Reducing the fallow period by using cover crops in a winter wheat (Triticum aestivum L.)–sorghum [Sorghum bicolor (L.) Moench]–fallow system has the potential to suppress weeds and improve wheat yield, yet limited information is available from the semiarid southern Great Plains (SGP) of the United States. This study determines the effects of spring‐planted cover crops on weed suppression and winter wheat yields in semiarid environments. The study used a randomized complete block design with eight cover crop treatments and three replications. The cover crop treatments consisted of fallow (weeds controlled with herbicide), pea (Pisum sativum L.), oat (Avena sativa L.), canola (Brassica napus L.), pea + oat, pea + canola, pea + oat + canola, and six‐species mixture of pea + oat + canola + hairy vetch (Vicia villosa L.) + forage radish (Raphanus sativus L.) + barley (Hordeum vulgare L.). Both winter wheat and cover crops received supplemental irrigation. The cover crops showed potential to suppress weeds and maintain good ground cover during summer. Specifically, weed biomass in the oat and oat mixtures with legumes and brassicas were 73 to 85% less than in fallow during 2018. Cover crops showed little effect on wheat yield, yield components, and water use efficiency. Although long‐term studies of cover crops effects on multiple ecosystem services may help to select the most effective cover crop on wheat yield and water use efficiency in the SGP, this study revealed benefit of cover cropping through weed suppression.

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Cover crops improve soil health and environmental quality by enhancing soil organic carbon (SOC) sequestration and nutrient cycling in agroecosystems. This study evaluated the effect of cover crops on soil CO2–C emissions, temperature, and water content during cover crop growth from April to October, 2017 and 2018. Treatments included fallow, pea (Pisum sativum L.), oat (Avena sativa L.), canola (Brassica napus L.), pea–oat (POmix), pea–canola (PCmix), pea–oat–canola (POCmix), and POC–hairy vetch (Vicia villosa L.)–forage radish (Raphanus sativus L.)–barley (Hordeum vulgare L.) (six species mixture; SSmix). The CO2–C emissions were monitored weekly from April to October each year using a portable infrared‐gas analyzer. Seasonal changes in CO2–C emissions varied with cover crops and peaked as soil temperature and water content following precipitation events. Average CO2–C emissions across sampling dates was 46–70% greater under pea than under fallow, canola, and POmix in 2017, but not different among cover crops in 2018. Although the emissions were higher than fallow, canola and POmix plots had lower CO2–C emissions than other cover crops. Pea as sole cover crop or in mixtures (PCmix, POCmix, SSmix) increased CO2–C emissions and microbial activity whereas canola and POmix mixture reduced the emissions during the period with higher precipitation.

In water-scarce regions, high yield and improved water use efficiency (WUE) of crops can be obtained if water and nitrogen (N) are properly applied. While water and N have been the subject of research worldwide, studies are needed to advance our understanding on the complexity of their interaction. A field experiment was conducted at the University of Wyoming Powell Research and Extension Center in 2014 and 2015 growing seasons to determine the effect of irrigation water and N on growth, dry matter (DM) yield, and WUE of silage corn (Zea mays L.) grown under on-surface drip irrigation (ODI). The experiment was laid out as a randomized complete block design in split-plot arrangement with three replications. Irrigation was the main treatment and included 100ETc (100% crop evapotranspiration), 80ETc, and 60ETc. Nitrogen was the sub-treatment and included 0, 90, 180, 270, and 360 kg N ha−1 as urea-ammonium-nitrate solution Results showed that irrigation water, N, and application timing significantly affected growth and DM yield, especially at late vegetative and mid reproductive growth stages. At harvest (R4), no significant difference was observed between 180 kg N ha−1 and 270 kg N ha−1 on DM yield and WUE. However, significant differences of DM yield were observed between irrigation treatments, and 100ETc and 80ETc did not differ in WUE. Our findings suggest that 100ETc and 180 kg N ha−1 is the best combination for high yielding corn for silage grown in a semi-arid climate under ODI.

Main conclusion Some salt stress response mechanisms can translate into sorghum forage yield and thus act as targets for genetic improvement. Abstract Sorghum is a drought-tolerant cereal that is widely grown in the vast Africa’s arid and semi-arid areas. Apart from drought, salinity is a major abiotic factor that, in addition to natural causes, has been exacerbated by increased poor anthropological activities. The importance of sorghum as a forage crop in saline areas has yet to be fully realized. Despite intraspecific variation in salt tolerance, sorghum is generally moderately salt-tolerant, and its productivity in saline soils can be remarkably limited. This is due to the difficulty of replicating optimal field saline conditions due to the great heterogeneity of salt distribution in the soil. As a promising fodder crop for saline areas, classic phenotype-based selection methods can be integrated with modern -omics in breeding programs to simultaneously address salt tolerance and production. To enable future manipulation, selection, and genetic improvement of sorghum with high yield and salt tolerance, here, we explore the potential positive correlations between the reliable indices of sorghum performance under salt stress at the phenotypic and genotypic level. We then explore the potential role of modern selection and genetic improvement programs in incorporating these linked salt tolerance and yield traits and propose a mechanism for future studies.