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Item Productivity and Sustainability of Intercropping Systems in the Northern Great Plains(North Dakota State University, 2017) Samarappuli, Dulan PravindaThe sustainability and productivity of cropping systems in the northern Great Plains is at risk because food, feed, and energy are produced mainly in very short crop rotations or monocultures. High input agriculture and lack of crop diversity has led to negative environmental impact either on- or off-site. Diverse cropping systems can reduce the need of external inputs such as fertilizer, decrease water pollution, reduce soil erosion, and improve land use efficiency, and resilience. The first study had the objective to determine the most resilient system to produce silage and biogas including monocultures and intercropping of maize (Zea mays L.) and forage sorghum (FS) [Sorghum bicolor (L.) Moench]. The results indicated that non-BMR (brown mid-rib) FS monocultures and maize-FS mixed cultures produced similar or higher biomass and biogas yield compared with maize monocultures. Intercropping resulted in a higher quality forage compared with FS monocultures. Within-row and inter-row intercropping of FS with maize is a promising alternative to maize silage, improving resiliency without compromising forage yield and quality. The second study focuses on the agronomic performance of winter camelina [Camelina sativa (L.) Crantz.] intersown as a cover crop into standing soybean [Glycine max (L.) Merr] or maize. Camelina sown on the same date as maize or soybean resulted in lower grain and biomass yield of both crops indicating that intersowing should be done after V3-V5 stages. The economic analysis indicated camelina broadcast seeding into soybean had higher net revenue compared with camelina intersown in maize. Winter camelina winter hardiness and nutrient scavenging makes it a crop with good potential as cover crop in maize-soybean systems in the US Midwest. The environmental impacts of 11 cropping systems involving late-season cover crops, intercropping, intersowing cover crops into standing cash crops, and current cropping systems in the North Central US was evaluated. Global warming potential was the highest in all systems that had maize, except for the maize-FS silage system. Including a cover crop in a system, resulted in higher CO2 emissions, due to additional inputs. Further research is needed to evaluate the long-term benefits and ecosystem services of cover crops.Item Cover Crops Impact on Energy and Forage Crops Productivity in North Dakota(North Dakota State University, 2013) Samarappuli, Dulan PravindaForage crops have gained interest as potential source of lignocellulosic feedstock to produce ethanol. More focus is needed on developing cropping systems to improve productivity. This study was conducted to identify the agronomic potential of six different cover crops on five different annual biomass crops. Results indicated that forage pea (Pisum sativum L. cv. Arvika) N uptake was 126 kg N ha-1 and was able to fix approximately 60 kg of N ha-1 in only 60 days in the fall. Results across locations indicated that forage sorghum (Sorghum bicolor L. Moench cv. FS-5), and sweet sorghum (Sorghum bicolor L. Moench cv. Theis) had the highest biomass yields among the forage crops with 17.8 Mg ha-1 followed by sweet sorghum with 15.3 Mg ha-1, respectively. Therefore forage sorghum and sweet sorghum can be considered as the most productive biomass sources, specially combined with a legume cover crop seeded the previous fall.