• Authors:
    • Mary, B.
    • Jeuffroy, M. H.
    • Amosse, C.
    • David, C.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 98
  • Issue: 1
  • Year: 2014
  • Summary: Nitrogen (N) management is a key issue in livestock-free organic grain systems. Relay intercropping with a legume cover crop can be a useful technique for improving N availability when two cash crops are grown successively. We evaluated the benefits of four relay intercropped legumes (Medicago lupulina, Medicago sativa, Trifolium pratense and Trifolium repens) on N dynamics and their contribution to the associated and subsequent cash crops in six fields of organic farms located in South-East France. None of the relay intercropped legumes affected the N uptake of the associated winter wheat but all significantly increased the N uptake of the succeeding spring crop, either maize or spring wheat. The improvement of the N nutrition of the subsequent maize crop induced a 30 % increase in grain yield. All relay intercropped legumes enriched the soil-plant system in N through symbiotic fixation. From 71 to 96 % of the N contained in the shoots of the legumes in late autumn was derived from the atmosphere (Ndfa) and varied between 38 and 67 kg Ndfa ha(-1). Even if the cover crop is expected to limit N leaching during wintertime, the presence of relay intercropped legumes had no significant effect on N leaching during winter compared to the control.
  • Authors:
    • Sainju, U. M.
  • Source: Agronomy Journal
  • Volume: 106
  • Issue: 4
  • Year: 2014
  • Summary: To determine farm C credit and reduce global warming potential, information is needed on the effect of management practices on soil C storage. The effects of tillage, cropping sequence, and N fertilization were evaluated on dryland crop biomass, surface residue C, and soil organic carbon (SOC) at the 0- to 120-cm depth in a Williams loam (fine-loamy, mixed, superactive, frigid, Typic Argiustolls) and their relationships with grain yields from 2006 to 2011 in eastern Montana. Treatments were no-till continuous malt barley ( Hordeum vulgare L.) (NTCB), no-till malt barley-pea ( Pisum sativum L.) (NTB-P), no-till malt barley-fallow (NTB-F), and conventional till malt barley-fallow (CTB-F), each with 0, 40, 80, and 120 kg N ha -1. Annualized crop grain and biomass yields, surface residue amount, and C contents were greater in NTB-P and NTCB than CTB-F and NTB-F and increased with increased N rates. At 0 to 5 and 5 to 10 cm, SOC was greater in NTB-P than CTB-F or NTCB with 40 kg N ha -1 and at 10 to 30 and 0 to 120 cm was greater in NTB-P than NTCB with 120 kg N ha -1. Surface residue C and SOC were related with grain yield and C content ( R2=0.21-0.55, P≤0.10, n=16). Greater amount of crop residue returned to the soil and turnover rate probably increased surface residue C, soil C storage, and crop yields in NTB-P with 40 and 120 kg N ha -1 than the other treatments. Soil organic matter and crop yields can be enhanced by using NTB-P with 40 kg N ha -1.
  • Authors:
    • Calegari, A.
    • Balota, E. L.
    • Nakatani, A. S.
    • Coyne, M. S.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 197
  • Year: 2014
  • Summary: Soil degradation in Brazil is a concern due to intensive agricultural production. Combining conservation practice, such as no-tillage, with winter cover crops may increase microbial activity and enhance soil quality more than either practice alone. This research evaluated the benefits of long-term (23 years) winter cover crops and reduced tillage on soil microbial quality indicators in an Oxisol from Parana State, Southern Brazil. The winter cover treatments were: fallow, black oat, wheat, radish, blue lupin, and hairy vetch in conventional (plow) or no-tillage management; the summer crop was a soybean/maize rotation. Soil quality parameters included organic C, microbial biomass C and N, total and labile polysaccharide, easily extractable and total glomalin-related soil protein, and enzyme activity. Winter crops increased soil microbial quality parameters compared to fallow in both tillage systems, with greater relative increase in conventional than no-tillage. No-tillage had higher microbial biomass, polysaccharide, glomalin-related soil protein, and soil enzyme activity than conventional tillage. Including legumes in the crop rotation was important for N balance in the soil-plant system, increasing soil organic C content, and enhancing soil quality parameters to a greater extent than grasses or radish. The microbial parameters proved to be more sensitive indicators of soil change than soil organic C. Cultivating winter cover crop with either tillage is a beneficial practice enhancing soil microbial quality and also soil organic C stocks.
  • Authors:
    • Engelbrecht, D.
    • Thamo, T.
    • Barton, L.
    • Biswas, W. K.
  • Source: JOURNAL OF CLEANER PRODUCTION
  • Volume: 83
  • Year: 2014
  • Summary: Agriculture production contributes to global warming directly via the release of carbon dioxide (CO2), methane and nitrous oxide emissions, and indirectly through the consumption of inputs such as fertilizer, fuel and herbicides. We investigated if including a grain legume (Lupinus angustifolius) in a cropping rotation, and/or applying agricultural lime to increase the pH of an acidic soil, decreased greenhouse gas (GHG) emissions from wheat production in a semi-arid environment by conducting a streamlined life cycle assessment analysis that utilized in situ GHG emission measurements, rather than international default values. We also assessed the economic viability of each GHG mitigation strategy. Incorporating a grain legume in a two year cropping rotation decreased GHG emissions from wheat production by 56% on a per hectare basis, and 35% on a per tonne of wheat basis, primarily by lowering nitrogen fertilizer inputs. However, a large incentive ($93 per tonne of carbon dioxide equivalents reduced) was required for the inclusion of grain legumes to be financially attractive. Applying lime was profitable but increased GHG emissions by varying amounts depending upon whether the lime was assumed to dissolve over one, five or 10 years. We recommend further investigating the impact of liming on both CO2 and non-CO2 emissions to accurately account for its effect on GHG emissions from agricultural production.
  • Authors:
    • Irigoyen, J. J.
    • Erice, G.
    • Baslam, M.
    • Goicoechea, N.
  • Source: JOURNAL OF PLANT PHYSIOLOGY
  • Volume: 171
  • Issue: 18
  • Year: 2014
  • Summary: Medicago sativa L. (alfalfa) can exhibit photosynthetic down-regulation when grown in greenhouse conditions under elevated atmospheric CO 2. This forage legume can establish a double symbiosis with nitrogen fixing bacteria and arbuscular mycorrhizal fungi (AMF), which may increase the carbon sink effect of roots. Our aim was to assess whether the association of alfalfa with AMF can avoid, diminish or delay the photosynthetic acclimation observed in previous studies performed with nodulated plants. The results, however, showed that mycorrhizal (M) alfalfa at the end of their vegetative period had lower carbon (C) discrimination than non-mycorrhizal (NM) controls, indicating photosynthetic acclimation under ECO 2 in plants associated with AMF. Decreased C discrimination was due to the acclimation of conductance, since the amount of Rubisco and the expression of genes codifying both large and small subunits of Rubisco were similar or slightly higher in M than in NM plants. Moreover, M alfalfa accumulated a greater amount of soluble sugars in leaves than NM plants, thus favoring a down-regulation effect on photosynthetic rates. The enhanced contents of sugars in leaves coincided with a reduced percentage of arbuscules in roots, suggesting decreased sink of carbohydrates from shoots to roots in M plants. The shorter life cycle of alfalfa associated with AMF in comparison with the NM controls may also be related to the accelerated photosynthetic acclimation in M plants. Further research is needed to clarify to what extent this behavior could be extrapolated to alfalfa cultivated in the field and subjected to periodic cutting of shoots under climatic change scenarios.
  • Authors:
    • Messiga, A. J.
    • Burton, D. L.
    • Hammermeister, A.
    • Lynch, D. H.
    • Sharifi, M.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 100
  • Issue: 2
  • Year: 2014
  • Summary: The effects of green manure, crop sequence and off-farm composts on selected soil quality parameters were assessed in a three-year organic potato (Solanum tuberosum L.) rotation in Eastern Canada. Three crop sequences varying in preceding green manure [red clover (RCl) + RCl, and beans/buckwheat or carrots + oats/peas/vetch mixture (OPV)] as main plots and four fertility treatments applied in the potato phase only [control; inorganic fertilizer; municipal solid waste compost (MSW); composted paper mill biosolid (PMB)] as subplots were compared. In 2008 and 2010, changes in selected soil quality parameters (0-15 cm) were assessed prior to planting of potatoes and at potato tuber initiation stage. Potentially mineralizable nitrogen (N) and the acid phosphatase enzyme activity average values across years were greater following RCl (1.51 abs and 622 kg ha(-1)) compared with OPV (1.32 abs and 414 kg ha(-1)) at potato planting. Soil NO3-N average value was greater following RCl compared with OPV (63 vs. 52 kg ha(-1)) at tuber initiation. For the other measured parameters, OPV and RCl were similar. The soil organic carbon (C) and particulate organic matter-C were greater under PMB and MSW (31.1 and 7.57 kg ha(-1)) compared with fertilizer treatment (27.9 and 6.05 kg ha(-1)). The microbial biomass C and microbial biomass quotient were greater under MSW (216 kg ha(-1) and 0.73 %) than PMB and fertilizer (147 kg ha(-1) and 0.50 %) across crop rotations. Annual legume green manures and off-farm composts can be used to satisfy potato N requirement and maintains soil quality in organic potato rotations.
  • Authors:
    • Allen, F. L.
    • Reed, D. L.
    • Taylor, A. M.
    • Ashworth, A. J.
    • Keyser, P. D.
    • Tyler, D. D.
  • Source: JOURNAL OF CLEANER PRODUCTION
  • Volume: 87
  • Year: 2014
  • Summary: As the use of second-generation biofuel crops increases, so do questions about sustainability, particularly their potential to affect fossil energy consumption and greenhouse gas emissions. This study used a life-cycle approach to compare environmental impacts associated with three switchgrass (Panicum virgatum L.) production scenarios: i) regional production from a pool of Tennessee farmers based on in-field inputs and biomass yield; ii) varying nitrogen (N)-input levels from a replicated field study for 8-yrs i.e., a 100% and 9% decrease, and an 81% and 172% increase from 'baseline levels' of N inputs used under objective i; and, iii) a legume-intercrop system compared to baseline levels in order to determine effects of displacing synthetic-N with legumes. When compared across all agricultural inputs, nitrogen fertilizer production and breakdown resulted in the greatest environmental impacts. Although fertilization increased lignocellulosic yields, a 100% reduction in N-inputs from baseline levels reduced the formation of carbon, methane, and nitrous oxides per unit of production, (or dry tonne of biomass over 10-yrs) compared to a 172% increase. Switchgrass yield response indicated a 'less is more' scenario, as inputs beyond the current recommended input level (67 kg N ha-1) are not environmentally remunerating. During switchgrass biomass production, inputs with lesser impacts included phosphorus, herbicides, pesticides, and diesel fuel. Legume-intercropping reduced greenhouse gas emissions and groundwater acidification (5% and 27% reduction in global warming potential and formation of acidifying species, respectively) compared with the 67 kg N ha-1rate. Although N-fertilizers impact environmental sustainability of regional switchgrass feedstock production, environmental consequences can be reduced under proper N-management i.e., =67 kg N ha-1 or legume intercropping. However, given that the aim of second-generation feedstocks is to reduce the current reliance on fossil fuels, their production still requires fossil energy-based inputs. Consequently, greenhouse gas reductions and the extent of cleaner feedstock production during the agricultural biofuel supply chain is contingent upon input management and optimizing synthetic fertilizer usage.
  • Authors:
    • Simmons, A.
    • Muir, S.
    • Brock, P.
  • Source: Conference Paper
  • Volume: 3
  • Year: 2014
  • Summary: Australian agricultural industries contribute approximately 14.6% of net annual national greenhouse gas (GHG) emissions, with N 2O emissions from agricultural soils the second greatest source of these emissions. Given that 25 M ha of land in Australia is cropped, the technical potential for GHG emissions reduction in Australian grain production systems is substantial. The New South Wales Department of Primary Industries (NSW DPI) has developed research capacity in Life Cycle Assessment (LCA) to assess this mitigation potential. In this paper we provide insights into the regionally-specific approach that we are taking, not only to provide credible management options at a grain grower level and ensure that detailed data are available for analysis by participants in the downstream supply chain, but also to provide data which, in an aggregated form, will underpin market access and inform national policy development. We report on initial NSW DPI studies and discuss a new project, funded by the Grains Research and Development Corporation (GRDC), to determine emissions reduction opportunities for each of Australia's agro-ecological zones. Initial studies show total emissions from wheat production in the order of 200 kg CO 2-e per tonne, with values ranging down to 140 kg CO 2-e per tonne. In one study, replacing synthetic nitrogenous fertiliser with biologically fixed N reduced emissions to 33% of prior values. The new project is particularly concerned with developing accurate foreground data by triangulating several sources of published literature (including official statistics) and conducting 'groundtruthing' through panels of regionally-based advisors to increase data specificity. The LCAs and associated mitigation strategies will be underpinned by a median and relevant distribution of values for inputs, practices and yields, with system assumptions clearly documented.
  • Authors:
    • Durlinger,B.
    • Tyszler,M.
    • Scholten,J.
    • Broekema,R.
    • Blonk,H.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector
  • Year: 2014
  • Summary: Agri-footprint is a new life cycle inventory database that focuses on the agriculture and food sector. The goal of this database is to support life cycle assessment practitioners to perform high quality assessments. The database contains a methodologically consistent dataset for a large number of crops, crop products, animal systems and animal products. These inventories can be used as secondary data in LCAs. Non-LCA models were used to calculate a wide array of elementary flows (such as land use change, water use, fertilizer application rates), to support assessment on a multitude of environmental issues. To safeguard relevance and data quality, the database will be updated regularly. As the public interest in food LCAs is expected to increase in the near future, Agri-footprint will be a helpful resource for practitioners in this field.
  • Authors:
    • Tammeorg,Priit
    • Simojoki,Asko
    • Makela,Pirjo
    • Stoddard,Frederick L.
    • Alakukku,Laura
    • Helenius,Juha
  • Source: Plant and Soil
  • Volume: 374
  • Issue: 1-2
  • Year: 2014
  • Summary: We studied the effect of different biochar (BC) application rates on soil properties, crop growth dynamics and yield on a fertile sandy clay loam in boreal conditions. In a three-year field experiment conducted in Finland, the field was divided into three sub-experiments with a split-plot experimental design, one for each crop: wheat (Triticum aestivum), turnip rape (Brassica rapa), and faba bean (Vicia faba). The main plot factor was BC rate (0, 5 and 10 t DM ha(-1)) and the sub-plot factor was the N-P-K fertiliser rate. Soil physico-chemical properties as well as plant development, yield components and quality were investigated. BC addition did not significantly affect the soil chemical composition other than the increased C and initially increased K contents. Increased soil moisture content was associated with BC application, especially at the end of the growing seasons. BC decreased the N content of turnip rape and wheat biomass in 2010, thus possibly indicating an initial N immobilisation. In dry years, the seed number per plant was significantly higher in faba bean and turnip rape when grown with BC, possibly due to compensation for decreased plant density and relieved water deficit. However, the grain yields and N uptake with BC addition were not significantly different from the control in any year. Even though BC application to a fertile sandy clay loam in a boreal climate might have relieved transient water deficit and thereby supported yield formation of crops, it did not improve the yield or N uptake.