Agricultural production systems in North America have become increasingly specialized. The lack of diversification has had negative economic, biological, and environmental consequences. One alternative approach to diversify agricultural production is to integrate cash grain cropping with ruminant livestock production. Our objective was to review research applicable to development of diversified croplivestock systems in the U.S. Corn Belt and discuss research priorities and constraints to adoption of those systems. One form of integration becoming more common in the U.S. Corn Belt occurs through contractual arrangements between spatially separated, specialized crop and livestock production farms. Less common is the spatial and temporal integration of crops and livestock on the same land base, which can occur via rotations of grain crops with perennial pastures, short rotations of grain crops with annual or short-season pastures, and utilization of grain crop residues for livestock grazing. We feel this latter model is truer to the concept of diversification. Based on published research and preliminary results from an integrated crop-livestock system project in Illinois, we suggest that integration of crops and livestock on the same land base offers tremendous potential to diversify farm ecosystems in the U.S. Corn Belt while being economically competitive and more environmentally compatible than prevailing specialized production systems. Although studies have addressed or are applicable to components of crop-livestock systems in humidcool environments, there remains a need for systems level research and funding opportunities for addressing the complex environmentplant-animal-economic-social interactions associated with integrated crop-livestock systems.

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Previous research has implied that forage yield in released alfalfa (Medicago sativa L.) cultivars declined slightly between 1978 and 1996. Our objective was to compare alfalfa cultivars released during the past five decades side by side in replicated yield trials to test for any changes in forage yield across time. Ten cultivars, two from each of the five decades, four recently released cultivars, and two check cultivars were compared for forage yield, persistence, and nutritive value at four locations. Cultivars were established in May 1999 at Iowa, Wisconsin, Ohio, and Minnesota. Forage was harvested three to four times in each of four production years depending on location. Plots were subsampled for nutritive value analyses for the first and third harvests in 2000 and 2001. Year × location × cultivar‐release date interactions demonstrated that forage yield and final stand densities differed among the cultivars in each year of the experiment at each location. Nutritive value traits were similar among all cultivars. Evidence for changes in forage yield for cultivars released between 1940 and 1995 was environmentally dependent. In environments where conditions lead to plant stand losses, recently released cultivars with multiple disease resistance had a yield advantage over older cultivars, but in environments where no differences in plant density occurred across time, older cultivars yielded the same as recent cultivars.

Crop-livestock systems are regaining their importance as an alternative to unsustainable intensive farming systems. Loss of biodiversity, nutrient pollution and habitat fragmentation are a few of many concerns recently reported with modern agriculture. Integrating crops and pastures in no-till systems can result in better environmental services, since conservation agriculture is improved by system diversity, paths of nutrient flux, and other processes common in nature. The presence of large herbivores can positively modify nutrient pathways and soil aggregation, increasing soil quality. Despite the low diversity involved, the integration of crops and pastures enhances nature's biomimicry and allows attainment of a higher system organization level. This paper illustrates these benefits focusing on the use of grazing animals integrated with crops under no-tillage systems characteristic of southern Brazil.

Predictive equations for alfalfa quality (PEAQ) based on height of the tallest stem and maturity stage of the most mature stem in a sample were developed to estimate neutral‐detergent fiber (NDF) and acid‐detergent fiber (ADF) concentrations in alfalfa (Medicago sativa L.). Field testing of these equations is limited outside the state of Wisconsin where they were developed. Our objectives were to test these equations for estimating alfalfa NDF and ADF across a wide geographic area and to evaluate the performance of PEAQ on a whole‐field basis by using within‐field subsampling. Alfalfa samples varying in height and maturity were collected throughout the growing season from fields in New York (n = 28), Pennsylvania (n = 23), Ohio (n = 48), California (n = 45), and Wisconsin (n = 48) in 1994 to 1996. Additional samples were collected in Ohio and Wisconsin from producer‐managed fields in which 5 to 10 subsamples per field were taken on each sampling date (n = 296 subsamples from 51 fields). Observed NDF and ADF values were regressed on estimated values. The accuracy of PEAQ in other states was at least equal to that observed in Wisconsin. Across all states, regression equations for NDF and ADF were slightly biased (b ≠ 1.0 and/or y‐intercept ≠ 0 at P < 0.01); however, prediction errors were sufficiently low to allow use of PEAQ as a preharvest management tool. Root mean square error values ranged from 19.1 to 23.9 g kg−1 for NDF and 15.0 to 19.0 g kg−1 for ADF. Prediction errors were 16.2 g kg−1 for NDF and 13.2 g kg−1 for ADF across Ohio and Wisconsin when regressing observed means on estimated means of five subsamples per fieldsampling date combination. We conclude that predictive equations for alfalfa quality based on a combination of stem height and maturity were robust across a wide range of environments.

Nutritive value of alfalfa (Medicago sativa L.) is limited by indigestible cell wall constituents, especially lignin. Commercially released genetically engineered alfalfa cultivars with reduced lignin (RL) concentration were developed recently by downregulation of the caffeoyl CoA 3‐O‐methyltransferase (CCoAOMT) enzyme in the lignin pathway. This research compared forage nutritive value and dry matter yield of a RL cultivar (‘HarvXtra‐008’) with non‐RL cultivars (‘54R02’ and ‘WL355RR’) across six states in the northern United States. A randomized complete block design with a split‐plot restriction on treatment randomization was used, where harvest intervals (28, 33, and 38 d) were assigned to whole plots and cultivars were the subplots. Harvest interval and cultivar effects were significant (P < 0.001) for all variables, and cultivars responded similarly across harvest intervals in that forage yield increased and nutritive value declined with increasing harvest interval. HarvXtra‐008 was consistently greater in forage nutritive value than non‐RL cultivars averaged across harvest intervals: it was 8.4% lower in acid detergent lignin, 3.5 to 7.5% lower in amylase‐treated neutral detergent fiber, and 5.3 to 7.7% greater in neutral detergent fiber digestibility, but 4.8 to 7.0% lower in dry matter yield. HarvXtra‐008 was slightly higher or similar in nutritive value and had similar or greater dry matter yield compared with non‐RL cultivars harvested on a harvest schedule 5 to 10 d earlier and more frequent. Thus, RL alfalfa can extend the time interval when it is possible to harvest forage with adequate fiber digestibility for animals with high energy requirements.

The benefits of cover crops within crop rotations are well documented, but information is limited on using cover crops for forage within midwestern United States cropping systems, especially under no‐tillage management. Our objective was to evaluate plant, animal, and soil responses when integrating winter cover crop forages into no‐till corn (Zea mays L.) silage production. Three cover crop treatments were established no‐till after corn silage in September 2006 and 2007 at Columbus, OH: annual ryegrass (Lolium multiflorum L.), a mixture of winter rye (Secale cereale L.) and oat (Avena sativa L.), and no cover crop. Total forage yield over autumn and spring seasons was 38 to 73% greater (P ≤ 0.05) for oat + winter rye than for annual ryegrass. Soil penetration resistance (SPR) in May 2007 was 7 to 15% greater (P ≤ 0.10) in the grazed cover crops than in the nongrazed no cover crop treatment; however, subsequent silage corn yield did not differ among treatments, averaging 10.4 Mg ha−1 in August 2007. Compared with the no cover crop treatment, cover crops had three‐ to fivefold greater root yield, threefold greater soil microbial biomass (MB) in spring 2008, and 23% more particulate organic carbon (POC) concentrations in the 0‐ to 15‐cm soil depth. Integration of forage cover crops into no‐till corn silage production in Ohio can provide supplemental forage for animal feed without detrimental effects on subsequent corn silage productivity, with the added benefit of increasing labile soil C.

Breeding to improve biomass production of switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) for conversion to bioenergy began in 1992. The purpose of this study was (i) to develop a platform for uniform regional testing of cultivars and experimental populations for these species, and (ii) to estimate the gains made by breeding during 1992 to 2012. A total of 25 switchgrass populations and 16 big bluestem populations were planted in uniform regional trials at 13 locations in 2012 and 2014. The reference region was USDA Hardiness Zones 3 through 6 in the humid temperate United States. Significant progress toward increased biomass yield was made in big bluestem and within upland‐ecotype populations, lowland‐ecotype populations, and hybrid‐derived populations of switchgrass. Four mechanisms of increasing biomass yield were documented: (i) increased biomass yield per se, (ii) later flowering to extend the growing season, (iii) combined later flowering from the lowland ecotype with survivorship of the upland ecotype in hybrid‐derived populations, and (iv) increased survivorship of late‐flowering lowland populations in hardiness zones that represent an expansion of their natural adaption zone. Switchgrass exhibited all four mechanisms in one or more improved populations, whereas improved populations of big bluestem were likely influenced by two of the four mechanisms. The uniform testing program was successful at documenting increases in biomass yield, identifying the mechanisms for increased yield, and determining adaptation characteristics and limitations of improved populations.