A pesticide transport submodel has been incorporated into a distributed parameter simulation model. AGNPS (AGricultural NonPoint Source Pollution Model) can evaluate the effect of agricultural pollution sources on surface runoff. Six pesticide classes are used: herbicides, insecticides, fungicides, nematicides, plant growth regulators, and desiccants/defoliants. User inputs for the model include the time of pesticide application (preplant, preemergence, or postemergence), application rate, application efficiency, percent canopy cover, soil and foliar pesticide residues, soil and foliar pesticide decay, water solubility, foliar washoff threshold and fraction, incorporation depth and efficiency, and sorption coefficient. Areas of pesticide losses and accumulations are indicated in tabular and graphical outputs. Alternative management practices can be simulated, and therefore assist in the optimization of practices to reduce pesticide runoff.
Dan James Pantone and Robert A. Young
Dan J. Pantone and Robert A. Young
Nonpoint-source pesticide pollution from horticultural and other agricultural activities is a primary factor determining the quality of surface water. A menu-driven, interactive pesticide transport submodel has been developed for the agricultural nonpoint-source (AGNPS) pollution model. AGNPS simulates the surface transport of pesticides, sediment, and water from the headwaters to the outlet in a stepwise manner so that an assessment can be made at any point within a watershed boundary. The model can be used by farmers, agricultural extension agents, agrichemical industry workers, or researchers to develop agricultural activities that minimize the surface transport of pesticides. This user-friendly pesticide transport model is available at no cost to users through the Internet.
Roland E. Roberts, David A. Bender, Jackie Smith, and Stanley Young
A market window for onion occurs when f.o.b. prices are above grower break-even price for a period of 4 to 6 weeks. Market windows were calculated to occur from late June to early August and from early October through December for northwest Texas onions. Five-year average prices ranged from $6.25 to $7.40 (1990–94), and a breakeven price of $5.38/50-lb sack was calculated from an analysis of total costs of production and marketing and historic yields. Ongoing research and grower demonstrations with advanced breeding lines, commercial cultivars, and selections from yellow, white, and red cultivars have defined certain cultivars that display superior attributes and mature within the market window. Superior cultivars adapted to the first market window include XPH-87N60, `Sunre 1445', `Sunre 1462', `Yula', `Spano', `Cimarron', `Riviera', `Utopia', and `Alabaster'. Superior cultivars adapted to the second market window include `Sweet Perfection', `Sterling', `Vega', `Bravo', `Capri', `Vaquero', `El Charro', `Quest', `Shasta', and `Vision'. `Vaquero', `Sunre 1462', `Sunre 1445', `El Charro', and `Viceroy' have potential for short-term storage for October to December markets.