Diversifying bioenergy crops increases yield and yield stability by reducing weed abundance.

Relationships between species diversity, productivity, temporal stability of productivity, and plant invasion have been well documented in grasslands, and these relationships could translate to improved agricultural sustainability. However, few studies have explored these relationships in agricultural contexts where fertility and weeds are managed. Using 7 years of biomass yield and species composition data from 12 species mixture treatments varying in native species diversity, we found that species richness increased yield and interannual yield stability by reducing weed abundance. Stability was driven by yield as opposed to temporal variability of yield. Nitrogen fertilization increased yield but at the expense of yield stability. We show how relationships between diversity, species asynchrony, invasion, productivity, and stability observed in natural grasslands can extend into managed agricultural systems. Increasing bioenergy crop diversity can improve farmer economics via increased yield, reduced yield variability, and reduced inputs for weed control, thus promoting perennial vegetation on agricultural lands.

A needle in a seedstack: an improved method for detection of rare alleles in bulk seed testing through KASP.

BACKGROUND: Amaranthus palmeri is an aggressive and prolific weed species with major impact on agricultural yield and is a prohibited noxious weed across the Midwest. Morphological identification of A. palmeri from other Amaranthus species is extremely difficult in seeds, which has led to genetic testing for seed identification in commercial seed lots. RESULTS: We created an inexpensive and reliable genetic test based on novel, species-specific, single nucleotide polymorphisms (SNPs) from GBS (Genotyping by Sequencing) data. We report three SNP-based genetic tests for identifying A. palmeri alone or in a mixed pool of Amaranthus spp. Sensitivity ranged from 99.8 to 100%, specificity from 99.59 to 100%. Accuracy for all three tests is > 99.7%. All three are capable of reliably detecting one A. palmeri seed in a pool of 200 Amaranthus spp. seeds. The test was validated across 20 populations of A. palmeri, along with eight other Amaranthus species, the largest and most genetically diverse panel of Amaranthus samples to date. CONCLUSION: Our work represents a marked improvement over existing commercial assays resulting in an identification assay that is (i) accurate, (ii) robust, (iii) easy to interpret and (iv) applicable to both leaf tissue and pools of up to 200 seeds. Included is a data transformation method for calling of closely grouped competitive fluorescence assays. We also present a comprehensive GBS dataset from the largest geographic panel of Amaranthus populations sequenced. Our approach serves as a model for developing markers for other difficult to identify species. © 2021 Society of Chemical Industry.

Reduced Potential for Nitrogen Loss in Cover Crop-Soybean Relay Systems in a Cold Climate.

Winter cover crops might reduce nutrient loss to leaching in the Upper Midwest. New oilseed-bearing cash cover crops, such as winter camelina ( L.) and pennycress ( L.), may provide needed incentives. However, the abilities of these crops to sequester labile soil nutrients are unknown. To address this unknown, N in shoot biomass, plant-available N and P in soil, and NO-N and soluble reactive P in soil water collected from lysimeters placed at 30, 60, and 100 cm were measured in cover crop and fallow treatments established in spring wheat ( L.) stubble and followed through a cover crop-soybean [ (L.) Merr.] rotation. Five no-till cover treatments (forage radish [ L.], winter rye [ L.], field pennycress, and winter camelina) were compared with two fallow treatments (chisel till and no-till). Pennycress and winter camelina were harvested at maturity after relay sowing of soybean. Winter rye and radish sequestered more N in autumn shoot biomass, ranging from 26 to 38 kg N ha, but overwintering oilseeds matched or exceeded N uptake in spring, ranging 28 to 49 kg N ha before soybean planting. Nitrogen uptake was reflected by reductions in soil water NO-N during cover crop and intercropping phases for all cover treatments (mean = 4 mg L), compared with fallow treatments (mean = 31 mg L). Cash cover crops like pennycress and winter camelina provide both environmental and potential economic resources to growers. They are cash-generating crops able to sequester labile soil nutrients, which protects and promotes soil health from autumn through early summer.