Northwest Irrigation and Soils Research Laboratory

Abstract Summer fallow practices are of increased interest in semi‐arid irrigated areas of the western United States as a means to replenish water resources. Understanding of cereal residue decomposition in these conditions is limited, and data are needed to develop guidance. Research was conducted from 2018 to 2020 in Aberdeen, ID. Residue decomposition bag studies assessed crop type (barley [ Hordeum vulgare L.], corn [ Zea mays L.], hard red wheat [ Triticum aestivum L.; HRW], and soft white wheat [SWW]), tillage (surface and incorporated), and supplemental fertilizer‐N rates (0, 56, and 112 kg N ha −1 ) collected after application (spring, summer, and fall). Barley, corn, HRW, and SWW carbon:nitrogen (C:N) ratios were 74, 62, 105, and 87, respectively. Crop type and tillage affected residue decomposition, but fertilizer‐N had no impact. Decomposition was greatest from post‐harvest to spring for incorporated corn (37%) and least for surface barley, HRW, and SWW (21%). At the fall sampling, patterns were largely the same with minor changes from spring. Fertilizer‐N decreased C:N ratio at the spring sampling but not at the summer or fall timings. First‐order decay constants ranged from 0.00075 to 0.00300 day −1 for surface HRW and incorporated corn, respectively. This equates to a timeframe of 231–929 days for 50% of residue to decompose. Additions of fertilizer‐N to increase residue decomposition were not supported by the data but incorporation of residue by tillage and lower C:N crop types did result in more rapid decomposition. Relatively slow rates of decomposition occurred, particularly when surface applied, and these estimates can be used to improve residue management in semi‐arid regions.

Cassava (Manihot esculentaCrantz) is a staple food for hundreds of millions across the global south. In this study, we investigated genomic diversity among over 1000 cassava genotypes, with a particular focus on the addition of 387 newly sequenced landrace varieties originating from diverse climates across Colombia. As cassava was domesticated in or near the Amazon basin, these landraces represent untapped genetic diversity that could be used to help improve modern varieties. As theory predicts, we found that landraces retain high genetic diversity, observing variation lacking in breeding lines from Asia and Africa, where introductions likely caused population bottlenecks. Genetic differentiation in landraces reflects both space and climate of origin, suggesting the combined effects of demography and selection. To identify alleles with the potential to inform targets for gene editing, we assessed the diversity of loss-of-function (LoF) mutations across these landraces. We found evidence that deleterious LoF alleles were purged by inbreeding. Notably, genes retaining LoF alleles despite inbreeding were significantly enriched for functions related to the biosynthesis of coumarins and the regulation of plant immunity, suggesting selection on postharvest quality and disease resistance. We further identified specific loci associated with climates of origin, motivating future experiments using targeted knockouts to test hypotheses about the adaptive value of specific LoF alleles. This work supports longstanding hypotheses about landraces as a reservoir of genetic diversity and establishes the foundation to leverage this variation in cassava to discover alleles for accelerated breeding via gene editing.

Sugar beet is highly susceptible to the beet curly top virus (BCTV), which significantly reduces sugar yield and is prevalent in semi-arid growing regions. Typical BCTV symptoms are leaf vein swelling, thickening, and curling, leading to chlorosis and plant death. Insecticide seed treatments with neonicotinoids have been the primary management option, but neonicotinoids face regulatory restrictions due to environmental concerns. Thus, insecticides and biochemicals that are relatively safer to use were evaluated for efficacy against BCTV during the 2024 growing season. New treatments identified in this work can potentially be used by the growers to improve sugar beet BCTV management.

Abstract Intensive dairy production in southern Idaho is associated with the annual application of manure to croplands. However, a one‐time heavy application of manure could alternatively be used as a means to improve soil fertility and health for years or even decades, circumventing the need for frequent applications. To determine if this practice would negatively affect soil properties in the short term, we analyzed chemical and biological indicators of soil health for 2 years after dairy manure incorporation. Soil indicators measured were pH, electrical conductivity, extractable nitrogen (N) and phosphorus, total carbon (C) and N, enzyme activities, net N mineralization, soil organic C, soil protein, active C, ammonia oxidation potential, and particulate organic matter. Manure (with and without synthetic fertilizer) was found to significantly affect chemical and biological indicators in both topsoil (0–15 cm) and subsoil (15–30 cm), but the responses were greater in the subsoil. This can be attributed to the fact that manure was incorporated to approximately 30 cm via moldboard plow. All indicators responded positively to manure, except pH, which decreased slightly in the subsoil in the first year after application. Principal component analysis of chemical and biological indicators, across all years and depths, showed that the first two components explained 62% and 8.5% of the variance. While soil indicators were not adversely affected by manure, silage corn (Zea mays L.) yields in year 1 were significantly lower in manured plots, though in year 2, barley grain (Hordeum vulgare L.) yields were statistically similar among manure and fertilizer.

Waste-to-energy systems can provide a functional demonstration of the economic and environmental benefits of circularity, innovation, and reimagining existing systems. This study offers a robust quantification of the greenhouse gas (GHG) emission reduction potential of the adoption of anaerobic digestion (AD) technology on applicable large-scale dairy farms in the contiguous United States. GHG reduction estimates were developed through a robust life cycle modeling framework paired with sensitivity and uncertainty analyses. Twenty dairy configurations were modeled to capture important differences in housing and manure management practices, applicable AD technologies, regional climates, storage cleanout schedules, and methods of land application. Monte Carlo results for the 90% confidence interval illustrate the potential for AD adoption to reduce GHG emissions from the large-scale dairy industry by 2.45-3.52 MMT of CO2-eq per year considering biogas use only in renewable natural gas programs and as much as 4.53-6.46 MMT of CO2-eq per year with combined heat and power as an additional biogas use case. At the farm level, AD technology may reduce GHG emissions from manure management systems by 58.1-79.8% depending on the region. Discussion focuses on regional differences in GHG emissions from manure management strategies and the challenges and opportunities surrounding AD adoption.

Beet curly top in sugar beet and common bean is a major yield-limiting factor that is caused by beet curly top virus (BCTV) and is vectored by the beet leafhopper (BLH; Circulifer tenellus). BLH populations in southern Idaho were tracked during the 2020 and 2021 growing seasons in desert areas and sugar beet and common bean fields with yellow sticky cards to assess BLH population levels and identify the curly top virus species/strains and phytoplasmas present. Plants from monitored crop fields were also assessed for the same pathogens. In one desert area (Elmore Co.), BLH populations began increasing in May and were present in double-digit numbers per card through the summer at all sites in both years. However, the BLH numbers at other desert sites were at or near zero. Local weed populations and not desert areas appeared to be the primary source of BLH in crop fields. Based on cytochrome oxidase gene sequence, two haplotypes dominated the BLH population. In both years, BCTV strains Worland and Colorado were the primary strains in BLH and plant samples. The California/Logan, pepper curly top (PeCT), and severe strains of BCTV were also detected in BLH, along with spinach curly top Arizona virus (SpCTAV). Phytoplasmas were detected in 1% of BLH samples in both years. Phytoplasmas, SpCTAV, and PeCT were not detected in plant samples. This project established the curly top species/strains for which host plant resistance is needed, as well as the time and areas when crops are at the highest risk for infection. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2024.

Methyl bromide (MeBr) is a sterilizing fumigant used to control quarantine pests that is restricted due to its detrimental atmospheric effects. The degradation of injected MeBr produces crop-available Br- . Up to five applications of MeBr were used in southeastern Idaho fields to combat the pale cyst nematode (Globodera pallida). Data regarding the uptake and partitioning of Br- in crops following MeBr application in the region were unavailable. Research determined background concentrations of Br- in alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), corn (Zea mays L.), potato (Solanum tuberosum L.), and wheat (Triticum aestivum L.) compared to MeBr-treated fields. Background Br- concentrations ranged from nondetectable (ND) to 33.0mg Br- kg-1 ; vegetative tissue concentrations were greater than reproductive, except corn where there was no difference. Nearly all crops grown in MeBr-treated fields had greater Br- concentrations than background. Background-baled-alfalfa tissue Br- concentration was 33.0mg kg-1 compared to 117.8mg Br- kg-1 from a MeBr-treated field. Br- concentration in green alfalfa decreased from 79.8 to 36.5mg Br- kg-1 at the final cutting in a MeBr-treated field, where time after application decreased crop Br- concentrations. Small grains had low Br- concentrations in reproductive tissue (1.7mg Br- kg-1 ) compared to vegetative tissue (106.5mg Br- kg-1 ). Corn stover concentration (12.7mg Br- kg-1 ) was low relative to small-grain straw, but corn ear (5.8mg Br- kg-1 ) was greater than small-grain reproductive tissue in the MeBr-treated field. Crop selection following MeBr applications should consider the likelihood of elevated Br- concentration for the plant fractions intended end use.

Livestock manure management systems can be significant sources of nitrous oxide (N2 O), methane (CH4 ), and ammonia (NH3 ) emissions. Many studies have been conducted to improve our understanding of the emission processes and to identify influential variables in order to develop mitigation techniques adapted to each manure management step (animal housing, outdoor storage, and manure spreading to land). The international project DATAMAN (http://www.dataman.co.nz) aims to develop a global database on greenhouse gases (N2 O, CH4 ) and NH3 emissions from the manure management chain to refine emission factors (EFs) for national greenhouse gas and NH3 inventories. This paper describes the housing and outdoor storage components of this database. Relevant information for different animal categories, manure types, livestock buildings, outdoor storage, and climatic conditions was collated from published peer reviewed research, conference papers, and existing databases published between 1995 and 2021. In the housing database, 2024 EFs were collated (63% for NH3 , 19.5% for CH4 , and 17.5% for N2 O). The storage database contains 654 NH3 EFs from 16 countries, 243 CH4 EFs from 13 countries, and 421 N2 O EFs from 17 countries. Across all gases, dairy cattle and swine production in temperate climate zones are the most represented animal and climate categories. As for the housing database, the number of EFs for the tropical climate zone is under-represented. The DATAMAN database can be used for the refinement of national inventories and better assessment of the cost-effectiveness of a range of mitigation strategies.