Jason Gilb

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School



Dryland crop production in western South Dakota is often limited by a lack of water. Traditionally, a wheat-fallow cropping system was used to increase water availability in the wheat year and reduce risk. No-till systems reduce water loss from evaporation and runoff without a fallow year and have been used to replace wheat-fallow systems. More intensive and flexible crop rotations are being adopted for no-till. Producers need information about crop yield response in different climatic scenarios, and the probability of receiving given amounts of timely precipitation to minimize the risk for intensive crops. Sampling was conducted at Bison, Highmore, Ralph, Selby, Pierre, and Wall, SD. on rotational and crop performance test sites. Barley (Hordeum vulgare L.), canola (Brassica napus L.), corn (Zea mays L.), field peas (Pisum sativum L.), oats (Avena sativa L.), proso millet (Panicum miliaceum L.), safflower (Carthamus tinctorius L.), soybean (Glycine max Merrill), sunflower (Helianthus annus L.), spring wheat (Triticum aestivum L.), and winter wheat were examined. Crops were analyzed for yields, water used, and water use efficiencies. Spring seeded crops in rotations with optional agronomic practices had higher yields and water use efficiencies with little or no effect on initial soil water content due to the previous crop. However when system water use efficiencies were calculated the more intense and diverse rotations had greater water use efficiencies than the winter wheat-fallow systems. This supports the concept of introducing more intense and diverse rotations in western South Dakota. The collected field data was also used to calibrate and verify the Environmental Policy Integrated Climate (EPIC) computer model for each crop. EPIC had some difficulties in accurately simulating annual crop years, but was better at simulating long term mean crop yields. Since EPIC was found to be suitable for long term simulations it was used to create a crop risk management tool for western South Dakota. A crop risk management tool was developed to evaluate crop production under conventional tillage, minimum tillage, and no-till with different levels of residue and beginning soil moisture based on long term weather patterns. The tool was developed using ten different crops for three different regions in western South Dakota and can be used as an aide in determining crop risk.

Library of Congress Subject Headings

Crops and water -- South Dakota
Arid regions agriculture -- South Dakota
Crop yields -- South Dakota -- Computer simulation
Soil moisture -- South Dakota



Number of Pages



South Dakota State University