• Authors:
    • Bozorgi, H. R.
    • Moraditochaee, M.
    • Azarpour, E.
  • Source: Journal of Applied Science and Agriculture
  • Volume: 9
  • Issue: 4
  • Year: 2014
  • Summary: Background: The suitability of the Life Cycle Assessment (LCA) methodology to analyze the environmental impact of agricultural production is investigated. Objective: This study was conducted to assess the impact of wheat production on environment under rain fed and watered farming systems in north of Iran. Life cycle assessment (LCA) was used as a methodology to assess all environmental impacts of wheat production through accounting and appraising the resource consumption and emissions. Data were collected from 72 farms by used a face to face questionnaire method during 2011 year in Guilan province. Results: In rain fed farming system, total green house gases emissions for wheat production were calculated to be 440.4 kg CO2 eq ha -1 calculated. In watered farming system, total green house gases emissions for wheat production were calculated to be 570.7 kg CO2 eq ha -1. Conclusion: Life cycle assessment (LCA) is defined as the compilation and evaluation of the inputs, outputs and potential environmental impacts of a product system throughout its life cycle. Thus, LCA is a tool for the analysis of the environmental burden of products at all stages in their life cycle.
  • Authors:
    • Lu, S.
    • Zhang, F.
    • Chen, Q.
    • Wang, J.
    • Ren, T.
  • Source: PLoS ONE
  • Volume: 9
  • Issue: 5
  • Year: 2014
  • Summary: With the goal of improving N fertilizer management to maximize soil organic carbon (SOC) storage and minimize N losses in high-intensity cropping system, a 6-years greenhouse vegetable experiment was conducted from 2004 to 2010 in Shouguang, northern China. Treatment tested the effects of organic manure and N fertilizer on SOC, total N (TN) pool and annual apparent N losses. The results demonstrated that SOC and TN concentrations in the 0-10cm soil layer decreased significantly without organic manure and mineral N applications, primarily because of the decomposition of stable C. Increasing C inputs through wheat straw and chicken manure incorporation couldn't increase SOC pools over the 4 year duration of the experiment. In contrast to the organic manure treatment, the SOC and TN pools were not increased with the combination of organic manure and N fertilizer. However, the soil labile carbon fractions increased significantly when both chicken manure and N fertilizer were applied together. Additionally, lower optimized N fertilizer inputs did not decrease SOC and TN accumulation compared with conventional N applications. Despite the annual apparent N losses for the optimized N treatment were significantly lower than that for the conventional N treatment, the unchanged SOC over the past 6 years might limit N storage in the soil and more surplus N were lost to the environment. Consequently, optimized N fertilizer inputs according to root-zone N management did not influence the accumulation of SOC and TN in soil; but beneficial in reducing apparent N losses. N fertilizer management in a greenhouse cropping system should not only identify how to reduce N fertilizer input but should also be more attentive to improving soil fertility with better management of organic manure.
  • Authors:
    • Yu, Y.
    • Zhang, W.
    • Li, T.
    • Wang, G.
  • Source: PLoS ONE
  • Volume: 9
  • Issue: 4
  • Year: 2014
  • Summary: Dynamics of cropland soil organic carbon (SOC) in response to different management practices and environmental conditions across North China Plain (NCP) were studied using a modeling approach. We identified the key variables driving SOC changes at a high spatial resolution (10 kmx10 km) and long time scale (90 years). The model used future climatic data from the FGOALS model based on four future greenhouse gas (GHG) concentration scenarios. Agricultural practices included different rates of nitrogen (N) fertilization, manure application, and stubble retention. We found that SOC change was significantly influenced by the management practices of stubble retention (linearly positive), manure application (linearly positive) and nitrogen fertilization (nonlinearly positive) - and the edaphic variable of initial SOC content (linearly negative). Temperature had weakly positive effects, while precipitation had negligible impacts on SOC dynamics under current irrigation management. The effects of increased N fertilization on SOC changes were most significant between the rates of 0 and 300 kg ha(-1) yr(-1). With a moderate rate of manure application (i.e., 2000 kg ha(-1) yr(-1)), stubble retention (i.e., 50%), and an optimal rate of nitrogen fertilization (i.e., 300 kg ha(-1) yr(-1)), more than 60% of the study area showed an increase in SOC, and the average SOC density across NCP was relatively steady during the study period. If the rates of manure application and stubble retention doubled (i.e., manure application rate of 4000 kg ha(-1) yr(-1) and stubble retention rate of 100%), soils across more than 90% of the study area would act as a net C sink, and the average SOC density kept increasing from 40 Mg ha(-1) during 2010s to the current worldwide average of similar to 55 Mg ha(-1) during 2060s. The results can help target agricultural management practices for effectively mitigating climate change through soil C sequestration.
  • Authors:
    • Lugato,E.
    • Montanarella, L.
    • Jones, A.
    • Bampa, F.
    • Panagos, P.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 1
  • Year: 2014
  • Summary: Proposed European policy in the agricultural sector will place higher emphasis on soil organic carbon (SOC), both as an indicator of soil quality and as a means to offset CO 2 emissions through soil carbon (C) sequestration. Despite detailed national SOC data sets in several European Union (EU) Member States, a consistent C stock estimation at EU scale remains problematic. Data are often not directly comparable, different methods have been used to obtain values (e.g. sampling, laboratory analysis) and access may be restricted. Therefore, any evolution of EU policies on C accounting and sequestration may be constrained by a lack of an accurate SOC estimation and the availability of tools to carry out scenario analysis, especially for agricultural soils. In this context, a comprehensive model platform was established at a pan-European scale (EU+Serbia, Bosnia and Herzegovina, Croatia, Montenegro, Albania, Former Yugoslav Republic of Macedonia and Norway) using the agro-ecosystem SOC model CENTURY. Almost 164 000 combinations of soil-climate-land use were computed, including the main arable crops, orchards and pasture. The model was implemented with the main management practices (e.g. irrigation, mineral and organic fertilization, tillage) derived from official statistics. The model results were tested against inventories from the European Environment and Observation Network (EIONET) and approximately 20 000 soil samples from the 2009 LUCAS survey, a monitoring project aiming at producing the first coherent, comprehensive and harmonized top-soil data set of the EU based on harmonized sampling and analytical methods. The CENTURY model estimation of the current 0-30 cm SOC stock of agricultural soils was 17.63 Gt; the model uncertainty estimation was below 36% in half of the NUTS2 regions considered. The model predicted an overall increase of this pool according to different climate-emission scenarios up to 2100, with C loss in the south and east of the area (involving 30% of the whole simulated agricultural land) compensated by a gain in central and northern regions. Generally, higher soil respiration was offset by higher C input as a consequence of increased CO 2 atmospheric concentration and favourable crop growing conditions, especially in northern Europe. Considering the importance of SOC in future EU policies, this platform of simulation appears to be a very promising tool to orient future policymaking decisions.
  • Authors:
    • Venterea, R. T.
    • Maharjan, B.
    • Rosen, C.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 2
  • Year: 2014
  • Summary: Irrigation and N fertilizer management are important factors affecting crop yield, N fertilizer recovery efficiency, and N losses as nitrous oxide (N 2O) and nitrate (NO 3-). Split application of conventional urea (split-U) and/or one-time application of products designed to perform as enhanced-efficiency N fertilizers may mitigate N losses. The objective of this study was to compare the effects of controlled-release polymer-coated urea (PCU), stabilized urea with urease and nitrification inhibitors (IU) and split-U on direct soil-to-atmosphere N 2O emissions, NO 3- leaching, and yield for fully irrigated and minimum-irrigated corn in loamy sand. Indirect N 2O emissions due to NO 3- leaching were estimated using published emission factors (EF 5). Split-U increased yield and N uptake compared with preplant-applied PCU or IU and decreased NO 3- leaching compared with PCU. Direct N 2O emissions were significantly less with IU or split-U than with PCU, and there was a trend for greater emissions with split-U than with IU ( P=0.08). Irrigation significantly increased NO 3- leaching during the growing season but had no significant effect on direct N 2O emissions. After accounting for significantly increased yields with irrigation, however, N losses expressed on a yield basis did not differ and in some cases decreased with irrigation. Post-harvest soil N and soil-water NO 3- in spring showed the potential for greater N leaching in minimum-irrigated than fully irrigated plots. Indirect emissions due to NO 3- leaching were estimated to be 79 to 117% of direct emissions using the default value of EF 5, thus signifying the potential importance of indirect emissions in evaluating management effects on N 2O emissions.
  • Authors:
    • Singh, S. D.
    • Paul, R. K.
    • Sehgal, V. K.
    • Chakraborty, D.
    • Chattaraj, S.
    • Daripa, A.
    • Pathak, H.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: Crop water requirement (CWR) under the projected climate change could be mediated through changes in other weather parameters including the air temperature. The present study was directed to assess the on-farm water requirement in wheat crop in future, in semi-arid Indo-Gangetic Plains of India, through field and computer simulations. Field simulation using temperature gradient tunnels shows 18% higher crop evapotranspiration (ET c) and 17% increase in root water extraction at 3.6°C elevated temperature compared to 1.5°C increase over the ambient. A time series model (ARIMA) with long-term (1984-2010) weather data of the experimental site and a global climate model (IPCC-SRES HADCM3) were used to simulate the potential ET (ET 0) of wheat for 2020-2021 and 2050-2051 years. The crop coefficient ( Kc) values for these years were generated through Kc-CGDD (Cumulative growing-degree-days) relation by using LARS-WG model-derived daily minimum and maximum temperatures. The CWR and NIR (Net Irrigation Requirement) are likely to be less in projected years even though air temperatures increase. The CWR reduces in ARIMA outputs owing to a lower reference ET (ET 0) due to decline in solar radiation. Under IPCC-SRES scenarios, the ET c-crop phenophase relation [CGDD-LGP (length of growing period) response] may offset the effect of rising temperature and a net decline in CWR is observed. It may be likely that the effect of temperature increase on CWR is manifested mostly through its relation with crop phenophase (thermal requirement to complete a specific growth stage) and not the temperature effect on ET 0 per se. This is certainly a ray of hope in managing the depleting irrigation water resources in the semi-arid wheat-growing regions of the IGP.
  • Authors:
    • Resop, J. P.
    • Sicher, R.
    • Barnaby, J.
    • Fleisher, D. H.
    • Timlin, D. J.
    • Reddy, V. R.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: Elevated carbon dioxide (CO 2) influences photosynthesis ( AN), transpiration (ET), and water use efficiency (WUE) for well-watered potato ( Solanum tuberosum L.). Little is known regarding effects of short-term drought and CO 2. Two experiments, differing in the quantity of solar radiation, were conducted in soil-plant-atmosphere-research chambers. Plants were grown at ambient (aCO 2) or twice-ambient CO 2 (eCO 2) and received one of three irrigation treatments: no water stress (C), short-term (11-16 d) water-withholding during vegetative and post-tuber initiation stages (VR), or post-tuber initiation (R) only. Canopy conductance to CO 2 transfer (tau) and water vapor ( Gv), light use efficiency (alpha), daily AN, and ET decreased at the onset of each drought and were correlated with volumetric water content. The rate of decrease was similar for R and VR. Gv declined more sharply than AN, resulting in higher WUE. Seasonal AN declined with the pattern of C > R > VR and was higher for eCO 2 C and R treatments. Seasonal WUE was higher for eCO 2 at all irrigation treatments. Total dry matter, harvest index, and leaf area were reduced ( p<0.05) for droughted treatments and total dry matter and harvest index were also higher for eCO 2 VR pots. Relative responses to drought and CO 2 were similar among experiments, with greater magnitude of response under high solar radiation. Findings were similar to those reported under longer-term water-withholding studies, suggesting that interactions between CO 2 and drought on carbon assimilation and water use are conserved across production zones with varying radiation and rainfall patterns.
  • Authors:
    • Horwath, W. R.
    • Burger, M.
    • Suddick, E.
    • Garland, G. M.
    • Six, J.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 195
  • Year: 2014
  • Summary: It is well known that agricultural production contributes to global warming through the release of greenhouse gases CO2, N2O, and CH4, the most potent of which is N2O. However, most N2O emission studies focus on intensively managed, annual cropping systems. Few have documented greenhouse gas production in perennial crops, which often have substantially different agricultural management practices and growth patterns compared to annual crops. Hence, the objectives of this study were to (1) quantify seasonal and annual direct N2O emissions from a Mediterranean vineyard and (2) determine how conventional management practices such as irrigation, fertigation, cover cropping and tillage affect the magnitude and duration of N2O emissions. This study took place in a wine grape vineyard (Vitis vinifera)in Arbuckle, CA over a two-year period using closed-flux chamber measurements. Annual emissions totaled 3.92 kg N2O-N ha(-1) the first year, when a leguminous cover crop was planted in the alleys, while emissions in the second year when the alleys were fallow showed a 7-fold reduction, reaching only 0.56 kg N2O-N ha(-1). During the growing season of both years, fertigation events in the crop rows produced slightly increased emissions, ranging from 11 to 23 g N2O-N ha(-1) day(-1) and lasting less than one week, compared to the low background values of 0.5 g N2O-N ha(-1) day(-1). The largest fluxes occurred during the dormant season in response to the first precipitation event of the year, especially in the alleys. Nitrous oxide emissions following precipitation events in the second year, when the alleys were fallow, did not follow the same pattern, indicating the significant influence of cover crop-derived N (and C), when coupled with precipitation events, on annual N2O emissions. The results of this study indicate that the effects of individual management practices such as cover cropping may not be seen immediately, but instead act in sequence with other events when conditions are favorable for N2O production. Hence, when determining specific management practices to employ, it is important to recognize the interaction between management, climatic events, and time as important drivers in total N2O production.
  • Authors:
    • Reardon-Smith, K.
    • Mushtaq, S.
    • Maraseni, T. N.
  • Source: JOURNAL OF WATER AND CLIMATE CHANGE
  • Volume: 5
  • Issue: 3
  • Year: 2014
  • Summary: While the prevailing rationale for new irrigation technology adoption is improved water use efficiency, this study evaluated trade-offs between water savings, greenhouse gas (GHG) emissions and economic gain associated with the conversion of a furrow irrigation system to a sprinkler irrigation (lateral-move) system on a cotton farm in eastern Australia. Trade-offs were evident when conversion to the pressurised sprinkler irrigation system was evaluated in terms of fuel and energy-related emission; the adoption of the new system saved water but increased GHG emissions. However, when we considered changes in farm machinery and input uses as a result of the conversion, we found an overall reduction in GHG emissions. Overall, the GHG modelling indicated that higher total quantities of GHGs were emitted from the furrow irrigation (4,453 kg CO 2e/ha) than from the sprinkler irrigation (3,347 kg CO 2e/ha) farming system. Water efficiency modelling indicated that, on average, water savings of 18% are possible, while economic modelling indicated that the conversion of irrigation technology is a viable option. Even at a carbon price of AUD$30/tCO 2e, investment in the sprinkler technology was an economically feasible option due to significant water savings and increased yield.
  • Authors:
    • Davis, J. G.
    • Reich, R.
    • Longchamps, L.
    • Khosla, R.
    • Moshia, M. E.
    • Westfall, D. G.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: Precision manure management is a relatively new concept that merges the best agronomic and manure management practices along with precision agricultural techniques, such as site-specific management zones (MZs), for agricultural productivity and environmental quality. The objective of the study was to assess the influence and compare the economic efficiency of variable-rate applications of animal manure on grain yield in maize ( Zea mays L.) fields across MZs in limited irrigation cropping systems. The study was conducted on furrow-irrigated maize fields in northeastern Colorado, USA. Fields were classified into low, medium, and high yielding MZs, based on soil color, elevation, and yield history. Experimental strips were 4.5 m wide and 540 m long spanning across all MZs with manure and N fertilizer management strategies nested within MZs. Variable-rate manure applications of 22, 44, and 67 Mg ha -1 were considered for variable yield goal (VYG) and constant yield goal (CYG) manure management strategies. The results of this study indicates that maize grain yield was significantly different across MZs a majority of times, however, not always consistent with the MZ productivity level. For instance, the low MZ showed a significantly ( P≤0.05) higher grain yield under a CYG manure management strategy. The enterprise budget analysis indicated that application of animal manure alone was economically inefficient for maize grain production. The study suggests that variable-rates of manure can be used in conjunction with synthetic N fertilizer to ensure that crop N requirements are met at early growth stages of maize.