Physical Sciences and Mathematics Commons^™

Formulation Enhanced Transport Of A Soil Applied Herbicide, V. P. Evangelou, Louis M. Mcdonald, Sandra Prima

KWRRI Research Reports

Because pesticides are applied as formulated particles and the affinity of the active ingredient for the formulation is higher than for the bulk water, we hypothesized that a formulation complex could affect active ingredient transport. Our objectives were to investigate the nature and extent of surfactant-atrazine-clay/oxide surface interactions. When atrazine and an anionic surfactant were dried onto plain or Fe-coated sand and leached, atrazine concentrations in the initial leachate were lower in the Fe-coated sand treatment. This was likely due to an electrostatic attraction between the sand and surfactant. When a nonionic surfactant was used, atrazine concentration in the initial …

Potential Of Surface Water Contamination From Three Triazine Herbicides, William W. Witt, Kip W. Sander

KWRRI Research Reports

The movement of atrazine, cyanazine, and simazine from the site of application was monitored under conventional, reduced, and no-tillage conditions. Less water and soil was lost from the no-tillage and reduced tillage conditions. Conventional tillage conditions had about 66,000 L/ha runoff in 1986-87 and about 123,000 L/ha runoff in 1987-88. Seasonal rainfall was 885 mm in 1986-87 and 397 mm in 1987-88. The rainfall intensity was greater during the first two events in 1987 than the corresponding events in 1986. The first rainfall event in 1986 accounted for 91, 89, and 78% of the total seasonal loss of atrazine, cyanazine, …

Abatement Of Nitrate Pollution In Groundwater And Surface Runoff From Cropland Using Legume Cover Crops With No-Till Corn, M. Scott Smith, Jac J. Varco

KWRRI Research Reports

Agricultural practices can have a significant impact on water quality. The effects of leguminous winter cover crops on leaching of NO^-₃; from soil have been investigated in this project. Legume cover crops, by fixation of atmospheric N, can reduce the amount of fertilizer N required to produce summer grain crops. The methods initially used to evaluate cover crop effects on No; transport included suction probe lysimeters and measurement of NO^-₃; in soil samples collected to a depth of 90 cm. These measurements demonstrated extreme spatial variability in NO^-₃; distribution and water …

Simulating The Water Requirements And Economic Feasibility Of Corn In The Midwest, Wendi L. Palmer, B. J. Barfield, M. E. Bitzer, C. T. Haan

KWRRI Research Reports

An evaluation of the economics of supplemental irrigation when using a surface water supply must be site specific in order to account for variations in soil moisture holding capacity, watershed area supplying the runoff, climatic conditions, and proposed irrigation management procedures.

With the use of farm specific simulation models to determine grain yields, availability of irrigation water, and economic expenditures involved in irrigation, an economic evaluation of supplemental irrigation can be performed, In the model presented in this report, the Duncan SIMAIZ model is used to predict grain yields using long-term daily weather information. SIMAIZ also determines irrigation water demand …

Development Of Prediction Relationships For Water Requirements With Irrigation Cooling, Billy J. Barfield, John N. Walker, F. A. Payne

KWRRI Research Reports

A model for predicting leaf temperatures during an off-on mist cycle is presented. The model uses a combination of energy budget and aerodynamic techniques. The model was tested for dry leaf temperature and evapotranspiration predictions using average hourly data from Arizona. The accuracy was good. It was also tested for dry leaf temperature predictions using two to three minute data with a widely varying net radiation. When reasonable values of stomatal resistance were used, the agreement was again good.

The model was tested for prediction of wet leaf temperature prediction with a ten minute on, fifty minute off mist irrigation …

Part I - Controlling The Soil Moisture Environment Of Transpiring Plants, Part Ii - Prediction Of Leaf Temperature Under Natural Atmospheric Conditions, Charles T. Haan, Billy J. Barfield, Robert Edling

KWRRI Research Reports

Part I

A technique for controlling the soil moisture potential in the root zone of transpiring plants was developed. The method uses the principles of unsaturated flow through a porous media to develop the desired moisture potential. In the case of non-steady state transpiration, the maximum possible fluctuation in the soil moisture potential can be determined by the techniques presented.

Part II

Two implicit leaf temperature prediction equations were derived from the energy balance approach. The equations define sensible and latent heat transfer from a plant population as a two step process:

1. Transfer between the plant leaf and the canopy …