• Authors:
    • Sullivan, D. G.
    • Balkcom, K. S.
    • Lamb, M. C.
    • Rowland, D. L.
    • Faircloth, W. H.
    • Nuti, R. C.
  • Source: Proceedings of the 27th Southern Conservation Tillage Systems Conference, Florence, South Carolina, USA, 27-29 June, 2005
  • Year: 2005
  • Summary: The interaction between reduced irrigation capacity and tillage, including the possible conservation of water with reduced tillage systems, is of vital interest to growers. A field study was initiated in the fall of 2001 to determine crop response under a simulated reduction in irrigation. Three tillage systems were replicated three times each under one of four irrigation levels (100% of a recommended amount, 66%, 33%, and 0% or dryland). Tillage systems were conventional tillage, wide-strip tillage and narrow-strip tillage. The test area was planted in triplicate, in a peanut-cotton-corn rotation, with each crop being present each year. A wheat (cv. AGS 1000) cover crop was drill-seeded each fall on conservation tillage plots. Cover crop termination was performed approximately three weeks prior to planting of each crop species. Tillage was significant for peanut yield and net return at the 0% irrigation level only. No trend in yield was evident, however, net return was consistently high with narrow-strip tillage in all years. Irrigation, at any level greater than 0%, masked tillage effects in both yield and net return. These data confirm the suitability of peanut to conservation tillage practices, including both wide- and narrow-strip tillage.
  • Authors:
    • Pookpakdi, A.
    • Juntakool, S.
    • Suwanketnikom, R.
    • Chinawong, S.
    • Woldetsadik, G.
  • Source: Kasetsart Journal: Natural Science
  • Volume: 39
  • Issue: 1
  • Year: 2005
  • Summary: A field experiment was conducted during the rainy season of 2003 to study the effects of nitrogen rates (0, 10, 20 and 30 kg/ha) and moisture conservation practices (flat bed, ridge furrow, flat bed + mulching and ridge furrow + mulching) on the soil, soil water, yield and yield components of maize ( Zea mays) grown in a rift valley in central Ethiopia. Grain yield was affected by nitrogen fertilizer levels but 1000-grain weight, total biomass, straw yield, soil temperature, soil moisture content, and infiltration rate were not affected by the nitrogen rates. Significant effects in harvest index and water use efficiency of nitrogen rates were observed only at Dera and Melkassa, respectively. Moisture conservation practices improved grain and straw yields, harvest index, and total biomass compared to the use of flat beds due to the availability of moisture. Bulk density, infiltration rate, water use efficiency, and soil moisture content were also affected by moisture conservation practices. Mulching reduced soil temperature prior to maize maturity.
  • Authors:
    • Sayre, K. D.
    • Govaerts, B.
    • Deckers, J.
  • Source: Field Crops Research
  • Volume: 94
  • Issue: 1
  • Year: 2005
  • Summary: Subtropical highlands of the world have been densely populated and intensively cropped. Agricultural sustainability problems resulting from soil erosion and fertility decline have arisen throughout this agro-ecological zone. This article considers practices that would sustain higher and stable yields for wheat and maize in such region. A long-term field experiment under rainfed conditions was started at El Batan, Mexico (2240 m a.s.l.; 19.31 degrees N, 98.50 degrees W;fine, mixed, thermic, Cumulic Haplustoll) in 1991. It included treatments varying in: (1) rotation (continuous maize (Zea mays) or wheat (Triticum aestivum) and the rotation of both); (2) tillage (conventional, zero and permanent beds); (3) crop residue management (full, partial or no retention). Small-scale maize and wheat farmers may expect yield improvements through zero tillage, appropriate rotations and retention of sufficient residues (average maize and wheat yield of 5285 and 5591 kg ha(-1)), compared to the common practices of heavy tillage before seeding, monocropping and crop residue removal (average maize and wheat yield of 3570 and 4414 kg ha(-1)). Leaving residue on the field is critical for zero tillage practices. However, it can take some time-roughly 5 years-before the benefits are evident. After that, zero tillage with residue retention resulted in higher and more stable yields than alternative management. Conventional tillage with or without residue incorporation resulted in intermediate yields. Zero tillage without residue drastically reduced yields, except in the case of continuous wheat which, although not high yielding, still performed better than the other treatments with zero tillage and residue removal. Zero tillage treatments with partial residue removal gave yields equivalent to treatments with full residue retention (average maize and wheat yield of 5868 and 5250 kg ha(-1)). There may be scope to remove part of the residues for fodder and still retain adequate amounts to provide the necessary ground cover. This could make the adoption of zero tillage more acceptable for the small-scale, subsistence farmer whose livelihood strategies include livestock as a key component. Raised-bed cultivation systems allow both dramatic reductions in tillage and opportunities to retain crop residues on the soil surface. Permanent bed treatments combined with rotation and residue retention yielded the same as the zero tillage treatments, with the advantage that more varied weeding and fertilizer application practices are possible. It is important small-scale farmers have access to, and are trained in the use of these technologies. (c) 2004 Elsevier B.V. All rights reserved.
  • Authors:
    • Trein, C.
    • Herzog, R.
    • Levien, R.
  • Source: Engenharia Agricola
  • Volume: 24
  • Issue: 3
  • Year: 2004
  • Summary: To evaluate soyabean productivity on natural pasture fields, grown once with oats to produce grain and straw for soil cover, an experiment was conducted on a Typic Paleudult Soil in Eldorado do Sul, Rio Grande do Sul, Brazil. After mechanically harvesting oats, the straw was returned to plots in amounts of 0, 2, 3, 4, 5 and 6 mg/ha and were divided according to the furrow opening depth (0.06 and 0.12 m). The area was divided in 2, with and without irrigation. The volume of soil mobilized by the fertilizer furrow openers was 53% higher when the working depth reached 0.12 m compared to 0.06 m, but no difference due to the amount of cover crop residues was attained. Grain yield, crop biomass and root mass up to 0.15 cm depth did not differ with both soil working depth and crop residue cover. Irrigation increased grain yield and total biomass of soyabeans. Even without irrigation, soyabean productivity was higher than the Rio Grande do Sul State average, showing its suitability to be grown on native pastures under the no-till system.
  • Authors:
    • Rogers, G. S.
    • Little, S. A.
    • Silcock, S. J.
    • Williams, L. F.
  • Source: Acta Horticulturae
  • Issue: 638
  • Year: 2004
  • Summary: A no-till system using permanent beds, permanent subsurface irrigation and organic mulches grown in situ was implemented as an alternative to conventional production in an experiment conducted in North Queensland, Australia. The system used a tropical legume, Centrosema pubescens 'Cavalcade', or the C 4 grasses Bothriochloa pertusa 'Keppel' or 'Hatch' as cover crops over summer and autumn. Cover crops were killed using glyphosate (1440 g a.i./ha) and residues were left on the soil surface. Vegetable seedlings were then planted through the mulch residues and grown using conventional agronomic techniques. Following harvest, crop residues were macerated and the following cover crop direct sown through the mulch residues. Soil from conventional production areas using polyethylene mulch had significantly lower aggregate stability than all other treatments. Soil aggregates taken from beneath cover crop mulches were more stable than aggregates under polyethylene mulch after one year under the no-till regime. Soil aggregates after three years of treatment showed similar statistical differences between the treatments. Bulk density in permanent beds under C. pubescens mulch was significantly lower than uncultivated bare soil and frequently cultivated polyethylene mulch. Soil under frequent cultivation was significantly more compacted than uncultivated bare soil. There were significantly more earthworms under C. pubescens and B. pertusa mulch than in uncultivated bare topsoil or under polyethylene mulch. No earthworms were found in any sample under polyethylene mulch. The yields of tomatoes after 5 harvests were not significantly different for conventional and no-till production.
  • Authors:
    • Chen, D.
    • White, R. E.
    • Chapman, D. F.
    • Eckard, R. J.
  • Source: Australian Journal of Dairy Technology
  • Volume: 59
  • Issue: 2
  • Year: 2004
  • Authors:
    • Anderson, R. L.
  • Source: Weed Technology
  • Volume: 18
  • Issue: 1
  • Year: 2004
  • Summary: Dryland rotations are changing in the semiarid Great Plains because of no-till systems. Producers now rotate summer annual crops such as corn with winter wheat and fallow, which can disrupt weed population growth because of diverse life cycles among crops. This study estimated changes in weed populations as affected by rotation design, with the goal of suggesting crop sequences that lower weed community density. We used an empirical life-cycle simulation based on demographics of jointed goatgrass and green foxtail to compare various rotations consisting of winter wheat, corn, proso millet, and fallow across a 12-yr period. The simulation indicated that designing rotations to include a 2-yr interval when seed production of either jointed goatgrass or green foxtail is prevented will drastically reduce weed populations. Arranging four different crops in sequences of two cool-season crops, followed by two warm-season crops was the most beneficial for weed management. Fallow, if used, serves in either life-cycle category. However, if the same crop is grown 2 yr in a row, such as winter wheat, the benefit of rotation design on weed density is reduced considerably. Impact of rotation design on weed density was enhanced by improving crop competitiveness with cultural practices. Rotations with balanced life-cycle intervals not only reduce weed density but enable producers to use alternative weed management strategies, improve effectiveness of herbicides used, and minimize herbicide resistance.
  • Authors:
    • Gibson, S. G.
    • Yarboro, W.
    • Hamrick, M.
    • Thompson, S.
    • King, R.
  • Source: Proceedings of the 26th Southern Conservation Tillage Conference for Sustainable Agriculture
  • Year: 2004
  • Summary: In addition to regular programming, County Agricultural Extension agents are asked many times to respond to questions, suggestions and concerns by their farmer clientele. In North Carolina as in other states an advisory leadership system is in place and farmers can formally and informally make suggestions and requests for on-farm demonstrational work. In many cases what the farmers are observing in their fields and/or things they have read "spark" the interactions with agents. Such has been the case in Cleveland County, NC. For example in the early continuous no-till era many area farmers were concerned about soil compaction. Measurements and simple demonstrations conducted by the Cleveland and Lincoln County agents and supported by the NCSU Soil Science Department and Cleveland County Government helped alleviate these concerns. Later as fields were in continuous no-till for 5 or more years, farmers began to notice a greater than expected development of their crops prior to major applications of fertilizer nitrogen. These observations led to a replicated test in wheat conducted by the Cleveland County Agricultural Extension agent comparing a field in a 2 year no-till wheat soybean rotation verses a nearby field in a 5 year continuous no-till wheat soybean rotation. Also a 6 year replicated test was initiated on Cleveland County owned land that had been in continuous no-till for 10 years. The test was set up as a continuous soybean corn rotation and in addition to the standard dryland portion, irrigation was used in part of the study to simulate a "good" corn year. Five nitrogen rates were used. The economics of the cost of fertilizer nitrogen was used to demonstrate that the Realistic Yield Expectation (RYE) method for determining nitrogen rates was very much applicable in continuous no-till. Both the wheat and corn tests indicated that residual soil nitrogen was indeed becoming a major factor in continuous no-till for these field crops and when farmers considered the realities of the weather very likely nitrogen rates can be reduced with confidence.
  • Authors:
    • Díaz, S.
    • Cabido, M.
    • Bonamici, I.
    • Pucheta, E.
  • Source: Austral Ecology
  • Volume: 29
  • Issue: 2
  • Year: 2004
  • Summary: We estimated the below-ground net plant productivity (BNPP) of different biomass components in an intensively and continuously 45-ha grazed site and in a neighbouring exclosure ungrazed for 16 years for a natural mountain grassland in central Argentina. We measured approximately twice as much dead below-ground biomass in the grazed site as in the ungrazed site, with a strong concentration of total below-ground biomass towards the upper 10 cm of the soil layer in both sites. The main contribution to total live biomass was accounted for by very fine (1 mm) in the grazed site. The seasonal variation of total live below-ground biomass mainly reflected climate, with the growing season being limited to the warmer and wetter portion of the year, but such variation was higher in the grazed site. Using different methods of estimation of BNPP, we estimated maximum values of 1241 and 723 g m-2 year-1 for the grazed and ungrazed sites, respectively. We estimated that very fine root productivity was almost twice as high at the grazed site as at the ungrazed one, despite the fact that both sites had similar total live biomass, and root turnover rate was twofold at the grazed site.
  • Authors:
    • Jones, P. G.
    • Atieno, F.
    • Kruska, R. L.
    • McCrabb, G.
    • Thornton, P. K.
    • Reid, R. S.
  • Source: Environment, Development and Sustainability
  • Volume: 6
  • Issue: 1-2
  • Year: 2004
  • Summary: Climate change science has been discussed and synthesized by the world's best minds at unprecedented scales. Now that the Kyoto Protocol may become a reality, it is time to be realistic about the likelihood of success of mitigation activities. Pastoral lands in the tropics hold tremendous sequestration potential but also strong challenges to potential mitigation efforts. Here we present new analyses of the global distribution of pastoral systems in the tropics and the changes they will likely undergo in the next 50 years. We then briefly summarize current mitigation options for these lands. We then conclude by attempting a pragmatic look at the realities of mitigation. Mitigation activities have the greatest chance of success if they build on traditional pastoral institutions and knowledge (excellent communication, strong understanding of ecosystem goods and services) and provide pastoral people with food security benefits at the same time.