• Authors:
    • Qu, A.
    • Rhinhart, K.
    • Petrie, S.
    • Machado, S.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 2
  • Year: 2007
  • Summary: Conventional tillage winter wheat (Triticum aestivum) (WW)-summer fallow reduces soil productivity and increases soil erosion. Conservation tillage management, together with intensive cropping may have the potential to reverse these sustainability concerns. The objective of this study was to determine the effects of conventional tillage (CT) and no-tillage (NT) systems on grain yield of long-term annual cropping of monoculture WW, spring wheat (SW), and spring barley (Hordeum vulgare) (SB) grown with or without fertilizer, in the Pacific Northwest region of the USA. In unfertilized crops, grain yield of WW, SW, and SB was 15%, 25%, and 50% higher, respectively, in CT than in NT plots, an indication of the involvement of yield limiting factors under the NT cropping system. When fertilized, there were no significant differences in grain yield of WW. Yields of SW and SB, however, remained 21% and 15% higher, respectively, in CT than in NT, an indication that factors other than fertility were involved. These results suggest that in order for NT management to be widely adopted by area growers, the yield-limiting factors need to be addressed.
  • Authors:
    • Herencia, J. F.
    • Ruiz, J. C.
    • Madejón, E.
    • Melero, S.
  • Source: European Journal of Agronomy
  • Volume: 26
  • Issue: 3
  • Year: 2007
  • Summary: Understanding of microbial processes in soil is important for the management of farming systems, particularly those that imply organic inputs of nutrients. In this work the effect of consecutive addition of two mature composts (vegetal and animal compost) at rates of 30 tm ha-1 over a 4-year period under a dryland system on the chemical and biochemical properties of a clay soil (Chromic Haploxeret) was investigated and compared to that of an inorganic fertilization. Soil chemical and biological status was evaluated by measuring the total organic carbon (TOC), humic acids, Kjeldahl-N, bicarbonate-extractable P (Olsen-P), ammonium acetate extractable-K (AAE-K), microbial biomass carbon (Cmic), enzymatic activities (dehydrogenase, protease, glucosidase, alkaline phosphatase) and Cmic/TOC ratio. At the end of the study, soils fertilised with composts showed increases in quantity (TOC) and quality (humic acids) of organic matter compared to inorganically fertilised soil. The nutrient content (Olsen-P and Kjeldahl-N) also showed an increase in the plots fertilised with composts. From the fourth crop cycle the plots fertilised with compost showed more clearly the increase in microbial biomass and enzymatic activities, which can have been related both with leguminous pre-crop and with the organic fertilization. In general, under a dryland system, an improvement of soil fertility was achieved in organically fertilised soils, confirming the positive effect of organic fertilization.
  • 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:
    • Gamroth, M.
    • Hart, J.
    • Sullivan, D.
    • Downing, T.
  • Source: Nutrient Management for Dairy Production
  • Year: 2007
  • 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:
    • Hedley, M. J.
    • Bolan, N. S.
    • Saggar, S.
    • Bhandral, R.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 2
  • Year: 2007
  • Summary: Animal trampling is one of the main factors responsible for soil compaction under grazed pastures. Soil compaction is known to change the physical properties of the soil thereby affecting the transformation of nitrogen (N) and the subsequent of release of N as nitrous oxide (N2O). The form of N source added to these compacted soils further affects N emissions. Here we determine the interactive effects of soil compaction and form of N sources (cattle urine and ammonium, nitrate and urea fertilizers) on the loss of N through N2O emission from grassland soil. Overall, soil compaction caused a seven-fold increase in the N2O flux, the total N2O fluxes for the entire experimental period ranged from 2.62 to 61.74 kg N2O-N ha-1 for the compacted soil and 1.12 to 4.37 kg N2O-N ha-1 for the uncompacted soil. Among the N sources, the highest emissions were measured with nitrate application, emissions being 10 times more than those from other N sources for compacted soil, suggesting that the choice of N fertilizer can go a long way in mitigating N2O emissions in compacted grasslands.
  • Authors:
    • Surek, D.
    • Karacam, M.
    • Meyvec, K.
    • Akar, T.
    • Avc, M.
  • Source: Wheat production in stressed environments. Proceedings of the 7th International Wheat Conference, Mar del Plata, Argentina, 27 November - 2 December, 2005
  • Year: 2007
  • Summary: Because most of the dryland cereal varieties were improved under fallow/cereal rotation system, their performances in other cropping systems were questionable and reported unsatisfactory by some farmers. Therefore, the objective of this study was to investigate the performances and adaptation of newly registered varieties in different two course rotations for targeted recommendations. 12 cereal varieties were tried on 9 different 23-year-crop rotations plots for three consecutive years, 1999/2000, 2000/2001, 2001/2002. The varieties were 4 barley (malting two rowed Aydanhanm, and feeding Tarm and six rowed Cetin and Avci), 4 durum wheat (Altn, Ankara, Altntas, and Ylmaz), and 4 bread (Dagdas, Gun, Krgz and Mzrak) wheat. The cereal varieties were rotated with fallow, wheat, winter vetch, winter lentil, sunflower, safflower, lentil, chickpea and barley/vetch mixture. Grain and biomass yields, plant height, harvest index, kernel per spike, kernel weight and spike number per square meter were traits determined. Biplot analysis showed that responses of cereal varieties varied in dry (2001), wet and cold (2000) and normal (2003) seasons. Overall evaluations of responses indicated that some varieties adapted more to certain rotations than other varieties such as Aydanhanm for Safflower/cereal rotation. There was a general tendency that Tarm and Gun varieties performed well in winter cold and dry seasons in all rotations. Dagdas yielded pretty well following winter legumes and winter legume/cereal mixture except dry season. Six rowed barleys, Altntas and Ylmaz, were better in mild winter season in all rotations. Traits correlations indicated that spike number per square meter was always positively correlated with grain yields for all experimental seasons. While all yield components had positive contribution to the grain yields in wet season, kernel weight and kernel per spike had negative contribution to grain yields in the dry season. General evaluation showed that cereals succeeding chickpea and spring lentil crops were leading in terms of height, biomass, harvest index and grain yields, except cereals following fallow which were exceptionally superior in dry season. They also had higher kernel weight in dry and normal seasons.
  • Authors:
    • Paulitz, T. C.
  • Source: European Journal of Plant Pathology
  • Volume: 115
  • Issue: 3
  • Year: 2006
  • Summary: Direct-seeding or no-till is defined as planting directly into residue of the previous crop without tillage that mixes or stirs soil prior to planting. No-till reduces soil erosion, improves soil structure and organic matter, and reduces fuel inputs. No-till is widely used in cereal production in Australia, Canada, Argentina, and Brazil, but has not been widely adopted in Europe and the Pacific Northwest of the U.S. One of the limitations is that root diseases may increase with a reduction in tillage. This paper discusses the importance and management of take-all, Fusarium dryland foot rot, Rhizoctonia bare patch and root rot, and Pythium root rot in dryland cereal production systems, and how they are influenced by changes in tillage practices. To address this challenge, specifically with Rhizoctonia and Pythium, our research group has (1) developed classical and molecular techniques to detect and quantify Rhizoctonia and Pythium spp. from the soil to assess disease risk; (2) studied the disease dynamics of root disease during the transition from conventional to no-till; (3) developed greenhouse methods to screen germplasm for tolerance or resistance to Pythium and Rhizoctonia, and (4) using GPS and geostatistics, has examined the spatial distribution of R. solani and R. oryzae at a field scale up to 36 ha, across a number of crop rotations and years. By a combination of ecological, epidemiological, field, and laboratory studies, we hope to provide growers with a set of disease management tools to permit the economical and sustainable production of dryland cereals without degradation of the soil resource.
  • Authors:
    • Pitts, T.
    • Atwood, J. D.
    • Williams, J. R.
    • Potter, S. R.
    • Wang, X.
  • Source: Transactions of the ASABE
  • Volume: 49
  • Issue: 3
  • Year: 2006
  • Summary: Sensitivity analysis for mathematical simulation models is helpful in identifying influential parameters for model outputs. Representative sets of APEX (Agricultural Policy/Environmental eXtender) model data from across the U.S. were used for sensitivity analysis to identify influential parameters for APEX outputs of crop grain yields, runoff/water yield, water and wind erosion, nutrient loss, and soil carbon change for a national assessment project: the Conservation Effects Assessment Project (CEAP). The analysis was based on global sensitivity analysis techniques. A test case, randomly selected from the representative sets of APEX model data, was first analyzed using both the variance-based sensitivity analysis technique and the enhanced Morris method. The analysis confirmed the reliability of the enhanced Morris measure in screening subsets of influential and non-influential parameters. Therefore, the enhanced Morris method was used for the national assessment, where the cost of applying variance-based techniques would be excessive. Although sensitivities are dynamic in both temporal and spatial dimensions, the very influential parameters (ranking 1st and 2nd) appear very influential in most cases. Statistical analyses identified that the NRCS curve number index coefficient is very influential for runoff and water-related output variables, such as soil loss by water, N and P losses in runoff. The Hargreaves PET equation exponent, moisture fraction required for seed germination, RUSLE C factor coefficient, and the potential heat units are influential for more than two APEX outputs studied.
  • Authors:
    • Grace, P. R.
    • Post, W. M.
    • Hennessy, K.
  • Source: Carbon Balance and Management
  • Volume: 1
  • Year: 2006