Enhancing Grain Production of Great Plains Cropping Systems with a Legume-Pasture Phase

View the project final report

• 2002 annual report

Commodities

• Agronomic: wheat
• Animals: bovine

Practices

• Animal Production: feed/forage
• Crop Production: agroforestry, no-till, application rate management
• Education and Training: demonstration, extension
• Farm Business Management: new enterprise development
• Production Systems: agroecosystems, integrated crop and livestock systems

Pasture-based cropping systems were demonstrated to approximately 200 commercial producers in the northern Great Plains. No adverse effects occurred on subsequent grain crops when shallow-rooted legume species were used for pasture. Interest in birdsfoot trefoil as a non-bloating alternative to alfalfa was generated. Results of this project along with related studies and a discussion forum can be accessed on the web at http://www.ag.ndsu.nodak.edu/dickinso, beginning on April 1, 2004. A working group of farmers and ranchers, extension educators, and agricultural scientists was formed to extend results of the project so that methods for developing pasture-based cropping systems on commercial operations are developed.

Introduction:

Negative economic returns are projected for many annual grain and seed crops grown in the Great Plains. Among selected crops grown in southwestern North Dakota, for example, returns to labor and management were projected by Swenson and Haugen (2000) to be -$36/acre (-89/ha) for spring wheat (Triticum aestivum L. emend. Thell) following summerfallow and -$14/acre (-$35/ha) when grown annually, -$15/acre (-$37/ha) for canola (Brassica napus L.), -43/acre (-$106/ha) for grain corn (Zea mays L.), -$7/acre (-$17/ha) for pea (Pisum sativum L. subsp. sativum), and -$6/acre (-$15/ha) for oil-type sunflower (Helianthus annuus L.). Economic reality suggests that new production and marketing methods are needed for annual grain and seed crops to be grown profitably in the Great Plains.

Pasture-based cropping systems have been used successfully for decades in Australia. These systems rely on subterranean clover (Trifolium subterraneum L.) and annual medic (Medicago) species to provide forage during a short-term (less than 3 yr) pasture phase (Walsh, 1999). Pastures first are established by seeding the legumes, then are maintained or re-established naturally from seed produced during the pasture phase (Krall and Schuman, 1996). The pastures provide forage throughout the winter growing season, as well as during the dry summer months. Pastures are rotated with wheat and sometimes other grain or seed crops.

Subterranean clover and annual medic produce excellent quality forage when managed properly (SAN, 1998). The forage is highly palatable, nutritious, and desired by livestock. The legumes also enhance soil fertility and tilth. Soil nitrogen (N) and water-stable soil aggregates increase during the pasture phase (Reeves, 1987), thereby benefiting subsequent crops in rotation with the legume species.

The benefits of rotating legume pasture with wheat became apparent as pasture-based cropping systems were adopted across the wheat belt region of southern Australia in the 1950s. Producers became convinced that cropping systems incorporating a legume pasture phase were superior to crop-summerfallow systems. Wheat yields increased 50% following adoption of pasture-based cropping systems, with much of the increase attributed to the impact of the legume pasture phase on soil N and tilth (Donald, 1981). By 1965, crop-summerfallow systems had been replaced by pasture-based cropping systems (Halse, 1989).

Pasture-based cropping systems are not unique to Australia. Advanced cropping systems incorporating a legume pasture phase are used by some wheat producers in Argentina (Ortmann et al., 1989). These systems have reduced or eliminated the need for fertilizer when growing wheat. By contrast, fertilizer comprised 27% of the total variable costs associated with wheat production in southwestern North Dakota in 1999 (NDSB, 2000).

Krall and Shuman (1996) concluded that pasture-based cropping systems can be profitable and sustainable in the Great Plains. However, evidence suggests that these systems are used by only a few producers in this region. Even less evidence exists that legume pastures are included in wheat production systems, even though legume pastures can enhance the yield of subsequent crops in a rotation. Krall and Shuman (1996) suggested that tradition and lack of managerial experience are two major factors limiting adoption of pasture-based cropping systems. Limitations in an infrastructure that supports pasture-based cropping systems also inhibit adoption.

Australian medic and other legume species suitable for grazing have been considered as a replacement to summerfallow in the Great Plains. Sims (1993) concluded that black medic (M. lupulina L.) could replace summerfallow in a wheat-summerfallow cropping system in Montana. Black medic was seeded in plots in 1979 and then reestablished naturally in 1980. Summerfallow plots also were maintained. Spring wheat was seeded in plots in 1981. Wheat yield was 46 bu/acre (3123 kg/ha) following black medic and 27 bu/acre (1819 kg/ha) following summerfallow. Black medic fixed more than 50 lb N/acre (56 kg/ha), which probably explains why yields were greater following black medic than summerfallow. Subsequent work showed a similar but non-significant trend in yield following black medic compared with summerfallow.

Gardner (1992) concluded that yellow-flowered sweetclover (Melilotus officinalis Lam.), hairy vetch (Vicia villosa Roth), foxtail dalea (Dalea alopecuroides L.), and 'Indianhead' lentil (Lens esculenta L.) had the greatest potential of substituting for summerfallow in cereal-summerfallow cropping systems in the central and northern Great Plains. However, soil water levels were depleted from 1 to 4 inches in the 0-to 4-ft depth following the cover crops compared with summerfallow, depending on the legume species seeded. Wheat yield was not elevated and sometimes was reduced following legume cover crops. These data indicate the importance of water use considerations when developing cereal-legume cropping systems in the Great Plains.

Several annual medic cultivars were studied over three years in eastern Wyoming (Walsh, 1999). Annual medic species showed promise as potential forage crops. Some cultivars produced more than 6250 lb/acre (7000 kg/ha) of high-quality forage. However, most medic species showed limited potential for regenerating naturally from the soil seed bank. Many medic species also were unable to compete with weeds for light, nutrients, and water. One study was abandoned prior to completion because of invasion by weeds. Results of this work suggest that many medic cultivars adapted to pasture-based cropping systems in Australia may not be suited to the Great Plains.

Australian medic and subterranean clover cultivars have been developed for Mediterranean climates with mild winter temperatures. Halse (1989) indicated that Australian cultivars are not adapted to regions with cold winter temperatures. Australian cultivars generally failed to produce much seed in eastern Wyoming, probably because growth and development periods were reduced in this climate (Walsh, 1999). Only a small percentage of the viable seed that was produced survived the cold winter months. Medic stands failed to regenerate naturally, and were either reseeded or abandoned. Walsh (1999) concluded by suggesting that adaptation studies were needed that identify legumes having the greatest potential when grazed in pasture-based cropping systems in the Great Plains.

Alfalfa has been used for pasture in pasture-based cropping systems (Dalal et al., 1991), and cultivars have been developed for grazing. Black medic and other legume species have been grazed in a non-replicated demonstration in the Great Plains (Gardner, 1991), but most farmers and ranchers are unaware of the grazing potential of these legume species. No replicated and randomized, large-scale paddocks exist demonstrating that cropping systems with a legume-pasture phase can be used successfully in the central and northern Great Plains, according to prominent, cropping-systems scientists located in Canada (M.H. Entz, personal communication, 2000) and the USA (D.W. Meyer and J.M. Krall, personal communication, 2000).

Demonstrate pasture-based cropping systems that can be used as alternatives to grain and seed-based annual cropping systems.

Demonstrate the economic consequences associated with changing from a grain- and seed-based cropping system to pasture-based cropping systems.

Develop a pasture-based cropping systems working group comprised of farmers and ranchers, researchers, and others in the north central region.