31. Soil organic carbon assessment using the Carbon Management Evaluation Tool for Voluntary Reporting and the Soil Conditioning Index

• Authors:
  • Franzluebbers, A. J.
  • Andrews, S. S.
  • Kome, C. E.
• Source: JOURNAL OF SOIL AND WATER CONSERVATION
• Volume: 68
• Issue: 4
• Year: 2013
• Summary: Simple, yet reliable models are needed to quantify soil organic carbon (SOC) changes for the wide diversity of agricultural management conditions in the United States. We compared the outputs of two relatively simple models currently available for farmers and government-financed farm support agencies: the Carbon (C) Management Evaluation Tool for Voluntary Reporting of Greenhouse Gases (COMET-VR) and the Soil Conditioning Index (SCI). Simulations were conducted for 18 locations throughout the United States for five soil textural regimes (loamy sand, sandy loam, silt loam, clay loam, and silty clay loam), three tillage management systems (conventional tillage [CT], minimum tillage [MT], and no tillage [NT]), and two crop rotations (wheat [Triticum aestivum L.]-potato [Solanum tuberosum L.] and wheat-four-year alfalfa [Medicago sativa L.] in western states and corn [Zea mays L.]-soybean [Glycine max L.] and corn-soybean-wheat in eastern states). Both models ranked SOC change as NT > MT > CT, whereby SOC change decreased with increasing soil disturbance with tillage However, models were divergent with regards to soil texture; SOC change was greater in coarse-textured than in fine-textured soils with COMET-VR, but SOC change was lower in coarse-textured than in fine-textured soils with SCI. For crop rotations, SOC change was greater or equal in simpler than in more complex rotation with COMET-VR, but smaller in simpler than in more complex rotations with SCI. Overall, SOC sequestration predicted by COMET-VR was positively related to SCI score, especially when accounting for differences in environmental conditions of a location. Our results suggest that both Models have value and limitations and that measures of SOC sequestration are predictable with these tools under a diversity of typical management conditions in the United States.

32. Effects of soil tillage and fertilization on resource efficiency and greenhouse gas emissions in a long-term field experiment in Southern Germany

• Authors:
  • Huelsbergen, K.-J.
  • Munch, J. C.
  • Kuestermann, B.
• Source: European Journal of Agronomy
• Volume: 49
• Issue: August
• Year: 2013
• Summary: Two factorial long-term field experiments were carried out at the experimental site of Scheyern, located in southern Germany, 40 km north of Munich (48 degrees 30'0' N, 11 degrees 26'60' E). Here three soil tillage systems were investigated: CT (conventional tillage with moldboard plough, 25 cm plowing depth), RT1 (reduced tillage with chisel plow, 18 cm working depth), and RT2 (reduced tillage with chisel plow, 8 cm working depth). At the same time, three fertilization systems were analyzed (high (N3), medium (N2) and low (N1) mineral N input) with a crop rotation of winter wheat (Triticum aestivum L) - potatoes (Solanum tuberosum L.) - winter wheat-corn (Zea mays L). The long-term effects of tillage and fertilization on yields, soil properties, nitrogen and energy efficiency, as well as greenhouse gas emissions (GGE) were investigated for the period of 1994-2005. On average conventional tillage (CT) produced yields of 8.03 (N1), 8.82 (N2) and 8.88 (N3) GE (grain equivalents) ha(-1) yr(-1); reduced tillage (RT1) yields of 7.82 (N1), 8.54 (N2) and 9.10 (N3) GE ha(-1) yr(-1) and RT2 yields of 6.9 (Ni), 7.82 (N2) and 8.6 (N3) GE ha(-1) yr(-1). The benefit of reduced soil tillage over CT. is a lower consumption of diesel fuel (reduced by 35%) and fossil energy (by 10%), C sequestration and N accumulation in soil. We recorded the highest soil organic carbon (SOC) in the RT2 treatments with the lowest tillage intensity (52.5 Mg ha(-1)) and the lowest SOC reserves in the CT plowed treatments (41.1 Mg ha(-1)). During the reported period, SOC reserves in the plowed treatments decreased by about 300 kg C ha-1 yr-1, whereas they increased by 150-500 kg C ha(-1) yr(-1) in the chiseled treatments. Similar results were achieved with the soil organic nitrogen (SON) reserves based on the type of tillage. This amounted to around 4000 kg ha-1 (CT), 4500 kg ha (RT1) and more than 5000 kg N ha-1 (RT2). The RT1 treatments were marked by high nutrient and energy efficiency. The disadvantage of reduced tillage lies in higher pesticide consumption and stronger soil compaction. The influence of reduced tillage was more pronounced in RT2 than in RT1 (higher SOC and SON content, higher soil dry bulk density, lower consumption of diesel fuel, higher pesticide input). The significant decreases in yield in the RT2 treatments reduced the nitrogen and energy efficiency and raised yield-related greenhouse gas emissions (GGE) in comparison to the RT1 treatments. In the case of reduced tillage combined with high N doses (RT1/N3, RT2/N2, RT2/N3), high N2O emissions of 10 to 12 kg ha(-1) yr(-1) were measured using closed chambers. It was found that as input of mineral N increased, GGE for tillage treatments, both area and yield related also increased. In RT1/N1, negative net GGE were recorded due to high C sequestration combined with moderate N2O and CO2 emissions (-220 kg CO2 (eq) ha(-1) yr(-1), -28 kg CO2 eq GE-(1)), whereas CT/N3 produced the highest net GGE (3587 kg CO2 (eq) ha(-1) yr(-1), 404 kg CO2 eq GE(-1)). (C) 2013 Elsevier B.V. All rights reserved.

33. Reducing greenhouse gas emissions with urban agriculture: A Life Cycle Assessment perspective

• Authors:
  • Chatterton, J.
  • Graves, A.
  • Kulak, M.
• Source: Landscape and Urban Planning
• Volume: 111
• Issue: March
• Year: 2013
• Summary: The production and supply of food currently accounts for 20-30% of greenhouse gas (GHG) emissions in the UK and the government and nongovernmental organisations are seeking to reduce these environmental burdens. Local authorities all over UK establish community farms with the aim to produce more sustainable food for citizens. This study used environmental Life Cycle Assessment (LCA) to quantify the potential savings of food-related GHG emissions that may be achieved with the establishment of an urban community farm, based on a case study recently found in the London Borough of Sutton. The work identified elements of the farm design that require the greatest attention to maximise these savings. The greatest reductions can be achieved by selecting the right crops: (i) providing the highest yields in local conditions and (ii) usually produced in energy-intensive greenhouses or air-freighted to UK from outside Europe. Implications from further development of the farm on the local, unused land were examined, taking into account market requirements. This showed that land used on an urban fringe for food production could potentially reduce greenhouse gas emissions in Sutton by up to 34 t CO(2)e ha(-1) a(-1). Although the percentage of this reduction in total diet emissions is relatively low, the result exceeds carbon sequestration rates for the conventional urban green space projects, such as parks and forests. (C) 2012 Elsevier B.V. All rights reserved.

34. Assessing greenhouse gas emissions from potato production and processing in the Czech Republic

• Authors:
  • Moudry, J.
  • Plch, R.
  • Jaresova, M.
  • Jelinkova, Z.
  • Moudry, J., Jr.
  • Konvalina, P.
• Source: Outlook on Agriculture
• Volume: 42
• Issue: 3
• Year: 2013
• Summary: This study evaluates the impact of selected potato farming and processing activities on the environment in terms of greenhouse gas emissions. The Life Cycle Assessment (LCA) methodology was used for this evaluation, and was applied to products cultivated under both conventional and organic production, and processed under technological conditions common in the Czech Republic. Farm questionnaires were supplemented with information from the scientific literature to acquire the necessary data for modelling. The SIMA Pro software and the ReCiPe Midpoint (H) method were used for simulation. The results show a lower level of emissions under organic production (0.126 kg CO(2)e per kg of potatoes, compared with 0.145 kg CO(2)e per kg of conventionally grown potatoes). However, this benefit is cancelled out by higher emissions due to the transportation of organic products over long distances.

35. Effects of 3,4-dimethylphyrazole phosphate-added nitrogen fertilizers on crop growth and N2O emissions in Southern Italy

• Authors:
  • Arena, C.
  • Amato, U.
  • Maglione, G.
  • Polimeno, F.
  • Ottaiano, L.
  • Vitale, L.
  • Di Tommasi, P.
  • Mori, M.
  • Magliulo, V.
• Source: Plant, Soil and Environment
• Volume: 59
• Issue: 11
• Year: 2013
• Summary: The effect of the nitrification inhibitor 3,4-dimethylphyrazole phosphate (DMPP) on N-fertilized crop growth and soil N2O emissions were studied at two experimental sites in Southern Italy, characterised by a Mediterranean climate and different soil texture. The experiments were a randomized block design of two treatments: crop fertilized with NH4NO3 (considered the control treatment) or amended with DMPP plus NH4NO3 (considered the DMPP treatment). ANOVA was performed to assess differences between treatments and fertilization periods whereas simple and multiple linear regressions were performed in order to assess the effect of the soil-related independent variables on soil gases emissions. Growth of potato plants fertilized with DMPP-added nitrogen was enhanced compared to control plants, whereas no benefit on maize plants grown during summer was observed. N2O emissions measured from soil to potato after the first fertilization with DMPP-added nitrogen was reduced during winter, but was higher than control after the second fertilizer application in spring, leading to comparable N2O emission factors (EF1) between treatments. In maize N2O emissions and EF1 were lower for DMPP compared to control treatment. The effectiveness of reduction in soil N2O emission was influenced by soil temperature and water-filled pore space (WFPS) in both experimental sites. However, the overall effect of WFPS was contrasting as N2O emissions were decreased in potato and enhanced in maize.

36. Twenty-five years of changes in soil cover on Canadian Chernozemic (Mollisol) soils, and the impact on the risk of soil degradation.

• Authors:
  • Huffman, T.
  • Coote, D. R.
  • Green, M.
• Source: Canadian Journal of Soil Science
• Volume: 92
• Issue: 3
• Year: 2012
• Summary: Agricultural soils that are covered by vegetation or crop residue are less susceptible to degradation by wind and water erosion, organic matter depletion, structural degradation and declining fertility. In general, perennial crops, higher yields, reduced tillage and continuous cropping provide more soil cover than annual crops, lower yields, intensive tillage, residue harvesting and fallowing. This study presents a model for estimating the number of days in a year that the soil surface is protected and demonstrates its application on the Canadian prairies over the period from 1981 to 2006. Over the 25-yr study period, the average soil cover on Canadian prairie soils increased by 4.8% overall. The improvement came primarily as a result of widespread adoption of no-till and a decline in the use of summerfallow, but the gains were offset to a great deal by a shift from higher-cover crops such as wheat, oats and barley to more profitable but lower-cover crops such as canola, soybeans and potatoes. The implication of these trends is that, even though protection of prairie agricultural soils has improved over the past 25 yr, soil cover could decline dramatically over the next several decades if crop changes continue, the adoption of conservation tillage reaches a peak and residue harvesting for biofuels becomes more common.

37. Twenty-five years of changes in soil cover on Canadian Chernozemic (Mollisol) soils, and the impact on the risk of soil degradation.

• Authors:
  • Huffman, T.
  • Green, M.
  • Coote, D.
• Source: Canadian Journal of Soil Science
• Volume: 92
• Issue: 3
• Year: 2012
• Summary: Agricultural soils that are covered by vegetation or crop residue are less susceptible to degradation by wind and water erosion, organic matter depletion, structural degradation and declining fertility. In general, perennial crops, higher yields, reduced tillage and continuous cropping provide more soil cover than annual crops, lower yields, intensive tillage, residue harvesting and fallowing. This study presents a model for estimating the number of days in a year that the soil surface is protected and demonstrates its application on the Canadian prairies over the period from 1981 to 2006. Over the 25-yr study period, the average soil cover on Canadian prairie soils increased by 4.8% overall. The improvement came primarily as a result of widespread adoption of no-till and a decline in the use of summerfallow, but the gains were offset to a great deal by a shift from higher-cover crops such as wheat, oats and barley to more profitable but lower-cover crops such as canola, soybeans and potatoes. The implication of these trends is that, even though protection of prairie agricultural soils has improved over the past 25 yr, soil cover could decline dramatically over the next several decades if crop changes continue, the adoption of conservation tillage reaches a peak and residue harvesting for biofuels becomes more common.

38. Evaluating greenhouse gas emissions inventories for agricultural burning using satellite observations of active fires.

• Authors:
  • Randerson, J.
  • Foley, J.
  • Giglio, L.
  • Jin, Y.
  • Lin, H.
• Source: Ecological Applications
• Volume: 22
• Issue: 4
• Year: 2012
• Summary: Fires in agricultural ecosystems emit greenhouse gases and aerosols that influence climate on multiple spatial and temporal scales. Annex 1 countries of the United Nations Framework Convention on Climate Change (UNFCCC), many of which ratified the Kyoto Protocol, are required to report emissions of CH 4 and N 2O from these fires annually. In this study, we evaluated several aspects of this reporting system, including the optimality of the crops targeted by the UNFCCC globally and within Annex 1 countries, and the consistency of emissions inventories among different countries. We also evaluated the success of individual countries in capturing interannual variability and long-term trends in agricultural fire activity. In our approach, we combined global high-resolution maps of crop harvest area and production, derived from satellite maps and ground-based census data, with Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) measurements of active fires. At a global scale, we found that adding ground nuts (e.g., peanuts), cocoa, cotton and oil palm, and removing potato, oats, rye, and pulse other from the list of 14 crops targeted by the UNFCCC increased the percentage of active fires covered by the reporting system by 9%. Optimization led to a different recommended list for Annex 1 countries, requiring the addition of sunflower, cotton, rapeseed, and alfalfa and the removal of beans, sugarcane, pulse others, and tuber-root others. Extending emissions reporting to all Annex 1 countries (from the current set of 19 countries) would increase the efficacy of the reporting system from 6% to 15%, and further including several non-Annex 1 countries (Argentina, Brazil, China, India, Indonesia, Thailand, Kazakhstan, Mexico, and Nigeria) would capture over 55% of active fires in croplands worldwide. Analyses of interannual trends from the United States and Australia showed the importance of both intensity of fire use and crop production in controlling year-to-year variations in agricultural fire emissions. Remote sensing provides an effective means for evaluating some aspects of the current UNFCCC emissions reporting system; and, if combined with census data, field experiments and expert opinion, has the potential to improve the robustness of the next generation inventory system.

39. Production and N nutrient performance of wheat-maize-soybean relay strip intercropping system and evaluation of interspecies competition.

• Authors:
  • Wan, Y.
  • Chen, X.
  • Xiang, D.
  • Yang, W.
  • Yong, T.
• Source: Acta Prataculturae Sinica
• Volume: 21
• Issue: 1
• Year: 2012
• Summary: The aim of this paper was to study the variation of interspecies competitiveness in two relay strip intercropping system; wheat-maize-soybean and wheat-maize-sweet potato. The character of biomass accumulation and nitrogen uptake were examined for five cropping systems using years of field experiment. The cropping systems included three sole cropping systems (wheat-soybean, wheat-sweet potato and maize) and two relay strip intercropping systems (wheat/maize/soybean and wheat/maize/sweet potato). Land equivalent ratio (LER), aggressiveness (A), and nutrition competition ratio (NCR) were introduced as indexes to evaluate the interspecies competitiveness in each treatment. The results showed that there was obvious relay strip intercropping advantage ( LER >1, Awc 1) in the wheat-maize-soybean relay strip intercropping system, maize occupied the dominant niche for the whole growing stage in the relay strip intercropping systems, and the interspecies competitiveness of wheat and soybean were lower than that of the maize. Comparing with the sole cropping systems and wheat-maize-sweet potato relay strip intercropping system, the grain yield and nitrogen uptake, total biomass and total nitrogen uptake above ground of crops were increased significantly at both flowering (or spinning) and maturity stages in the wheat-maize-soybean relay strip intercropping system. The values of biomass and nitrogen uptake for the relay strip intercropping system were greater than the sole cropping systems, and that of soybean stubble were greater than sweet potato stubble. The total economic returns of crops in the wheat/maize/soybean relay strip intercropping system was higher 28.02% than those of crops in the wheat/maize/sweet potato relay strip intercropping system.

40. Effect of wheat/maize/soybean and wheat/maize/sweet potato relay strip intercropping on bacterial community diversity of rhizosphere soil and nitrogen uptake of crops.

• Authors:
  • Zhu, Z.
  • Xiang, D.
  • Yang, W.
  • Yong, T.
• Source: Acta Agronomica Sinica
• Volume: 38
• Issue: 2
• Year: 2012
• Summary: The aim of this study was to understand the relationship between diversity of rhizosphere bacterial community and nitrogen uptake of crops in two relay strip intercropping systems: wheat/maize/soybean and wheat/maize/sweet potato. We analyzed the diversities of rhizosphere bacterial community in five cropping systems using denaturing gradient gel electrophoresis (DGGE) based on 16S rDNA. The cropping systems included wheat-soybean (A1), wheat-sweet potato (A2), maize single cropping (A3), wheat/maize/soybean (A4), and wheat/maize/sweet potato (A5). Compared to the sole cropping systems (A1, A2, and A3 treatments), the A4 treatment showed increases in grain nitrogen uptake and total nitrogen uptake amounts of aboveground of crops at both flowering (or silking) and maturity stages, and the Shannon-Weiner indices for rhizosphere bacterial community diversity was also increased significantly. The values of nitrogen uptake and the Shannon-Weiner index in the relay strip intercropping systems were greater than those in sole cropping systems, and the values in the treatment with soybean stubble were greater than those in the treatment with sweet potato stubble. The number and strength of the DNA bands from DGGE profiles varied with the cropping systems, especially for the distinguished bands. The comparability of rhizosphere bacterial community composition was low among different cropping systems. The similarity coefficient ( Cs) was higher between two relay strip intercropping systems than between relay strip intercropping system and sole cropping system, but the Cs value was low between A4 and A5 treatments. However, there was obvious difference of rhizosphere bacterial community composition between A4 and A5 treatments, and the A4 treatment was propitious to enhancing rhizosphere bacterial community diversity and increasing nitrogen uptakes of crops.