• Authors:
    • Jacobsen, J. S.
    • Jones, C. A.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 34
  • Issue: 13/14
  • Year: 2003
  • Summary: Granular phosphorus (P) fertilizers are often treated with coatings, such as oil or wax, to decrease dust production during packaging, shipping, storage, and spreading. Unconfirmed reports from the field suggest these coatings may negatively impact plant response to applied P fertilizers. A three-phase study was conducted in Montana, USA to determine if these coatings significantly affect P dissolution rates, soil P test levels, P uptake, or yield. Coated and uncoated monoammonium phosphate granules were obtained from two fertilizer manufacturers. In Phase I, fertilizer dissolution rates in water were measured for fertilizer application rates representing both irrigated and dryland conditions. In Phase II, dissolution rates were evaluated in an acid-washed sand at two moisture contents. In Phase III, Olsen P, P uptake, and dry biomass in maize ( Zea mays) were measured in a low pH and high pH soil for both broadcast and incorporated fertilizer applications. Dust control coatings did not significantly decrease dissolution rates, Olsen P levels, P uptake amounts, or biomass for any of the treatments or at any time. In a small percentage of comparisons, coatings significantly increased solubility, Olsen P levels, P uptake, or biomass; although, in general, coatings caused no significant differences in these parameters.
  • Authors:
    • Thornton, P. K.
    • Jones, P. G.
  • Source: Conservation Ecology
  • Volume: 5
  • Issue: 2
  • Year: 2003
  • Summary: Making decisions in natural resource management involves an understanding of the risk and uncertainty of the outcomes, such as crop failure or cattle starvation, and of the normal spread of the expected production. Hedging against poor outcomes often means lack of investment and slow adoption of new methods. At the household level, production instability can have serious effects on income and food security. At the national level, it can have social and economic impacts that may affect all sectors of society. Crop models such as CERES-Maize are excellent tools for assessing weather-related production variability. WATBAL is a water balance model that can provide robust estimates of the potential growing days for a pasture. These models require large quantities of daily weather data that are rarely available. MarkSim is an application for generating synthetic daily weather files by estimating the third-order Markov model parameters from interpolated climate surfaces. The models can then be run for each distinct point on the map. This paper examines the growth of maize and pasture in dryland agriculture in southern Africa (includes the southern part of Tanzania, Malawi, much of Mozambique, and all of Zimbabwe, and extends west from the Indian Ocean to include Zambia, the southeastern part of the Democratic Republic of Congo and small portions of Angola). Weather simulators produce independent estimates for each point on the map; however, we know that a spatial coherence of weather exists. We investigated a method of incorporating spatial coherence into MarkSim and show that it increases the variance of production. This means that all of the farmers in a coherent area share poor yields, with important consequences for food security, markets, transport, and shared grazing lands. The long-term aspects of risk are associated with global climate change. We used the results of a global circulation model to extrapolate to the year 2055. We found that low maize yields would become more likely in the marginal areas, whereas they may actually increase in some areas. The same trend was found with pasture growth. We outline areas where further work is required before these tools and methods can address natural resource management problems in a comprehensive manner at local community and policy levels.
  • Authors:
    • Thottappilly, G.
    • Loebenstein, G.
  • Source: Virus and virus-like diseases of major crops in developing countries
  • Issue: xlvii + 800 pp
  • Year: 2003
  • Summary: This book is a comprehensive up-to-date treatise on virus and virus-like diseases of the major crops (cassava, potatoes, sweet potato, yam, rice, maize, sorghum, other cereal crops, cowpea, soyabean, groundnut, common bean, other legumes, banana, pawpaw, cocoa, sugarcane, coconut, palm trees, citrus, tomato, cucurbits, other vegetables, cotton, sunflower and spices) in developing countries and their detection, isolation, biological and molecular characterization, transmission and possible approaches for their control. Also included are chapters on the general impact of these diseases, epidemiology, quarantine and technology transfer.
  • Authors:
    • Blumenthal, J. M.
    • McLean, G. B.
    • Hammer, G. L.
    • Lyon, D. J.
  • Source: Agronomy Journal
  • Volume: 95
  • Issue: 4
  • Year: 2003
  • Summary: In a 2-yr multiple-site field study conducted in western Nebraska during 1999 and 2000, optimum dryland corn ( Zea mays L.) population varied from less than 1.7 to more than 5.6 plants m -2, depending largely on available water resources. The objective of this study was to use a modelling approach to investigate corn population recommendations for a wide range of seasonal variation. A corn growth simulation model (APSIM-maize) was coupled to long-term sequences of historical climatic data from western Nebraska to provide probabilistic estimates of dryland yield for a range of corn populations. Simulated populations ranged from 2 to 5 plants m -2. Simulations began with one of three levels of available soil water at planting, either 80, 160, or 240 mm in the surface 1.5 m of a loam soil. Gross margins were maximized at 3 plants m -2 when starting available water was 160 or 240 mm, and the expected probability of a financial loss at this population was reduced from about 10% at 160 mm to 0% at 240 mm. When starting available water was 80 mm, average gross margins were less than $15 ha -1, and risk of financial loss exceeded 40%. Median yields were greatest when starting available soil water was 240 mm. However, perhaps the greater benefit of additional soil water at planting was reduction in the risk of making a financial loss. Dryland corn growers in western Nebraska are advised to use a population of 3 plants m -2 as a base recommendation.
  • Authors:
    • Hubbard, K. G.
    • Mahmood, R.
  • Source: Journal of Hydrology
  • Volume: 280
  • Issue: 1/4
  • Year: 2003
  • Summary: Soil moisture (SM) plays an important role in land surface and atmospheric interactions. It modifies energy balance at the surface and the rate of water cycling between the land and atmosphere. In this paper we provide a sensitivity assessment of SM and ET for heterogeneous soil physical properties and for three land uses including irrigated maize, rainfed maize, and grass at a climatological time-scale by using a water balance model. Not surprisingly, the study finds increased soil water content in the root zone throughout the year under irrigated farming. Soil water depletes to its lowest level under rainfed maize cultivation. We find a 'land use' effect as high as 36 percent of annual total evapotranspiration, under irrigated maize compared to rainfed maize and grass, respectively. Sensitivity analyses consisting of comparative simulations using the model show that soil characteristics, like water holding capacity, influence SM in the root zone and affect seasonal total ET estimates at the climatological time-scale. This 'soils' effect is smaller than the 'land use' effect associated with irrigation but, it is a source of consistent bias for both SM and ET estimates. The 'climate' effect basically masks the 'soils' effect under wet conditions. These results lead us to conclude that appropriate representation of land use, soils, and climate are necessary to accurately represent the water and energy balance in real landscapes.
  • Authors:
    • Kasha, K. J.
    • Maluszynski, M.
    • Forster, B. P.
    • Szarejko, I.
  • Source: Doubled haploid production in crop plants: a manual
  • Year: 2003
  • Summary: This manual presents a set of protocols for the production of doubled haploid plants in 22 major crops species including 4 tree species, and includes protocols from different germplasm of the same species. The crops covered include barley, wheat, maize, rice, triticale, rye, oats, durum wheat, timothy grass ( Phleum pratense), ryegrass ( Lolium), rape, broccoli, tobacco, potato, flax/linseed, sugarbeet, asparagus, onion, apple, poplar, cork oak ( Quercus suber), and citrus. All steps of doubled haploid production are detailed from donor plant growth conditions, through in vitro procedures, media composition and preparation, to regeneration of haploid plants and chromosome doubling methods. The practical protocols are supplemented with a list of published protocols for other crop plants, and separate chapters deal with major application of doubled haploids in breeding, mutant production, transgenesis, genetic mapping and genomics.
  • Authors:
    • Norman, J. M.
    • Morgan, C. L. S.
    • Lowery, B.
  • Source: Soil Science Society of America Journal
  • Volume: 67
  • Issue: 2
  • Year: 2003
  • Summary: The variability of crop yield in dryland production is primarily affected by the spatial distribution of plant-available water even for seemingly uniform fields. The most productive midwestern soils, which are loess caps over glacial till or outwash, can have a wide range of water-holding capacities in individual fields because of landscape processes and management. An inverse yield model was created as a robust method to quantify the spatial and temporal role of plant-available water on large agricultural fields to improve management options in precision agriculture. Plant-available water maps for a field were estimated from yield maps using inverse water-budget modeling based on measurements of solar radiation, temperature, precipitation, and vapor pressure deficit. The model presented in this paper was applied to 5 yr of corn ( Zea mays L.) yield-monitor data from a field in Waunakee, WI, having three soil mapping units, Plano silt loam (fine-silty, mixed, mesic Typic Argiudoll), St. Charles silt loam (fine-silty, mixed, mesic Typic Hapludalf), and Griswold loam (Fine-loamy, mixed, mesic Typic Argiudoll). The comparison of measured and inverse-modeled plant-available water suggests that the simple inverse yield model produces reasonable results in drier years with uncertainties of about 28 mm of plant-available water. The model helped to quantify the role of plant-available water in determining crop yield. Because of limited input requirements, the model shows promise as a practical tool for using precision farming to improve management decisions, and as a tool to obtain input for landscape-based models.
  • Authors:
    • Tope, K. L.
    • Gaddis, S. E.
    • Petersen, B. E.
    • Sterner, R. T.
    • Poss, D. J.
  • Source: Crop Protection
  • Volume: 22
  • Issue: 4
  • Year: 2003
  • Summary: During 2000-2001, small mammals, birds, and potential corn/soybean damage were studied at a low-tillage, non-irrigated agricultural research site in the Colorado Piedmont. A small mammal survey involved four trapping sessions and 18, 12-live-trap grids each. Within years, two grids each were placed at random, fixed locations in experimental corn, fallow, millet, pea, soyabean, sunflower, and wheat plots at the site; two off-plot grids each were set at random, fixed locations
  • Authors:
    • Ostergard, H.
    • Pedersen, S.
    • Kjellsson, G.
    • Holm, P. B.
    • Gylling, M.
    • Buus, M.
    • Boelt, B.
    • Andersen, S. B.
    • Tolstrup, K.
    • Mikkelsen, S. A.
  • Source: DIAS Report, Plant Production
  • Issue: 94
  • Year: 2003
  • Summary: The paper focuses on the possible sources of dispersal (cross pollination, seed dispersal, vegetative dispersal, dispersal by farming machinery, dispersal during handling and transport) from genetically modified crop production to conventional and organic production, the extent of dispersal and the need for control measures, and the possible control measures for ensuring the co-existence of genetically modified production with conventional and organic production systems. Specific sections are provided on the crops currently genetically modified in Denmark or likely to be within the next few years (oilseed rape, maize, beet, potatoes, barley, wheat, triticale, oats, rye, forage and amenity grasses, grassland legumes, field peas, faba beans and lupins, and vegetable seeds). Brief discussions on the legislation, seed production, monitoring and analytical methods used, and measures to ensure crop purity (such as reducing pollen dispersal, reducing seed dispersal, adopting cultural methods reducing pollen and seed dispersal) are also presented.
  • Authors:
    • Huang, D. L.
    • Dai, Z. Y.
    • Liang, G. W.
    • Pang, X. F.
    • Yang, Y. Z.
  • Source: Journal of Yangzhou University, Agricultural and Life Sciences Edition Issue: 2
  • Volume: 24
  • Issue: 2
  • Year: 2003
  • Summary: The development of cotton bollworm (H. armigera) fed with different host foods was investigated. Higher values for pupal weight and eggs per female were recorded for the cotton bollworms fed with pea and soyabean leaves, compared with those fed with aubergine fruit and groundnut leaf. The rate larval development was highest with pea leaf, followed by maize fruits, and lowest for cotton leaf, flower, bud and boll. Based on values of the index of population trend, the preference of the cotton bollworm to different host foods were as follows: pea > soyabean > maize > Chinese sorghum > cotton > groundnut > aubergine. The results of a study of the dynamics of the cotton bollworm population in a cotton field in China are presented.