• Authors:
    • Burgener, P. A.
    • Felter, D. G.
    • Nielsen, D. C.
    • Lyon, D. J.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 2
  • Year: 2007
  • Summary: Winter wheat (Triticum aestivum L.) is the foundation of dryland cropping systems in the Central Great Plains. The objective of this study was to quantify the effects of four short-season spring-planted crops used to replace summer fallow on the subsequent winter wheat crop. Wheat was seeded into four crop stubbles [spring triticale (xTriticosecale Wittmack), dry pea (Pisum sativum L.), foxtail millet (Setaria italica L. Beauv.), and proso millet (Panicum miliaceum L.)] at sites near Akron, CO, and Sidney, NE, in the fall of 2004 and 2005. These summer fallow replacement crops were planted into silt loam soils at three different soil water levels at planting (low, medium, and high). Winter wheat water use was 3.6 cm greater, and grain yield was 662 kg ha-1 greater in the high water treatment compared with the low water treatment averaged across all sites and years. Winter wheat used an average of 4.3 cm more water following early planted summer crops (triticale and dry pea) than after late planted summer crops (foxtail and proso millet), but this increased water use did not consistently translate into increased grain yield as a result of terminal drought at Sidney in 2006. The high water treatment always had a positive net return. The high cost of pea seed ($3.30 kg-1, USD) strongly reduced profitability. The flexible summer fallow cropping system appears to be most applicable when using short-duration summer annual forage crops such as triticale and foxtail millet.
  • Authors:
    • Harben, R.
    • Beyer, J.
    • Dusault, A.
    • Fry, R.
    • Shrestha, A.
    • Klonsky, K. M.
    • Mitchell, J. P.
  • Source: Australian Journal of Experimental Agriculture
  • Volume: 47
  • Issue: 12
  • Year: 2007
  • Summary: While there have been several similarities between the development of cropping systems in Australia and California ( including climate, the need for irrigation and very diverse, highly specialised crop rotations), the historical patterns of conservation tillage development in the two regions have been quite different. Current estimates indicate that conservation tillage ( CT) practices are used on less than 2% of annual crop acreage in California's Central Valley. Tillage management systems have changed relatively little since irrigation and cropping intensification began throughout this region, more than 60 years ago. The University of California ( UC) and United States Department of Agriculture ( USDA) Natural Resource Conservation Service ( NRCS) CT Workgroup is a diverse group of UC, NRCS, farmer, private sector, environmental group and other public agency people. It has provided wide- ranging services aimed at developing information on reduced tillage alternatives for California's production valleys. In a short span of 7 years, the CT Workgroup has grown to over 1000 members and has conducted over 60 demonstration evaluations of CT systems. While CT is still quite new in California, a growing number of farmers has become increasingly interested in it, for both economic and environmental reasons. They are now pursuing a wide range of activities and approaches aimed at developing sustainable CT systems. As successful CT systems continue to be demonstrated, the rate of adoption is expected to increase.
  • Authors:
    • Paustian, K.
    • Capalbo, S.
    • Antle, J.
    • Gerow, K.
    • Mooney, S.
  • Source: Climatic Change
  • Volume: 80
  • Issue: 1-2
  • Year: 2007
  • Summary: Several studies have suggested that geostatistical techniques could be employed to reduce overall transactions costs associated with contracting for soil C credits by increasing the efficacy of sampling protocols used to measure C-credits. In this paper, we show how information about the range of spatial autocorrelation can be used in a measurement scheme to reduce the size of the confidence intervals that bound estimates of the mean number of C-credits generated per hectare. A tighter confidence interval around the mean number of C-credits sequestered could increase producer payments for each hectare enrolled in a contract to supply C-credits. An empirical application to dry land cropping systems in three regions of Montana shows that information about the spatial autocorrelation exhibited by soil C could be extremely valuable for reducing transactions costs associated with contracts for C-credits but the benefits are not uniform across all regions or cropping systems. Accounting for spatial autocorrelation greatly reduced the standard errors and narrowed the confidence intervals associated with sample estimates of the mean number of C-credits produced per hectare. For the payment mechanism considered in this paper, tighter confidence intervals around the mean number of C-credits created per hectare enrolled could increase producer payments by more than 100 percent under a C-contract.
  • Authors:
    • Essah, S. Y. C.
    • Sparks, R. T.
    • Dillon, M. A.
    • Delgado, J. A.
  • Source: Journal of Soil and Water Conservation
  • Volume: 62
  • Issue: 5
  • Year: 2007
  • Summary: This literature review examines a decade of advances in cover crops including how cover crops with limited irrigation can increase yields, crop quality, and nutrient and water use efficiencies while protecting the environment.
  • Authors:
    • Verge, X. P.
    • Worth, D. E.
    • Campbell, C. A.
    • Desjardins, R. L.
    • Smith, W. N.
    • Grant, B. B.
    • Hutchinson, J. J.
  • Source: Canadian Journal of Soil Science
  • Volume: 87
  • Issue: 2
  • Year: 2007
  • Summary: Using a revised Intergovernmental Panel on Climate Change (IPCC) methodology and the process-based model DeNitrification and DeComposition (DNDC), we estimated N2O emissions from agroecosysterns in Canada for each census year from 1981 to 2001. Based on the IPCC methodology, direct emissions of N2O ranged from 12.9 to 17.3 with an average of 15.1 Tg CO2 equivalents, while the DNDC model predicted values from 16.0 to 24.3 with an average of 20.8 Tg CO2 equivalents over the same period, and showed a large interannual variation reflecting weather variability. On a provincial basis, emissions estimated by IPCC and DNDC methods were highest in Alberta, Saskatchewan and Ontario, intermediate for Manitoba and Quebec and lowest in British Columbia and the Atlantic provinces. The greatest source of emissions estimated by the IPCC method was from N fertilizer (avg. 6.32 Tg CO2 equiv. in Canada), followed by crop residues (4.24), pasture range and paddocks (PRP) (2.77), and manure (1.65). All sources of emissions, but especially those from fertilizers, increased moderately over time. Monte Carlo Simulation was used to determine the uncertainty associated with the 2001 emission estimates for both IPCC and DNDC methodologies. The simulation generated most likely values of 19.2 and 16.0 Tg CO2 equivalents for IPCC and DNDC, respectively, with uncertainties of 37 and 41%, respectively. Values for the IPCC estimates varied between 28% for PRP and manure and 50% for N fertilizer and crop residues. At the provincial level, uncertainty ranged between 15 and 47% with higher values on the prairies. Sensitivity analyses for IPCC estimates showed crop residues as the most important source of uncertainty followed by synthetic N-fertilizers. Our analysis demonstrated that N2O emissions can be effectively estimated by both the DNDC and IPCC methods and that their uncertainties can be effectively estimated by Monte Carlo Simulation.
  • Authors:
    • Chicago Climate Exchange
  • Year: 2007
  • Summary: Chicago Climate Exchange (CCX) is the world's first and North America's only active voluntary, legally binding integrated trading system to reduce emissions of all six greenhouse gases (GHGs), with Offset Projects worldwide. CCX employs independent verification and has been trading GHG emission reductions since 2003. CCX Members that cannot reduce their own emissions can purchase credits from those who make extra emission cuts or from verified Offset Projects. CCX issues tradable Carbon Financial Instrument (CFI) contracts to owners or aggregators of eligible projects on the basis of sequestration, destruction or displacement of GHG emissions. Eligible projects include: agricultural methane, landfill methane, coal mine methane, agricultural and rangeland soil carbon, forestry and renewable energy.
  • Authors:
    • Ali, M. K.
    • Paustian, K.
    • Capalbo, S. M.
    • Antle, J. M.
  • Source: Climatic Change
  • Volume: 80
  • Issue: 1-2
  • Year: 2007
  • Summary: The purpose of this paper is to develop and apply a new method to assess economic potential for agricultural greenhouse gas mitigation. This method uses secondary economic data and conventional econometric production models, combined with estimates of soil carbon stocks derived from biophysical simulation models such as Century, to construct economic simulation models that estimate economic potential for carbon sequestration. Using this method, simulations for the central United States show that reduction in fallow and conservation tillage adoption in the wheat-pasture system could generate up to about 1.7 million MgC/yr, whereas increased adoption of conservation tillage in the corn-soy-feed system could generate up to about 6.2 million MgC/yr at a price of $200/MgC. About half of this potential could be achieved at relatively low carbon prices (in the range of $50 per ton). The model used in this analysis produced estimates of economic potential for soil carbon sequestration potential similar to results produced by much more data-intensive, field-scale models, suggesting that this simpler, aggregate modeling approach can produce credible estimates of soil carbon sequestration potential. Carbon rates were found to vary substantially over the region. Using average carbon rates for the region, the model produced carbon sequestration estimates within about 10% of those based on county-specific carbon rates, suggesting that effects of spatial heterogeneity in carbon rates may average out over a large region such as the central United States. However, the average carbon rates produced large prediction errors for individual counties, showing that estimates of carbon rates do need to be matched to the spatial scale of analysis. Transaction costs were found to have a potentially important impact on soil carbon supply at low carbon prices, particularly when carbon rates are low, but this effect diminishes as carbon prices increase.
  • Authors:
    • Valizadeh, M.
    • Ghassemi-Golezani, K.
    • Abdulrahmani, B.
    • Asl, V.
  • Source: Journal of Food Agriculture & Environment
  • Volume: 5
  • Issue: 3/4
  • Year: 2007
  • Summary: This research was designed to compare the effects of hydropriming, osmopriming (10% PEG, 20% PEG, 2.5 mM CaCl 2 and 5 mM CaCl 2) and nutrient priming (in ZnSO 4 solutions with 10, 50 and 100 mM Zn, in KH 2PO 4 with 10, 50 and 100 mM P together with their combinations) on seedling vigor of barley. Laboratory tests were conducted as CR design and field experiment was carried out as RCB design at Dryland Agricultural Research Institute (DARI) in Iran. Analysis of variance of laboratory data showed that all traits such as percentages of viable seeds and germination, electrical conductivity (EC) of seed leachates, germination rate, root and shoot dry weight and seedling dry weight were significantly affected by seed priming. Nutrient priming in P solutions was superior, compared to other priming technics. This priming media improved root and shoot dry weight by 25 and 12.5% over unprimed seeds, respectively. The superior treatments in laboratory including hydropriming, 10% PEG, 5 mM CaCl 2, 10 mM Zn, 50 mM P, 100 mM P, 10 mM Zn+50 mM P and 10 mM Zn+100 mM P solutions were applied on seeds which subsequently sown in the field. Priming treatments had significant (p≤0.05) effects on mean seedling emergence percentage and rate in the field. Maximum seedling emergence percentage and rate were achieved with 100 mM P and 10 mM Zn+100 mM P primings, respectively. Therefore, these priming techniques could be used to improve seedling establishment of barley in the field.
  • Authors:
    • Paustian, K.
    • Capalbo, S.
    • Antle, J.
    • Gerow, K.
    • Mooney, S.
  • Source: Climatic Change
  • Volume: 80
  • Issue: 1/2
  • Year: 2007
  • Summary: Several studies have suggested that geostatistical techniques could be employed to reduce overall transactions costs associated with contracting for soil C credits by increasing the efficacy of sampling protocols used to measure C-credits. In this paper, we show how information about the range of spatial autocorrelation can be used in a measurement scheme to reduce the size of the confidence intervals that bound estimates of the mean number of C-credits generated per hectare. A tighter confidence interval around the mean number of C-credits sequestered could increase producer payments for each hectare enrolled in a contract to supply C-credits. An empirical application to dry land cropping systems in three regions of Montana shows that information about the spatial autocorrelation exhibited by soil C could be extremely valuable for reducing transactions costs associated with contracts for C-credits but the benefits are not uniform across all regions or cropping systems. Accounting for spatial autocorrelation greatly reduced the standard errors and narrowed the confidence intervals associated with sample estimates of the mean number of C-credits produced per hectare. For the payment mechanism considered in this paper, tighter confidence intervals around the mean number of C-credits created per hectare enrolled could increase producer payments by more than 100 percent under a C-contract.
  • Authors:
    • Gracia, R.
    • Lopez, M.
    • Arrue, J.
    • Moret, D.
  • Source: European Journal of Agronomy
  • Volume: 26
  • Issue: 1
  • Year: 2007
  • Summary: Winter barley is the major crop on semiarid drylands in central Aragon (NE Spain). In this study we compared, under both continuous cropping (BC) (5-6-month fallow) and a crop-fallow rotation (BF) (16-18-month fallow), the effects of three fallow management treatments (conventional tillage, CT; reduced tillage, RT; no-tillage, NT) on the growth, yield and water use efficiency (WUE) of winter barley during three consecutive growing seasons in the 1999-2002 period. Daily precipitation measurements and monthly measurements of soil water storage to a depth of 0.7 m were used to calculate crop water use (ET) and its components. The average growing season precipitation was 195 mm. Above-ground dry matter (DM) and corresponding WUE were high in years with high effective rainfalls (>10 mm day -1) either in autumn or spring. However, the highest values of WUE for grain yield were mainly produced by effective rainfalls during the time from stem elongation to harvest. Despite the similarity in ET for the three tillage treatments, NT provided the lowest DM production, corresponding to a higher soil water loss by evaporation and lower crop transpiration ( T), indicated by the lowest T/ET ratio values found under this treatment. No clear differences in crop yield were observed among the tillage treatments in the study period. On average, and regardless of the type of tillage, BF provided the highest values of DM and WUE and yielded 49% more grain than BC. These differences between cropping systems increased when water-limiting conditions occurred in the early stages of crop growth, probably due to the additional soil water storage under BF at sowing. Although no significant differences in precipitation use efficiency (PUE) were observed between BC and BF, PUE was higher under the BC system, which yielded 34% more grain than the BF rotation when yields were adjusted to an annual basis including the length of the fallow. The crop yield under BF was not dependent on the increase in soil water storage at the end of the long fallow. In conclusion, this study has shown that, although conventional tillage can be substituted by reduced or no-tillage systems for fallow management in semiarid dryland cereal production areas in central Aragon, the practice of long-fallowing to increase the cereal crop yields is not longer sustainable.