• Authors:
    • Reeves, D. W.
    • Burmester, C. H.
    • Motta, A. C. V.
  • Source: Making Conservation Tillage Conventional: Building a Future on 25 Years of Research. Proceedings of 25th Annual Southern Conservation Tillage Conference for Sustainable Agriculture, Auburn, AL, USA, 24-26 June, 2002 - Special Report no. 1, Alabama Agricult
  • Year: 2002
  • Summary: A replicated cotton (Gossypium hirsutum) rotation experiment has been conducted for 22 years (1980-2001) on a Decatur silt loam (fine, kaolinitic, thermic, Rhodic Paleudults) in the Tennessee Valley of northern Alabama, USA. The highly productive soil with little disease and nematode problems resulted in cotton yield increases from rotations of generally less than 10% during the first 15 years of the study. A switch to no-tillage in all rotations except continuous cotton in 1995 greatly improved cotton yield response to rotations. From 1995 to 2001 cotton yield increases to rotation have averaged between 5% and 18%. In this study, yield increases due to rotations seem linked to increases in soil organic matter and consequent improvements in soil quality. From 1979 to 1994 using conventional tillage, the only rotation that produced a greater than 10% yield increase was cotton rotated with wheat ( Triticum aestivum) and double-cropped soyabean ( Glycine max). This rotation was also the only rotation that significantly increased organic matter levels under conventional tillage. From 1995 to 2001, all rotations were no-tilled and the greater yield increases to rotations can also be associated with higher soil organic matter levels. Wheat as a grain rotation or cover crop often produced the greatest yield increases to the following cotton crop. Under conventional tillage the wheat residue provided increased organic matter residue. With no-tillage the wheat cover crop reduced surface soil compaction. No-tillage and rotations that increased residue production were linked to increased cotton yields on this soil.
  • Authors:
    • Myers, R.
    • Pullins, E.
  • Source: American Journal of Alternative Agriculture
  • Volume: 13
  • Issue: 3
  • Year: 1998
  • Summary: The agronomic and economic performance of five alternative crops was assessed in comparison to the no-till wheat-soyabean double-cropping system prevalent in the southern Corn Belt of the USA. A field site was established in 1992 at the University of Missouri-Columbia and two further sites in Missouri were added in 1993. Amaranth, buckwheat, sunflower, and pearl millet were planted after the harvest of canola [rape] or wheat, or after fallow. Alternative double-crop grain yield, production costs, and net returns were compared with those of double-crop soyabean. Wheat yielded more than canola. Sunflower grain yields did not differ significantly after winter-crop treatments at any site. Yields of amaranth, buckwheat, soyabean, and pearl millet differed after winter crops at some sites. At three study yield levels, net returns were positive and greatest for double-crop wheat-amaranth, canola-amaranth, wheat-sunflower, and canola-sunflower systems. All double-crop systems except canola-pearl millet had positive net returns at median study yield levels. Low or negative net returns resulted from the combination of low yield and low price for some double crops. Canola was shown to be an economically feasible alternative to wheat in a double-cropping system for central and southern Missouri. Buckwheat and sunflower were shown to be agronomically and economically competitive alternatives to soyabean following either canola or winter wheat, with buckwheat most valuable in late-season planting conditions.
  • Authors:
    • Bauer, P. J.
    • Hunt, P. G.
    • Matheny, T. A.
  • Source: Journal of Production Agriculture
  • Volume: 10
  • Issue: 3
  • Year: 1997
  • Summary: Cotton (Gossypium hirsutum L.) production has dramatically increased in the Southeast, but the role of conservation tillage in doublecropped cotton systems has not been clearly defined. Therefore, from 1988 to 1994, we investigated doublecropped wheat (Triticum aestivum L.) and cotton on plots that had been in continuous conservation vs. conventional tillage since 1979. The experimental site wits located near Florence, SC, on a Norfolk loamy sand (fine-loamy, siliceous, thermic Typic Kandiudult). Conventional tillage consisted of multiple diskings and cultivations; surface tillage was eliminated for conservation tillage. Wheat yields were not significantly affected by tillage, but cotton yields were significantly higher for conservation tillage (P less than or equal to 0.01). Cotton planting dates ranged from 7 to 18 June, and 5 of the 7 yr had more than 145 frost-free days. Two years had crop failure because of early freezes, and a June drought prevented the planting of cotton in 1 yr. In the 4 yr with harvestable yields, seed cotton yields among the eight cultivars ranged from about 500 to 2200 and 300 to 1850 lb/acre for conservation and conventional tillage, respectively. The early maturing cultivar, 'Deltapine (DP) 20,' had the highest seed cotton yields with means of 1442 and 1123 lb/acre for conservation and conventional tillage, respectively Development of earlier maturing cotton and wheat cultivars will be important for this cropping system in the northern Coastal Plain portion of the Cotton Belt.
  • Authors:
    • Porter, P.
  • Source: Journal of Production Agriculture
  • Volume: 8
  • Issue: 2
  • Year: 1995
  • Summary: A study was conducted on an Orangeburg loamy sand (fine-loamy, siliceous, thermic Typic Paleudults) near Blackville, South Carolina in 1990-92 to determine the effect of deep tillage on both canola [rape] and wheat, the subsequent response of doublecropped soyabeans, and response of wheat grown following the soyabean crop when controlled traffic and minimum tillage practices were used. Canola yields averaged 37.8 bu/acre in 1991 and 43.2 bu/acre in 1992, whereas wheat yields were 58.0 and 72.5 bu/acre, respectively. In both years, deep tillage (chiselling to 11 in) had no effect on wheat yields when compared with discing. Deep tillage increased canola yields by 12.5% in the drier of the two growing seasons. Soyabean yields were not significantly affected by the tillage used for the previous crops. Subsoiled soyabeans yielded 33.7 vs. 31.9 bu/acre for no-till soyabeans in 1991, and 22.6 vs. 19.4 bu/acre in 1992. In 1992, soyabean tillage following wheat did not affect soyabean yield but following canola, in-row subsoiling resulted in greater soyabean yields than no-till. Wheat following soyabeans was not affected by the tillage practice used for the previous winter crops, and the 1992 wheat yields were unaffected by previous winter crop or soyabean tillage. In 1993, soyabean tillage did not affect subsequent wheat yield but following canola, in-row subsoiling resulted in greater wheat yields than no-till. It is suggested that canola has no adverse effect on either soyabeans or wheat when grown in sequence on a Coastal Plain soil.
  • Authors:
    • Lindwall, C. W.
    • Roman, E. S.
    • Moyer, J. R.
    • Blackshaw, R. E.
  • Source: Crop Protection
  • Volume: 13
  • Issue: 4
  • Year: 1994
  • Summary: Soil erosion by wind or water is a serious problem in North and South America. When no-till or reduced tillage is used to control erosion, the density of certain annual and perennial weeds can increase and new weed control techniques are usually required. The effects of conservation tillage on annual and perennial weeds, weeds that are spread by wind, plants from rangelands and pasture as weeds and volunteer plants as weeds arc reviewed. Current weed control methods with minimum tillage, herbicides, cover crops and other cultural practices in conservation tillage systems in North and South America are described. Some producers are successfully controlling weeds in continuous summer cropping systems in North America and in double cropping systems that include wheat in the winter and soybean or corn in the summer in Brazil, Argentina and southeastern United States. Successful conservation tillage systems usually involve cropping sequences of three or more crop types and several herbicides. In these cropping sequences, the ground is covered with a crop during most of the period in which the climate is favourable for weed growth. Perennial weeds are a problem in all tillage systems and there is a general dependence on glyphosate for perennial weed control. In successful conservation tillage systems, the amount and cost of herbicides used is similar to that for herbicides used in conventional tillage systems.