RT Journal Article SR Electronic T1 Resource-conserving crop rotations and the 1990 farm bill JF Journal of Soil and Water Conservation FD Soil and Water Conservation Society SP 145 OP 151 VO 47 IS 2 A1 Jeffery R. Williams A1 Penelope L. Diebel YR 1992 UL http://www.jswconline.org/content/47/2/145.abstract AB