• Authors:
    • Hernandez, C. F.
    • Casanova, M. R.
  • Source: Avance Agroindustrial
  • Volume: 14
  • Issue: 57
  • Year: 1994
  • Summary: In field trials on degraded or fertile soils at 2 sites in Tucuman in 1991-93, maize was sown directly or following a range of cultivations as part of a rotation with wheat and soyabeans, or in a system of continuous cultivation, and with or without application of N and P. Application of 60-80 kg N as urea was recommended under trial conditions; P had no further beneficial effect. The importance is stressed of maintaining the water balance by reducing disturbance of the soil and of increasing N use efficiency through management of stubble and cover crops. Production systems based on direct sowing, rotations, green manures, and sowing into stubble with application of complementary fertilizer were recommended to give the highest grain yields.
  • Authors:
    • Shennan, C.
    • Stivers, L. J.
  • Source: Journal of Production Agriculture
  • Volume: 4
  • Issue: 3
  • Year: 1991
  • Summary: Results from the first 2 years of the experiment are used to compare the productivity of several legume green manures and to determine if they can provide adequate available soil N to support yields of a subsequent crop of processing tomatoes (Lycopersicon lycopersicum L. Karsten var. lycopersicum) typical for this area. Lana woolly-pod vetch (Vicia dasycarpa Ten.), bell beans (Vicia faba L.), berseem clover (Trifolium alexandrinum L.), Austrian winter peas (Pisum arvense L.), oats (Avena sativa L.), and an oats and vetch mixture, planted in October and disked under in April, were compared with various levels of ammonium sulfate fertilizer.
  • Authors:
    • Hargrove,W. L.
  • Year: 1991
  • Authors:
    • McCormick, B.
    • Dekker, J.
  • Source: Proceedings, North Central Weed Control Conference
  • Issue: Vol. 41
  • Year: 1986
  • Summary: Results are summarized of a long-term study started in 1985 at Boone County, Iowa, to determine the effect of several annual and perennial cover crops on maize and soyabean yields. Best soyabean yields were obtained with annual cover crops, Kentucky bluegrass ( Poa pratensis) and the bare soil control. Best maize seed yields were obtained with the bare soil control, winter rapeseed and winter barley cover crops.
  • Authors:
    • Partoharjono, S.
    • Hairiah, K.
    • Van Noordwijk, M.
    • Labios, R. V.
    • Garrity, D. P.
  • Source: Agroforestry Systems
  • Volume: 36
  • Issue: 1-3
  • Summary: Purely annual crop-based production systems have limited scope to be sustainable under upland conditions prone to infestation by Imperata cylindrica if animal or mechanical tillage is not available. Farmers who must rely on manual cultivation of grassland soils can achieve some success in suppressing Imperata for a number of years using intensive relay and intercropping systems that maintain a dense soil cover throughout the year, especially where leguminous cover crops are included in the crop cycle. However, tabour investment increases and returns to tabour tend to decrease in successive years as weed pressure intensifies and soil quality declines. Continuous crop production has been sustained in many Imperata-infested areas where farmers have access to animal or tractor draft power. Imperata control is not a major problem in such situations. Draft power drastically reduces the tabour requirements in weed control. Sustained crop production is then dependent more solely upon soil fertility management. Mixed farming systems that include cattle may also benefit from manure application to the cropped area, and the use of non-cropped fallow areas for grazing. In extensive systems where Imperata infestation is tolerated, cassava or sugarcane are often the crops with the longest period of viable production as the land degrades. On sloping Imperata lands, conservation farming practices are necessary to sustain annual cropping. Pruned tree hedgerows have often been recommended for these situations. On soils that are not strongly acidic they may consistently improve yields. But tabour is the scarcest resource on small farms and tree-pruning is usually too tabour-intensive to be practical. Buffer strip systems that provide excellent soil conservation but minimize tabour have proven much more popular with farmers. Prominent among these are natural vegetative strips, or strips of introduced fodder grasses. The value of Imperata to restore soil fertility is low, particularly compared with woody secondary growth or Compositae species such as Chromolaena odorata or Tithonia diversifolia. Therefore, fallow-rotation systems where farmers can intervene to shift the fallow vegetation toward such naturally-occurring species, or can manage introduced cover crop species such as Mucuna utilis cv. cochinchinensis, enable substantial gains in yields and sustainability. Tree fallows are used successfully to achieve sustained cropping by some upland communities. A variation of this is rotational hedgerow intercropping, where a period of cropping is followed by one or more years of tree growth to generate nutrient-rich biomass, rehabilitate the soil, and suppress Imperata. These options, which suit farmers in quite resource-poor situations, should receive more attention.