Monday, 7 November 2005 - 2:30 PM
102-3

Dynamic Cropping Systems for Effective Use of Soil Water.

Stephen D. Merrill, Donald L. Tanaka, Joseph M. Krupinsky, Mark A. Liebig, and Jonathan D. Hanson. USDA-ARS, North Great Plains Research Laboratory, 1701 10th Ave., S.W., Mandan, ND 58554

The principles of dynamic cropping systems require that producers consider climatic, market, ecological, and other factors on an annual basis in making crop choices. One of the factors that must be considered in dryland management is that the different amounts of water depleted from the soil by different crops can impact following crops. May-to-September soil water depletion was determined over 1.8 m of soil depth by neutron moisture meter for 3 years in a crop sequence project. The experiment consisted of a 10 x 10 species biennial matrix under no-till management on Haploboroll soil and land in central North Dakota. Crops depleted soil water in the following order, from highest to lowest: sunflower, maize, sorghum, spring wheat, canola, buckwheat, proso millet, chickpea, lentil, and dry pea. On average, sunflower depleted 8.1 cm more soil water than dry pea. Sunflower left the least amount of water in the soil the next spring, dry pea the most – 4.0 cm more than sunflower. Superior overwinter snow capture by 4th highest water-depleting spring wheat caused it to rank 2nd only to dry pea in spring soil water, 3.9 cm greater than sunflower. High seasonal water depletion by sunflower has been observed in our experiment and also by area producers to have negative effects on following crops under relative drought.


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