Potential of Forages to Diversify Cropping Systems in the Northern Great Plains

Abstract

Cultivated forage crops are grown on almost 12 million ha on the northern Great Plains. This paper reviews the benefits of diversifying annual crop rotations with forage crops and highlights innovations in forage systems. Agronomic benefits of rotating forage crops with annual grain crops include higher grain crop yields following forages (up to 13 yr in one study), shifts in the weed population away from arable crop weeds, and improved soil quality. Perennial legumes in rotation also reduce energy requirements by adding significant amounts of N to the soil. Soil water availability may limit the extent to which forages benefit following crops. Under semiarid conditions, forages can actually reduce yields of the following crops, and as such, tillage practices that conserve soil water have been developed to partially address this problem. Forages in rotation provide environmental benefits, such as C sequestration, critical habitat for wildlife, and reduced NO3 leaching. A wider range of annual plant species are now used in forage systems in an effort to extend the grazing season and to maximize use of water resources. Intensive pasture management using cultivated forages is on the increase as is the use of alfalfa (Medicago sativa L.) in grazing systems; in some cases, bloat‐reduced alfalfa cultivars are used. Pasture‐based systems appear to provide benefits for both animal and human health and arguably the health of the environment. Pasture systems are less nutrient exhausting than hay systems. As a result, nutrient management strategies will differ in the following crop. Additional research is required to optimize the role of cultivated pastures in grain‐based cropping systems.

Grazing Management Effects on Sediment and Phosphorus in Surface Runoff

“…Soil losses from forage systems are generally low (Gard et al 1943) because of improved soil structure (Entz et al 2002), increased soil microporosity (McDowell et al 2003), rainfall infiltration (Alderfer and Robinson 1947), protection of soil surface from raindrop impact (Pearce et al 1998), and filtration of sediment from surface runoff (Pearce et al 1998). Despite the benefits associated with forage production systems, several reports have implicated livestock grazing in the degradation of surface water quality (CAST 2002;Gillingham and Thorrold 2000).…”

Impact of Climate Change Adaptation Strategies on Winter Wheat and Cropping System Performance across Precipitation Gradients in the Inland Pacific Northwest, USA

“…Crop intensification, diversification, reduced tillage, and variable N management are among the strategies proposed to mitigate and adapt monocultures to projected climate shifts (Burney et al, 2010;Smith and Olesen, 2010;Tilman et al, 2011;Powlson et al, 2014;Ponisio et al, 2015). Diversifying crop options may increase the resiliency of agroecosystems (Lin, 2011) and stabilize cropping systems vulnerable to a changing climate (Altieri et al, 2015) through agronomic (Johnston et al, 2005;Kirkegaard et al, 2008;Hansen et al, 2012;Seymour et al, 2012;Cutforth et al, 2013;Angus et al, 2015), economic (Entz et al, 2002;Zentner et al, 2002bZentner et al, , 2004, and environmental Gan et al, 2011;Davis et al, 2012) benefits. In the summer-dominate precipitation region of the North American Great Plains, soil conservation practices have enabled crop intensification through fallow replacement (Lafond et al, 1992;Anderson et al, 2003), which has increased opportunities to diversify crops (Halvorson et al, 1999;Zentner et al, 2002b;Tanaka et al, 2005;Roberts and Johnston, 2007), enhance N and water use efficiencies (Pikul et al, 2012).…”

The Sustainability of Organic Grain Production on the Canadian Prairies—A Review

“…The use of perennial forage crops such as alfalfa, in crop rotations, has been reported to markedly reduce weeds in the following year [31]. Cover cropping (planting generally leguminous crops in lieu of fallow), underseeding (planting nurse leguminous crops with grains) and the use of green manures (plowing in cover crops) are cropping strategies of potential value for organic grain production, as they represent non-chemical methods for controlling weeds and improving soil quality [32].…”

“…Conversely, Malhi et al [34] did not observe a consistent effect of crop diversity on extractable P under organic management, even though P tended to be lower under organic management than under reduced or high input conventional management. Despite the more rapid P depletion under forage-grain rotations, there are a number of potential benefits of including forage crops in rotation, such as increased grain yield following the forage crop, enhanced weed suppression, nitrogen fixation, and carbon sequestration [31]. Such studies highlight the challenges of balancing rotational strategies for maintaining soil quality with overall productivity and grain yield.…”

“…The use of manure from conventional sources is permitted by Canadian organic standards provided no organic source is available and it meets certain conditions [61], but critics have voiced concerns about the presence of antibiotics and other contaminants from conventionally-raised livestock [71]. Recently, there has been renewed interest in integrated crop-livestock systems [72], which could help mitigate the P depletion issue on organically managed land while maximizing the rotational benefits of forages for both grazing and subsequent grain production [31]. In fact, it has been suggested that such an integrated approach may be key to the longterm sustainability of organic grain production on the Canadian Prairies [73].…”