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CropFlex is a management system for irrigated crops. The goal of CropFlex is to provide irrigation and fertility management advice to assist farmers in maintaining or increasing yields while minimizing the potential of leaching nitrates.


The United States Department of Agriculture/Natural Resources Conservation Service (USDA/NRCS) National Water Management Center (NWMC) and the University of Arkansas at Pine Bluff (UAPB) have had a strong partnering effort since the inception of the Water Management Center. One of the recent activities in this partnership is the CropFlex evaluation being conducted in 2000 and 2001.

CropFlex is a computer software program that consists of four components:
1. Irrigation Scheduler
2. Fertility Scheduler
3. Yield Prediction Model
4. Leaching Model

The purpose of the Irrigation Scheduler is to recommend the amount and timing of irrigation applications. The irrigation scheduler uses a soil/water mass balance to calculate the soil moisture within the crop root zone for every day of the growing season. The amount of water used by the crop is calculated from reference evapo-transpiration methods. It then uses pre-set, critical soil moisture depletion levels to determine if the current soil moisture is dry enough to warrant irrigation.

Julius Handcock prepares to irrigate Cropflex corn plot

The Fertility Scheduler provides nitrogen, phosphorus and potassium nutrient recommendations. It tells the user when to fertilize and how much fertilizer to apply in order to supply the crop's nutrient needs. The fertility scheduler uses a series of different methods to arrive at its conclusions, including: the Colorado State University soil test method, the Nebraska soil test method for corn, the inorganic nitrogen mass balance, or crop uptake efficiency methods.

The Yield Prediction Model predicts the end of season yield based on the number of Growing Degree Days (GDD) in the first few weeks of the season. This tool is used for the midseason fertilizer recommendation corrections and it is available only for corn.

Inspection of corn plant to determine its growth stage

The Leaching Model assesses the amount of nitrate leached under the proposed irrigation and fertility management scheme. It provides an analysis of the nitrate leaching implications of the proposed management strategy. It also estimates the yield reduction sustained if the nitrogen fertilizer is reduced to eliminate the leaching problem.

Activities in 2000

This year the CropFlex is being evaluated on corn and soybeans. Climate data from the adjacent SCAN site is being entered into CropFlex on a daily basis to determine irrigation timings. The yield results from the CropFlex plots will be compared to the yield results of plots which have been managed by our "human expert".

To download CropFlex:
Science and Technology Conservation Tools Software

To access SCAN data:

Contact Information:
National Water Management Center
101 East Capitol Avenue, Suite B-100
Little Rock, Arkansas 72201-3811
Phone: 501-210-8900
Fax: 855-681-7079


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