Benefits and barriers to perennial forage crops in Iowa corn and soybean rotations

Abstract

The transition away from forage-based cropping systems in Iowa to corn and soybean rotations since World War II has corresponded with degraded economic and environmental conditions in the state. Falling net incomes for farmers and concern over global warming and the effects of agriculture-related pollution on water, wildlife and human health have increased interest in diversified cropping systems. This paper reviews the benefits of diversifying Iowa corn and soybean rotations with perennial forage species such as alfalfa and red clover. Perennial forage crops improve soil quality, decrease NO 3 -N leaching and soil erosion, increase carbon sequestration and decrease pesticide and herbicide needs by controlling weed and insect pests. Forage legumes reduce N fertilizer needs for succeeding corn crops at a higher rate than soybeans, and corn crops following forages have higher yields than after corn or soybeans. Farmers who add alfalfa to corn and soybean rotations could realize significant economic gains. A simulated 5-year rotation in Iowa including corn-soybeansoats/alfalfa-alfalfa-alfalfa would result in a 24% net income increase over 5 years of corn-soybean-corn-soybean-corn, even with government farm support payments for the row crops. Farm policies that encourage commodity production create little incentive for Iowa farmers to diversify their cropping systems beyond corn and soybeans, despite the clear economic and ecological benefits. We recommend increasing federal support for conservation programs that reward environmentally beneficial farm practices such as the Conservation Securities Program and we encourage land grant universities to hire researchers interested in alternative agricultural systems.

Review: Redesigning Canadian prairie cropping systems for profitability, sustainability, and resilience

“…Perennial crops are rotated with annual crops on 5Á15% of arable land in the NGP region . The benefits of perennial forages in rotation are well documented Olmstead and Brummer 2008). A key benefit of perennial forages in rotation is yield of annual rotation crops.…”

“…Perennial forages contribute to enhanced soil health and pest suppression, both of which can provide benefits to subsequent crops (Entz et al 2002 and references therein;Olmstead and Brummer 2008;Meiss et al 2010). Moisture availability is a major determinant of forage-related benefits, since moisture depletion by perennial forages can reduce yield of subsequent crops in dry regions ; however, no-till establishment and termination of perennial forage stands can allow their successful integration in more arid regions of the prairies (Jefferson et al 2007).…”

“…Their deep root systems are able to retrieve nutrients from subsoil, thus reducing nitrate leaching, and can sequester C deep in the profile Olmstead and Brummer 2008;Malhi et al 2009). Perennial forages also provide habitat for wildlife, in particular nesting birds and pollinators (Jefferson et al 1999;Carvell et al 2006;Arnold et al 2007).…”

Forage and Grasslands in a Sustainable Agriculture: New Challenges for Breeding

“…In the Midwestern US, for instance, maize and soybean production is supported by various governmental programs that are not available for alfalfa (or other forage) crops, such as federally subsidized crop insurance. As a consequence, even though alfalfa production is economically viable and environmentally desirable, the increased risk of producing the crop in the absence of government programs likely limits its inclusion in crop rotations (Olmstead and Brummer 2008 ).…”

Adoption potential of nitrate mitigation practices: an ecosystem services approach

“…Like wetlands, cover crops and perennial diversified crop rotations increase the diversity of vegetation within the landscape, but these two in-field approaches are able to retain nutrients in the field (Dinnes et al 2002, Kaspar et al 2008, Olmstead and Brummer 2008. In terms of N load reduction, the three engineered, structural practices have been estimated to have mean removals on the order of 33-52% (Christianson 2011, ISU 2013.…”