The research explored strategies to improve cover crop (CC) establishment and nitrogen (N) uptake in response to the time constraints commonly faced by Mid-Atlantic farmers. The first study examined whether broadcasting CCs at corn harvest—using various incorporation techniques—can reduce nitrate leaching and enhance biomass production, compared to broadcasting or drilling CCs 4-weeks post-harvest. Four seeding methods were tested across a range of CC species, including cereal rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), rapeseed (Brassica napus L.), and their mixture. Over two years, data revealed that CCs planted at corn harvest achieved significantly higher fall biomass (721 to 846 kg ha-1) than those seeded four weeks later (134 to 200 kg ha-1). Year 2 data showed a reduction in fall soil nitrate levels with at-harvest planting (5.2 mg kg-1), compared to post-harvest CC planting (11.4 to 11.8 mg kg-1). Additionally, certain at-harvest treatments, particularly those with hairy vetch and the mix, increased aboveground N accumulation (181 to 208 kg ha-1) and, in Year 1, improved corn yield (10,113 to 11,586 kg ha-1). The second study focused on a combine-mounted seeder's capacity to address similar N management goals in corn-soybean systems, allowing for seeding CCs directly at harvest and bypassing the need for additional field passes. Results from one year demonstrated that the combine-mounted seeder produced equal or greater biomass and N accumulation compared to delayed drilling. Following corn, the combine seeded treatments increased fall biomass tenfold (205 kg ha-1 vs. 1116 to 1314 kg ha-1) and nearly doubled spring biomass (2345 kg ha-1 vs. 5867 to 6323 kg ha-1). The effectiveness of at-harvest broadcasting was also evident even in late-season drought conditions following soybean, showing comparable results to drilling two weeks post-harvest (4528 kg ha-1 vs. 4434 kg ha-1). Both studies highlight that earlier CC establishment, whether by broadcast seeding with or without incorporation or utilizing combine-mounted seeders, offers a promising approach for enhancing biomass production and reducing fall nitrate leaching in Mid-Atlantic farming systems. / Master of Science / This research examined ways to aid Mid-Atlantic farmers in establishing earlier cover crops (CCs) and improving CC nitrogen (N) uptake. The first part of the study compared broadcasting CCs at corn harvest with waiting four weeks to either broadcast or drill them after harvest. Four species of CCs were tested, including cereal rye, hairy vetch, rapeseed, and a mixture of these. Results over two years showed that broadcasting CCs at corn harvest resulted in significantly more biomass growth in the fall, with levels ranging from 721 to 846 kg per hectare (643 to 755 lb per acre), compared to just 134 to 200 kg per hectare (120 to 178 lb per acre) with later planting. Additionally, soil nitrate levels were lower when CCs were planted at harvest—5.2 mg/kg, compared to 11.4 to 11.8 mg/kg when planted later. Certain combinations, especially those including hairy vetch, led to higher N accumulation and improved corn yields. The second part of the study evaluated a new combine-mounted seeder that allows farmers to plant CCs during cash crop harvest, reducing the number of times they need to work the fields. Results after one year showed that the combine-seeded method produced similar or greater biomass and N accumulation than conventional post-harvest drilling. Following corn, fall biomass increased tenfold and spring biomass nearly doubled compared to delayed drilling. Even with drought conditions in soybeans, the combine-seeded method yielded results comparable to drilling CCs two weeks later. The second year of the study is still in progress. Overall, both studies suggest that starting cover crops earlier, whether by broadcasting or using the combine seeder, can significantly boost biomass growth while reducing nitrate leaching in farming systems throughout the Mid-Atlantic region. Future research is needed to test the effectiveness of the combine-mounted cover crop seeder in different soil types and climates.

The sagebrush steppe is a particularly sensitive ecosystem that is easily disturbed by fires, oil and gas extraction, woody-plant encroachment, and overgrazing. The natural regeneration of native species following a disturbance within this system is typically slow and sporadic, which allows invasive grasses to occupy the landscape. Attempts to assist the recovery of these landscapes through direct seeding is commonly met with poor success rates, particularly in lower elevation, drier sites. Novel seed enhancement technologies and planting techniques that mitigate limiting factors impairing restoration efforts may improve the likelihood of restoring these degraded areas. For chapter 1, we evaluated a solid-matrix priming technique, where bluebunch wheatgrass (Pseudoroegneria spicata) and Lewis flax (Linum lewisii) were primed and then the priming matrix and seed were pelleted together. We evaluated primed seed that had been incorporated into pellets at two field sites against seed that was pelleted but been left unprimed, and untreated seed (control). These three seed treatments were planted in the spring (mid-march) in shallow (2-cm) and deep (15-cm) furrows, in a complete factorial design. We found that primed seeds generally produced higher plant densities than control seed at the beginning of the growing season; however, its influence diminished towards the end of the growing season. We also found that deep furrows increased plant density throughout the growing season and even into the following year. The combination of priming and deep furrows outperformed control seed in shallow furrows in all measured metrics. For chapter 2, we evaluated a seed conglomeration technique for improving Wyoming big sagebrush (Artemisia tridentata ssp. Wyomingensis) emergence and survival under fall and winter plantings. The trial was implemented at five sites across Utah and Nevada in a randomized complete block-split-split plot design, with site, and planting season, comprising the split-plot factors. Each site and season combination was seeded with conglomerated and control seed. We found that in most cases, a fall seeding of Wyoming big sagebrush was either the same or more successful compared to planting on the snow in the winter, which is the current suggested practice. Our results also demonstrated that seed conglomeration produced higher plant densities compared to control seed throughout the growing season. The higher density of plants produced from conglomerates combined with the improved seed delivery provided by the conglomeration technique was estimated to offset the cost in producing conglomerates and reduce overall restoration costs by 41%.