Core Ideas Within year, harvest frequency has the greatest effect on DM production of native warm‐season grasses. Nitrogen has little effect on native warm‐season grass DM yield. Eastern gamagrass can tolerate consecutive years of frequent defoliations and maintain yield. Five native warm‐season grass species and mixtures were grown in east‐central Mississippi on a coarse‐loamy, siliceous, semiactive, thermic Glossic Fragiudult, to determine their potential as forage grasses in response to harvest frequency and N application. Established stands were harvested at 30, 40, 60, and 120 d intervals, and were fertilized with N rates of 0, 56, 112, 168, and 224 kg N ha−1 for two consecutive years (2016 and 2017). Dry matter (DM) yield and agronomic nitrogen use efficiency (aNUE) were analyzed. Year, treated as a repeated measure, was the main source of variation affecting DM yields. Within year, harvest frequency had the greatest effect on cumulative yields in 2016, accounting for 44% of the variation observed. This effect was not observed in 2017. Frequent defoliations led to overall lower yields in 2017. Nitrogen was significant, but moderately, accounting for 2 and 4% of variation for 2016 and 2017, respectively. Species was also significant for both years. Agronomic N use efficiency varied between year, species, N rate, and harvest frequency. Eastern gamagrass [Tripsacum dactyloides (L.) L.] was the only species in which cumulative DM yield remained consistent across both years of the study, regardless of harvest frequency or N application. Results suggest that rest periods should be based on species present, and that less frequent harvests are required for sustained DM yields.

Overseeding dormant bermudagrass [Cynodon dactylon (L.) Pers.] ‘Tifton 85’ with cool‐season annuals in the southeastern United States could provide winter and spring forage or bioenergy feedstock. We overseeded cool‐season annual legumes and grasses in monocultures or mixtures into dormant Tifton 85 and compared aboveground dry matter (DM) and N yields of single harvests at peak biomass production and a multiple harvest forage system. We also measured first‐cut spring Tifton 85 yields. Wheat (Triticum aestivum L.) yielded as much or more (P ≤ 0.05) biomass in a single‐harvest system than other grasses only during a dry cool season. Well‐distributed precipitation, in combination with multiple cool‐season grass legume harvests, resulted in lower yields than the single harvest system, whereas the reverse occurred when precipitation was erratic. Hairy vetch (Vicia villosa Roth) matured later in the spring, and monocultures or mixes with it yielded more (P ≤ 0.05) DM and N than the more precocious crimson clover (Trifolium incarnatum L.). A drier cool season followed by a spring with good precipitation, as well as repeated cool‐season grass and legume harvests, resulted in more (P ≤ 0.05) spring first‐cut Tifton 85 DM regrowth. Results provide several management options to maximize cool‐season, annual legume, and grass bioenergy feedstock or forage while minimizing negative and maximizing positive effects on subsequent early spring Tifton 85 regrowth.

Alfalfa is a high quality forage that is not often utilized in the southeastern United States because of its perceived lack of adaptability to the area. However, the risk of growing alfalfa could be partially mitigated by its inclusion into an existing bermudagrass system that makes up a large portion of pastures and hay fields in Mississippi. Alfalfa was planted into an existing bermudagrass hay field at a rate of 17, 22, 28 and 39 kg•ha −1 in no-till and minimum till sod preparation and analyzed for three growing seasons. Tillage did not affect any of the variables observed but seeding rate and time affected DM (dry matter) yield, forage nutritive value and plot composition. The increasing alfalfa seeding rate increased alfalfa yield in the plot but this was isolated to only the first year. Dry matter yields decreased over the three years due to the decrease in alfalfa composition, but throughout the growing season DM yields increased after the first year suggesting bermudagrass recolonization within the plot. Forage nutritive value was positively affected with as little as 20% of the plot composed of alfalfa suggesting that even thinning stands by the third year might offer economic advantages.

Annual ryegrass (Lolium multiflourum) is the most important cool-season forage crop in Mississippi. It is seeded on more than 500,000 acres every year in the state and consequently seed companies intensely market the area with claims of superior genetic performance. Marketing literature observed in Mississippi focuses on the performance of tetraploid (4×) versus diploid (2×) with claims that 4× varieties provide better yield, disease resistance, and seedling vigor. These claims have rarely been substantiated on long-term performance variety trials. Archived Mississippi State forage variety test data from 1987 to 2012 were compiled for 10 diploid and tetraploid varieties grown at four physiographic locations (Starkville, Raymond, Newton, and Poplarville). Differences in the mean yields between 2× and 4× were only detected in Newton and Poplarville, where 2× varieties had a 4% yield advantage and 4× averaged 10% greater yields, respectively. Across the state, ryegrass yields for both ploidy levels increased over time (4×, R = 0.19931, P = 0.0105 & 2×, R = 0.18816, P = 0.0003), but correlations were variable by location. Biomass yields for both ploidy levels decreased over time in Starkville despite an increase in GDD (Growing Degree Days). With the exception of Raymond, year was the only factor influencing yield. The data suggest that ploidy level of ryegrass in Mississippi has minimal impact on seasonal yield production. However, genetic improvement other than polyploidy induction has increased yield over time.

Eighty forage sorghum cultivars were compared in 1986 for agronomic and silage quality traits. Silage yield ranged from 5.3 to 10.0 tons (t) of dry matter (DM) per acre (mean, 7.4 t); grain yield, from 13 to 113 bushels (bu) per acre (mean, 66 bu). Percent lodging was extremely high, with a mean of 51% and only one cultivar free of lodging. Pre-ensiled DM content ranged from 22.2 to 35.4% (mean, 27.4%) and plant height from 85 to 180 inches (mean, 121 inches). Silage quality results showed that in vitro DM digestibility ranged from 44.6 to 62.1% (mean, 53%); crude protein from 4.5 to 8.2% (mean, 6.8%); neutral detergent fiber from 48.3 to 71.9% (mean, 58.4%); and acid detergent fiber from 27.1 to 49.8% (mean, 35.7%). From the 80 cultivars in 1986, 60 were selected for the 1987 trial. When compared to 1986, the 1987 means showed slightly lower silage (7.0 t) and grain (63 bu) yields and much shorter plants (93 inches). Lodging scores were dramatically lower in 1987 (10%), and DM content was higher (29.1%). The year to year effect influenced all of the agronomic traits measured. Eighty forage sorghum cultivars were compared in 1986 for agronomic and silage quality traits. Silage yield ranged from 5.3 to 10.0 tons (t) of dry matter (DM) per acre (mean, 7.4 t); grain yield, from 13 to 113 bushels (bu) per acre (mean, 66 bu). Percent lodging was extremely high, with a mean of 51% and only one cultivar free of lodging. Pre-ensiled DM content ranged from 22.2 to 35.4% (mean, 27.4%) and plant height from 85 to 180 inches (mean, 121 inches). Silage quality results showed that in vitro DM digestibility ranged from 44.6 to 62.1% (mean, 53%); crude protein from 4.5 to 8.2% (mean, 6.8%); neutral detergent fiber from 48.3 to 71.9% (mean, 58.4%); and acid detergent fiber from 27.1 to 49.8% (mean, 35.7%).From the 80 cultivars in 1986, 60 were selected for the 1987 trial. When compared to 1986, the 1987 means showed slightly lower silage (7.0 t) and grain (63 bu) yields and much shorter plants (93 inches). Lodging scores were dramatically lower in 1987 (10%), and DM content was higher (29.1%). The year to year effect influenced all of the agronomic traits measured. The 1986 growing season favored the early maturing forage sorghums, whereas 1987 favored the late maturing cultivars.