Perennial forage grasses can be viewed as modular organisms. The phytomer is usually considered the basic unit of the grass plant and consists of a leaf blade and sheath, the internode, the node, and the associated axiliary bud below the point of sheath attachment. The
Current knowledge of yield potential and best agronomic management practices for perennial bioenergy grasses is primarily derived from small-scale and short-term studies, yet these studies inform policy at the national scale. In an effort to learn more about how bioenergy grasses perform across multiple locations and years, the U.S. Department of Energy (US DOE)/Sun Grant Initiative Regional Feedstock Partnership was initiated in 2008. The objectives of the Feedstock Partnership were to (1) provide a wide range of information for feedstock selection (species choice) and management practice options for a variety of regions and (2) develop national maps of potential feedstock yield for each of the herbaceous species evaluated. The Feedstock Partnership expands our previous understanding of the bioenergy potential of switchgrass, Miscanthus, sorghum, energycane, and prairie mixtures on Conservation Reserve Program land by conducting long-term, replicated trials of each species at diverse environments in the U.S. Trials were initiated between 2008 and 2010 and completed between 2012 and 2015 depending on species. Field-scale plots were utilized for switchgrass and Conservation Reserve Program trials to use traditional agricultural machinery. This is important as we know that the smaller scale studies often overestimated yield potential of some of these species. Insufficient vegetative propagules of energycane and Miscanthus prohibited farm-scale trials of these species. The Feedstock Partnership studies also confirmed that environmental differences across years and across sites had a large impact on biomass production. Nitrogen application had variable effects across feedstocks, but some nitrogen fertilizer generally had a positive effect. National yield potential maps were developed using PRISM-ELM for each species in the Feedstock Partnership. This manuscript, with the accompanying supplemental data, will be useful in making decisions about feedstock selection as well as agronomic practices across a wide region of the country.
documented for switchgrass and big bluestem (Perry and Baltensperger, 1979;George and Hall, 1983; Griffin Predicting forage quality would help producers schedule hay har- and Jung, 1983; Mitchell et al., 1994a). However, most vesting to obtain desired hay quality. Our objective was to determine if growing degree day (GDD), day of the year (DOY), mean stage of the studies that have evaluated changes in forage count (MSC), and mean stage weight (MSW) could be used to predict quality have been comparisons of switchgrass and big in vitro digestible dry matter (IVDDM), crude protein (CP), and bluestem on specific DOYs or at generalized vegetative neutral-detergent fiber (NDF) of 'Trailblazer' switchgrass (Panicum or reproductive stages. No studies have been conducted virgatum.) and 'Pawnee' big bluestem (Andropogon gerardii Vitman) where changes in the forage quality of switchgrass and grown in Nebraska and Kansas. This field study was conducted from big bluestem have been documented with quantified 1990 to 1993 at Mead, NE on Typic Argiudoll soils and from 1992 to changes in morphological development. 1993 at Manhattan, KS on Aquic Argiudoll soils. Plants were sampled The morphological development of perennial grasses at 1-wk intervals in 1990 and 1991 and at 2-wk intervals in 1992 and is an important consideration when making forage man-1993. They were morphologically classified as MSC and MSW and agement decisions (Kalu and Fick, 1983; Moore and analyzed for IVDDM, CP, and NDF. Switchgrass IVDDM and CP were best predicted by GDD models, which accounted for 86 and Moser, 1995). Plant maturity is the primary factor affect-91% of the variation, respectively, whereas NDF was best predicted ing the morphological development and forage quality by MSC and MSW. Big bluestem IVDDM was best predicted by within a species (Kalu and Fick, 1983; Nelson and Moser, MSW and CP was best predicted by GDD, which both accounted for 1994). A system for quantifying the morphological de-90% of the variation. Mean stage weight accounted for 74% of the velopment of perennial grasses based on the MSC and variability in big bluestem NDF. The DOY model adequately pre-MSW was developed by Moore et al. (1991). This system dicted forage quality due primarily to the determinate growth habit was used to quantify the morphological development of these species. Morphological development accurately predicted of switchgrass and big bluestem in Nebraska and Kansas forage quality in many instances. Although no universal parameter (Mitchell et al., 1997) and differentiate the developadequately predicted concentrations of IVDDM, CP, and NDF, it mental stages in weeping lovegrass [Eragrostis curvula was possible to accurately predict quality with readily available environmental data and measures of plant maturity. R. Mitchell and D. Wester, Dep. of Range, Wildlife, and Fisheries Management, Texas Tech Univ., Lubbock, TX 79409; J. Fritz, Dep. ments in the central Great Plains. of Agron., Kansas State Univ., Manhattan, KS 66506; K. Moore,
The Midwestern U.S. landscape is one of the most highly altered and intensively managed ecosystems in the country. The predominant crops grown are maize (Zea mays L.) and soybean [Glycine max (L.) Merr]. They are typically grown as monocrops in a simple yearly rotation or with multiple years of maize (2 to 3) followed by a single year of soybean. This system is highly productive because the crops and management systems have been well adapted to the regional growing conditions through substantial public and private investment. Furthermore, markets and supporting infrastructure are highly developed for both crops. As maize and soybean production have intensified, a number of concerns have arisen due to the unintended environmental impacts on the ecosystem. Many areas across the Midwest are experiencing negative impacts on water quality, soil degradation, and increased flood risk due to changes in regional hydrology. The water quality impacts extend even further downstream. We propose the development of an innovative system for growing maize and soybean with perennial groundcover to recover ecosystem services historically provided naturally by predominantly perennial native plant communities. Reincorporating perennial plants into annual cropping systems has the potential of restoring ecosystem services without negatively impacting grain crop production and offers the prospect of increasing grain crop productivity through improving the biological functioning of the system.
Common bean (Phaseolus vulgaris L.) is an important staple food crop in households worldwide. Genotype and location influence phenotypic nutrient composition. However, there are limited data on the magnitude of this variation for common bean yield and nutritive value. The objective of this study was to determine the effect of location on yield and seed nutritional composition. Four globally important varieties (dark red kidney/‘Montcalm’, great northern /‘Taurus’, black /‘Eclipse’ and yellow Mayocoba/‘MY06326’) were planted for two years in four locations (Iowa, Colorado, Michigan, in the USA, and Masaka, Uganda). Yield and seed weight differed among locations and varieties. Yield in Colorado and Michigan was 42% and 56% higher than in Iowa and 76% and 81% greater than in Uganda, respectively. Eclipse had greater yield than Taurus (6%), MY06326 (16%), and Montcalm (35%). Concentration of P, K, Mg, S, and crude protein (CP) differed among varieties. Montcalm had 18%, 7%, and 4% greater P concentration and 13%, 9%, and 5% greater CP than Eclipse, MY06326 and Taurus, respectively. The location × variety interaction was significant only for seed Zn concentration. Despite differences in edaphic factors among locations, elemental concentrations other than Zn were comparatively stable among locations. Stability in seed elemental concentrations across locations and environments is important knowledge for better understanding human nutrition and malnutrition.
Integrating alfalfa (Medicago sativa L.) with corn (Zea mays L.) for grain will increase biodiversity, reduce the negative environmental impact of corn monoculture and increase farm profitability. The objectives of this research were to evaluate forage productivity and nutritive value, along with stand establishment of alfalfa in a corn grain system in Iowa, Minnesota, and North Dakota. The experimental design was a randomized complete block with four replicates at each site. Treatments included were: sole corn (i.e., check; T1), sole alfalfa (T2), alfalfa intercropped into corn (T3), a prohexadione-treated alfalfa intercropped with corn (T4), and a spring-seeded alfalfa in the year after intercropping (T5), which was planted in plots with T1 the previous year. All sites had below normal rainfall in 2016 and 2017. Corn grain yield was significantly lower when intercropped with alfalfa (T3 and T4) compared with the check corn crop (no alfalfa, T1). Corn grain yield reduction ranged from 14.0% to 18.8% compared with the check (T1). Corn biomass yield was reduced by intercropped alfalfa (T3 and T4) by 15.9% to 25.8%. In the seeding year, alfalfa seasonal forage yield was significantly greater when corn competition was absent in all environments. The intercropped alfalfa from the previous season (T3 and T4) had almost double the forage yield than the alfalfa in the seeding year (spring-seeded alfalfa; T5). In the second production year, there were no meaningful forage yield differences (p > 0.05) across all treatments, indicating alfalfa in intercropping systems does not affect forage yield past the first production year. Prohexadione-calcium, a growth regulator, did not affect alfalfa stand density, forage yield and nutritive value. The forage nutritive value was dependent on harvest date not the alfalfa intercropping treatments. Results of our study suggest that establishing alfalfa with corn is feasible and can be a potential alternative for the upper Midwest region. However, when under drought conditions, this system might be less resilient since competition between alfalfa and corn for soil moisture will be intensified under drought or moisture-limited conditions, and this will likely depress corn grain yield. Research targeted to reintroduce perennial crops into the current dominant corn–soybean systems in the US Corn Belt is urgently needed to improve stability and resiliency of production systems.
Weed control during the establishment year of switchgrass (Panicum virgatum L.) is critical for a successful stand. Laboratory and field studies were conducted for 2 yr to evaluate the effectiveness of seed safeners for protecting switchgrass seed from the preemergent herbicide metolachlor. Initial evaluations of six seed safeners determined that fluxofenim was the only successful protectant tested for switchgrass seedling germination. Safener rates 0, 25, 50, and 100% of the recommended rate (40 mg a.i. 100 g per seed), method of application (coating vs. controlled hydration), ecotype (lowland vs. upland), dry matter yield, and number of crowns per row were analyzed in replicated field trials conducted in Starkville, MS, Ames, IA, Blacksburg, VA, and Brookings, SD, in a randomized complete block design. Two establishment years were planted in single‐row (6.1 m) plots spaced 50.8 cm apart. Subsequent biomass yield was harvested at the end of each growing season. Exceptional stands were achieved with all rates of safener in both years due to the reduction or elimination of annual grassy weeds and no crop injury was experienced at any test location. The controlled hydration (combination of 25, 50, or 100% fluxofenim) method resulted in significantly greater yields and crown counts than the coating technique at most locations for both years.
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