reduce these N losses. We measured N losses and cycling in establishing miscanthus ( Miscanthus * giganteus), switchgrass ( Panicum virgatum L. fertilized with 56 kg N ha -1 yr -1), and mixed prairie, along with a corn ( Zea mays L.)-corn-soybean [ Glycine max (L.) Merr.] rotation (corn fertilized at 168-202 kg N ha -1). Nitrous oxide emissions, soil N mineralization, mid-profile nitrate leaching, and tile flow and nitrate concentrations were measured. Perennial crops quickly reduced nitrate leaching at a 50-cm soil depth as well as concentrations and loads from the tile systems (year 1 tile nitrate concentrations of 10-15 mg N L -1 declined significantly by year 4 in all perennial crops to <0.6 mg N L -1, with losses of <0.8 kg N ha -1 yr -1). Nitrous oxide emissions were 2.2 to 7.7 kg N ha -1 yr -1 in the corn-corn-soybean rotation but were <1.0 kg N ha -1 yr -1 by year 4 in the perennial crops. Overall N balances (atmospheric deposition+fertilization+soybean N 2 fixation-harvest, leaching losses, and N 2O emissions) were positive for corn and soybean (22 kg N ha -1 yr -1) as well as switchgrass (9.7 kg N ha -1 yr -1) but were -18 and -29 kg N ha -1 yr -1 for prairie and miscanthus, respectively. Our results demonstrate rapid tightening of the N cycle as perennial biofuel crops established on a rich Mollisol soil.
  • Authors:
    • McConnaughay, K. D.
    • Bernacchi, C. J.
    • Richter, K. T.
    • Bryant, J. J.
    • Twine, T. E.
    • Morris, S. J.
    • Leakey, A. D. B.
  • Source: Global Change Biology
  • Volume: 19
  • Issue: 9
  • Year: 2013
  • Summary: The physiological response of vegetation to increasing atmospheric carbon dioxide concentration ([CO 2]) modifies productivity and surface energy and water fluxes. Quantifying this response is required for assessments of future climate change. Many global climate models account for this response; however, significant uncertainty remains in model simulations of this vegetation response and its impacts. Data from in situ field experiments provide evidence that previous modeling studies may have overestimated the increase in productivity at elevated [CO 2], and the impact on large-scale water cycling is largely unknown. We parameterized the Agro-IBIS dynamic global vegetation model with observations from the SoyFACE experiment to simulate the response of soybean and maize to an increase in [CO 2] from 375 ppm to 550 ppm. The two key model parameters that were found to vary with [CO 2] were the maximum carboxylation rate of photosynthesis and specific leaf area. Tests of the model that used SoyFACE parameter values showed a good fit to site-level data for all variables except latent heat flux over soybean and sensible heat flux over both crops. Simulations driven with historic climate data over the central USA showed that increased [CO 2] resulted in decreased latent heat flux and increased sensible heat flux from both crops when averaged over 30 years. Thirty-year average soybean yield increased everywhere (ca. 10%); however, there was no increase in maize yield except during dry years. Without accounting for CO 2 effects on the maximum carboxylation rate of photosynthesis and specific leaf area, soybean simulations at 550 ppm overestimated leaf area and yield. Our results highlight important model parameter values that, if not modified in other models, could result in biases when projecting future crop-climate-water relationships.
  • Authors:
    • Deng, J.
    • Zhou, Z. X.
    • Yao, Z. S.
    • Cui, F.
    • Zheng, X. H.
    • Yan, G. X.
    • Xu, Y.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 178
  • Year: 2013
  • Summary: Given the common problem of fertilizer overuse, agronomists are calling for a reduction of the high nitrogen dose by 1/3. We carried out a field experiment over two full winter wheat-summer maize rotations in the North China Plain (NCP) to determine whether this degree of nitrogen reduction will significantly reduce the emissions of nitrous oxide (N 2O) and nitric oxide (NO). Three treatments were investigated in the field trial: a control with no nitrogen application, the conventional practice with nitrogen over-application and the optimal practice with a reduced dose of nitrogen by 1/3. Our observations across all treatments over the experimental period reveal significant correlations of the fluxes of either gas with soil temperature and moisture as well as the concentrations of soil ammonium, nitrate and dissolvable organic carbon. There were strong correlations within the functions of the dual Arrhenius and Michaelis-Menten kinetics, giving apparent activation energy values of 40-97 and 59-92 kJ mol -1 for N 2O and NO fluxes, respectively. Our results provide annual direct emission factors of 0.48-0.96% for N 2O and 0.15-0.47% for NO and demonstrate a significant correlation between N 2O emission induced by fertilization and fertilizer nitrogen use efficiency (NUE). The correlation indicates a significant potential of N 2O mitigation via enhancing NUEs. A reduction in the nitrogen dose did not obviously mitigate either the annual NO emission in both rotations or the annual N 2O emission in the second one. However, nitrogen reduction significantly decreased the annual total N 2O emission by 38% during the first rotation. These inconsistencies in the responses of N 2O emission to the reduced nitrogen dose can be attributed to improper fertilization practices, such as broadcasting urea prior to heavy rainfalls or irrigation events during the maize season, which implies a need for further fertilization practice options/techniques in addition to the reduction of nitrogen doses.
  • Authors:
    • Christie, P.
    • Gao, B.
    • Huang, T.
    • Ju, X.
  • Source: Biogeosciences
  • Volume: 10
  • Issue: 12
  • Year: 2013
  • Summary: The effects of nitrogen and straw management on global warming potential (GWP) and greenhouse gas intensity (GHGI) in a winter wheat-summer maize double-cropping system on the North China Plain were investigated. We measured nitrous oxide (N2O) emissions and studied net GWP (NGWP) and GHGI by calculating the net exchange of CO2 equivalent (CO2-eq) from greenhouse gas emissions, agricultural inputs and management practices, as well as changes in soil organic carbon (SOC), based on a long-term field experiment established in 2006. The field experiment includes six treatments with three fertilizer N levels (zero N (control), optimum and conventional N) and straw removal (i.e. N-0 N-opt and N-con) or return (i.e. SN0, SNopt and SNcon). Optimum N management (N-opt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (N-con, SNcon), with no significant effect on grain yields. Annual mean N2O emissions reached 3.90 kg N2O-N ha(-1) in N-con and SNcon, and N2O emissions were reduced by 46.9% by optimizing N management of N-opt and SNopt. Straw return increased annual mean N2O emissions by 27.9 %. Annual SOC sequestration was 0.40-1.44Mg C ha(-1) yr(-1) in plots with N application and/or straw return. Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51 %, comprising 25% from decreasing N2O emissions and 75% from reducing N fertilizer application rates. Straw return treatments reduced NGWP by 30% compared to no straw return because the GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return. The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP. In conclusion, optimum N and straw return significantly reduced NGWP and GHGI and concomitantly achieved relatively high grain yields in this important winter wheat-summer maize double-cropping system.
  • 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:
    • Govindaraj, M.
    • Prabukumar, G.
    • Arunachalam, P.
    • Kannan, P.
  • Source: African Journal of Agricultural Research
  • Volume: 8
  • Issue: 21
  • Year: 2013
  • Summary: Atmospheric rise of CO 2, N 2O and CH 4 over years, accelerated increase in global temperature, has led to uncertainty in monsoon rainfall and also leading to recurrence of drought, which in turn is severely affecting crop productivity and livelihood security of the farmers in Semi Arid Tropics. Agriculture contributes considerable amount of CO 2, N 2O and CH 4 emission into the atmosphere through different soil and crop management practices. Nevertheless agricultural activities contribute to global warming. The medium of crop production, soil is one of the major sinks of global warming gaseous and it helps to sequester more carbon and cut the N 2O emission by adopting smart soil and crop management techniques. Biochar is one of the viable organic amendments to combat climate change and sustain the soil health with sustainable crop production. It is an anaerobic pyrolysis product derived from organic sources and store carbon on a long term basis in the terrestrial ecosystem and also capable of reducing greenhouse gases (GHG) emission from soil to the atmosphere. Biochar application improved the soil health, increase the carbon capture and storage, reduce the GHG emission and enhance the crop yield with sustained soil health, which enables to meet out the food grain needs of the ever growing population.
  • Authors:
    • Ghorbani, R.
    • Khorasani, R.
    • Mahallati, M. N.
    • Koocheki, A.
    • Khorramdel, S.
  • Source: Soil and Tillage Research
  • Volume: 133
  • Issue: October
  • Year: 2013
  • Summary: Carbon sequestration could be an effective way to reduce atmospheric carbon dioxide which is the most important greenhouse gas. Two field experiments were conducted at Agricultural Research Station of Ferdowsi University of Mashhad, Iran, during growing seasons of 2008-2009 and 2009-2010. Four treatments including two low input management systems based on application of cow manure or compost municipal made from house-hold waste, a medium input system and a high input system were applied. In low input system 30 t ha(-1) cow manure or 30 t ha(-1) compost municipal made from house-hold-waste was applied and twice hand weeding were carried out. In medium input system, 15 t ha(-1) compost, 150 kg ha(-1) urea, disking and ploughing, 1.5 l ha(-1) 2,4-D applied at five leaf stage with only one hand weeding. In high input system, management practices included twice disking, twice ploughing, 21 ha(-1) Paraquat applied after planting and 1.5 1 ha(-1) 2,4-D applied at five leaf stage. Results showed that the maximum carbon and nitrogen yields in corn residues observed in high input system (0.8 and 0.02 kg m(-2)) and its minimum were in low input system with using compost (0.5 and 0.01 kg m-2). The highest and lowest labile and recalcitrant carbon rates were observed in low input system with manure (0.92 and 1.05%) and high input system (0.06 and 0.004%), respectively. The maximum sequestered carbon obtained in low input management system with using cow manure (4.1 t ha(-1)) and the minimum sequestered carbon were in high input management system (0.01 t ha(-1)). In low input system due to slow releasing nutrients, long term crop growth and hence higher recalcitrant carbon content of the soil were enhanced which could be an indication of its potential for carbon sequestration in low input management system. (C) 2013 Published by Elsevier B.V.