Tall Fescue: Forage and Seed Production Economics

Irrigated grass pastures are essential components of western U.S. agriculture, especially on cattle ranches of the intermountain region. Unfortunately, the yield and quality of these grasslands are relatively low compared to the national average because of current management practices (Jacobs et al., 1993). Attempts have been made to increase forage yields of these pastures by fertilization and applying or controlling irrigations but these efforts have resulted in minimum success (Jacobs et al., 1993). The price increase of fertilizer, energy, and fuel has made improvement of these natural grasslands more difficult and thus threatens the profitability and sustainability of current production systems. Tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) is one of the most productive cool-season grasses in the U.S. It can grow on a wide range of soils, has high drought and winter hardiness, and can be used for pasture, hay, stockpiling, silage, soil conservation, and turf grass (Balasko, 1981). Also, it has prolific seed production ability. Therefore, tall fescue may have potential for forage and seed production in northwest Wyoming of U.S., perhaps other areas including neighboring states. The objectives of this project were to find out the suitability of tall fescues that are adaptable to the western mountain regions, specifically the Bighorn Basin, and generate information on growth, forage yield, and seed yield that could benefit growers in the Bighorn Basin and other areas of Wyoming and beyond

Agronomic Traits in Tall Fescue Populations under Irrigated and Rain-Fed Conditions

Grasslands and native rangelands are the predominant land-use all over the world. Tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] is a cool-season perennial grass widely grown throughout the temperate regions of the world and an important component of the grasslands. Drought can have serious consequences on performance of agriculture, soil and plant health, and economics. Developing drought tolerant plants that can maintain productivity during drought, will have great environmental and economic benefits to farmers. A tall fescue population was developed by crossing a drought tolerant genotype to a susceptible genotype. The population was evaluated for different morphological and yield traits under irrigated and rain-fed conditions at the University of Wyoming, USA. Large variations among the 252 tall fescue genotypes for several traits of interest have been observed. Plants under irrigated conditions were about 1.5 times more vigorous and 1.9 times taller than those grown in rain-fed conditions. Rain-fed conditions greatly reduced the tillering ability (\u3c 2.6 fold) of tall fescue plants. Plants under irrigated conditions were 2.9 times more productive than those grown in rain-fed condition. The largest difference in a year for water content (WC) between the plants grown in the two conditions was 8.06%. Genotypes with better tolerance to drought have been identified in the population which could be useful to develop drought tolerant tall fescue cultivars

Nitrogen Fixation and Transfer in Agricultural Production Systems

There is a consensus within the scientific community that nitrogenous fertilizers are almost indispensable in today’s agriculture. However, the geometric increase in nitrogenous fertilizer applications and the associated environmental concerns call for focus on more sustainable alternatives. Biological dinitrogen (N2) fixation (BNF) is one of the most sustainable approaches to meeting crop nitrogen (N) demands. The BNF is, especially, important in low value crops (e.g., forages) and in developing economies. However, just like synthetic N fertilizers, BNF has issues of its own. Among the issues of great importance is the low and highly variable proportion of fixed N2 transferred to non-N2-fixing plants. The proportion of transfer ranges from as low as 0% to as high as 70%, depending on a myriad of factors. Most of the factors (e.g., N fertilizer application, species, and cultivar selection) are management related and can, therefore, be controlled for improved N2 fixation and transfer. In this chapter, we discuss current trends in BNF in selected legume crops, the global economics of BNF, and recent reports on N2 transfer in agricultural production systems. Additionally, factors affecting N2 transfer and management considerations for improving N2 fixation and transfer are discussed

Understanding Species Traits and Biodiversity Indices to Solve Problems Associated with Legume Persistence in Cropping Systems

Shading and competition for mineral nutrients by grass impair legume functions and production in mixed cropping systems. Sustained stress from competition and adverse environments contribute to shortened legume life spans in such cropping systems. This creates negative consequences to forage productivity. There are opportunities to solve the challenge of legume persistence by understanding species traits and plant community dynamics that foster coexistence and complementary resource use. Together with species’ unique ability to tolerate adverse soil factors such as water stress, acidity and salinity, self-seeding, and shade tolerance are positive traits among legume species that grow in mixed crops. In communities, converging leaf and shoot conformations as well as asynchrony in dry matter distribution among species can avert negative effects of species competition. While seeding ratios can influence forage production and quality, management including harvest frequency and optimizing phosphorus (P) and potassium (K) fertilizers have crucial roles in perpetuating legume growth and function in mixtures with grass. Some facts on species competition for light, water, and nutrient resources; shade avoidance; and biodiversity mechanisms are highlighted in this chapter

Grass-Legume Mixtures for Improved Soil Health in Cultivated Agroecosystem

Planting grass-legume mixtures may be a good option to improve soil health in addition to increased forage productivity, improved forage nutritive value, and net farm profit in a hay production system. A field experiment was conducted from 2011 to 2014 at Lingle, Wyoming to evaluate soil microbial biomass under different seeding proportions of two forage grasses (meadow bromegrass, Bromus biebersteinii Roem. & Schult.; and orchardgrass, Dactylis glomerata L.) and one legume (alfalfa, Medicago sativa L.). Nine treatments included monoculture grass, monoculture legume, one grass and one legume mixture, two grasses and one legume mixture, and a control (not seeded with grass or legume). Monoculture grass received either no nitrogen (N) or N fertilizer (150 kg N ha−1 year−1 as urea) whereas monoculture legume, grass-legume mixtures, and control plots received no N fertilizer. The study was laid out as a randomized complete block design with three replications. The plots were harvested 3–4 times each year after the establishment year. Soil samples were collected and analyzed for microbial biomass using phospholipid fatty acid (PLFA) analysis at the end of May in 2013 and 2014. Soil samples were also analyzed for mineralizable carbon (C) and N in 2013 and 2014. The total above-ground plant biomass was higher in 50–50% mixture of grass and alfalfa than monoculture alfalfa and monoculture grass (with and without N fertilizer) during the entire study period. The application of N fertilizer to the grass hay production system had little effect on improving mineralizable soil C, N, and soil microbial biomass. However, grass-legume mixture without N fertilizer had great effect on improvement of mineralizable soil C and N, and total, bacterial, and actinomycetes microbial biomass in soil. The 50–50% mixture of grass and alfalfa performed consistently well and can be considered to use in Wyoming conditions for improving soil health and forage productivity

Diversified Forage Cropping Systems and Their Implications on Resilience and Productivity

Plant diversity is associated with resilient ecosystems. Loss of plant biodiversity triggered by anthropogenic and climatic factors jeopardizes environmental stability and sustainable forage production. The understanding of biodiversity mechanisms and functional traits of species can help to design forage production systems to buffer against perturbations. Resilience and productivity are linked to plant species characteristics and interactions that enable them to recover from adverse conditions and compensate for the loss of susceptible species. Benefits of diversified crops including enhanced carbon assimilation, nitrogen fixation, and turnover are transferred to soil microbes which in return contribute to resilience against drought and poor soil fertility. In the absence of disturbances, these mechanisms are credited for stability and climax ecosystems. Cultivated systems are more fragile because management interferes with many functions while maintaining few. Strategies that sustain an entire range of functions can increase production regardless of climatic and management factors. This has been demonstrated in binary mixtures of cool season grasses including meadow bromegrass (Bromus biebersteinii Roem. & Schult.), orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), and intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey) with alfalfa (Medicago sativa L.). Suitable combinations of perennial species and cultivars bred for compatible traits can enhance resilience and productivity in a wide range of ecosystems

Evaluation of Silage Corn Yield Gap: An Approach for Sustainable Production in the Semi-Arid Region of USA

Water and nitrogen (N) play an important role in closing the yield gap of crops by reducing associated stresses and yield variability. Field research data coupled to the CSM-CERES-Maize model of Decision Support System Agrotechnology Transfer were used to advance our understanding of the effect of water and N on silage corn growth and yield. The objectives of the study were to determine: (i) the best combination of irrigation water and N for optimum biomass yield, and (ii) the yield gap of silage corn grown at different locations in Wyoming, USA. Field experiments were conducted under sub-surface drip irrigation using a randomized complete block design in a split-plot arrangement with four replications. The main plot was irrigation and consisted of 100% crop evapotranspiration (100ETc), 80% (80ETc), and 60% (60ETc), and the sub-plot was N rates, including 0, 90, 180, 270, and 360 kg N ha−1 as urea-ammonium-nitrate. The simulated results indicated full irrigation and at least 150 kg N ha−1 as the best combination for silage corn production in Wyoming. Our observed and simulated results show the potential to increase the biomass and reduce the yield gap of silage corn in the region if irrigation water and N are properly managed

Effect of Irrigation and Nitrogen Fertilization Strategies on Silage Corn Grown in Semi-Arid Conditions

In water-scarce regions, high yield and improved water use efficiency (WUE) of crops can be obtained if water and nitrogen (N) are properly applied. While water and N have been the subject of research worldwide, studies are needed to advance our understanding on the complexity of their interaction. A field experiment was conducted at the University of Wyoming Powell Research and Extension Center in 2014 and 2015 growing seasons to determine the effect of irrigation water and N on growth, dry matter (DM) yield, and WUE of silage corn (Zea mays L.) grown under on-surface drip irrigation (ODI). The experiment was laid out as a randomized complete block design in split-plot arrangement with three replications. Irrigation was the main treatment and included 100ETc (100% crop evapotranspiration), 80ETc, and 60ETc. Nitrogen was the sub-treatment and included 0, 90, 180, 270, and 360 kg N ha−1 as urea-ammonium-nitrate solution Results showed that irrigation water, N, and application timing significantly affected growth and DM yield, especially at late vegetative and mid reproductive growth stages. At harvest (R4), no significant difference was observed between 180 kg N ha−1 and 270 kg N ha−1 on DM yield and WUE. However, significant differences of DM yield were observed between irrigation treatments, and 100ETc and 80ETc did not differ in WUE. Our findings suggest that 100ETc and 180 kg N ha−1 is the best combination for high yielding corn for silage grown in a semi-arid climate under ODI

Ranking acidity tolerance and growth potential of Austrodanthonia accessions

Some Australian native perennial grasses that evolved on acidic soils are useful pasture species such as the 25 species of Austrodanthonia. We evaluated the range of acidity tolerance and growth potential in the field of 9 species of Austrodanthonia, comprising 18 accessions collected from southern temperate New South Wales (NSW) as well as the commercial cultivars Taranna and Bunderra. The soil had natural differences in pH in 10 mM calcium chloride (pHCa) and was classified as a brown chromosol to kurosol (yellow/red podsolic). After germination and growth in pots for 9 weeks, seedlings were transplanted into plots with pH differences (mean 4.3 or mean 4.9). Plant growth was scored for 116 days after transplanting and survival monitored for a further 361 days. Visual scoring of plant growth was highly correlated with dry weights (r2 = 0.99). Survival and shoot dry weight were greater at pHCa 4.9 than at pHCa 4.3. For example, survival was 74% at the higher pH and 47% at the lower pH after 116 days and declined very slowly subsequently. Dry weight and survival at pHCa 4.9 were separately and linearly related to dry weight and survival at pHCa 4.3, respectively. Austrodanthonia accessions/cultivars exhibited about a threefold range of acidity tolerance and dry matter production. When acidity tolerance was ranked using either dry weight or survival, the rankings were similar; however, dry weight data had a greater dispersion, thus dry weight may be the more sensitive tolerance index. On the other hand, survival may be the more cost-effective indicator of acidity tolerance. It is likely that tolerance of acidity may be attributed to tolerance of aluminum rather than of the hydrogen ion. Some accessions produced more dry matter, had higher survival and greater acidity tolerance than the commercial cultivars and thus show potential as useful pasture components

Benefits of mixed grass–legume pastures and pasture rejuvenation using bloat-free legumes in western Canada: a review

Forage mixtures containing legume out-yield monocultures, fix atmospheric nitrogen, and have lower carbon footprints. However, evidence-based information on creating forage mixtures by direct seeding legumes into existing pastures is limited, and information on bloat-free legumes is nonexistent. Traditionally, pastures requiring improvement in western Canada were fully replaced by breaking up the old stand and reseeding. With new and improved forage cultivars, better seeding equipment, and increased knowledge about pasture management, there is a growing interest among producers in rejuvenating pastures instead of replacing them. Pasture rejuvenation refers to the improvement in biomass productivity and (or) nutritional quality of existing pasture without removing the existing vegetation. This can be done through fertilizer application, which is generally expensive and causes negative environmental impacts. Amelioration of compacted pastureland via mechanical aeration is short-lived and can lead to weed problems. As an alternative, direct seeding of productive, nutritive and bloat-free legume species into existing pasture is an attractive option for pasture rejuvenation. For high performance grazing systems, identification of suitable bloat-free legumes and methods for direct seeding into old grass and legume stands will be essential strategies. This review includes information on the benefits of mixed pastures and seeks possible methods of introducing bloat-free forage legumes into existing pastures in western Canada for rapid improvement in productivity and quality while positively influencing animal, soil, and environmental health.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author