• Authors:
    • Duffy, M.
    • Chase, C.
  • Source: American Journal of Alternative Agriculture
  • Volume: 6
  • Issue: 04
  • Year: 1991
  • Summary: Labor requirements, production costs, yields, and economic returns were evaluated for conventional and reduced-chemical cropping systems in northeast Iowa from 1978 to 1989. Continuous corn (C-C) and corn-soybean (C-Sb) rotations represented the conventional system; a corn-oat-meadow (C-O-M) rotation represented the reducedchemical system. The C-C and C-Sb rotations used both commercial pesticides and fertilizers. The C-O-M rotation used manure for fertilization and applied pesticides only in emergencies. Operations for all systems were implemented by one farm manager. The C-Sb rotation had the highest corn yield over the 12-year period, and the C-O-M rotation the lowest. The corn within the C-O-M rotation, however, produced the second highest average return to land, labor, and management. With costs of production substantially lower than the conventional systems, the C-O-M corn crop had competitive returns despite lower yield. The C-Sb average return to land, labor, and management was significantly higher than for the other systems. Hourly labor charges of $4, $10, $20, and $50 had little effect on the rankings of economic returns. Because of unusually high alfalfa reseeding costs and low average oat yields, returns to the C-O-M rotation were significantly lower than C-Sb but comparable to C-C. With better alfalfa establishment and higher average oat yields, the reduced-chemical system might have been competitive with the C-Sb conventional system.
  • Authors:
    • Kitchen, N. R.
  • Source: Dissertation Abstracts International. B, Sciences and Engineering
  • Volume: 51
  • Issue: 8
  • Year: 1990
  • Summary: A long-term study was conducted at 2 sites in E. Colorado to study the influence of N fertilizer rate and source/placement/timing (NSP), and crop rotation wheat/fallow (WF), and wheat, maize or sorghum/fallow (MSF) on no-tillage dryland cropping systems. Grain yield and vegetative biomass increased linearly with fertilizer N rate up to 84 kg/ha for wheat and 101 kg/ha for maize indicating that current N recommendations at Colorado State University may be insufficient for meeting N needs of no-tillage crops. N fertilizer recovery efficiency (NFRE) decreased with N fertilizer rate. Production increased more with N fertilizer additions in the MSF than in the WF rotation system. If differences occurred with NSP treatments, banding gave greater production and NFRE than broadcast application. In 1989 at one location, wheat production from the MSF rotation was greater than from the WF rotation. The av. annual grain and vegetative production from MSF was approx. double that produced in the WF cropping system. Water conservation with no-tillage systems allowed more intense cropping than a WF rotation. N loss from the MSF rotation was significant, increased with N rate and was attributed to N loss in both inorganic- and organic-N pools. Nitrate leaching in the no-tillage MSF rotation was unlikely since NO 3 decreased with soil depth.
  • Authors:
    • Harman, W.
    • Jones, O.
    • Smith, S.
  • Source: Optimum erosion control at least cost. Proceedings of the National Symposium on Conservation Systems, December 14-15, 1987, Chicago, IL, USA
  • Year: 1987
  • Summary: Graded-terraced field-size watersheds have been cropped in a dryland wheat - fallow - sorghum - fallow (2 crops in 3 years) sequence with no-till and conventional (stubble-mulch) tillage systems at Bushland, Texas since 1982. No-till had little effect on wheat yields but increased sorghum yields 14% due to reduced evaporation, as a result of surface residue. No-till reduced erosion by 66%; however, soil loss with conventional tillage was also low due to terracing and contouring. NPK loss was very low. Economically, no-till performed very well, due mainly to reduced equipment inventories and lower operating costs. No-till gave increased storm runoff due to soil crusting, and there were problems with grass weeds. A system consisting of successive no-tillage and stubble-mulch tillage is proposed.
  • 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.