Perennial agriculture is an alternative agricultural paradigm with potential to improve soil health and reduce energy input. Cereal-legume intercropping (or biculture) is often suggested together with perennial crops as a way to reduce exogenous nitrogen (N) input. In developing new perennial cereal varieties, a crop's ability to adapt to neighboring legumes and optimize interactions between crops is of particular interest. The rhizosphere microbial community plays a major part in this plant adaptation since much of the N transfer between cereals and legumes is facilitated by microbial activity. Therefore, we conducted a field study to examine plant performance and rhizosphere communities of the recently domesticated perennial cereal Kernza (Thinopyrum intermedium (Host) Barkworth & D.R.Dewey), annual wheat (Triticum turgidum L. subsp. durum (Desf.) Husn.), and their hybrid, perennial wheat. Each genotype was planted either in monoculture or in biculture with alfalfa (Medicago sativa L.), and its rhizosphere microbial community was profiled using 16S and ITS amplicon sequencing. The 16S rRNA gene amplicon profiles of perennial wheat were distinct from those of annual wheat and were similar to those of Kernza (pairwise PERMANOVA, p = 0.012, p = 0.316, respectively); the hybrid seemingly inherited microbial recruitment traits of its perennial parent more so than from the annual parent. Interestingly, the inclusion of alfalfa led to the convergence of 16S profiles, likely due to its competitive pressure across genotypes. In contrast, the fungal community did not show a clear genotype effect (PERMANOVA, p = 0.551). In conclusion, we found that crop genotype influenced rhizosphere microbial communities, with rhizosphere microbiome inheritability skewed toward the annual parent, and that this was further shaped by legume competition. Our study demonstrates the importance of including rhizosphere plant genotype-microbial interactions in the evaluation of novel cereal crops in both monoculture and cereal-legume biculture.

Mine lands contaminted with heavy metals pose environmental risks, and thus reclamation is paramount for improving soil, plant, animal, and ecosystem health. A metal-contaminated alluvial mine tailing, devoid of vegetation, received 224 ​Mg ​ha−1 of both lime and biosolids in 1998, and long-term reclamation success was quantified in 2019 with respect to soils, plants, and linkages to animals. Reclamation success was quantified using the Soil Management Assessment Framework (SMAF), in conjunction with bioavailable (0.01 ​M CaCl2 extractable) and plant-available (Mehlich-3 extractable) soil metal concentrations, X-ray absorption spectroscopy, plant metal concentrations, and plant quality characteristics. Results showed that all soil indicators were improved in successfully-reclaimed areas as compared to on-site degraded areas, including increases in soil aggregate stability, pH, plant-available P and K, soil organic C, potentially-mineralizable N, microbial biomass C and β-glucosidase activity and decreases in soil bulk density and electrical conductivity. Ofindicators, unitless soil health scores were assigned based on the SMAF, with data suggesting that bulk density, wet aggregate stability, potentially- mineralizable N, microbial biomass C, pH, and electrical conductivity should be monitored in the future. The long-term effects of lime and biosolids application have improved soil physical, biological, and overall soil health. Plant metal concentrations have decreased by an order of magnitude since early reclamation, with most plant metal concentrations being tolerable for domestic livestock consumption. From an animal health perspective, feeding grasses from this site during latter parts of a growing season may need supplemental feed to provide greater protein and energy content, and to reduce potentially-harmful Cd concentrations from food chain bioaccumulation. However, a health concern exists based on soil bioavailable Cd and Zn concentrations that exceed ecological soil screening levels. Still, plants have stabilized the soil and acidity remains neutralized, leading to long-term improvements in soil health, with overall improved ecosystem health.

Since the adoption of national rules for organic agriculture in the United States, there has been a continued interest in meeting crop nitrogen (N) needs using animal manure. However, a lack of consistent information on the N supplying potential of manure creates uncertainty for farmers and often leads to overapplication, which can negatively impact both crop productivity and environmental sustainability. We investigated short‐term N mineralization and microbial biomass carbon (MBC) and nitrogen (MBN) following dairy manure (DM) and its compost (DMC) application to organic annual forage production system. N mineralization was determined based on the change in mineral N during a ≤75‐day in‐field soil core‐resin bag incubation. DM and DMC application rates were targeted to supply 123 and 56 kg potentially plant‐available nitrogen (PAN) ha−1 in the first and second year of application, respectively. Net N mineralization exhibited a range of 42–277 kg N ha−1 in Year 1 and 31–54 kg N ha−1 in Year 2 across amendment treatments and increased over the course of incubation duration in both years. The proportion of total N added that was mineralized in Year 1 was greater from DM than DMC (≤35% vs. ≤7%, respectively), suggesting the inability of DMC to supply optimal levels of N to annual forages in the first crop season. In Year 2, net N mineralization did not differ between DM and DMC, but was significantly less in the unamended control than both amendments. MBC and MBN were more influenced by seasonality and soil sampling depth than by organic amendments.

Recent Colorado, USA water law provisions allow a portion of irrigation water to be leased between agricultural and other users. Reducing consumptive use (CU) through deficit irrigation while maintaining some crop production could allow farmers to earn revenue from leasing water rights. This observational study aimed to determine if deficit irrigation of alfalfa (Medicago sativa L.) can be used to reduce CU, provide parameters for an alfalfa crop water production function (WPF), and evaluate the potential for improved farm income by leasing water. Soil water balance, evapotranspiration (ET), and dry matter yield from eight commercial fields (1.70 to 2.14 ha zones), growing subsurface drip-irrigated alfalfa, were monitored for five seasons (2018–2022) at Kersey, Colorado. Four irrigation treatments [Standard Irrigation (SI) = irrigate when soil water deficit (D) exceeds management allowed depletion (MAD); Moderate Deficit Irrigation (MDI) = 70% of SI; Severe Deficit Irrigation (SDI) = 50% of SI; and Over Irrigation (OI) = 120% of SI] were applied, with two zones per treatment. Reductions in CU ranged from 205 to 260 mm per season. The shape of the alfalfa WPF (dry biomass yield vs. ET) was concave, indicating that water use efficiency (WUE) could be optimized through deficit irrigation. The average WUE was 0.17 Mg ha−1 cm−1 and tended to increase with greater deficits. Deficit irrigation also increased the relative feed value. If conserved CU from deficit irrigation can be leased into a transfer water market, farmers could profit when the water lease revenue exceeds the forgone profit from alfalfa production. We found incremental profit from deficit irrigation and water leasing to be positive, assuming 2020 prices for hay ($230 bale−1) and water prices above $0.50 m−3.

Management-intensive Grazing (MiG) has been proposed to sustainably intensify agroecosystems through careful management of livestock rotations on pastureland. However, there is little research on the soil health impacts of transitioning from irrigated cropland to irrigated MiG pasture with continuous livestock rotation. We analyzed ten soil health indicators using the Soil Management Assessment Framework (SMAF) to identify changes in nutrient status and soil physical, biological, and chemical health five to six years after converting irrigated cropland to irrigated pastureland under MiG. Significant improvements in biological soil health indicators and significant degradation in bulk density, a physical soil health indicator, were observed. Removal of tillage and increased organic matter inputs may have led to increases in β-glucosidase, microbial biomass carbon, and potentially mineralizable nitrogen, all of which are biological indicators of soil health. Conversely, trampling by grazing cattle has led to increased bulk density and, thus, a reduction in soil physical health. Nutrient status was relatively stable, with combined manure and fertilizer inputs leading to stabilized plant-available phosphorous (P) and increased potassium (K) soil concentrations. Although mixed effects on soil health were present, overall soil health did increase, and the MiG system appeared to have greater overall soil health as compared to results generated four to five years earlier. When utilizing MiG in irrigated pastures, balancing the deleterious effects of soil compaction with grazing needs to be considered to maintain long-term soil health.

AbstractManagement‐intensive grazing (MiG) on irrigated, perennial pastures has steadily increased in the western United States due to pressure for reducing public lands grazing, overall declining land available for pasture, and decreasing commodity prices. However, there are still many unknowns regarding MiG and its environmental impact, especially with regards to soil health. Over a 2‐yr period, a study evaluating the change in soil health under a full‐scale, 82‐ha pivot‐irrigated perennial pasture system grazed with ∼230 animal units (AUs) using MiG. Soil analysis included 11 soil characteristics aggregated into the Soil Management Assessment Framework (SMAF), which outputs results for soil biological, physical, nutrient, chemical, and overall soil health indices (SHIs). Over time, positive impacts were observed in the chemical and biological SHI due to decreases in salt content and increases in microbial and enzymatic activities. Soil organic C (SOC) remained unchanged, yet positive biological SHI changes are potential precursors to future SOC increases. The chemical and nutrient SHI increased in the soil surface due to reductions in salt content in conjunction with increased plant‐available soil P, as a result of salt leaching via irrigation and pre‐study inorganic P fertilizer application in conjunction with manure deposition due to MiG, respectively. Finally, a negative impact was also observed in the physical SHI, driven primarily by increasing bulk density due to hoof pressure from cattle grazing. If managed correctly, compaction issues can be avoided, with MiG systems having potential success in supporting grazing while promoting soil health for environmental and economic sustainability.

Cover crops are important for soil conservation efforts but can compete with cash crops for limited water in dryland agricultural systems. Grazing cover crops may provide additional income to improve the profitability of cover cropped systems, but the effect of grazing cover crops on soil health remains poorly understood in semiarid regions. We conducted on-farm research to examine the short-term effects of grazed and un-grazed springplanted cover crops compared to full summer fallow on soil health metrics and wheat yields across ten no-till, dryland producer fields over two years in eastern Colorado, western Kansas and western Nebraska, USA. Soils were evaluated at cover crop termination following two to three months of growth for differences in a suite of soil physical and chemical properties. Grazed and un-grazed cover crops increased soil aggregation relative to summer fallow by 30-50%. Surface bulk density (0-5 cm) decreased by 4% with un-grazed cover crops, while bulk density under grazed cover crop was similar to fallow. Soil moisture in the top180 cm depth was reduced by 4?22 % with cover crops, with the greatest water depletion occurring below 30 cm, and grazing did not appear to affect soil moisture compared to un-grazed cover crops. Both cover crop treatments reduced wheat yields by roughly 20 %. The short-term improvements to key soil health metrics with cover crops were largely maintained with grazing, indicating the potential for livestock integration as a management option to offset the short-term yield impacts of cover crop moisture use in water-limited environments.

Abstract. Management-intensive Grazing (MiG) on irrigated, perennial pastures has steadily increased in the western US due to pressure for reducing public lands grazing, overall declining land available for pasture, and decreasing commodity prices. However, there are still many unknowns regarding MiG and its environmental impact, especially with regards to soil health. Over a two-year period, we studied changes in soil health under a full-scale, 82 ha pivot-irrigated perennial pasture system grazed with ~ 230 animal units (AUs) using MiG. Soil analysis included 11 soil characteristics aggregated into the Soil Management Assessment Framework (SMAF), which outputs results for soil biological, physical, nutrient, chemical, and overall soil health indices (SHI). Positive impacts were observed in the biological SHI due to increases in microbial and enzymatic activities, even though soil organic C (SOC) remained relatively unchanged; however, positive biological SHI changes are likely precursors to future SOC increases. The nutrient SHI declined due to a reduction in plant-available soil P over time, potentially due to greater plant uptake. A negative impact was also observed in the physical SHI, driven primarily by increasing bulk density due to hoof pressure from cattle grazing. If managed correctly, results suggest that irrigated, MiG systems have the potential for success with regards to supporting grazing while promoting soil health for environmental and economic sustainability.

Miscanthus is a perennial grass with potential for lignocellulosic ethanol production. To ensure its utility for this purpose, breeding efforts should focus on increasing genetic diversity of the nothospecies Miscanthus × giganteus (M×g) beyond the single clone used in many programs. Germplasm from the corresponding parental species M. sinensis (Msi) and M. sacchariflorus (Msa) could theoretically be used as training sets for genomic prediction of M×g clones with optimal genomic estimated breeding values for biofuel traits. To this end, we first showed that subpopulation structure makes a substantial contribution to the genomic selection (GS) prediction accuracies within a 538-member diversity panel of predominately Msi individuals and a 598-member diversity panels of Msa individuals. We then assessed the ability of these two diversity panels to train GS models that predict breeding values in an interspecific diploid 216-member M×g F2 panel. Low and negative prediction accuracies were observed when various subsets of the two diversity panels were used to train these GS models. To overcome the drawback of having only one interspecific M×g F2 panel available, we also evaluated prediction accuracies for traits simulated in 50 simulated interspecific M×g F2 panels derived from different sets of Msi and diploid Msa parents. The results revealed that genetic architectures with common causal mutations across Msi and Msa yielded the highest prediction accuracies. Ultimately, these results suggest that the ideal training set should contain the same causal mutations segregating within interspecific M×g populations, and thus efforts should be undertaken to ensure that individuals in the training and validation sets are as closely related as possible.

1 Soil physical damage can occur when grazing through pugging and compaction, especially when soils are wet. Removing cattle early in a precipitation event can minimize the most detrimental impacts from grazing on wet soils. Remediation of pasture soils from compaction using mechanical methods has shown variable results. Cattle management, soil monitoring, and contingency plans can be used to mitigate negative impacts to soil. Livestock Series | Management Fact Sheet 1.634

Abstract Overwintering ability is an important selection criterion for Miscanthus breeding in temperate regions. Insufficient overwintering ability of the currently leading Miscanthus biomass cultivar, M. ×giganteus (M×g) ‘1993–1780', in regions where average annual minimum temperatures are −26.1°C (USDA hardiness zone 5) or lower poses a pressing need to develop new cultivars with superior cold tolerance. To facilitate breeding of Miscanthus, this study characterized phenotypic and genetic variation of overwintering ability in an M. sinensis germplasm panel consisting of 564 accessions, evaluated in field trials at three locations in North America and two in Asia. Genome‐wide association (GWA) and genomic prediction analyses were performed. The Korea/N China M. sinensis genetic group is a valuable gene pool for cold tolerance. The Yangtze‐Qinling, Southern Japan, and Northern Japan genetic groups were also potential sources of cold tolerance. A total of 73 marker–trait associations were detected for overwintering ability. Estimated breeding value for overwintering ability based on these 73 markers could explain 55% of the variation for first winter overwintering ability among M. sinensis. Average genomic prediction ability for overwintering ability across 50 fivefold cross‐validations was high (~0.73) after accounting for population structure. Common genomic regions for overwintering ability were detected by GWA analyses and a previous parallel QTL mapping study using three interconnected biparental F1 populations. One QTL on Miscanthus LG 8 encompassed five GWA hits and a known cold‐responsive gene, COR47. The other overwintering ability QTL on Miscanthus LG 11 contained two GWA hits and three known cold stress‐related genes, carboxylesterase 13 (CEX13), WRKY2 transcription factor, and cold shock domain (CSDP1). Miscanthus accessions collected from high latitude locations with cold winters had higher rates of overwintering, and more alleles for overwintering, than accessions collected from southern locations with mild winters.

Core Ideas In this study, switchgrass grew well on marginally saline soil with limited irrigation.The southern‐origin cultivars had greater biomass yield than the northern cultivars.Irrigation increased above and below ground biomass, but not soil C and N content.Switchgrass had the potential to sequester C into the soil. Limited information is available on switchgrass (Panicum virgatum L.) productivity in semiarid environments. A field experiment was conducted in semiarid Colorado, with the objectives were to determine: 1) aboveground biomass production of six upland switchgrass cultivars, and 2) soil organic carbon content of two switchgrass cultivars grown on a marginally saline soil under rainfed and minimal irrigation conditions. The experiment was a split plot design with rainfed vs. minimal irrigation treatment as the main plot and six cultivars [three southern cultivars (Blackwell, Pathfinder, and Trailblazer) and three northern cultivars (Sunburst, Forestburg, and Dacotah)] as subplot with three replications. Aboveground biomass for the six cultivars ranged from 1.1 to 7.8 Mg ha−1yr−1 in the establishment year, and 3.2–9.3 and 3.3–11.7 Mg ha−1yr−1 under rainfed and minimally irrigated conditions, respectively, during the following three stand years. Minimal irrigation (mean annual irrigation water of 21 cm) increased biomass yield compared to the rainfed control. Southern‐origin cultivars produced more biomass than the northern lines under both rainfed and minimal irrigation. Four years after establishment, within the top 0.6 m of soil, irrigation increased root biomass, with averages of 9.9 and 5.2 Mg ha−1 yr−1 for irrigation and rainfed treatments, respectively. Soil organic carbon accumulated rapidly at 0–20 cm soil depth in Blackwell and Pathfinder plots, at the rates of 1.07–1.36 Mg C ha−1 yr−1. Switchgrass growth in the semiarid environment was improved with limited supplemental irrigation and had the potential to sequester C into soil.

To improve the efficiency of breeding of Miscanthus for biomass yield, there is a need to develop genomics-assisted selection for this long-lived perennial crop by relating genotype to phenotype and breeding value across a broad range of environments. We present the first genome-wide association (GWA) and genomic prediction study of Miscanthus that utilizes multilocation phenotypic data. A panel of 568 Miscanthus sinensis accessions was genotyped with 46,177 single nucleotide polymorphisms (SNPs) and evaluated at one subtropical and five temperate locations over 3 years for biomass yield and 14 yield-component traits. GWA and genomic prediction were performed separately for different years of data in order to assess reproducibility. The analyses were also performed for individual field trial locations, as well as combined phenotypic data across groups of locations. GWA analyses identified 27 significant SNPs for yield, and a total of 504 associations across 298 unique SNPs across all traits, sites, and years. For yield, the greatest number of significant SNPs was identified by combining phenotypic data across all six locations. For some of the other yield-component traits, greater numbers of significant SNPs were obtained from single site data, although the number of significant SNPs varied greatly from site to site. Candidate genes were identified. Accounting for population structure, genomic prediction accuracies for biomass yield ranged from 0.31 to 0.35 across five northern sites and from 0.13 to 0.18 for the subtropical location, depending on the estimation method. Genomic prediction accuracies of all traits were similar for single-location and multilocation data, suggesting that genomic selection will be useful for breeding broadly adapted M. sinensis as well as M. sinensis optimized for specific climates. All of our data, including DNA sequences flanking each SNP, are publicly available. By facilitating genomic selection in M. sinensis and Miscanthus  ×  giganteus , our results will accelerate the breeding of these species for biomass in diverse environments.

To breed improved biomass cultivars of Miscanthus ×giganteus, it will be necessary to select the highest‐yielding and best‐adapted genotypes of its parental species, Miscanthus sinensis and Miscanthus sacchariflorus . We phenotyped a diverse clonally propagated panel of 569 M. sinensis and nine natural diploid M . × giganteus at one subtropical (Zhuji, China) and five temperate locations (Sapporo, Japan; Leamington, Ontario, Canada; Fort Collins, CO; Urbana, IL; and Chuncheon, Korea) for dry biomass yield and 14 yield‐component traits, in trials grown for 3 years. Notably, dry biomass yield of four Miscanthus accessions exceeded 80 Mg/ha in Zhuji, China, approaching the highest observed for any land plant. Additionally, six M. sinensis in Sapporo, Japan and one in Leamington, Canada also yielded more than the triploid M . × giganteus ‘1993‐1780’ control, with values exceeding 20 Mg/ha. Diploid M . × giganteus was the best‐yielding group at the northern sites. Genotype‐by‐environment interactions were modest among the five northern trial sites but large between Zhuji, and the northern sites. M. sinensis accessions typically yielded best at trial sites with latitudes similar to collection sites, although broad adaptation was observed for accessions from southern Japan. Genotypic heritabilities for third year yields ranged from 0.71 to 0.88 within locations. Compressed circumference was the best predictor of yield. These results establish a baseline of data for initiating selection to improve biomass yield of M. sinensis and M . × giganteus in a diverse set of relevant geographies.

Core Ideas Annual cool‐season forages with high biomass yields may be stockpiled for fall grazing. Species composition was affected by the seeding rates of individual species used within the bulk seeding rate. Controlling millet regrowth with herbicide prior to seeding resulted in greater establishment, yield, and nutritive value of the seeded cool‐season forages. Annual forages can meet the requirements of beef cattle grazing during the fall and early winter. Cool‐season annual forages can provide grazing for beef cattle during fall and early winter. The objective of this study was to evaluate yield and nutritive value of nine forage combinations seeded in early August into pearl millet (Pennisetum glaucum L.) hay stubble that was either sprayed or allowed to regrow. Grass species included spring triticale (×Triticosecale Wittmack), winter wheat (Triticum aestivum L.), and winter barley (Hordeum vulgare L.). Each grass was then combined with a brassica mixture {turnip [Brassicas rapa L. var. rapa], rape [Brassica napus L. var. napus], radish [Raphanus sativus var. oleifer Strokes], and hybrid Chinese cabbage [Brassica rapa L. chinensis) × Turnip]}. A legume mixture (hairy vetch [Vicia villosa Roth] and Austrian winter pea [Pisum sativum subsp. arvense L.]) was then added to the grass–brassica mixtures. All species and mixtures produced sufficient forage (3080–5580 kg dry matter [DM] ha−1) to be stockpiled for fall grazing. The millet and brassicas dominated yield and nutritive value of the unsprayed and sprayed mixtures, respectively. The concentration of neutral detergent fiber (aNDF) was greater in unsprayed than sprayed mixtures (510–579 and 229–246 g kg−1, respectively), but the concentrations of crude protein (CP) (169–180 and 185–202 g kg−1, respectively) and in vitro true digestibility (IVTD) (755–799 and 909–922 g kg−1, respectively) were less. The lesser nutritive value and yield potential associated with letting the millet regrow must be weighed against the extra inputs but greater yield potential and nutritive value when the regrowth is controlled prior to seeding.