• Authors:
    • Drinkwater, L. E.
    • David, M. B.
    • Tonitto, C.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 112
  • Issue: 1
  • Year: 2006
  • Summary: The availability of Haber-Bosch nitrogen (N) has permitted agricultural intensification and increased the productive capacity of agroecosystems; however, approximately 50% of this applied fertilizer N is lost from agricultural landscapes. Extensive efforts have been devoted to improving the N use efficiency of these systems. Diversified crop rotations using cover crops to provide a variety of ecosystem functions, including biological N fixation (BNF), could maintain yields while reducing N losses. Although leguminous plants used as green manures are capable of fixing N in quantities which exceed cash crop demand, the prospect of replacing significant quantities of Haber-Bosch N with BNF is widely viewed as impractical due to yield reductions. Likewise, the practice of replacing bare fallows with non-leguminous cover crops in systems receiving Haber-Bosch N is generally deemed not economically viable. We conducted a quantitative assessment of cash crop yields and N retention in rotations that implemented these practices. We performed a meta-analysis on experiments comparing crop yield, nitrate leaching, or soil nitrate between conventional (receiving inorganic fertilizer with a winter bare fallow) and diversified systems managed using either a non-legume over-wintering cover crop (amended with inorganic fertilizer) or a legume over-wintering cover crop (no additional N fertilizer). Only studies with rotations designed to produce a cash crop every year were included in our analysis. Many yield comparisons were found in the literature, but only a limited number of nitrate leaching or soil inorganic N studies met the criteria for inclusion in a meta-analysis. Long-term studies were also uncommon, with most data coming from experiments lasting 2-3 years. Yields under non-legume cover crop management were not significantly different from those in the conventional, bare fallow systems, while leaching was reduced by 70% on average. Relative to yields following conventional N-fertilization, the legume-fertilized crops averaged 10% lower yields. However, yields under green manure fertilization were not significantly different relative to conventional systems when legume biomass provided >=110 kg N ha-1. On average, nitrate leaching was reduced by 40% in legume-based systems relative to conventional fertilizer-based systems. Post-harvest soil nitrate status, a measure of potential N loss, was similar in conventional and green manure systems suggesting that reductions in leaching losses were largely due to avoidance of bare fallow periods. These results demonstrate the potential for diversified rotations using N- and non-N-fixing cover crops to maintain crop yields while reducing the anthropogenic contributions to reactive N fluxes.
  • Authors:
    • Perez, A.
    • Ali, M.
    • Pollack, S.
    • Lucier, G.
  • Year: 2006
  • Summary: The U.S. fruit and vegetable industry accounts for nearly a third of U.S. crop cash receipts and a fifth of U.S. agricultural exports. A variety of challenges face this complex and diverse industry in both domestic and international markets, ranging from immigration reform and its effect on labor availability to international competitiveness. The national debate on diet and health frequently focuses on the nutritional role of fruit and vegetables, and a continued emphasis on the benefits of eating produce may provide opportunities to the industry. In the domestic market, Americans are eating more fruit and vegetables than they did 20 years ago, but consumption remains below recommended levels. In terms of per capita consumption expressed on a fresh-weight basis, the top five vegetables are potatoes, tomatoes, lettuce, sweet corn, and onions while the top five fruit include oranges, grapes (including wine grapes), apples, bananas, and pineapples. The industry also faces a variety of trade-related issues, including competition with imports. During 2002-04, imports accounted for 21 percent of domestic consumption of all fresh and processed fruit and vegetables, up from 16 percent during 1992-94.
  • Authors:
    • Mallory-Smith, C.
    • William, R. D.
    • Peachey, B. E.
  • Source: Weed Technology
  • Volume: 20
  • Issue: 1
  • Year: 2006
  • Summary: The effects of spring tillage sequence on summer annual weed populations were evaluated over two cycles of a 3-year crop rotation of snap beans ( Phaseolus vulgaris), sweetcorn ( Zea mays), and winter wheat ( Triticum aestivum). Continuous no-till (N) planting of vegetable crops each spring (NNNN) reduced summer annual weed density by 63-86% compared with that of continuous conventional tillage (CCCC), depending upon the site and herbicide level. Hairy nightshade ( Solanum sarrachoides) populations were reduced by 88 to 96% when spring tillage was eliminated from the crop rotation. The effects of the NNNN spring tillage sequence on weed density were similar at two sites even though the crop rotations at the two sites began with different crops. The rotational tillage sequence of NCNC at the East site, in a crop rotation that began with maize, reduced summer annual weed density by 46-51% compared with that of continuous conventional tillage and planting (CCCC) at low and medium herbicide rates, respectively. In contrast, the tillage sequence of CNCN in the same crop rotation and at the same site increased weed density by 80% compared with that of CCCC at a low herbicide rate. The effects of the NCNC and CNCN rotational tillage sequences on weed density were reversed at the West site, and was probably caused by pairing sweetcorn with conventional tillage rather than no-tillage. The reduction in summer annual weed density caused by reduced spring tillage frequency did not significantly increase crop yields.
  • Authors:
    • Duchovskiene, L.
    • Starkute, R.
    • Zalatorius, V.
  • Source: Straipsnis leidinyje: Sodininkystė ir daržininkystė
  • Volume: 25
  • Issue: 4
  • Year: 2006
  • Summary: In 2003-05 in Lithuanian Institute of Horticulture, in trial field for ecologically grown vegetables, plant availability for green manure and its influence on ecologically grown onions yield were evaluated. Investigated plants included: barley; barley with undersown clover; summer wheat, peas and oats; and rape. Control treatment was black fallow. The biomass of plants for green manure leaves in the soil was evaluated under different amounts of organic matter. The highest amount of green matter (43.2 t/ha) was from peas and oats; summer wheat showed 32.5 t/ha; barely with undersown clover, 30.2 t/ha; and the lowest was from barely and rape (24.5 and 27.0 t/ha, respectively). There were no significant differences in the number of Thrips tabaci between treatments. Green manure from peas and oats increase onion yield by 3.1%; green manure from summer wheat by 5.7%; and green manure from barely with undersown clover by 7.3%. The lowest impact for onion yield has had green manure from barely and rape. The highest number of weeds (191 unit/m 2) was found in onions grown after barely with undersown clover, while the lowest number of 29 unit/m 2 was in onions grown after peas and oats.
  • Authors:
    • Mohamed, A. E. M.
    • Arab, Y. A.
    • El-Shehaby, A. I.
  • Source: Egyptian Journal of Agricultural Research
  • Volume: 84
  • Issue: 1
  • Year: 2006
  • Summary: Growing some summer crops - preceding garlic - in heavily infested potted soil significantly reduced white rot disease (Sclerotium cepivorum) of garlic. Reductions in disease incidence obtained with sugarcane, roquette [ Eruca vesicaria] and sorghum as intercrops were 80.0, 73.3 and 66.7% of the control treatment, respectively. Reductions in disease incidence obtained with maize, squash, pepper, soyabean, cotton, sesame, cowpea and roselle ranged between 53.3 and 40.0%. Cauliflower, lucerne, broad bean, nigella, Egyptian clover, coriander and roquette grown in pots, as winter crops preceding garlic, exhibited 46.7-26.7% reduction in white rot disease. Intercropping cauliflower, coriander and roquette with garlic reduced the disease by 46.0-53.8%. Seedling root exudates of cauliflower, coriander and sorghum significantly reduced mycelial growth of S. cepivorum on PDA plates more than did radish and sugarcane. Cauliflower exhibited the highest reduction in mycelial growth, followed by sorghum and coriander. Ascending rates of cauliflower root exudates resulted in a higher reduction in fungus growth. Counts of fungi were significantly higher in soil of sorghum and roquette compared with sugarcane and coriander, while coriander rhizosphere yielded the highest density of fungi. Actinomycetes were detected in the rhizosphere at a highest count with coriander but were completely absent in the soil. Bacteria, in contrast, existed only in the soil where actinomycetes were completely absent. The highest count of bacteria was detected in sorghum soil. Actinomycetes inhabited soil only while bacteria and fungi existed in soil and rhizosphere of cauliflower, radish and garlic intercropped with the two crops. Cauliflower significantly increased counts of fungi and bacteria in rhizosphere when intercropped with garlic compared with those detected with garlic alone. Some recommendations are made.
  • Authors:
    • Shimi, P.
    • Kazemi, H.
  • Source: Iranian Journal of Weed Science
  • Volume: 1
  • Issue: 1
  • Year: 2005
  • Summary: An isolate of F. moniliforme [Gibberella moniliformis], a pathogen of winter wild oat (A. ludoviciana [A. sterilis var. ludoviciana]), was obtained from Tehran Province, Iran, in 1994. A host range test performed on wheat, barley, maize, rye, millet, crested wheatgrass, faba bean, red bean, green bean, sunflower, soyabean, oilseed rape, cotton, safflower, cucumber, water melon, berseem clover, and sainfoin, resulted in no symptom induction by the pathogen. However, winter wild oat, crested wheatgrass, johnsongrass and tomato showed susceptibility to the pathogen with 78, 24, 19 and 17% mortality, respectively. The results indicate that this pathogen could be considered as a potential biological agent for the control of winter wild oat.
  • Authors:
    • Chattopadhyay, N.
    • Das, H. P.
  • Source: Advances in Indian entomology: productivity and health (a silver jubilee supplement)
  • Volume: 1
  • Issue: 3
  • Year: 2005
  • Summary: Every year crops (such as rice, cotton, pigeon pea, sorghum, soyabean, groundnut, sugarcane and vegetables) are being damaged by pests and diseases. Due to lack of proper operational forecasting system for the incidences of pests and diseases, it becomes difficult to adopt efficient plant protection measures at the right time. It has been established with fair degree of accuracy that climate/weather plays major role in the incidences of pests and diseases. Thus, there is a tremendous scope of utilizing meteorological parameters for the advance information of the occurrences of the pests and diseases and ultimately scheduling of prophylactive measures can be taken scientifically and judiciously. Quite a number of studies in this regards have been made in the Agricultural Meteorology Division, India Meteorological Department (Pune, Maharashtra, India). In the present paper, a comprehensive review of the work done in this division on the impact of weather on pests and diseases of crops is presented. This information will probably help the agricultural community of the country to save the crops from the infestation of pest and disease incidences.
  • Authors:
    • NASDA
  • Year: 2004
  • Authors:
    • Skinner, D. Z.
    • Liang, G. H.
  • Year: 2004
  • Summary: This book contains chapters on: genetic transformation; mechanisms of transgene locus formation; gene stacking through site-specific integration; transgenics of plant hormones and their potential application in horticultural crops; avidin in transgenic maize; genetic engineering protocols and use to enhance stress tolerance in wheat; development and utilization of transformation in Medicago spp.; sorghum transformation for resistance to fungal pathogens and drought; current progress and future prospects in rice transformation; successes and challenges in cotton transformation; progress in transforming the recalcitrant soyabean; progress in vegetable crop transformation and future prospects and challenges; genetic transformation of turfgrass; and risks associated with genetically engineered crops.
  • Authors:
    • Riley, H.
    • Løes, A. K.
    • Brandsæter, L. O.
  • Source: European weed research society. Proceedings of the 6th EWRS workshop on physical and cultural weed control, Lillehammer, Norway, 8-10 March, 2004
  • Year: 2004
  • Summary: Due to official regulations, Norwegian agriculture is divided into cereal cropping areas with very little animal husbandry, and areas with high livestock density in the coastal and mountain regions. Stockless organic farming requires a good management of green manure crops. This paper presents crop rotations designed for organic farming with low livestock density, combining weed control and nutrient supply. Rotation 1 consists of green manure, followed by barley with subcropped legume, oats and peas, green manure or winter rye, rye, ryegrass-clover, and late planted rapeseed. Rotation 1 is designed for a full-time farmer with good access to cultivated land, where 66% of the land is used for cereals and rapeseed, and 34% for green manure. Rotation 2 consists of cereal or lettuce, followed by 4-5 rotations of ley, then potatoes, green manure, cabbage with early mulch, and carrots with late mulch. Rotation 2 is designed for a part-time farmer with less farmland who wants to keep the land in shape and produce some cash crops, but cannot manage to cultivate all the farmland intensively. Forty-four percent of the land is then used for vegetables and herbs, and 56% to produce mulch or green manure crops. Green manure and mulch leys must be cut regularly to control perennial weeds.