A survey of CRP land in Minnesota: I. Legume and grass persistence

The federal Conservation Reserve Program (CRP), which had goals including reduced soil erosion and increased wildlife habitat, funded diversion of land from annual crops into permanent vegetation. The survival of grasses and legumes planted in CRP fields was not known. Our objectives were to assess the persistence and coverage of grasses and legumes in 6- to 8-yr-old CRP fields and to determine changes in soil pH, P, and K levels. We studied 151 CRP fields chosen from 10 counties in four geographical regions of Minnesota: 108 in the conservation practice 1 (CP-1) cover type (planted cool-season perennial grasses and legumes); 17 in the CP-2 cover type (planted warm-season native grasses); and 26 in the CP-10 cover type (existing vegetation). Statewide, legumes persisted in 82% of CP-1 fields planted to legumes, with 23% groundcover. Grasses persisted in 90% of the planted CP-1 fields with 47% groundcover. Alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.), the most persistent legumes, persisted in 90 and 67% of the planted fields with 21 and 32% groundcover, respectively. Smooth bromegrass (Bromus inermis Leyss), reed canarygrass (Phalaris arundinacea L.), and switchgrass (Panicum virgatum L.) persisted in over 90% of the planted fields and had 50% groundcover or more. Other legumes and grasses persisted in 50% or less of the planted fields and had 10% groundcover or less. To maintain legumes in CRP fields, clipping is required or cultivars should be developed that persist without defoliation. Generally, soil pH, P, and K levels did not change from initial to final samples and should be adequate to obtain low levels of forage production.