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Understanding soil organic matter (SOM) dynamics along gradients of land intensification is critical to guide conservation goals towards improvements in soil carbon (C) and nitrogen (N) storage. In this study, we clarified (a) how the C and N concentrations within SOM fractions of distinct ecological relevance responded to soil management representing a cropland‐grassland gradient and (b) how these operationally defined fractions affected soil physicochemical and biological properties. We compared sites with annual row crop rotations with and without cover crops (i.e. cropland soils) with perennial grassland sites (i.e. reference soil) by sampling near‐surface soils from statewide on‐farm cover crop experiments replicated across four agro‐ecoregions in Midwest USA. Soil management had a significant main effect on C and N content in SOM fractions, but responses were site‐ and fraction‐specific. We found that C content of free particulate organic matter and water‐extractable organic matter (WEOM) of reference soils were 58%–76% and 31%–59% greater than those of the cropland soils in two of the four sites. Differences in N content of WEOM because of soil management were observed in two of the four sites. These reference soils had between 40% and 60% greater N than cropland soils. Additionally, the N content of aggregate occluded POM (o‐POM) of reference soils was three times greater than those of the cropland soils in one of the four sites. Broadly across bulk and SOM fractions, high declines in cropland C and N relative to reference soils were observed in non‐irrigated and strip‐till sites and coarse‐texture soils. Free and o‐POM C and N were strongly associated with aggregate stability, water infiltration and enzyme activity, whereas C and N contents of WEOM and MAOM were correlated with soil's ability to hold onto essential nutrients (e.g. calcium, magnesium, potassium and sodium). Although the potential of cover crops to drive changes on ecologically meaningful SOM fractions is less pronounced in the short (3 year) term, the findings demonstrate the potential of continuous living cover as an approach to agroecosystem design to improve soil functions closely related to SOM characteristics. [ABSTRACT FROM AUTHOR]

Interseeding perennial cool‐season grass pastures with annual warm‐season grasses may increase forage accumulation and nutritive value. Our understanding of how N fertilizer rate and timing affect the forage mass, herbage composition, and N use efficiency (NUE) of interseeded pastures remains limited. In 2018–2020, we evaluated the responses of smooth bromegrass (Bromus inermis Leyss.) to two interseeding and five fertilizer rate and timing treatments in eastern Nebraska. Interseeding treatments included unseeded smooth bromegrass and smooth bromegrass interseeded with sorghum‐sudangrass [Sorghum bicolor (L.) Moench  × S. bicolor var. sudanense]. Fertilizer rate and timing treatments included: 0 lb N acre–1, 80 lb N acre–1 in spring, 40 lb N acre–1 in spring and summer, 80 lb N acre–1 in summer, and 80 lb N acre–1 in spring and summer. Summer applications occurred after sorghum‐sudangrass emergence. Across years, fertilizer rate and timing had the greatest effects on forage and weed responses. Applying N at 80 lb acre–1 in spring increased spring and total spring + summer forage mass by 33% while increasing NUE compared with summer application. Interseeding did not increase summer and total forage mass, and summer N applications did not enhance the success of sorghum‐sudangrass and were problematic, increasing weediness and reducing NUE. Practitioners should fertilize smooth bromegrass with 80 lb N acre–1 in spring or 40 lb N acre–1 in split spring and summer applications in eastern Nebraska. Interseeding sorghum‐sudangrass may increase forage accumulation and nutritive value, but establishment methods need improvement.Core Ideas: Establishment of sorghum‐sudangrass in smooth bromegrass needs improvement.Nitrogen fertilizer rate and timing affects forage mass but not establishment success.Fertilizer should be applied in spring or split in spring and summer to smooth bromegrass. [ABSTRACT FROM AUTHOR]

Harvesting cover crops (CCs) for livestock and biofuel production can be an important ecosystem service from CCs, but this potential service has not been widely discussed. We reviewed the potential use of CCs for livestock or biofuel production, impacts of CC harvesting on soils and crops, the amount of harvestable CC biomass, and strategies to enhance CC biomass production. We searched literature in Web of Science using terms such as "cover crops," "harvesting," "soil properties," and "crop yield," among others, and found about 30 papers. The literature indicates that CC harvesting does not generally affect soil properties, crop yields, and weed suppression, although the studies are relatively few. Leaving 7.5‐10 cm of CC stubble after harvest could maintain soil ecosystem services. Cover crops produce 3.37 ± 2.96 Mg ha−1 (mean ± SD) of aboveground biomass and 1.33 ± 0.98 Mg ha−1 of belowground (root) biomass. Root biomass input, representing about 30% of the total CC biomass production, could be critical to the maintenance of soil services after CC harvest. The amount of harvestable biomass while maintaining soil services ranges from 1‐3 Mg ha−1 in semiarid regions and from 1‐6 Mg ha−1 in humid regions for high‐biomass‐producing CCs. Strategies to increase CC biomass production include planting CCs early and terminating late, adapting cropping systems by using earlier‐maturity group varieties, and using flexible cropping systems. Overall, CC harvesting appears feasible, but additional research on CC management and harvesting effects on ecosystem services is needed before harvesting CCs at large scales. [ABSTRACT FROM AUTHOR]

Forage mixtures including oat (Avena sativa L.) and spring pea (Pisum sativum L. spp. sativum) provide opportunities to optimize forage production with increasing forage quality, relative to single species stands. Under different climate scenarios, adjusting seeding rates of these mixtures may produce variable results in forage quantity and quality. We conducted a 2‐yr study at three study sites to evaluate forage characteristics within mixtures of oat and spring pea stands across a semi‐arid to subhumid precipitation gradient. At the western‐most and driest location (219 mm March–June precipitation), the oat monoculture produced 16−19% more total biomass than seeding treatments with mixtures of oat and spring pea. In contrast, at the moderate‐precipitation site (255 mm precipitation), no differences in total biomass were detected for the oat monoculture and seed mixtures of oat and spring pea. Large variation at the wettest site (339 mm precipitation) limited our ability to detect differences for total biomass production across treatments, but weed pressure in Year 2 of the study reduced forage production. Typically, crude protein (CP) concentration decreased linearly (P <.01) as spring pea decreased in the seeding rate, but CP concentration and total CP yield varied for the seeding rate treatments at the different study sites. Environmental condition may influence the benefit of substituting spring pea into a properly managed oat forage crop to increase forage quality. The contribution of spring pea forage in the total forage biomass of mixtures may be limited, especially in drier conditions. [ABSTRACT FROM AUTHOR]

Cover crop (CC) grazing can be a potential strategy to support livestock and crop production while enhancing soil ecosystem services, but research on this potential multi‐functionality of CCs is limited. We assessed 3‐yr cereal rye (Secale cereale L.) CC grazing impacts on soil compaction, structure, water infiltration, fertility, and crop yields on an on‐farm irrigated strip‐till continuous corn (Zea mays L.) silage experiment on a sandy loam with <1% slope in west‐central Nebraska. Treatments were: (a) non‐grazed CC, (b) grazed CC, and (c) no CC. Across the 3 yr, cattle grazed CCs at 5.9 AUM ha−1 with grazing occurring over a 4‐mo period during winter and/or spring, depending on the year. We measured soil properties within 5 d after grazing ended in spring before tilling and planting corn. Cattle grazing resulted in a 92% decrease of CC biomass, compared with non‐grazed CCs. Grazing did not affect soil penetration resistance (compaction parameter), bulk density, aggregate stability, pH, and concentration of organic matter and nutrients except in the 2nd yr where it reduced cumulative infiltration by 80% and increased penetration resistance from 1.23 to 1.72 MPa but such increase was below root growth thresholds (<2 MPa). Cover crop grazing had no negative effect on corn silage yields although data were variable. Overall, CC grazing for 3 yr had small and variable effects on soils and crop yields, indicating that it can be a management option to support livestock production but more long‐term data from different tillage and cropping systems, and climates are needed to further understand CC grazing implications. [ABSTRACT FROM AUTHOR]

Reduced first-year yields and competition from weeds often limits alfalfa (Medicago sativa L.) planting and establishment. This study was conducted to evaluate sorghum- sudangrass (Sorghum bicolor × S. bicolor var. sudanese) use as a companion crop for increased forage production and weed suppression during alfalfa establishment. In 2016 and 2017, alfalfa was drill seeded in the same row with a sorghum-sudangrass companion crop (SSGCC) treatment harvested either three (2016) or two (2017) times in a Lincoln, NE, experiment. Pairing effects were compared with non-weeded control (NWC) and weeded control (WC) alfalfa monoculture seeding treatments. Total dry matter yields in the seeding year averaged 11.73 and 2.36 Mg ha-1 in the NWC and WC treatments, respectively. The SSGCC treatment, meanwhile, increased total dry matter yields to 26.37 Mg ha-1 while reducing weed yields by 63% relative to the NWC. The increase in total dry matter yield, though, came at a cost to seeding-year alfalfa yields, which averaged 0.19 Mg ha-1 in the SSGCC treatment, compared with 0.56 and 2.29Mgha-1 in theNWC andWC treatments, respectively. In spring the year after seeding, alfalfa yields averaged 4.32, 8.05, and 3.68 Mg ha-1 in the NWC, WC, and SSGCC treatments indicating that seeding with sorghum-sudangrass could be an option to increase seeding-year forage production and establish fair-to-moderately productive alfalfa stands in subsequent years. Alfalfa yields in the year after seeding, though, were greatest for the WC treatment indicating presence of benefits and tradeoffs of establishment with companion crops. [ABSTRACT FROM AUTHOR]

Integrated crop-livestock systems (ICLSs) can help increase food production while benefiting soils and the environment. This review summarizes recent impacts of ICLSs on crop and livestock production and rural economics and discusses lessons learned in the northern Great Plains (NGP). Research on ICLS conducted in the NGP indicates that the crop residue grazing, swath grazing, and annual forage grazing can positively influence crop production; whereas, livestock performance varies with season, forage nutritive value, and grazing management. Furthermore, ICLSs can reduce the costs and risks of agricultural production. The success of ICLSs in NGP region depends on trade-offs, planning, economic benefits, policies, regulations, community acceptance, and management skills. The ICLSs could play a strategic role in future agricultural production. The lessons learned from adopting ICLSs in the NGP include the lack of available land for fertilizer (manure) management, that to implement ICLS practices skills and knowledge must be maintained, and ICLS provides an entry point for young farmers and ranchers however capital is needed. These experiences and lessons could be valuable references for producers to adopt ICLSs in the NGP or other regions. [ABSTRACT FROM AUTHOR]

Systematic performance trials have been conducted in several states for more than 20 yr to evaluate agronomic performance of annual rye- grass (Lolium multiflorum Lam.). Despite development and testing of many annual ryegrass cultivars, the first improved cultivar, Gulf, has remained one of 10 to 12 cultivars recommended for planting in the southeastern USA. Our objectives were to evaluate cultivar yield performance across 12 yr at five locations, to assess cultivar yield distribution within growing seasons, and to estimate cultivar yield stability (consistency of relative performance environments). Efficacy measures were early-season yield (total before 1 March), late-season yield (total after 1 March), and total annual yield. Overall means for all cultivars and individual cultivar performance (for common years) were compared with Gulf or Marshall. Neither location effects nor cultivar × location interactions were found. Cultivar and year effects, plus cultivar × year interactions were detected (P < 0.05) for all three yield responses. Mean early season yields ranged from 2.3 to 4.6 Mg ha-1, with mean late-season yields ranging from 5.1 to 7.4 Mg ha-1. No trend existed for mean total yield relative to Gulf or Marshall to increase over time in association with availability of newer cultivars. Given large yearly fluctuation in yields, it is apparent that unpredictable environmental factors, including climate and perhaps pests, are the primary determinants of annual ryegrass performance rather than differences in yield potential among cultivars. Thus, yield stability may be an appropriate selection factor to include among the criteria for development of improved annual ryegrass cultivars. [ABSTRACT FROM AUTHOR]

Differences among annual ryegrass (Lolium multiflorum Lam.) cultivars for weight gain of grazing steers have been reported, even though plot experiments suggest that forage dry matter yield among cultivars should not be a limiting factor. Likewise, forage nutritive value differences among cultivars have not been assessed. The objectives of this research were to evaluate differences in cumulative forage yield, yield distribution, and nutritive value among 'Gulf', 'Jackson', 'Marshall', 'Rio', 'Rustmaster', and 'Surrey' annual ryegrass. Plots were harvested six times beginning in December at approximate 30-d intervals during the 1997-1998 and 1998-1999 growing seasons. Nutritive value measurements included crude protein (CP), neutral detergent fiber (NDF), in vitro true digestibility (IVTD), and digestible NDF (DNDF). There were no differences among cultivars for cumulative forage yield (P = 0.99). However, for the January harvest, Surrey and Gulf averaged 1030 (±65) kg DM ha[sup -1], whereas Marshall yielded only 672 (±79) kg DM ha[sup -1]. For the March harvest, yields of all varieties were similar and averaged 1350 (±95) kg DM ha[sup -1]. At the May harvest, Marshall and Jackson yielded 1232 (±123) kg DM ha[sup -1], whereas Gulf yielded only 929 (±74) kg DM ha[sup -1]. Crude protein concentration differed significantly among harvests with a general decrease from 260 to 120 g CP kg[sup -1] as the growing season progressed. Similar declines in nutritive value occurred for NDF, IVTD, and DNDF. Trends in yield distribution and forage quality may indicate a need for cultivar specific recommendations based on intended forage need and season of use. [ABSTRACT FROM AUTHOR]

Quantifies yield and forage quality response of forage soybean intercropped with forage sorghum. Comparison to measurements of monocrop soybean; Morphological and forage quality measurements on leaf and stem fractions; Decrease of dry matter accumulation due to intercropping.

Determines fiber digestion of sward components within switchgrass populations and which aspects of fiber digestion dynamics caused in vitro dry matter disappearance differences of six switchgrass populations. Determination of fiber digestibility and decomposition on leaf blade, sheath and stem fractions of the primary growth stages; Improvements in forage digestion.