- Authors:
- Volk, L. B. D.
- Cogo, N. P.
- Castro, L. G.
- Source: Revista Brasileira de Ciência do Solo
- Volume: 30
- Issue: 2
- Year: 2006
- Summary: Although being temporary, the presence of tillage-induced surface roughness in the soil is an important requirement in conservation tillage systems. The reason is that surface roughness increases both surface retention and surface infiltration of water in the soil, reduces runoff velocity and volume, and traps eroded sediments, thus reducing water erosion damages. With this in mind, this study was developed with the objective of evaluating modifications in soil surface roughness by tillage and rainfall actions related to water erosion, in the absence and presence of mulch cover. The experiment was carried out in the field, at the Agriculture Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), in Eldorado do Sul County, Rio Grande do Sul State, Brazil, in 1996 and 1997, using simulated rainfalls on a sand), clay loam Paleudult with 0.07 m m(-1) slope steepness. The tillage types evaluated in the study included plowing, plowing plus double-disking and no-till, all them in the absence and presence of 60% soil cover (oat residue), submitted to four simulated rainfall tests. The first test consisted of a rainfall segmented in four portions, lasting for 20, 20, 30, and 30 min, separated 30 to 40 min front each other, applied immediately after tillage. The remaining tests consisted of uninterrupted rains of 90-min duration, applied 1, 20, and 35 days after the first rain. These rainfalls were applied with the rotating-boom rainfall simulator at a constant intensity of 64.0 mm h(-1). Tillage caused greater changes in the soil surface roughness titan rainfall. Soil surface roughness was most reduced by rain action in the very first event in recently-tilled soil, in the pre-runoff period. Soil surface roughness impeded or delayed runoff ill treatments with soil Mobilization in the rainfall segments with short duration applied soon after tillage, impeding or reducing water and soil losses in that period, regardless of soil cover. In the continuous, subsequent long rains, surface roughness did not influence water loss in the studied treatments without cover, where it was high throughout the experimental period, but it did reduced water loss in the presence of cover. Water loss in no-till was high for such rains throughout the experiment. Under the same rain type, soil loss reduction as influenced by roughness was more evident in the absence of cover, whereas it was substantially obscured in its presence. Mulch of crop residue added to the soil surface did not preserve the initially high surface roughness created by tillage in the degraded soil used in the study. Nevertheless, by the end of the experiment more than half of the theoretical initial water and sediment retention capacity still remained in the microdepressions formed by roughness. The obtained data were consistent with theories and concepts used in soil erosion mechanics studies.
- Authors:
- Franzluebbers, A. J.
- Causarano, H. J.
- Reeves, D. W.
- Shaw, J. N.
- Source: Journal of Environmental Quality
- Volume: 35
- Issue: 4
- Year: 2006
- Summary: Past agricultural management practices have contributed to the loss of soil organic carbon (SOC) and emission of greenhouse gases (e.g., carbon dioxide and nitrous oxide). Fortunately, however, conservation-oriented agricultural management systems can be, and have been, developed to sequester SOC, improve soil quality, and increase crop productivity. Our objectives were to (i) review literature related to SOC sequestration in cotton (Gossypium hirsutum L.) production systems, (ii) recommend best management practices to sequester SOC, and (iii) outline the current political scenario and future probabilities for cotton producers to benefit from SOC sequestration. From a review of 20 studies in the region, SOC increased with no tillage compared with conventional tillage by 0.48 +/- 0.56 Mg C ha(-1) yr(-1) (H(0): no change,p
- Authors:
- Kenny, S. N.
- O'Brien, G. B.
- Ward, G. N.
- Jacobs, J. L.
- Chapman, D. F.
- Beca, D.
- McKenzie, F. R.
- Source: Proceedings of the New Zealand Grassland Association
- Volume: 68
- Year: 2006
- Summary: Continued improvements in home grown forage consumption are needed to support the long-term profitability of the dairy industry in southern Australia. Most home grown forage currently comes from perennial ryegrass pastures, which have significant limitations in the southern Australia environment. These limitations threaten future productivity gains, and we therefore consider opportunities for using other plant species. Data on the production of alternative perennial grasses, brassica summer crops, C4 summer crops and winter cereals grown for whole-crop silage are limited and generally show large variation in yields between sites and years. Simulation models suggest that, once the base ryegrass pasture is well-utilised, incorporating complementary forages can return $70-$100/ha extra operating profit for every additional tonne of home grown forage DM consumed per ha. Double cropping (winter cereal or annual ryegrass followed by a summer crop of turnips or maize) and summer-active pastures such as tall fescue show particular promise. Further information is required on how to integrate these forages into whole farm feeding systems to realise the additional profit with manageable business and environmental risk.
- Authors:
- Cavigelli, M. A.
- Szlavecz, K.
- Clark, S.
- Purrington, F.
- Source: Environmental Entomology
- Volume: 35
- Issue: 5
- Year: 2006
- Summary: Ground beetle assemblages were compared in organic, no-till, and chisel-till cropping systems of the USDA Farming Systems Project in Maryland. The cropping systems consisted of 3-yr rotations of corn ( Zea mays L.), soybean ( Glycine max L. Merr.), and wheat ( Triticum aestivum L.) that were planted to corn and soybean during the 2 yr of field sampling (2001-2002). Each year, ground beetles were sampled using pitfall traps during three 9- to 14-d periods corresponding to spring, summer, and fall. A total of 2,313 specimens, representing 31 species, were collected over the 2 yr of sampling. The eight most common species represented 87% of the total specimens collected and included Scarites quadriceps Chaudoir, Elaphropus anceps (LeConte), Bembidion rapidum (LeConte), Harpalus pensylvanicus (DeGeer), Poecilus chalcites (Say), Clivina impressefrons LeConte, Agonum punctiforme (Say), and Amara aenea (DeGeer). Canonical variates analysis based on the 10 most abundant species showed that the carabid assemblages in the three cropping systems were distinguishable from each other. The organic system was found to be more different from the no-till and chisel-till systems than these two systems were from each other. In 2002, ground beetle relative abundance, measured species richness, and species diversity were greater in the organic than in the chisel-till system. Similar trends were found in 2001, but no significant differences were found in these measurements. Relatively few differences were found between the no-till and chisel-till systems. The estimated species richness of ground beetles based on several common estimators did not show differences among the three cropping systems. The potential use of ground beetles as ecological indicators is discussed.
- Authors:
- Source: PNAS, Proceedings of the National Academy of Sciences
- Volume: 103
- Issue: 49
- Year: 2006
- Summary: The defining features of any cropping system are (i) the crop rotation and (ii) the kind or intensity of tillage. The trend worldwide starting in the late 20th century has been (i) to specialize competitively in the production of two, three, a single, or closely related crops such as different market classes of wheat and barley, and (ii) to use direct seeding, also known as no-till, to cut costs and save soil, time, and fuel. The availability of glyphosate- and insect-resistant varieties of soybeans, corn, cotton, and canola has helped greatly to address weed and insect pest pressures favored by direct seeding these crops. However, little has been done through genetics and breeding to address diseases caused by residue- and soil-inhabiting pathogens that remain major obstacles to wider adoption of these potentially more productive and sustainable systems. Instead, the gains have been due largely to innovations in management, including enhancement of root defence by antibiotic-producing rhizosphere-inhabiting bacteria inhibitory to root pathogens. Historically, new varieties have facilitated wider adoption of new management, and changes in management have facilitated wider adoption of new varieties. Although actual yields may be lower in direct-seed compared with conventional cropping systems, largely due to diseases, the yield potential is higher because of more available water and increases in soil organic matter. Achieving the full production potential of these more-sustainable cropping systems must now await the development of varieties adapted to or resistant to the hazards shown to account for the yield depressions associated with direct seeding.
- Authors:
- Barker-Reid, F.
- Gates, W. P.
- Eckard, R. J.
- Wilson, K.
- Baigent, R.
- Galbally, I. E.
- Meyer, C. P.
- Weeks, I. A.
- Source: 4th International Symposium on non-CO2 Greenhouse Gases
- Year: 2005
- Authors:
- R,Leuning
- IE,Galbally
- K,Kelly
- R,Edis
- Y,Li
- D,Turner
- D,Chen
- Source: 4th International Symposium on non-CO2 Greenhouse Gases
- Year: 2005
- Authors:
- Denmead, O.T.
- Bryant, G.
- Reilly, R.
- Griffith, D. W. T.
- White, I.
- Stainlay, W.
- Melville, M. D.
- Macdonald, B. C. T.
- Source: Proceedings of the Australian Society of Sugar Cane Technologists
- Volume: 27
- Year: 2005
- Authors:
- Kelly, K.
- Baigent, R.
- Eckard, R.
- Weeks, I.
- Leuning, R.
- Phillips, F.
- Barker-Reid, F.
- Gates, W.
- Grace, P.
- Galbally, I.
- Meyer, M.
- Bentley, S.
- Source: Environmental Sciences
- Volume: 2
- Issue: 2-3
- Year: 2005
- Authors:
- Source: Soil Use and Management
- Volume: 21
- Issue: 4
- Year: 2005
