Dr. Wiedenfeld conducts research in soil fertility and plant nutrition, water management and crop production systems in the Lower Rio Grande Valley of Texas. Areas of study include sugarcane fertilization; sugarcane water use and irrigation management; residue management practices for sugarcane; conservation tillage and crop production systems; citrus fertilization practices; and vegetable fertilization.
Numerous challenges face the sugarcane industry in the U.S. With urbanization, water availability is declining. Burning of the crop before harvesting is becoming increasingly socially unacceptable. Efficiently meeting crop nutrient requirements without contaminating drainage waters is always a challenge. Field studies are being conducted to monitor sugarcane water use in order to develop efficient irrigation recommendations; to evaluate the effects of harvesting methods and develop production practices to accommodate high residue loads; and to develop fertilization practices which efficiently meet crop nutrient needs while minimizing waste and potential contamination of drainage waters.
Tillage systems, cover crops and double cropping effects on water use
Conservation tillage is being adopted throughout the U.S. for benefits such as lower cost, improved soil physical properties and improved soil moisture retention. Due to limited availability of irrigation water and increasing production costs, there is a need to determine whether similar benefits could be achieved in the suptropical South Texas. Early studies in South Texas show only slight improvement in soil properties with conservation tillage, while fall cover crops and double cropping result in increased water use.
Citrus and vegetable fertilization
Elaborate fertilization programs are often used in order to supply the nutritional requirements of citrus and vegetables, yet little objective scientific information is available to establish the effectiveness of many such programs. Studies are being conducted to evaluate various programs and products including foliar applications, micronutrient and controlled release products. Results thus far indicate that the primary nutrient input required is nitrogen, and that much of the requirement for this nutrient can be provided by residual in the soil, thus lowering fertilization requirements. Excess N application decreases fruit qualities.