19662015
  • Authors:
    • Mcleod, M.
    • Schwenke, G.
    • Wilson, B. R.
    • Cowie, A.
    • Tighe, M.
    • Rabbi, S. M. F.
    • Badgery, W.
    • Baldock, J.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: This project aimed to identify land uses and soil management practices that have significant associations with soil organic carbon (SOC) stocks (0-0.3 m) in New South Wales (NSW), Australia. The work presented in this paper is based on a one-off survey targeting key land uses and management practices of eastern NSW. Because of the nature of the work, the land uses and management combinations surveyed in different soils and climatic conditions were significantly unbalanced, and separately analyzing associations after breaking the dataset into different land uses may lead to significant increases in Type errors. Therefore, redundancy analysis (RDA) was undertaken to explore the association between explanatory variables (i.e., land uses, soil management, soil properties and environmental variables) and the variation in stocks (mass per unit area) of particulate organic carbon (POC), humic organic carbon (HOC) and resistant organic carbon (ROC) across 780 sites in eastern NSW, south eastern Australia. Results indicated that soil properties, land uses, soil management and environmental variables together could explain 52% of total variation in stocks of the SOC fractions. Specifically soil properties and environmental variables explained 42.8%, whereas land uses and management practices together explained 9.2% of the total variation in SOC fractions. A forward selection RDA was also undertaken considering soil properties and environmental variables as covariates to assess the statistical significance of land uses and management practices on stocks of POC, HOC and ROC. We found that pasture had significant positive associations on stocks of carbon fractions. Among the soil properties and environmental variables rainfall, longitude and elevation had a significant positive influence while pH and bulk density had a significantly negative influence on the HOC, POC and ROC stocks. Using a novel multivariate technique, the current work identified the land uses and soil management that had significant impact on carbon stocks in soil after accounting for influences soil properties and environmental variables.
  • Authors:
    • Varvel, G. E.
    • Wienhold, B. J.
    • Jin, V. L.
    • Schmer, M. R.
    • Follett, R. F.
  • Source: Soil Science Society of America Journal
  • Volume: 78
  • Issue: 6
  • Year: 2014
  • Summary: Demand for corn (Zea mays L.) stover as forage or as a cellulosic biofuel has increased the importance of determining the effects of stover removal on biomass production and the soil resource. Our objectives were to evaluate grain yield, soil organic C (SOC), and total soil N (0-150 cm) in a 10-yr, irrigated, continuous corn study under conventional disk tillage (CT) and notill (NT) with variable corn stover removal rates (none, medium, and high). Natural abundance C isotope compositions ( d13C) were used to determine C additions by corn (C4-C) to the soil profile and to evaluate the retention of residual C3-C. After 10 yr of management treatments, mean grain yields were 7.5 to 8.6% higher for NT when stover was removed compared with no stover removal, while grain yields were similar for CT in all stover removal treatments. Turnover of SOC occurred as C3-C stocks were replaced by C4-C in the 0- to 120-cm soil profile. Total SOC and N stocks changed mainly in surface soils (0-30 cm), with no detectable cumulative changes at 0 to 150 cm. Specifically, SOC declined after 10 yr under CT at 0 to 15 cm and was affected by residue management at 15 to 30 cm. Total soil N was greater when no stover was removed (P = 0.0073) compared with high stover removal at 0 to 15 cm. Long-term NT ameliorated medium stover removal effects by maintaining near-surface SOC levels. Results support the need to evaluate SOC cycling processes below near-surface soil layers.
  • Authors:
    • Li, S.
    • You, D. H.
    • Lu, X. C.
    • Liu, T.
    • Tian, X. H.
    • Wang, S. J.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 6
  • Year: 2014
  • Summary: Soil water, organic C, and N management practices exert strong influences on winter wheat ( Triticum aestivum L.) yield and soil properties under dryland farming conditions. Here, a 9-yr field experiment was conducted in northwestern China using treatments that included nine factorial combinations of three cultivation practices, conventional cultivation (CC), straw mulching (SM), and supplementary irrigation (SI), and three N application rates (0, 120, and 240 kg N ha -1). Relative yield gradually declined under CC and SM with N, yet remained steady under SI. Without N, yield decreased by 50 to 60%. Soil organic carbon (SOC), labile organic carbon (LOC), total nitrogen (TN), and available potassium (AK) in the 0 to 20 cm (upper) soil layer were significantly increased by SM but were unaffected by SI treatments. After wheat harvest, N application increased SOC, LOC, and TN in the upper soil layer by an average of 4.81, 20.70, and 7.61%, respectively, and decreased AK by 6.12%. The cultivation practice and N fertilizer effects on soil properties were more pronounced in upper than deeper layer (20-40 cm). At soil depths of 0 to 100 cm, nitrate accumulation under N 240 exceeded 69.27% of the critical environmental risk value. Thus, SI+N 120 achieved a high and stable wheat yield, and SM+N 120 increased soil fertility. However, the two combinations applied over 9 yr did not meet both high soil fertility and high productivity needs. Additionally, cultivation practices with high N fertilizer are not sustainable soil management techniques in dryland regions.
  • Authors:
    • Wang, B.
    • Qin, X.
    • Wan, Y.
    • Li, Y.
    • Duan, Z.
  • Source: Transactions of the Chinese Society of Agricultural Engineering
  • Volume: 30
  • Issue: 24
  • Year: 2014
  • Summary: Maize production inevitably generates greenhouse gas (GHG) emissions which contribute to global warming. The greenhouse gas intensity (GHGI) of maize production was controlled by various management techniques. Fuel, fertilizer production, herbicide production, seed consumption, transportation, and on-farm energy consumption all result in GHG emissions. Life cycle assessment (LCA) methodology was adopted in this study to calculate GHG emissions under different fertilization treatments aiming at comprehensively evaluating the effects of different fertilization treatments on GHG emissions and selecting the options with both economic benefits and GHG mitigation. Four different fertilization treatments are: local traditional fertilization; urea treatment; sulfur coated urea; and urea added with dicyandiamide treatment. Static chamber and gas chromatography (GC) systems were used to continuously monitor N2O emissions from maize cropland. N2O emissions under different fertilization treatments were calculated. Data on the amount and type of fertilizer applied, energy consumption for the tillage, herbicide consumption, irrigation area and Diesel consumption, for tillage, electricity consumption for irrigation, and seed consumption were collected. Total GHG emissions from fertilizer production, energy consumption, seed production were estimated. GHG emission intensity based on grain yield and economic benefit were also calculated. The result showed that N2O emissions from fertilization, total GHG emission of the whole life cycle, emission intensities based on yield and output were all ranked as local traditional fertilization>urea treatment>urea added with dicyandiamide treatment>sulfur coated urea treatment. N2O emissions from the local traditional fertilization treatment was very significantly higher than that from the other three treatments (P0.05). Total GHG emissions from the treatments of local traditional fertilization, urea, sulfur coated urea, and urea added with dicyandiamide were 4.11, 2.71, 2.56, and 2.61 t/(hm2·a) respectively. Emission per unit of yield for the treatments of local traditional fertilization, urea, sulfur coated urea, and urea added with dicyandiamide were 364.1, 238.3, 216.6, and 223.4 kg/t maize, respectively. Emission per 10 000 yuan for the treatments of local traditional fertilization, urea, sulfur coated urea, and urea added with dicyandiamide were 2.19, 1.32, 1.15, and 1.18 t /10 000 yuan respectively. Compared with a traditional fertilization treatment, sulfur coated urea could reduce total GHG emissions, GHG emission per unit of yield and per 10 000 yuan net output by 37.8%, 40.5%, and 47.3% respectively, while the urea added with dicyandiamide treatment could reduce total GHG emissions, GHG emission per unit of yield, and per 10 000 yuan by 36.5%, 38.6%, and 45.9% respectively. Production of fertilizers, especially nitrogen fertilizer, makes the greatest contribution to total GHG emissions for maize cultivation, accounting for 42.4%-55.0% of the total GHG emissions from the four treatments, followed by fertilizer application, accounting for 20.8%-26.1% of the total GHG emissions from the four treatments. In order to ensure grain output and economic benefits, two fertilization treatments, sulfur coated urea treatment and urea added with dicyandiamide treatment, resulted in relatively low total emissions and emission intensity. They can be recommended as options to mitigate GHG emissions from maize production.
  • 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:
    • Escobar,N.
    • Ribal,F. J.
    • Clemente,G.
    • Sanjuan,N.
  • Source: Proceedings of the 9th International Conference on Life Cycle Assessment in the Agri-Food Sector
  • Year: 2014
  • Summary: Imported biodiesel has accounted for a large share of the total amount consumed in Spain, the main supplier of which was Argentina at least until anti-dumping duties on biodiesel imports from this origin were approved by the European Commission in November 2013. A consequential LCA is carried out in the present study to compare this pathway, which was the prevailing one until almost 2014, with the alternative of using domestic biodiesel from Used Cooking Oil (UCO). System expansion is performed in order to take the indirect functions of both systems into account, functions arising from interactions between co-products (protein meals) in the animal feed market. The marginal suppliers of these co-products in the international market are identified and emissions from direct and indirect Land Use Change (LUC) are calculated. When they are not considered, imported soybean biodiesel leads to lower GHG emissions, due to the carbon uptake by biomass. However, when global LUC is taken into account, UCO biodiesel generates a much lower impact, because it causes a contraction in the area diverted to biofuel feedstock production in other parts of the world. The results underline the importance of considering emissions from LUC when comparing biodiesel alternatives and, thus, interactions in the global market must be addressed.
  • Authors:
    • Peter,C.
    • Fiore,A.
    • Nendel,C.
    • Xiloyannis,C.
  • Year: 2014
  • Summary: In this paper, we discuss different methods to calculate greenhouse gas field emissions from fertilization and soil carbon changes to be integrated into Carbon Footprint (CFP) of food and biomass products. At regional level, the simple Tier 1 approach proposed in the IPCC (2006a) AFOLU guidelines is often insufficient to account for emission variability which depends on soil type, climate or crop management. However, the extensive data collection required by Tier 2 and 3 approaches is usually considered too complex and time consuming to be practicable in Life Cycle Assessment. We present four case studies to compare Tier 1 with medium-effort Tier 2 and 3 methodologies. Relevant differences were found: for annual crops, a higher Tier approach seems more appropriate to calculate fertilizer-induced field emissions, while for perennial crops the impact on CFP was negligible. To calculate emissions related to soil carbon change higher Tiers are always more appropriate.
  • Authors:
    • Halvorson, A. D.
    • Jantalia, C. P.
    • Follett, R. F.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 77
  • Issue: 3
  • Year: 2013
  • Summary: Conventional tillage (CT) with high N rates and irrigation is used more frequently than no-till (NT) for growing continuous corn (Zea mays L.) in the central Great Plains of the United States. The objective of this study was to evaluate soil organic C (SOC) stocks throughout the soil profile as well as the potential for maintaining or sequestering SOC within the soil profile (0- 120 cm) under irrigated, continuous corn as affected by NT and CT and three N rates. Isotopic δ13C techniques provided information about the fate of C added to soil by corn (C4-C) and of residual C3-C from cool-season plants grown before this study. Relative contributions of C4-C and C3-C to SOC stocks after 8 yr were determined. Retention of C4-C from corn was measured under NT and CT. Nitrogen fertilization slowed losses of C3-C and improved retention of C 4-C. No-till was superior to CT in maintaining SOC. Deep soil sampling to 120 cm and the use of stable C isotope techniques allowed evaluation of changes in SOC stocks during the 8-yr period. Change in SOC under NT vs. CT resulted from greater loss of C3-C stocks under CT throughout the soil profile. Irrigated corn has a low potential to sequester SOC in the central Great Plains, especially under CT. The results of this study indicate that stability of the soil organic matter and its perceived "recalcitrance" is altered by environmental and biological controls. © Soil Science Society of America.
  • Authors:
    • Evans, R. G.
    • Stevens, W. B.
    • Sainju, U. M.
    • Iversen, W. M.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 77
  • Issue: 4
  • Year: 2013
  • Summary: Irrigation and tillage systems may affect surface residue and soil C and N fractions by influencing crop biomass yield, residue placement, and movement of water soluble C and N in the soil. We studied the effects of irrigation (mid-elevation spray application [MESA] and low energy precision application [LEPA ]) and tillage (conventional [CT] and strip-tillage [ST]) systems on crop biomass (stems and leaves) yield, surface residue, and soil C and N fractions at the 0- to 20-cm depth from 2004 to 2007 in a Savage clay loam (fine, smectitic, frigid Vertic Argiustolls) in Sidney, MT. Soil C and N fractions were soil organic carbon (SOC) and total nitrogen (STN), particulate organic carbon and nitrogen (POC and PON), microbial biomass carbon and nitrogen (MBC and MBN), potential carbon and nitrogen mineralization (PCM and PNM), NH4-N, and NO3-N. While crop biomass across treatments increased from 2004 to 2007, surface residue was greater with ST than with CT from 2005 to 2007. The NH4-N and NO3-N contents at 5 to 10 and 10 to 20 cm in 2005 and STN at 0 to 5 cm in 2007 were greater with ST than with CT, but SOC at 5 to 10 and 10 to 20 cm, POC and MBN at 5 to 10 cm, and PNM at 0 to 5 cm in 2007 were greater with CT than with ST. The MBC at 0 to 5 cm and MBN at 10 to 20 cm were greater in LEPA than in MESA. The PCM at 10 to 20 cm was greater with CT than with ST in LEPA . While ST increased surface soil residue and N storage, residue incorporation to a greater depth in CT increased soil C storage, microbial activity, and N mineralization. Slow rate of water application near the soil surface increased microbial biomass in LEPA.
  • Authors:
    • Garnier, J.
    • Sanz-Cobena, A.
    • Lassaletta, L.
    • Aguilera, E.
    • Vallejo, A.
  • Source: Agriculture Ecosystems and Enviroment
  • Volume: 164
  • Year: 2013
  • Summary: Environmental problems related to the use of synthetic fertilizers and to organic waste management have led to increased interest in the use of organic materials as an alternative source of nutrients for crops, but this is also associated with N 2O emissions. There has been an increasing amount of research into the effects of using different types of fertilization on N 2O emissions under Mediterranean climatic conditions, but the findings have sometimes been rather contradictory. Available information also suggests that water management could exert a high influence on N 2O emissions. In this context, we have reviewed the current scientific knowledge, including an analysis of the effect of fertilizer type and water management on direct N 2O emissions. A meta-analysis of compliant reviewed experiments revealed significantly lower N 2O emissions for organic as opposed to synthetic fertilizers (23% reduction). When organic materials were segregated in solid and liquid, only solid organic fertilizer emissions were significantly lower than those of synthetic fertilizers (28% reduction in cumulative emissions). The EF is similar to the IPCC factor in conventionally irrigated systems (0.98% N 2O-N N applied -1), but one order of magnitude lower in rainfed systems (0.08%). Drip irrigation produces intermediate emission levels (0.66%). Differences are driven by Mediterranean agro-climatic characteristics, which include low soil organic matter (SOM) content and a distinctive rainfall and temperature pattern. Interactions between environmental and management factors and the microbial processes involved in N 2O emissions are discussed in detail. Indirect emissions have not been fully accounted for, but when organic fertilizers are applied at similar N rates to synthetic fertilizers, they generally make smaller contributions to the leached NO 3- pool. The most promising practices for reducing N 2O through organic fertilization include: (i) minimizing water applications; (ii) minimizing bare soil; (iii) improving waste management; and (iv) tightening N cycling through N immobilization. The mitigation potential may be limited by: (i) residual effect; (ii) the long-term effects of fertilizers on SOM; (iii) lower yield-scaled performance; and (iv) total N availability from organic sources. Knowledge gaps identified in the review included: (i) insufficient sampling periods; (ii) high background emissions; (iii) the need to provide N 2O EF and yield-scaled EF; (iv) the need for more research on specific cropping systems; and (v) the need for full GHG balances. In conclusion, the available information suggests a potential of organic fertilizers and water-saving practices to mitigate N 2O emissions under Mediterranean climatic conditions, although further research is needed before it can be regarded as fully proven, understood and developed.