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Long-term no-tillage systems enhance cotton yield resilience to climate extremes through improved soil quality in Tennessee, USA, according to a 29-year rain-fed plot-scale cotton experiment.

Abstract Seasonal flooding following heavy rain deposits large amounts of sediments on productive lands in the lower parts of fields in western Tennessee. The deposited sediments have high proportion of sand particles that negatively affect soil physiochemical properties, which make the soil uneconomic for farming. Soil amendments such as biochar, a by‐product of renewable energy production from organic waste materials, have the potential to remediate sandy soil left after flood events and improve crop yields by increasing water holding capacity and soil nutrient content. The objective of this project was to evaluate the effect of biochar produced from two types of hardwood feedstocks on water retention and corn (Zea mays L.) growth in sandy soil. A greenhouse experiment quantifying the growth of corn was conducted in a randomized complete block design with five replications. Sandy soil was amended with three biochar rates (0, 10, and 20% by volume) under two irrigation levels. The irrigation levels were control and a dry treatment based on the past 10 yr of rainfall data. Biochar application greatly improved water retention in the flooded sandy soil. Biochar increased soil K and P concentration. However, at the end of the study, corn growth was not different in biochar amended and non‐amended sandy soil. This research demonstrated that biochar as a soil amendment has the potential to improve quality attributes of poor soil, such as the soil water and nutrient concentration in a previously flooded sandy soils.

Abstract Weed communities may potentially reduce row‐crop yields resulting in a loss of revenue for producers. Studies have reported a decrease in the efficacy of chemical methods of weed control due to increased weed resistance. With the goal of reducing reliance on chemical weed control and promoting sustainable crop production in mind, we evaluated different winter cover crop (CC) types (single‐, double‐, and multi‐species) and CC planting methods (broadcasting vs. drilling) on CC and weed groundcover and row‐crop yield in a no‐till corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation system in Tennessee from 2013 to 2017. Our results showed that winter CC reduced spring weed ground coverage by 64–76% compared with winter fallow with no herbicide application. A five‐species CC mixture increased soybean yields by 6 to 8.5% across seeding method treatments compared with other CC treatments and winter fallow. This yield increase was more visible in a drought year. Corn, grown in years with normal weather patterns, did not show a yield response to CC types. From this study, cover cropping was found to be an effective strategy for weed control compared with leaving the field fallow without herbicide application following row‐crop harvest; however, no consistent species‐specific trends were observed on weed suppression and row‐crop yield. Future research should focus on understanding CC species composition and biomass production in double‐ and multi‐species mixtures from this field experiment to draw robust conclusions on agronomic responses of individual CC species and planting methods.

Soybean is an important oil-producing crop in the Fabaceae family and there are increasing demands for soybean oil and other soybean products. Genetic improvement of soybean is needed to increase its production. In order to provide genetic diversity and resources for identifying important genes, a new ethyl methane sulfonate (EMS) mutagenized soybean population was generated using the newly released germplasm, JTN-5203 (maturity group V). Treatment of soybean seeds with 60 mM EMS concentration was found to be suitable for inducing mutation. A total of 1,820 M1 individuals were produced from 15,000 treated seeds. The resulting M2 population was planted in the field for phenotyping. After harvest, seed traits including total oil, protein, starch, moisture content, fatty acid and amino acid compositions were measured by NIR. Phenotypic variations observed in this population include changes in leaf morphology, plant architecture, seed compositions, and yield. Of most interest, we identified plants with increased amounts of total protein (50% vs. 41% for control) and plants with higher amounts of total oil (25% vs. 21.2% control). Similarly, we identified plants with increases in oleic acid content and decreases in linoleic acid and linolenic acid. This EMS mutant population will be used for further studies including screening for various traits such as amino acid pathways, allergens, phytic acids, and other important soybean agronomic traits. In addition, these mutant individuals will be evaluated in the next generation to assess the heritability. Beneficial traits from these mutants can be exploited for future soybean breeding programs. This germplasm can also be used for discovering novel mutant alleles and for functional gene expression analysis using reverse genetics tools such as TILLING.