19832015
  • Authors:
    • Kreye, H.
  • Source: Bulletin OILB/SROP
  • Volume: 27
  • Issue: 10
  • Year: 2004
  • Summary: In a long-term field trial, the effects of three different tillage systems on harmful organisms and yield were investigated. The focus was on fungal diseases, weeds and slugs. With the ploughing system as the standard, a non-inversion/conservation tillage and a direct drilling/no till system were compared with one another. The crop rotation oilseed rape-wheat-barley, which was established in 1995, was reconverted into a crop rotation oilseed rape-wheat-wheat in 1998 due to problems with volunteer wheat in the following barley in the two ploughless tillage systems. The occurrence of Phoma root-collar and stem disease, the most important in Germany, was not affected in comparison over the years by the intensity of the cultivation. For Sclerotinia stem rot, a correlation could only be determined with the tillage systems in one year of the trial series. The infection became more severe with decreasing intensity of soil cultivation. Whether this result can be reproduced in future growing seasons remains to be seen. Effects on the incidence of Verticillium longisporum could not be determined. Other diseases arose only sporadically at very low levels. However, in comparison, the occurrence of weeds was affected significantly. The amount of grass weed species ( Alopecurus myosuroides, Apera spica-venti, volunteer barley) increased in the systems without ploughing. The effect on dicotyledonous weed species was dependent on the particular species. In individual years, heavy slug damage could be correlated with direct drilling system.
  • Authors:
    • Merrill, S.
    • Lares, M.
    • Tanaka, D.
    • Krupinsky, J.
  • Source: Agronomy Journal
  • Volume: 96
  • Issue: 1
  • Year: 2004
  • Summary: Crop diversification and crop sequencing can influence plant disease risk in cropping systems. The objective of this research was to determine the effect of 10 previous crops on leaf spot diseases of barley ( Hordeum vulgare L.) and hard red spring wheat ( Triticum aestivum L.). Barley and spring wheat were direct-seeded (no till) in the crop residue of 10 crops {barley, canola ( Brassica napus L.), crambe ( Crambe abyssinica Hochst. ex R.E. Fr.), dry bean ( Phaseolus vulgaris L.), dry pea ( Pisum sativum L.), flax ( Linum usitatissimum L.), safflower ( Carthamus tinctorius L.), soybean [ Glycine max (L.) Merr.], sunflower ( Helianthus annuus L.), and spring wheat}. Barley was evaluated for leaf spot diseases 15 times over 2 yr. Results indicate that risk for leaf spot disease on barley would be lower following wheat, crambe, canola and dry pea compared with the barley-after-barley treatment. Although barley yields were similar across all treatments one year, differences were detected in another year with the barley-after-barley treatment having the lowest yield. Spring wheat was evaluated for leaf spot diseases 22 times over 2 yr. Differences among treatments were more detectable in earlier evaluations, indicating a greater influence of crop residue and carryover of inoculum early in the season compared with later. The risk for leaf spot disease was lower when wheat was grown after canola, barley, crambe, and flax than when grown after the other crops. Although wheat yields were similar across all treatments one year, differences were detected in another year with the wheat-after-wheat treatment having the lowest yield.
  • Authors:
    • Correa, R.
    • Wilkins, D.
    • Siemens, M.
  • Source: Transactions of the ASAE
  • Volume: 47
  • Issue: 2
  • Year: 2004
  • Summary: Adoption of conservation tillage in the Pacific Northwest lags that of the U.S. in part due to the lack of reliable seeding equipment for planting into the high residue densities encountered in this region. To overcome this problem, a drill attachment was developed to manage heavy residue next to the furrow opening tines of hoe-type no-till drills. The U.S. patented device consists of a fingered rubber wheel, a rubber inner ring, and a spring-loaded arm that pivots about vertical and horizontal axes. The performance of the device was evaluated in terms of stand establishment and yield in Oregon and Washington. Test site locations varied significantly in the amount and condition of crop residue and were planted to a variety of different crops. As compared to the standard no-till drill without the attachment, use of the residue management wheel was found to increase the stand establishment of small seeded crops such as canola and mustard by over 40% and large seeded crops such as wheat and barley by approximately 17%. Increases in stand establishment were attributed to fewer piles of residue covering the seed row. Use of the device also significantly increased crop yield by up to 12% in 8 of the 20 trials conducted (P≤0.10). Although the residue management wheel costs $300 per unit to fabricate, using the device may be economically feasible if it results in significant improvements in both stand establishment and yield.
  • Authors:
    • Reddy, G. B.
    • Brock, B.
    • Naderman, G.
    • Raczkowski, C. W.
  • Source: Proceedings of the 26th Southern Conservation Tillage Conference for Sustainable Agriculture 8-9 June, 2004, Raleigh, North Carolina
  • Year: 2004
  • Summary: This study reports the results of sampling soil within a field experiment at CEFS, the Cherry Farm, Goldsboro, North Carolina. The experiment tested effects of six years of conservation tillage with cover crops, contrasted with chisel plow/disk tillage without cover crops, under three crop rotations. In April, 2003 two sets of undisturbed core samples were collected from six mapped soil areas, at depth increments of 0-2 and 2-5 inches, replicated four times. One set was used for soil bulk density; the other provided soil carbon and total nitrogen contents. The study found strong and consistent inverse correlations between soil carbon content and bulk density. Under conservation tillage the surface two inches generally sustained suitable density for root activities. However, at 2-5 inches density approached or exceeded 1.6 g cm-3. Given the textures involved, this density likely would affect root growth, especially under non-ideal, wet/cool or dry/hard conditions. This would be especially important for crop establishment within this prime rooting zone. This low carbon/high-density problem was less likely for soils containing the influences of more silt with less sand. It was greater when corn, peanut and cotton were grown compared to producing soyabean or wheat/soybean with corn. This study revealed increased carbon sequestration from the conservation tillage systems used, along with increased total N content in the surface five inches of soil. Conservation tillage as practiced helped to reduce the "greenhouse effect" and lessened N leaching losses, holding more of these elements within the topsoil.
  • Authors:
    • Rich, J.
    • Wiatrak, P.
    • Katsvairo, T.
    • Marois, J.
    • Wright, D.
  • Source: Proceedings of the 26th Southern Conservation Tillage Conference for Sustainable Agriculture, Raleigh, North Carolina, USA, 8-9 June, 2004
  • Year: 2004
  • Summary: Soils in the southeast have low organic matter content, low native fertility, and low water holding capacity which has resulted in stagnant yields. Long term studies across the country (Morrow, Sanborn, Magruder, Old Rotation [Auburn]) have shown that land coming out of long term perennial grasses often has an organic matter content of over 4% and decreases as it stays in continuous annual cropping and levels off after 80-100 years once the level reaches about 1 1/2% with use of conservation tillage, cover crops, proper rotation, and modern fertility practices. Years of research in the southeast have shown that perennial grasses such as bahiagrass can help improve soil structure and reduce pests such as nematodes and increase crop yields, sometimes dramatically. Research in the southeast with this perennial grasses grown in rotation with crops has shown higher yields (50% more groundnuts than under conventional annual cropping systems), increased infiltration rates (more than 5 times faster), higher earthworm numbers (thousands per acre vs. none in many cases), and a more economically viable (potential for 3-5 times more profit) cropping system. Diversification into livestock can add another dimension to the farming system making it more intensive and provide a readily available use for perennial grasses.
  • Authors:
    • Laslo, J. J.
    • Meers, S.
    • Hall, L. M.
    • Beckie, H. J.
    • Stevenson, F. C.
  • Source: Weed Technology
  • Volume: 18
  • Issue: 3
  • Year: 2004
  • Summary: A 3-yr study was conducted in Wheatland County, Alberta to determine if agronomic practices of growers influenced the occurrence of herbicide resistance in wild oat. Wild oat seeds were collected in 33 fields in 1997 and in 31 fields in each of 1998 and 1999 (one field per grower). Seedlings were screened for resistance to two acetyl-CoA carboxylase (ACCase) inhibitors, imazamethabenz, an acetolactate synthase (ALS) inhibitor, and triallate, a thiocarbamate herbicide. A questionnaire on herbicide resistance awareness and management practices was completed by each grower. Both ACCase and ALS inhibitor resistance in wild oat were linked to a lack of crop rotation diversity. In addition, ALS inhibitor-resistant wild oat was associated with conservation-tillage systems and recent use of herbicides with that mode of action. Results of this study suggest that timely tillage and inclusion of fall-seeded and perennial forage crops in rotations will effectively slow the selection of resistance in this grass species.
  • Authors:
    • Marland, G.
    • West, T. O.
  • Source: Biogeochemistry
  • Volume: 63
  • Issue: 1
  • Year: 2003
  • Summary: There is a potential to sequester carbon in soil by changing agricultural management practices. These changes in agricultural management can also result in changes in fossil-fuel use, agricultural inputs, and the carbon emissions associated with fossil fuels and other inputs. Management practices that alter crop yields and land productivity can affect the amount of land used for crop production with further significant implications for both emissions and sequestration potential. Data from a 20-year agricultural experiment were used to analyze carbon sequestration, carbon emissions, crop yield, and land-use change and to estimate the impact that carbon sequestration strategies might have on the net flux of carbon to the atmosphere. Results indicate that if changes in management result in decreased crop yields, the net carbon flux can be greater under the new system, assuming that crop demand remains the same and additional lands are brought into production. Conversely, if increasing crop yields lead to land abandonment, the overall carbon savings from changes in management will be greater than when soil carbon sequestration alone is considered.
  • Authors:
    • Chan, K. Y.
    • Heenan, D. P.
    • So, H. B.
  • Source: Australian Journal of Experimental Agriculture
  • Volume: 43
  • Issue: 4
  • Year: 2003
  • Authors:
    • Liu, A.
    • Hamel, C.
    • Madramootoo, C.
    • Elmi, A.
  • Source: Biology and Fertility of Soils
  • Volume: 38
  • Issue: 6
  • Year: 2003
  • Summary: There is a growing interest in the adoption of conservation tillage systems [no-till (NT) and reduced tillage (RT)] as alternatives to conventional tillage (CT) systems. A 2-year study was conducted to investigate possible environmental consequences of three tillage systems on a 2.4-ha field located at Macdonald Research Farm, McGill University, Montreal. The soil was a sandy loam (0.5 m depth) underlain by a clay layer. Treatments consisted of a factorial combination of CT, RT, and NT with the presence or absence of crop residue. Soil NO 3 --N concentrations tended to be lower in RT than NT and CT tillage treatments. Denitrification and N 2O emissions were similar among tillage systems. Contrary to the popular assumption that denitrification is limited to the uppermost soil layer (0–0.15 m), large rates of N 2O production were measured in the subsurface (0.15–0.45 m) soil, suggesting that a significant portion of produced N 2O may be missed if only soil surface gas flux measurements are made. The N 2O mole fraction (N 2O:N 2O+N 2) was higher in the drier season of 1999 under CT than in 2000, with the ratio occasionally exceeding 1.0 in some soil layers. Dissolved organic C concentrations remained high in all soil depths sampled, but were not affected by tillage system .
  • Authors:
    • Kandji, S. T.
    • Albrecht, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 99
  • Issue: 1
  • Year: 2003
  • Summary: Removing atmospheric carbon (C) and storing it in the terrestrial biosphere is one of the options, which have been proposed to compensate greenhouse gas (GHG) emissions. Agricultural lands are believed to be a major potential sink and could absorb large quantities of C if trees are reintroduced to these systems and judiciously managed together with crops and/or animals. Thus, the importance of agroforestry as a land-use system is receiving wider recognition not only in terms of agricultural sustainability but also in issues related to climate change. The objective of this paper was to analyse C storage data in some tropical agroforestry systems and to discuss the role they can play in reducing the concentration of CO2 in the atmosphere. The C sequestration potential of agroforestry systems is estimated between 12 and 228 Mg ha-1 with a median value of 95 Mg ha-1. Therefore, based on the earth's area that is suitable for the practice (585-1215x10^6 ha), 1.1-2.2 Pg C could be stored in the terrestrial ecosystems over the next 50 years. Long rotation systems such as agroforests, homegardens and boundary plantings can sequester sizeable quantities of C in plant biomass and in long-lasting wood products. Soil C sequestration constitutes another realistic option achievable in many agroforestry systems. In conclusion, the potential of agroforestry for CO2 mitigation is well recognised. However, there are a number of shortcomings that need to be emphasised. These include the uncertainties related to future shifts in global climate, land-use and land cover, the poor performance of trees and crops on substandard soils and dry environments, pests and diseases such as nematodes. In addition, more efforts are needed to improve methods for estimating C stocks and trace gas balances such as nitrous oxide (N2O) and methane (CH4) to determine net benefits of agroforestry on the atmosphere.