Robert W. Hill

Best management of pesticide/furrow irrigation systems

SummaryEffects of furrow irrigation designs, water management practices (irrigation scheduling, etc.), soil types and pesticide parameters on pesticide leaching were simulated. A hydraulic kinematic-wave irrigation model was used to estimate water infiltration for alternative furrow lengths and inflow rates. A one-dimensional simulation model then simulated the movement of pesticides through soils following furrow irrigation. Potential ground-water contamination by pesticides can be reduced by an integrated use of the best management practices (BMPs) such as careful selection and use of pesticides, efficient furrow irrigation designs and improved water management techniques (irrigation scheduling, etc.). Procedures for designing an appropriate furrow irrigation system for a particular site and pesticide, and selecting pesticides for a particular site, crop and furrow irrigation system are illustrated. These procedures are being used to develop decision support computer models for developing different BMPs for pesticide-agricultural management decisions.

Irrigation scheduling and cantaloupe yield model for the Jordan Valley

Abstract A crop yield and soil water management simulation model (CRPSM) developed at Utah State University was modified and calibrated using data from a trickle irrigation experiment with different mulched treatments on cantaloupe ( Cucumis melo L.) in the Jordan Valley. The soil water budget model was adapted to the field conditions through input describing rooting depth, field capacity, wilting point and wet soil surface air-drying characteristics. Observed field crop growth progress was used for the models phenology clock. Calibration of the yield model was accomplished by adjusting model parameters to obtain a reasonable match between model and field yields. Simulated possible irrigation schedules were tested using different options provided by the model. By using 1.5 cm per irrigation for a total of 44 to 47 irrigations and starting the first instead of the last of April, simulated yields were about double what was actually obtained in the field. This indicates that the date of first irrigation as well as total water applied is important for maximizing yield. Plants in the field were apparently subjected to water stress prior to late April when irrigation was initiated. The use of the CRPSM model could reduce the number of plots needed in further field experimentation since the less successful possibilities could be identified by simulation. Thus, field efforts can be concentrated on treatments most likely to provide higher yields with improved irrigation management.

SPRINKLER IRRIGATION­ PESTICIDE BEST MANAGEMENT SYSTEMS

The relative reduction in potential groundwater contamination due to pesticides at several sites in Utah was determined by comparing alternative irrigation system designs, water management practices, and pesticides.

A model to evaluate intensive vs. extensive irrigation practices for irrigated rice production system in Bangladesh

Abstract A model was developed to evaluate the effects of intensive versus extensive irrigation strategy for rice cultivation in the Ganges-Kobadak Irrigation Project, Bangladesh. The model application indicates that for most tertiary canals in the project, the respective service areas can not be intensively irrigated in either of the two main rice seasons (Aus and Aman) without significantly increasing canal flows. The model-estimated irrigated areas by tertiary canals were in close agreement with actual values for both the Aus (early summer) and Aman (autumn) rice seasons. However, the agreement was better for the Aus season than for the Aman season which received much more rainfall. The model can be used for determining irrigation water allocation and distribution targets for various parts of a rice irrigation system for given flows under different field water management conditions.