PT  - JOURNAL ARTICLE
AU  - W. W. Frye
AU  - R. L. Blevins
TI  - Economically sustainable crop production with legume cover crops and conservation tillage
DP  - 1989 Jan 01
TA  - Journal of Soil and Water Conservation
PG  - 57--60
VI  - 44
IP  - 1
4099  - http://www.jswconline.org/content/44/1/57.short
4100  - http://www.jswconline.org/content/44/1/57.full
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.