• Authors:
    • Swanton, C.
    • Vyn, T. J.
    • Hooker, D. C.
    • Weersink, A.
    • Yiridoe, E. K.
  • Source: Canadian Journal of Agricultural Economics
  • Volume: 48
  • Issue: 2
  • Year: 2000
  • Summary: Conservation tillage systems have not been widely adopted on clay soils. There are few empirical studies on the production potential and economic feasibility of conservation tillage systems for corn (Zea mays L.) and soybean (Glycine max L.) production on clay soils. On some soils in some regions, crop yields and possibly profitability can be increased and yield and net farm returns risks may be reduced through the use of conservation tillage systems. Stochastic dominance efficiency criteria are used to rank net return distributions for one conventional tillage (CT) and seven conservation tillage (including five reduced tillage and two no-till) systems conducted for corn and soybean cropping systems on two clay soils located in the 3050 to 3100 Corn Heat Unit areas of Ontario. Average yields are similar under conventional tillage and reduced tillage systems, although actual corn and soybean yield response to tillage treatment is affected by drought (year). Average net returns differ among tillage treatments due to two factors. First, actual corn and soybean yields vary among tillage systems for each soil type, depending on weather (i.e., year) effects. In addition, machinery costs that are crop-specific increase costs of production and therefore reduce net returns In general, CT systems dominate both reduced tillage and no-till systems for almost all risk intervals for both clay soils, except for slightly high-risk-preferring intervals.
  • Authors:
    • Hulugalle, N. R.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 31
  • Issue: 5-6
  • Year: 2000
  • Authors:
    • Subak, S.
  • Source: Global Environmental Change
  • Volume: 10
  • Issue: 3
  • Year: 2000
  • Summary: The Kyoto Protocol introduces the possibility that changes in carbon stock on agricultural and forest land and soils may be counted against countries' commitments to reduce their greenhouse gas emissions. Including activities related to land use change and forestry in the international climate change agreement may stimulate new incentives for soil-conservation practices domestically. However, a primary criteria for their inclusion relates to the level of accuracy and transparency with which carbon stock changes can be assessed. Parties will also be concerned with the wider environmental impact of different sequestration practices, and the impact of offsets on overall emissions targets. This paper examines these issues for agricultural soils, considering recent research in North America. It is argued that incentives for carbon sequestration practices may need to be implemented independently of actual stock changes because farm-level soil monitoring would be very costly. In the USA, priority should be given to establishing incentives for cover crops and to expanding conservation tillage programs. These activities provide a range of ancillary environmental benefits. In contrast, improvements in biomass yield tend to rely on higher fertilizer inputs with their related environmental costs. Carbon accumulated through any of these activities is easily lost if the practices are discontinued, and so assessment procedures are needed that would avoid overestimating sequestration. Annual accumulation in agricultural soils could be equivalent to about 10% of Annex I carbon dioxide emissions, and therefore options for limiting sink credits from soils should be considered.
  • Authors:
    • Olsson, K. A.
    • Cockroft, B.
  • Source: Australian Journal of Soil Research
  • Volume: 38
  • Issue: 1
  • Year: 2000
  • Summary: A study on irrigated orchards in northern Victoria, Australia, on a fine sandy loam over clayey red-brown earth showed soil hardening within 2-3 months after the initial cultivation. This common yet distinct form of soil hardening is termed coalescence. Coalescence is the slow increase in soil hardness which develops during cycles of wetting and drying. The structure of a well-prepared bed of soil that is water-stable and not trafficked changes to one that is hard, although perforated with biopores. These pores facilitate the infiltration of water, drainage, and some growth of roots, but the hard matrix causes root growth and activity to be substantially reduced compared with roots in loose soil and this reduces the productivity of the crop. Coalescence is an important cause of poor responses in productivity to zero and minimum tillage systems of soil management. Isolated examples of soils in the field that remain soft, loose, and porous, after more than 2 years since cultivation were found. This suggests that it might be possible to prevent coalescence. These coalescence-stable soils, in common with virgin soils, have properties that enable them to resist coalescing. High organic matter (>4% w/w total C content) is closely related to zero coalescence.
  • Authors:
    • NRCS,USDA
  • Year: 1999
  • Summary: from intro: "Cultural farming practices have a major influence on the quality of wildlife habitat provided by croplands on the agricultural landscape. In considering tillage practice alternatives, measures that reduce the amount of soil erosion are generally considered to help protect and enhance aquatic resources. However, it also is important to consider how various tillage practices affect terrestrial wildlife such as birds, mammals, reptiles and amphibians, and beneficial insects found in cropland situations."
  • Authors:
    • Sanabria, J.
    • Atwood, J. D.
    • Uri, N. D.
  • Source: Science of The Total Environment
  • Volume: 216
  • Issue: 1-2
  • Year: 1998
  • Summary: Every production practice, including conservation tillage, has positive or negative environmental consequences that may involve air, land, water, and/or the health and ecological status of wildlife. The negative impacts associated with agricultural production, and the use of conventional tillage systems in particular, include soil erosion, energy use, leaching and runoff of agricultural chemicals, and carbon emissions. Several of these impacts are quantified. The conclusions suggest that the use of conservation tillage does result in less of an adverse impact on the environment from agricultural production than does conventional tillage by reducing surface water runoff and wind erosion. Additionally, wildlife habitat will be enhanced to some extent with the adoption of conservation tillage and the benefits to be gained from carbon sequestration will depend on the soil remaining undisturbed. Finally, further expansion of conservation tillage on highly erodible land will unquestionably result in an increase in social benefits, but the expected gains will be modest.
  • Authors:
    • Vitosh, M. L.
    • Pierce, F. J.
    • Christenson, D. R.
    • Peters, S. E.
    • Frye, W. W.
    • Blevins, R. L.
    • Dick, W. A.
  • Source: Soil & Tillage Research
  • Volume: 47
  • Issue: 3-4
  • Year: 1998
  • Summary: Soil organic matter has recently been implicated as an important sink for atmospheric carbon dioxide (CO2), However, the relative impacts of various agricultural management practices on soil organic matter dynamics and, therefore, C sequestration at spatial scales larger than a single plot or times longer than the typical three year experiment have rarely been reported. Results of maintaining agricultural management practices in the forest-derived soils of the eastern Corn (Zea mays L.) Belt states of Kentucky, Michigan, Ohio and Pennsylvania (USA) were studied. We found annual organic C input and tillage intensity were the most important factors in affecting C sequestration. The impact of rotation on C sequestration was primarily related to the way it altered annual total C inputs. The removal of above-ground plant biomass and use of cover crops were of lesser importance, The most rapid changes in soil organic matter content occurred during the first five years after a management practice was imposed with slower changes occurring thereafter. Certain management practices, e.g, no-tillage (NT), increased the soil's ability to sequester atmospheric CO2. The impact of this sequestration will be significant only when these practices are used extensively on a large percentage of cropland and when the C-building practices are maintained, Any soil C sequestered will be rapidly mineralized to CO2 if the soil organic matter building practices are not maintained,
  • Authors:
    • Mulla, J. D.
    • Burnside, O. C.
    • Wilkins, D. E.
    • Allmaras, R. R.
  • Source: Advances in Soil and Water Conservation
  • Year: 1998
  • Authors:
    • Mitchell, C. C.,Jr.
    • Reeves, D. W.
    • Hubbs, M. D.
  • Source: Proceedings 21st Annual Southern Conservation Tillage Conference for Sustainable Agriculture/Arkansas Agricultural Experiment Station Special Report 186
  • Issue: 186
  • Year: 1998
  • Summary: Investigations were conducted on a Typic Hapludult in USA, to assess the effects of a 3 year rotation (cotton-grain crops plus a winter legume cover crop), a 2 year rotation (cotton-grain crops-winter legume), and 3 continuous cropping systems on soil quality after 100 years. Soil quality was better in the 3 year rotation plus legume cover crop. This was attributed to higher soil C, cation exchange capacity, water retention and water stable aggregates, and reduced surface soil strength. Under continuous cotton, soil strength was increased down to 5 in depth. N fertilizer and/or legume cover crop within continuous cotton increased soil C over the past 100 years. Because of continuous tillage over the 100 years the rotation treatments had little effect on soil extractable nutrients. The semi-quantitative assessment of the USDA-Soil Quality Kit gave higher variability of parameters relative to standard procedures. The Kit should therefore be used only to evaluate trends and comparisons.
  • Authors:
    • Papendick, R.
    • Parr, J.
  • Source: Annals of Arid Zone
  • Volume: 36
  • Issue: 3
  • Year: 1997
  • Summary: Most dryland fanning systems depend an tillage to grow crops. There is overwhelming evidence that repeated tillage is destroying the soil resource base and causing adverse environmental impacts. Tillage degrades the fertility of soils, causes air and water pollution, intensifies drought stress, destroys wildlife habitat, wastes fuel energy, and contributes to global warming. Consequently, most tillage-based systems in a dryland environment are not sustainable in the long-term. Today, dryland farmers are expected to produce food in ever greater quantities. This is becoming more difficult to do in view of declining soil quality, most of which is caused by soil tillage. It is becoming well documented scientifically that continuous no-till is the most effective, and practical approach for restoring and improving soil quality which is vital for sustained food production and a healthy environment. With this way of farming crop, residues or other organic amendments are retained on the soil surface and sowing/fertilizing is done with minimal soil disturbance. Research and farmers' experience indicate that with continuous no-till soil organic matter increases, soil structure improves, soil erosion is controlled, and in time crop yields increase substantially from what they were under tillage management, due to improved water relations and nutrient availability. These changes help to promote a cleaner and healthier environment and a more sustainable agriculture. A major obstacle that farmers often face with change to continuous no-till is overcoming yield-limiting factors during the transition years, that is, the first years of no-till following a history of intensive conventional tillage. These factors are often poorly understood and may be biologically-driven. Some of the problems involve residue management and increased weed and disease infestations. Farmer experience seems to indicate that many problems during the transition are temporary and become less important as the no-till system matures and equilibrates. The judicious use of crop rotations, cover crops and same soil disturbance may help reduce agronomic risks during the transition years. Farmers switching to continuous no-till must often seek new knowledge and develop new skills and techniques in order to achieve success with this new and different way of farming. Answers to their questions are urgently needed to provide strategies far promoting no-till as a way to enhance agricultural sustainability for future generations.