Patrick M. Carr

Potential of forages to diversify cropping systems in the Northern Great Plains

cated to cultivated forage crop production in the three Canadian prairie provinces (Manitoba, Saskatchewan, Cultivated forage crops are grown on almost 12 million ha on the and Alberta) and three U.S. states (North Dakota, northern Great Plains. This paper reviews the benefits of diversifying annual crop rotations with forage crops and highlights innovations in South Dakota, and Montana) totals 7.8 million ha of forage systems. Agronomic benefits of rotating forage crops with cultivated hay and 3.8 million ha of cultivated pasture annual grain crops include higher grain crop yields following forages (Alberta Agric., Food, and Rural Dev., 1999; Manitoba (up to 13 yr in one study), shifts in the weed population away from Agric. and Food, 1999; Saskatchewan Agric. and Food, arable crop weeds, and improved soil quality. Perennial legumes in 1999; NASS, 1999). Many farmers and ranchers use culrotation also reduce energy requirements by adding significant tivated forages to complement the approximate 44 milamounts of N to the soil. Soil water availability may limit the extent lion ha (Alberta Agric., Food, and Rural Dev., 1999; to which forages benefit following crops. Under semiarid conditions, Manitoba Agric. and Food, 1999; Saskatchewan Agric. forages can actually reduce yields of the following crops, and as such, and Food, 1999; NASS, 1999) of native rangeland in tillage practices that conserve soil water have been developed to this region. partially address this problem. Forages in rotation provide environmental benefits, such as C sequestration, critical habitat for wildlife, Forage is produced and conserved during the short and reduced NO3 leaching. A wider range of annual plant species are growing season and fed during the remainder of the now used in forage systems in an effort to extend the grazing season year. Hay is the predominant winter feed, followed by and to maximize use of water resources. Intensive pasture managestraw, silage, stockpiled perennial pasture, and swathed ment using cultivated forages is on the increase as is the use of alfalfa annual pastures (Small and McCaughey, 1999). The win(Medicago sativa L.) in grazing systems; in some cases, bloat-reduced ter feeding period for beef cattle (Bos taurus) in western alfalfa cultivars are used. Pasture-based systems appear to provide Canada is widely reported to exceed 200 d per year benefits for both animal and human health and arguably the health (Mathison, 1993). However, this varies by region and of the environment. Pasture systems are less nutrient exhausting than year, mainly depending on period of snow cover. In hay systems. As a result, nutrient management strategies will differ Alberta during 1999, the mixed grassland region, most in the following crop. Additional research is required to optimize the role of cultivated pastures in grain-based cropping systems. representative of the NGP area, had an average 155 winter feeding days compared with 201 in the boreal transition zone, which lies to the north of the prairie (Anonymous, 2000). Approximately 10% of forage proF production in the northern Great Plains duction is used for dairy cows located in the NGP region. (NGP) of the USA and Canada involves cultivated Some forage is also exported outside North America and native pasture and hay production. The area dedi[e.g., dehydrated alfalfa cubes and pellets and compacted timothy (Phleum pratense L.) hay]. Very little M.H. Entz, Dep. of Plant Sci., Univ. of Manitoba, Winnipeg, MB, Canada R3T 2N2; V.S. Baron, Agric. and Agri-Food Can., Lacombe forage is typcially imported into this region although reRes. Cent., Lacombe, AB, Canada T4L 1W1; P.M. Carr, North Dakota distribution of forage does occur when localized droughts State Univ., Dickinson Res. and Ext. Cent., 1089 State Ave., Dickinreduce forage supply. son, ND 58601; D.W. Meyer, Dep. of Plant Sci., North Dakota State Alfalfa is the main forage legume and is grown on Univ., Fargo, ND 58105; S.R. Smith, Jr., Dep. of Crop, Soil, and 61% of cultivated forage hayland in the U.S. NGP. AlEnviron. Sci., 424 Smyth Hall, Virginia Tech, Blacksburg, VA 240610404; and W.P. McCaughey, Agric. and Agri-Food Can., Brandon falfa’s role in grazing systems is increasing (Smith and Res. Cent., Brandon, MB, Canada R7A 5Y3. Received 22 Jan. 2001. *Corresponding author (m_entz@umanitoba.ca). Abbreviations: CLA, conjugated linoleic acid; DM, dry matter; NGP, northern Great Plains. Published in Agron. J. 94:240–250 (2002). ENTZ ET AL.: DIVERSIFYING CROPPING SYSTEMS WITH FORAGES IN THE NORTHERN GREAT PLAINS 241 Singh, 2000). Other forage legumes are also grown 50% higher from land previously cropped to alfalfa for 3 yr than from land previously cropped to nonlegumes where alfalfa is not adapted [e.g., red clover (Trifolium pratense L.) and alsike clover (T. hybridium L.) in wetter such as corn (Zea mays L.), wheat, or flax (Linum usitatissimum L.). Similar results continue to be reported from and acid soil zones, sainfoin (Onobrychis viciafolia L.) in dryland pastures, or where a nonbloating legume is studies at Melfort, SK (Campbell et al., 1990); Winnipeg, MB (Poyser et al., 1957); and Lethbridge, AB (Ellert, desired]. There is significant potential to utilize these better adapted, alternative perennial forage legumes in 1995) as well as from two ongoing classical long-term studies of crop rotation in western Canada: The Univerthe region though grower education is required. Many different grass species are used in cultivated forage syssity of Alberta’s Breton Plots (initiated in 1930) (Ellert, 1995) and Agriculture and Agri-Food Canada’s longtems, ranging from the droughtand salt-tolerant wheatgrasses (Agropyron spp.) to flooding-tolerant reed caterm study at Indian Head, SK (initiated in 1958) (Campbell et al., 1990). narygrasses (Phalaris spp.). Many annual C3 and C4 plant species are used to fill gaps in the feed supply (Kilcher In a survey of Manitoba and Saskatchewan forage producers, 71% of respondents indicated higher grain and Heinrichs, 1961; Baron et al., 1992; Carr et al., 1998). Forage is defined as, “any plant whose vegetation is yields after forages than in annual crop rotations (Entz et al., 1995). Rotational yield benefits were greatest in eaten by livestock” (Heath et al., 1973), and as such, many different plants are used, including crop residues eastern and northern zones and lowest in drier, western and southern zones. In one of the best studies ever (e.g., corn stalks and chaff) and hay harvested for remnant areas and roadside ditches. These forage sources published on the long-term residual yield benefits of including forage in a cropping system (McLennan, AB), are especially important in drought years such as 2000 in Montana. Forage seed production is also an important Hoyt (1990) reported that for the first 8 yr after forage termination, wheat yields were 66 to 114% greater after industry in the region though it occupies a relatively small area compared with forage production. forage relative to continuous wheat. Yield differences started to decline after 8 yr although wheat yields in The percent of arable cropland that is rotated with forage ranges from 5 to 15% in the region. Two recent the alfalfa systems were still higher (P 0.05) than the control in the 10th and 13th year after sward breaking. surveys have characterized forage and beef production in western Canada (Entz et al., 1995; Small and McIn areas of the NGP where water seriously limits crop productivity, inclusion of perennial forages can reduce Caughey, 1999). Objectives of this paper are to (i) review agronomic, crop yield in following crops due to forage-induced drought. Working in west-central Saskatchewan, Brandt economic, and environmental benefits and risks of diversifying cropping systems with forage crops; (ii) idenand Keys (1982) determined that available soil water in spring was lower after a 2-yr alfalfa crop than in a tify means to enhance the positive attributes of forages in NGP cropping systems and to make forages a more continuous grain rotation. A full year of fallow was insufficient to fully replenish the soil profile with water important component of the cropping system; and (iii) highlight research challenges for the future. in the alfalfa system relative to the grain system. In central Saskatchewan, Austenson et al. (1970) reported that alfalfa in rotation depressed wheat yield in the first ROTATIONAL BENEFITS OF FORAGES crop after breaking even after a full year of summer IN THE NORTHERN GREAT PLAINS fallow. Interestingly, they observed that alfalfa with CROPPING SYSTEMS bromegrass (Bromus inermis Leyss.) or bromegrass Forage benefits have received less attention in the alone did not affect wheat yields significantly. Others NGP than elsewhere, such as the humid U.S. Midwest (e.g., C.A. Campbell, personal communication, 2000) where alfalfa has traditionally been rotated with grain have suggested that low cereal yields after alfalfa could crops or areas of Australia where unique, self-regeneratbe due to allelopathic effects from alfalfa, and such ing forage species are grown in grain-based cropping effects are greatest under dry soil conditions. However, systems (Grace et al., 1995). The short growing season no studies have been conducted to substantiate this sugand relatively dry conditions (i.e., low precipitation and gestion. high evaporative demand for water) in the NGP will In wetter areas of the NGP, these water-depleting modify rotational benefits of forages relative to wetcharacteristics of alfalfa and other perennial forages are ter areas. often viewed as desirable. For example, dewatering Some of the best information on forage rotational characteristics of perennial forages play an important benefits in the NGP has come from long-term crop role in soil salinity management. Soil salinization is a rotation studies, many of which were established soon threat to the long-term sustainability of cro

Editorial: Overview and comparison of conservation tillage practices and organic farming in Europe and North America

Editorial: Overview and comparison of conservation tillage practices and organic farming in Europe and North America.

Organic zero-till in the northern US Great Plains Region: Opportunities and obstacles

The use of killed cover crop mulch for weed suppression, soil erosion prevention and many other soil and crop benefits has been demonstrated in organic no-till or zero-till farming systems in eastern US regions and in Canada. Implements have been developed to make this system possible by terminating cover crops mechanically with little, if any, soil disturbance. Ongoing research in the US northern Great Plains is being conducted to identify cover crop species and termination methods for use in organic zero-till (OZ) systems that are adapted to the crop rotations and climate of this semi-arid region. Current termination strategies must be improved so that cover crop species are killed consistently and early enough in the growing season so that subsequent cash crops can be grown and harvested successfully. Delaying termination until advanced growth stages improves killing efficacy of cover crops and may provide weed-suppressive mulch for the remainder of the growing season, allowing no-till spring seeding of cash crops during the next growing season. Excessive water use by cover crops, inability of legume cover crops to supply adequate amounts of N for subsequent cash crops and failure of cover crops to suppress perennial weeds are additional obstacles that must be overcome before the use of killed cover crop mulch can be promoted as a weed control alternative to tillage in the US northern Great Plains. Use of vegetative mulch produced by killed cover crops will not be a panacea for the weed control challenges faced by organic growers, but rather one tool along with crop rotation, novel grazing strategies, the judicious use of high-residue cultivation equipment, such as the blade plow, and the use of approved herbicides with systemic activity in some instances, to provide organic farmers with new opportunities to incorporate OZ practices into their cropping systems. Emerging crop rotation designs for organic no-till systems may provide for more efficient use of nutrient and water resources, opportunities for livestock grazing before, during or after cash crop phases and improved integrated weed management strategies on organic farms.

Potential carbon sequestration and nitrogen cycling in long-term organic management systems

The fertility and soil health of organic agroecosystems are determined in part by the size and turnover rate of soil carbon (C) and nitrogen (N) pools. Our research contrasts the effects of best management practices (BMP) (reduction in soil disturbance, addition of organic amendments) on C and N cycling in soils from two field sites representing five organic agroecosystems. Total soil organic C (SOC), a standard measure of soil health, contains equal amounts of biologically and non-biologically active C that is not associated with release of mineral N. A three-pool first-order model can be used to estimate the size and turnover rates of C pools but requires data from a long-term incubation. Our research highlights the use of two rapid C fractions, hydrolysable and permanganate (0.02 M) oxidizable C, to assess shifts in biologically active C. Adoption of BMP in organic management systems reduced the partitioning of C to the active pool while augmenting the slow pool C. These pools are associated with potentially mineralizable N supplied by residues, amendments and soil organic matter affecting the concentration and release of mineral N to crops. Our data show that minimizing disturbance (no tillage, pasture) and mixed compost additions have the potential to reduce carbon dioxide emissions while enhancing slow pool C and or its turnover, a reservoir of nutrients available to the soil biota. Use of these rapid, sensitive indicators of biological C activity will aid growers in determining whether a BMP fosters nutrient loss or retention prior to shifts in total SOC.

Impact of tillage on field pea following spring wheat

Tillage is being reduced in semiarid regions. The impact of changing tillage practices on field pea (Pisum sativum L.) performance has not been considered in a major pea-producing area within the US northern Great Plains. A study was conducted from 2000 through 2005 to determine how field pea performance compared following spring wheat (Triticum aestivum L.) in clean-till (CT), reduced-till (RT), and no-till (NT) systems arranged in a randomized complete block at Dickinson in southwestern North Dakota. Seed yield increased over 1600 kg ha-1 in 2000 and almost 400 kg ha-1 in 2003 under NT compared with CT, and by 960 kg ha-1 in 2000 under NT compared with RT (P < 0.05). Differences in seed yield were not detected between tillage systems in other years. Plant establishment was improved as tillage was reduced, averaging 66 plants m-2 under NT and RT compared with 60 plants m-2 under CT management. The soil water conservation that can occur after adopting NT may explain the increased seed yields that occurred...

Producer participatory spring wheat variety evaluation for organic systems in Minnesota and North Dakota

Summary Organic producers in Minnesota and North Dakota, USA, indicated that they wanted to participate in hard red spring wheat (Triticum aestivum L. emend. Thell) variety evaluations. The objectives were to determine if a farmer–researcher developed scoring system could be used to rank wheat varieties for yield potential when grown in certified organic fields, identify views of organic producers about on-farm research, and identify the educational impact of the participatory variety evaluation process. Hard red spring wheat varieties were compared for grain yield at six locations on certified organic farms in Minnesota and North Dakota over a three-year period. A scoring system was developed and then used to identify the relative rank of adapted varieties for yield. Producers were asked to rank all varieties on a scale from 1 to 9, where 1 is lowest yield potential and 9 is highest yield potential. Producers were able to distinguish higher producing varieties as a group in 2003 and 2004. ‘Oklee’ a high yielding variety was ranked lowest in 2005. There was a significant linear relationship between producer ranking and yield (P < 0.05) even though producers could not pick the highest yielding varieties consistently in the field. The producer survey showed that grain yield, protein content, wheat scab resistance, leaf disease resistance, early seedling vigor, test weight and canopy closure were traits producers valued most in a variety. Heading date, impact on succeeding crops, straw and stubble production were ranked lower. Multi-year variety evaluation on certified organic land was highly valued by the producers surveyed. From an educational perspective, the exercise was successful in that producers had to observe individual varieties carefully in order to come to a consensus producer ranking. The model of participatory research can be used for a variety of field research projects and field days.

Yield and quality of hard red spring wheat cultivars following fallow and wheat

Continuous wheat (Triticum aestivum L. emend. Thell.) and other intensive cropping systems are replacing t he wheat-fallow (WF) system in the semiarid prairie region of Canada and the northern USA. However, most wheat cultivar recommendations are based on performance in a WF system. Our objective was to determine if cultivar ranking for grain yield, grain protein concentration, and kernel weight changed for hard red spring wheat in WF compared with continuous wheat (WW) systems. Ten cultivars were seeded on a Dark Brown Chernozem loam following fallow and wheat over 3 consecutive years at Dickinson, ND, USA. Fertilizer was applied for equivalent yields in both systems based on soil test results. More grain and heavier kernels were produced during the crop phase of the WF system than the WW system, in part because soil-water content was greater after fallow than wheat in 2 of 3 yr. Grain protein concentration was unaffected by cropping system. Grain yield, grain protein concentration, and kernel weight dif...

Barley Cultivar Performance Following Canola, Corn, Pea, and Spring Wheat

Patrick M. Carr,* Richard D. Horsley, Glenn B. Martin, and Martin R. Hochhalter Abstract High-residue farming and crop diversification practices are replacing conventional tillage and crop-fallow in the Great Plains. Our objective was to determine if cultivar ranking changed when six barley (Hordeum vulgare L.) cultivars were grown following canola (Brassica napus L.), corn (Zea mays L.), pea (Pisum sativum L. subsp. sativum), and spring wheat (Triticum aestivum L. emend. Thell.) from 2010 through 2013 in southwestern North Dakota. An interaction between the previous crop and barley cultivar was detected in 2011 and 2013 for grain yield (P < 0.10). However, one cultivar in 2011 and three cultivars in 2013 produced equal or greater yields than those produced by other cultivars, regardless of previous crop. Grain yield was comparable with or greater following field pea to that following other crops in 2010 and 2012 when a previous crop cultivar interaction did not exist. Interactions between the previous crop and barley cultivar occurred in only 2 of 12 instances for grain quality traits, and even then at least one cultivar was among the top performers consistently after each previous crop treatment. These results suggest that the previous crop is not an important consideration when making barley cultivar recommendations.

Spring wheat cultivar harrowing evaluation in Minnesota.

Weed control is a major management issue in the production of spring wheat (Triticum aestivum L.). Harrowing can be used in an integrated weed management program. The objectives of this research were to determine initial plant density, plant density reduction, spike density, yield, and the relationship between plant and spike density with yield of spring wheat cultivars after harrowing on a certified organic farm with farm size equipment near Fertile, MN, in 2003 to 2005. Averaged across cultivars, there was a 16, 8, and 12% reduction in emerged seedlings relative to planted live seeds in 2003, 2004, and 2005, respectively. Post-emergence harrowing reduced plant density by 46% in 2003 (harrowed 2×), 16% in 2004 (harrowed 2×), and 25% in 2005 (harrowed 1×). Post-harrowing plant density and yield were positively correlated in 2003, uncorrelated in 2004, and negatively correlated in 2005. There were differences in yield among the tested cultivars. No cultivar could be identified with consistent lower plant density reduction percentage after harrowing. Our suggestion is to adjust the live seeding rate to locally recommended established wheat plant density, by considering anticipated plant loss before plant establishment (average is 12%), and plant density reduction from post-emergence harrowing (average is 29%).