Alfalfa stand length and subsequent crop patterns in the upper midwestern United States

Alfalfa (Medicago sativa L.) can provide many economic and environmental benefits to crop rotations. Our objectives were to quantify alfalfa stand lengths, identify the two crops following alfalfa, and determine the soil and temporal factors affecting them. The USDA-National Agricultural Statistics Service (NASS) Cropland Data Layers (CDLs) for 2006 to 2012 and USDA-NRCS soil survey layers for North Dakota, South Dakota, Nebraska, Minnesota, Iowa, and Wisconsin were combined and used to meet these objectives. Location and soil textural class generally determined stand length, with alfalfa being kept in production longer outside the major Corn Belt area of this region. Soil textural class effects on stand length varied by state. Corn (Zea mays L.) was the most common crop planted during the first- and second-year following alfalfa (79 and 61%, respectively), except in North Dakota (35% both years). Soybean [Glycine max (L.) Merr.] was grown in 11 and 28% of cases, respectively. Small grains were planted as the first-year crop in 29% of cases in the Dakotas and 6% of cases in the other four states. As a second-year crop, small grains occurred in 26% of cases in North Dakota and 5% of cases in the other five states. Stand length, soil textural class, state, and year significantly influenced grower choice of both following crops. These geographic assessments will guide research and extension education designed to increase use of perennials for economic and environmental benefits. Similar methods can be applied to other crop rotations or U.S. regions.