Project : USDA ARS

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Research Project: Sustainable Small Farm and Organic Grass and Forage Production Systems for Livestock and Agroforestry

Location: Dale Bumpers Small Farms Research Center

2024 Annual Report

Objectives
Objective 1. Management systems for improved growth, handling and storage of harvested biomass for optimized quality and utilization for improved livestock management and positive environmental benefits. Sub-objective 1A. Forage and biomass production systems that better utilize nutrients to increase productivity and/or reduce energy and nutrient input requirements. Sub-objective 1B. Biomass harvest and storage systems that enhance the value of the feedstock for livestock production. Sub-objective 1C. Efficient strategies for producing livestock on forage-based diets, targeting optimal productivity. Sub-objective 1C1. Identification and selection of animal phenotypes that are productive and thrive on low-input pasture systems to minimize management inputs. Sub-objective 1C2. Understanding grazing behavior and spatial distribution of sheep naturally infected with gastrointestinal nematodes. Objective 2: Develop integrated tools to foster improved management of pasture and forages which maintain productivity while providing economic and environmental benefits. Sub-objective 2A. Measuring and monitoring system status and function at various scales. Sub-objective 2A1. Develop tools to identify environmental factors affecting forage production to maximize productivity and environmental/ecosystem benefits in diverse environments. Sub-objective 2A2. Utilize spatial information to develop site specific recommendations for warm season forage species, nutrient requirements and economic inputs for improved farm management. Sub-objective 2B. Provide tools that support management decisions and aid implementation. Sub-objective 2B1. Determine site specific recommendations coupling soil water availability with nutrient requirements to optimize forage production for economic sustainability. Sub-objective 2B2. Farm-scale recommendations that provides a decision support tools for producers that will allow optimization of farm management for whole farm productivity, economic viability and environmental sustainability. Sub-objective 2C. Pasture-based livestock management practices that improve resilience to climate change, conserve soil or protect water quality, optimizing production, conservation and environmental goals. Sub-objective 2D. Targeted grazing strategies to reduce invasive grasses and forbs and promote desirable perennial grasses and woody species. Sub-objective 2E. Grazing management strategies for maintenance of a diverse native plant pasture that serves livestock and wildlife including native pollinators. Sub-objective 2E1. Impact of grazing on insect pollinators and beneficial arthropod community in pasture ecosystems designed for multiple use of livestock grazing and pollinator habitat. Sub-objective 2E2. Impact of native forbs and grasses on insect pollinators and beneficial arthropods and plant- pollinator interactions in pasture ecosystems designed for multiple use of livestock grazing and pollinator habitat.

Approach
Our goal is to increase long-term sustainability of small farms by integrating management of pasture and silvopasture-based livestock systems to augment whole-farm productivity and profitability, encourage crop diversification which spreads biological and financial risk, and enhances ecosystem services. Involving both short- and long-term studies, we will determine practices that provide environmental and economic benefit to small farms. Studies will focus on improving forage and/or livestock production while enhancing soil, landscape and forage attributes at multiple scales. These studies include examining conventional and nonchemical parasite control on sheep production efficiency, grazing management on forage finished beef and lamb, and improving nutrient-use efficiency on forage pastures. Additionally spatial information will be used to understand interactions at multiple scales to develop decision support tools for increasing efficiency for soil-forage system management. We will also continue a long-term study that utilizes controlled watersheds to determine the impacts of various pasture management strategies (rotational grazing, overgrazing, haying, tree buffers) on pasture hydrology and nutrient runoff. To evaluate diversification, we will examine effects of integrating agroforestry management with crop and/or livestock production.

Progress Report
This is the final report for this project which has been replaced by project 6020-21500-001-000D, "Innovations for Small Farms Pasture and Silvopasture". Subsurface poultry litter application improves nutrient utilization compared with surface application. Rye-ryegrass forage yields were 30% greater with litter applied subsurface (Nieman et al., 2021). However, when cool-season forage mixtures are diverse, very few differences in nutrient composition may be observed (Nieman et al., 2021). In a similar study with warm-season grasses, an increase in crude protein was observed with subsurface applied poultry litter, indicating greater capture and uptake of litter N by plants (Nieman et al., 2023) Harvesting forages as baleage provides flexibility for producers, as forages can be cut, baled, and wrapped in one or two days when forage moisture ranges from 45-65%. Final post-fermentation baleage quality is greatly dependent on the initial forage quality, but also moisture at the time of wrapping. In rye-ryegrass baleage, greater bale moisture resulted in greater production of fermentation acids, which quickly reduced bale pH (negative relationship with bale moisture; Nieman et al., 2021). Low pH is favorable, as it indicates that fermentation was successful, and that silage will be more stable while in storage. Mechanical breakdowns and changes in the weather may disrupt the baleage making process and delay wrapping. Warm-season forages that were baled, rained on, and then wrapped 17-h later had similar post-fermentation nutrient composition to bales that wrapped within 2-h of baling (Nieman et al., 2023). Identification and selection of animal phenotypes that are productive and thrive on low-input pasture systems to minimize management inputs. Examining seasonal differences in worm parasites and lamb growth, winter born lambs required more supplementation due to the poorer quality forages and had greater morbidity related to parasites but fall born ram lambs finished on cool season grasses performed well with or without supplement and had minimal issues with parasites, requiring fewer deworming in fall compared with winter born lambs (Wood et al., 2019). The first study conducted in a U.S. sheep population estimated the impacts of production system (conventional vs. organic) and birth season (winter vs. fall) on lamb growth and GIN infection. Historical records collected over nearly 20 yr from pasture reared Katahdin lambs were analyzed. Performance was similar between conventional and organically managed lambs. Results can be used to aid the producer decision making process to balance expected returns and costs of alternative management strategies (Murphy et al., 2024 in review). A long-term research project on selection of Katahdin sheep for parasite resistance balanced with maternal traits using estimated breeding values (EBV) and phenotypic traits demonstrated that the ARS and U.S. flocks consistently showed a downward trend (lower fecal egg counts) toward improved parasite resistance over the last 10 years. These sheep are genetically connected to animals from several farms in the United States. An EBV for the peri-parturient rise fecal egg count, a measure of parasite resistance around the time of lambing was developed and reported on (Notter et al., 2018). It was also determined that selection for parasite resistance would have little impact on maternal and growth traits (Ngere et al., 2018). To determine factors that contribute to reduced fertility in spring breeding ewes. In order to understand limitations to the success of out-of-season breeding, up to 200 ewes in in each of years 2018 to 2021 from both organic and conventional management systems, ranging in age from 8 months to up to 10 years. Body weights, body condition, hair coat score, rectal temperature, pregnancy and lambing rate were recorded. Statistical analyses showed that cytochrome P450 was not a good marker for fescue toxicosis, and serum concentrations of prolactin were highly variable, especially in spring months. Another small study on a subset of ewes was conducted in 2019 and 2020 to determine the effect of endophyte-free or -infected tall fescue on serum concentrations of prolactin, rectal temperature. These ewes showed the expected reduction in serum concentrations of prolactin associated with endophyte-infected tall fescue in both spring and fall months. A related study was completed and published that examined the concentrations of anti-mullerian hormone in serum as an indicator of fertility (Acharya et al., 2020). No relationship was found, but estimated breeding values determined by flock data submitted to the National Sheep Improvement Program were highly correlated with lambing rate of ewes. In subsequent years, multi-sire breeding was used in spring breeding, leading to pregnancy rates comparable to fall breeding due to increased libido among rams and ewes with more rams. To identify genetic loci associated with resistance to gastrointestinal nematodes in sheep. Five thousand sheep from 21 farms across the United States have been genotyped using an ovine genotyping array (50K) SNP. All sheep had phenotypes for parasite resistance (fecal egg counts determined around the time of weaning). A study on a smaller sub-population has been published (Becker et al., 2020). An additional 600 samples from the same population were genotyped using a high density SNP for a more in depth look at genes responsible for parasite resistance (Becker et al., 2020, 2022; Notter et al., 2022). While there were potential differences between high and low parasite infected lambs, these were not consistent enough from study to study or published literature to develop reliable genomic markers for parasite resistance selection. Understanding grazing behavior and spatial distribution of sheep naturally infected with GIN. Weaned lambs that were naturally infected with gastrointestinal nematodes (GIN) were fitted with GPS collars for 72 hours weekly for six weeks to examine behavior in 2019. Measures of GIN infection (fecal egg counts, packed cell volume), rectal temperature and body weights were determined every 7 days. The study did not occur in 2020 due to the pandemic. Targeted grazing strategies to reduce invasive grasses and forbs and promote desirable perennial grasses and woody species. Impact of grazing on insect pollinators and beneficial arthropod community in pasture ecosystems designed for multiple use of livestock grazing and pollinator habitat. The impact of grazing native forb and grasses on bees and other insects in livestock pastures were examined. Native forages were established in 6-0.4 ha livestock plots and divided into grazed or non-grazed. Blue vane traps and yellow and blue pan traps were used to collect bees and other insects. Plant species composition in both types of pastures was also recorded. Bee communities were more diverse and higher evenness observed in non-grazed compared to grazed pastures, possibly due to differences in availability of flowering forages. However, bee abundance and species richness were similar among grazing treatments (Acharya et al., 2022). Another study was conducted to examine the effects of grazing or no grazing of plots planted with native grasses and forbs important for pollinator habitat. Arthropod samples were collected using multiple collection devices (pan traps, nets, blue vein traps) to determine species and prevalence of pollinators within each grazing management treatment in 2018 and 2019. Thousands of arthropod samples were speciated and counted for bee and non-bee species. In general, because sheep enjoyed consumption of important pollinator plant species, there were fewer that existed in the grazed plots which was associated with fewer important pollinator insects (Acharya et al., 2024). Impact of native forbs and grasses on insect pollinators and beneficial arthropods and plant-pollinator interactions in pasture ecosystems designed for multiple use of livestock grazing and pollinator habitat. Four different colors of pan traps (blue, green, yellow, and purple) were examined for their utility in sampling bees in livestock pasture ecosystem comprised of native forage species. We analyzed relative abundance, richness, similarity, and community assemblage patterns associated. The blue color traps were the most attractive to bees and were effective for sampling bees in a livestock pasture ecosystem. Purple color traps were the second most effective, followed by yellow and green color traps (Acharya et al., 2021). Another study was conducted to assess the impact of different vane colors of a passive trap on wild bee sampling. There were 2230 bees recorded comprising 49 species, and five families. Traps with bright blue vanes captured the highest number of bees and most diverse bee species compared with bright yellow, dark blue, dark yellow, and purple vanes. Red vane traps captured the least diverse bee species. Out of the 49 bee species, only nine were found in all vane color types. Bright blue vanes attracted the greatest number of unique species. Vanes with higher light reflectance properties (within 400-600 nm range) attracted the highest number of bee species. These results suggest that bees respond differently to different light wavelength and reflectivity of vanes of passive traps (Acharya et al., 2022). Another study examined establishment of important native plants for pollinators and found that the establishment of pastures using seed mixes of native forbs, legumes, and grasses and warm season grasses resulted in variable success, with undesirable species often comprising over 50% of the plant community (Acharya et al., 2024).

Accomplishments
1. Use of sub-surface poultry litter injection for greater nutrient utilization in mixed warm-season baleage and effects of delayed wrapping on mixed warm-season grass baleage quality. Poultry litter is a common fertilizer used in the southeastern United States due to the high density of poultry production in the region. However, broadcast application of poultry litter onto hay fields and pastures can result in nutrient losses from volatilization and run-off. Injection of poultry litter under the soil surface (sub-surface) reduces these nutrient losses and thus improves nutrient utilization and forage nutritive value compared to broadcast (surface) application. Wrapping bales within 4 hours after baling is generally recommended to create an oxygen barrier and start the fermentation process. Delayed wrapping of wet bales, which can happen due to unexpected rain or mechanical breakdown, results in dry matter losses and heating that can damage forage proteins, reducing their digestibility. ARS researchers in Booneville, Arkansas, and Marshfield, Wisconsin, evaluated nutrient composition of mixed warm-season forages with poultry litter applied either sub-surface or surface and wrapped with 2-h or 17-h post baling. Delayed wrapping was a secondary treatment, bales were wrapped 2 or 17-h after baling. Sub-surface poultry litter application decreased fiber concentrations and increased crude protein and fermentation products in the post-ensiled baleage. Delayed wrapping had several effects on pre-ensiled forage nutrient composition, but nutrient composition did not differ in the final post-ensiled forage. This information is important to forage producers in the southeast because of the prevalence of poultry production and farmers’ interest in improving nutrient utilization in harvested forages.

2. Pollinators require a diverse array of perennial native forages that can be incorporated in livestock pastures. A greater understanding is needed on types of traps to identify important pollinators for these sites, abundance and diversity of pollinators, and the effect of grazing practices on the pasture ecosystem. Collaborators from the ARS researchers in Booneville, Arkansas, University of Arkansas, Long Island University, and University of Maine determined that 1) a diverse array of bees (59 species) and other insects (at least 93 species) were found in the livestock-grazed pastures, but the abundance, diversity, and evenness of bee communities and other insects were greater in non-grazed plots; 2) blue pan traps attracted the highest rate of bees and enabling the understanding of species richness, but yellow and green traps captured more insects in general than blue and purple; 3) using vane traps, a passive form of trap, bright blue vane traps attracted the highest rate of bees with the greatest diversity relative to other colors (yellow, purple, red) and that bright compared with dark colors attracted more bees; 4) establishing and maintaining native forages in a pasture system was extremely challenging since sheep prefer to consume forages at the time they flower, competing with needs of pollinators. Scientists learned about the best trapping methods, that reduction in bee and insect diversity in grazed areas highlight the importance of rotational grazing regimes to allow for sufficient floral resources for pollinators and understand that pollinator habitat may be better adjacent to grazing pastures to allow for sufficient floral resources for pollinators. These concepts are important to entomologists, food scientists, environmentalists and ecologists to preserve and attract more native pollinators in agricultural settings.

3. Soil moisture and water status drives responses in soils. Predicting soil moisture spatially has not been possible which limits extrapolation of soil moisture sensor data. ARS researchers in Booneville, Arkansas, developed 4 dimensional soil mapping that predicts spatial soil moisture with depth over time. The method was developed using output from a distributed hydrology model which was re-calculated for soil moisture predictions. These data will provide a platform for understanding nutrient use and nutrient transformations. The data can build on crop growth models and support machine learning with ultimate goal of artificial intelligence.

U.S. DEPARTMENT OF AGRICULTURE

Dale Bumpers Small Farms Research Center: Booneville, AR