19842015
  • Authors:
    • Chan, K. Y.
    • Heenan, D. P.
    • So, H. B.
  • Source: Australian Journal of Experimental Agriculture
  • Volume: 43
  • Issue: 4
  • Year: 2003
  • Authors:
    • Acosta-Martinez, V.
    • Gill, T. E.
    • Zobeck, T. M.
    • Kennedy, A. C.
  • Source: Biology and Fertility of Soils
  • Volume: 38
  • Issue: 4
  • Year: 2003
  • Summary: Microbes (i.e., fungi and bacteria) are needed to maintain the quality of semiarid soils and crop production. Enzyme (produced by microbes) activities were increased in the soil when cotton was rotated with sorghum or wheat under reduced or no-tillage in comparison to continuous cotton under tillage. Soil bacteria and fungi did not change, according to one analysis conducted, due to crop rotation under reduced or no-tillage in comparison to continuous cotton under tillage. The increases in enzyme activities, however, are indicating that microbes and their enzymes will be increased, and thus nutrients will be more available to plants, more organic matter will be formed, and other soil properties will also positively change if crop rotations with reduced or no-tillage are applied to semiarid soils in comparison to the typical current practice of continuous cotton with tillage.
  • Authors:
    • Hutchinson, R. L.
    • Boquet, D. J.
    • Paxton, K. W.
  • Source: Louisiana Agriculture
  • Volume: 46
  • Issue: 2
  • Year: 2003
  • Summary: Studies were conducted in Louisiana, USA, between 1987 and 2002 to determine the effects of tillage practices (no-till and surface till), cover crops (winter wheat, winter hairy vetch and volunteer winter native (fallow) vegetation) and nitrogen rates (0, 35, 70, 105 and 140 pounds per acre) under rainfed or irrigated conditions on cotton growth and yield. Following a cotton crop and without additional fertilizer, the native, vetch and wheat cover crops produced an average 1054, 2054 and 4045 pounds above-ground biomass per acre, respectively. Nitrogen concentration of the cover crop vegetation averaged 2.0, 4.0 and 1.5% in native, vetch and wheat, respectively. The total nitrogen in the cover crop biomass averaged across year, tillage regime and nitrogen rate was 27, 90 and 38 pounds per acre in native, vetch and wheat, respectively. Initially, lint yields in surface-till and no-till were similar but, after five years, no-till yields were higher. No cover crop + tillage treatment recorded the lowest yield. Savings in equipment and labour costs increased the returns for cotton grown with no-till practices. Cotton following vetch needed no nitrogen fertilizer. Cotton following wheat required high nitrogen rates for optimum yield. At the optimum nitrogen rate, all tillage cover crop regimes produced similar yields. Lint yields were lower in rainfed than irrigated conditions. Wheat cover crop was more beneficial to yield in rainfed than irrigated cotton. No-till + wheat cover crop recorded the highest yields and returns from rainfed cotton. No-till cotton produced yields similar to or higher than cotton planted in surface-till treatments.
  • Authors:
    • Bouma, J.
    • Marinissen, J.
    • Jongmans, A.
    • Pulleman, M.
  • Source: Soil Use and Management
  • Volume: 19
  • Issue: 2
  • Year: 2003
  • Summary: We compared the effects of conventional and organic arable farming on soil organic matter (SOM) content, soil structure, aggregate stability and C and N mineralization, which are considered important factors in defining sustainable land management. Within one soil series, three different farming systems were selected, including a conventional and an organic arable system and permanent pasture without tillage. The old pasture represents optimal conditions in terms of soil structure and organic matter inputs and is characterized by high earthworm activity. More than 70 years of different management has caused significant differences in soil properties. SOM content, mineralization, earthworm activity and water-stable aggregation decreased as a result of tillage and arable cropping when compared with pasture, but were significantly greater under organic farming than under conventional farming. Total SOM contents between 0 and 20 cm depth amounted to 15, 24 and 46 g kg-1 for the conventional arable, organic arable and permanent pasture fields, respectively. Although less sensitive to slaking than the conventionally managed field, the soil under organic farming was susceptible to compaction when high pressures were exerted on the soil under wet conditions. The beneficial effects of organic farming are generally associated with soil biochemical properties, but soil physical aspects should also be considered. Depending on soil type and climate, organic farmers need to be careful not to destroy the soil structure, so that they can enjoy maximum advantage from their organic farming systems.
  • Authors:
    • Cadisch, G.
    • Cook, H.
    • Regar, A.
    • Pihlatie, M.
    • Stevenson, M.
    • Baggs, E. M.
  • Source: Plant and Soil
  • Volume: 254
  • Issue: 2
  • Year: 2003
  • Summary: Emissions of N2O were measured following combined applications of inorganic N fertiliser and crop residues to a silt loam soil in S. E. England, UK. Effects of cultivation technique and residue application on N2O emissions were examined over 2 years. N2O emissions were increased in the presence of residues and were further increased where NH4NO3 fertiliser (200 kg N ha(-1)) was applied. Large fluxes of N2O were measured from the zero till treatments after residue and fertiliser application, with 2.5 kg N2O- N ha(-1) measured over the first 23 days after application of fertiliser in combination with rye ( Secale cereale) residues under zero tillage. CO2 emissions were larger in the zero till than in the conventional till treatments. A significant tillage/residue interaction was found. Highest emissions were measured from the conventionally tilled bean ( Vicia faba) (1.0 kg N2O- N ha(-1) emitted over 65 days) and zero tilled rye (3.5 kg N2O-N ha(-1) over 65 days) treatments. This was attributed to rapid release of N following incorporation of bean residues in the conventionally tilled treatments, and availability of readily degradable C from the rye in the presence of anaerobic conditions under the mulch in the zero tilled treatments. Measurement of N-15-N2O emission following application of N-15-labelled fertiliser to microplots indicated that surface mulching of residues in zero till treatments resulted in a greater proportion of fertiliser N being lost as N2O than with incorporation of residues. Combined applications of N-15 fertiliser and bean residues resulted in higher or lower emissions, depending on cultivation technique, when compared with the sum of N2O from single applications. Such interactions have important implications for mitigation of N2O from agricultural soils.
  • Authors:
    • Gracia, R.
    • Moret, D.
    • Arrúe, J. L.
    • López, M. V.
  • Source: Soil & Tillage Research
  • Volume: 72
  • Issue: 1
  • Year: 2003
  • Summary: Maintenance of crop residues on the soil surface is considered the most effective method to control wind erosion. In semiarid Aragon (NE Spain), where the risk of wind erosion can be high, the adoption of conservation tillage systems has been encouraged as a fallow management alternative. However, little information concerning the dynamics of residue cover during fallow is available for this area. We report here results on the evolution of barley residues during two fallow periods under conventional tillage (CT), reduced tillage (RT) and no-tillage (NT). The three tillage treatments were compared under both continuous cropping (CC) and cereal-fallow (CF) rotation. The CC system involves a summer fallow period of 5-6 months and the CF rotation a long-fallow of 17-18 months. Effects of specific tillage operations on soil cover are also presented and discussed in relation to wind erosion control during the long-fallow period. Average dry mass of barley residues at harvest was 1395 and 729 kg ha(-1) in the first and second year of the study, respectively. In general, crop residues at harvest were not significantly affected by tillage or cropping system. Primary tillage operations had the major influence on residue incorporation with reduction percentages of residue cover of 90-100% in CT (mouldboard ploughing) and 50-70% in RT (chiselling). During the two long-fallow periods, large clods (4-10 cm diameter) produced by mouldboard ploughing did not fully compensate for the complete burial of residues and the soil surface was insufficiently protected against wind erosion (soil covers
  • Authors:
    • Mir, Z.
    • Acharya, S. N.
    • Moyer, J. R.
    • Doram, R. C.
  • Source: Canadian Journal of Plant Science
  • Volume: 83
  • Issue: 1
  • Year: 2003
  • Summary: Fenugreek (Trigonella foenum-graecom L.) is an annual legume that has potential as a forage crop on the Canadian Prairies. Experiments were established to determine the tolerance of fenugreek to several herbicides and their efficacy on various weeds. Potentially, fenugreek could be grown in conservation tillage systems in rotation with other annual crops. Therefore, additional multi-factor experiments were conducted to determine the effect of herbicides, seeding method, and 11 previous crops on fenugreek yield. Without herbicide application, weeds contributed 37 to 86% to total dry matter production. When imazamox/imazethapyr, or-combinations of imazamoz/imazethapyr or imazethapyr with ethalfluralin was applied, weed contents were about 5% of the total dry matter and the herbicides did not reduce fenugreek yield compared to the hand-weeded check. Total forage samples with a low weed content had lower fibre content and higher protein and digestible dry matter content than forages with a high weed content. When imazamox/imazethapyr was used for weed control, fenugreek yields and weed biomass were similar after direct seeding and after cultivation plus seeding. In addition, the effect of previous crop and the previous crop by seeding method interaction was not significant for fenugreek yield and weed biomass. Therefore, irrigated fenugreek can be successfully grown in conservation tillage systems in rotation with several crops provided an effective herbicide is used for weed control.
  • Authors:
    • Ostergard, H.
    • Pedersen, S.
    • Kjellsson, G.
    • Holm, P. B.
    • Gylling, M.
    • Buus, M.
    • Boelt, B.
    • Andersen, S. B.
    • Tolstrup, K.
    • Mikkelsen, S. A.
  • Source: DIAS Report, Plant Production
  • Issue: 94
  • Year: 2003
  • Summary: The paper focuses on the possible sources of dispersal (cross pollination, seed dispersal, vegetative dispersal, dispersal by farming machinery, dispersal during handling and transport) from genetically modified crop production to conventional and organic production, the extent of dispersal and the need for control measures, and the possible control measures for ensuring the co-existence of genetically modified production with conventional and organic production systems. Specific sections are provided on the crops currently genetically modified in Denmark or likely to be within the next few years (oilseed rape, maize, beet, potatoes, barley, wheat, triticale, oats, rye, forage and amenity grasses, grassland legumes, field peas, faba beans and lupins, and vegetable seeds). Brief discussions on the legislation, seed production, monitoring and analytical methods used, and measures to ensure crop purity (such as reducing pollen dispersal, reducing seed dispersal, adopting cultural methods reducing pollen and seed dispersal) are also presented.
  • Authors:
    • Bundy, L. G.
    • Andraski, T. W.
    • Kilian, K. C.
  • Source: Journal of Environmental Quality
  • Volume: 32
  • Issue: 5
  • Year: 2003
  • Summary: Manure additions to cropland can reduce total P losses in runoff on well-drained soils due to increased infiltration and reduced soil erosion. Surface residue management in subsequent years may influence the long-term risk of P losses as the manure-supplied organic matter decomposes. The effects of manure history and long-term (8-yr) tillage [chisel plow (CP) and no-till (NT)] on P levels in runoff in continuous corn (Zea mays L.) were investigated on well-drained silt loam soils of southern and southwestern Wisconsin. Soil P levels (0-15 cm) increased with the frequency of manure applications and P stratification was greater near the surface (0-5 cm) in NT than CP. In CP, soil test P level was linearly related to dissolved P (24-105 g ha(-1)) and bioavailable P (64-272 g ha(-1)) loads in runoff, but not total P (653-1893 g ha(-1)). In NT, P loads were reduced by an average of 57% for dissolved P, 70% for bioavailable P, and 91% for total P compared with CP. This reduction was due to lower sediment concentrations and/or lower runoff volumes in NT. There was no relationship between soil test P levels and runoff P concentrations or loads in NT. Long-term manure P applications in excess of P removal by corn in CP systems ultimately increased the potential for greater dissolved and bioavailable P losses in runoff by increasing soil P levels. Maintaining high surface residue cover such as those found in long-term NT corn production systems can mitigate this risk in addition to reducing sediment and particulate P losses.
  • Authors:
    • Steiner, J. L.
    • Franzluebbers, A. J.
  • Source: Agricultural Practices and Policies for Carbon Sequestration in Soil
  • Year: 2002
  • Summary: No-tillage crop production has become an accepted practice throughout the U.S. The Kyoto Protocol on climate change has prompted great interest in conservation tillage as a management strategy to help sequester CO2 from the atmosphere into soil organic matter. Numerous reports published in recent years indicate a large variation in the amount of potential soil organic carbon (SOC) storage with no tillage (NT) compared with conventional tillage (CT). Environmental controls (i.e., macroclimatic variables of temperature and precipitation) may limit the potential of NT to store SOC. We synthesized available data on SOC storage with NT compared with CT from published reports representing 111 comparisons from 39 locations in 19 states and provinces across the U.S. and Canada. These sites provided a climatic continuum of mean annual temperature and precipitation, which was used to identify potential SOC storage limitations with NT. Soil organic C storage potential under NT was greatest (~0.050 kg · m -2· yr-1) in subhumid regions of North America with mean annual precipitation-to-potential evapotranspiration ratios of 1.1 to 1.4 mm · mm-1. Although NT is important for water conservation, aggregation, and protection of the soil surface from wind and water erosion in all climates, potential SOC storage with NT compared with CT was lowest in cold and dry climates, perhaps due to prevailing cropping systems that relied on low-intensity cropping, which limited C fixation. Published data indicate that increasing cropping intensity to utilize a greater fraction of available water in cold and dry climates can increase potential SOC storage with NT. These analyses indicate greatest potential SOC storage with NT would be most likely in the relatively mild climatic regions rather than extreme environments.