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United States Department of Agriculture

Agricultural Research Service

Title: Crop Rotation, Soil Water Content and Wheat Yields

item Nielsen, David

Submitted to: Conservation Tillage Fact Sheet
Publication Type: Other
Publication Acceptance Date: September 1, 2002
Publication Date: October 1, 2002

Interpretive Summary: Central Great Plains producers exhibit some reluctance to change from the traditional wheat-fallow (W-F)cropping system to systems of more frequent cropping and use of corn (C)and proso millet (M)in rotation with winter wheat. This fact sheet demonstrates and quantifies the impact that reducing tillage and intensifying cropping system has on wheat yield. Greater soil water content at wheat planting and higher wheat yields are associated with no-till W-F compared with conventional till W-F. There is no significant difference in water content at wheat planting or yield with either W-C-F or W-C-M compared with W-F no-till. Wheat yields are strongly influenced by amount of available soil water at planting, but in extremely dry years the yield response is only about 30% of the yield response seen in moderately dry, average, and wet years. These results suggest that producers need to monitor soil water at planting and adjust management plans to avoid uneconomical crop yields. Producers should have little concern regarding potentially lower wheat yields when moving from W-F to W-C-F or W-M-F.

Technical Abstract: Reduced and no-till dryland cropping systems in the central Great Plains have led to increased precipitation storage efficiency and more frequent cropping than the traditional wheat (Triticum aestivum L.)-fallow (W-F) system. Many producers express concern regarding the effect that more frequent cropping has on soil water content at wheat planting and subsequent yields. This fact sheet quantifies the effects of cropping system on soil water at winter wheat planting and subsequent grain yield. Data are presented from a study conducted over the 1993 through 2001 growing seasons at Akron, CO. Crop rotations evaluated were no-till systems of W-F, W-C-F, W-M-F, and W-C-M, and a W-F conventional till system. Use of conventional tillage resulted in 2.8 in less soil water at planting in the W-F systems. Lowest water content at planting (4.3 in) was found in the W-C-M system. Grain yields were correlated with soil water at planting according to the following relationships: bu/a = 5.56 + 5.34*in (moderately dry, average, and wet years); bu/a = 13.35 + 1.5*in (very dry years). Increasing cropping intensity to two crops in three years had little effect on water content at wheat planting and subsequent grain yield, while continuous cropping and elimination of the fallow period reduced soil water at planting by 4.4 in and yields by 6.7 to 24.6 bu/a, depending on growing season precipitation.

Last Modified: 4/1/2015
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