RT Journal Article
SR Electronic
T1 Economically sustainable crop production with legume cover crops and conservation tillage
JF Journal of Soil and Water Conservation
FD Soil and Water Conservation Society
SP 57
OP 60
VO 44
IS 1
A1 W. W. Frye
A1 R. L. Blevins
YR 1989
UL http://www.jswconline.org/content/44/1/57.abstract
AB A legume cover crop, when used to create a mulch in conservation tillage, reduces runoff and evaporation of water and increases soil organic matter, soil N, water infiltration, and water use efficiency. A live legume cover crop depletes soil water in the spring by 3 to 5 percentage points below that of a soil without a cover crop. Within about 2 weeks after kill-down of the cover crop, however, the soil water content usually becomes appreciably greater under the mulch of the cover crop. The N supplied by a legume cover crop usually is not sufficient to meet the needs of a corn crop, but fertilizer N use can be reduced somewhat while maintaining optimum grain yields. Often, grain yield response to N fertilizer is greater with a legume cover crop than without one. This has been attributed variously to increased soil water efficiency, improved weed control, and the rotation effect. In a Kentucky study, grain yields with a hairy vetch mulch and 100 kg/ha (89 pounds/acre) N steadily increased at an average rate of about 500 kg/ha/yr (8 bushels/acre/year), relative to winter fallow and 100 kg/ha N. These higher yields help to make the use of legume cover crops with conservation tillage economically feasible and this form of row-crop agriculture more sustainable.