Matt A. Sanderson

Comparison of growth and performance in upland and lowland switchgrass types to water and nitrogen stress.

The objective of the study was to examine lowland (Alamo and Kanlow) and upland (Blackwell and Caddo) cultivars of switchgrass (Panicum virgatum L.) for differences in response to water deficit and nitrogen fertilizer. Cultivars were grown in pots with fritted clay at two water levels: well watered and deficit conditions (-0.1 and -1.0 MPa) and two nitrogen levels (10 and 100 kg ha(-1)). Nitrogen determined growth potential of the cultivars more than water availability. The lowland cultivars produced greater biomass yields than upland cultivars. However, upland cultivars showed a smaller response to drought stress. Under water stress conditions all cultivars exhibited a higher leaf percentage of total dry matter (DM), with the upland cultivars having the highest leaf percentage of total DM. Nitrogen proved to have more of an effect on single-leaf photosynthesis rates than water. Alamo demonstrated the greatest biomass production among all cultivars. The differences found between the two lowland cultivars suggest that Alamo would be better suited for forage and biomass production in central Texas, being a higher producer under drought and non-drought conditions than Kanlow as well as upland cultivars.

Patterns of plant species richness in pasture lands of the northeast United States

Pasture lands are an important facet of land use in the northeast United States, yet little is known about their recent diversity. To answer some fundamental questions about the diversity of these pasture lands, we designed a broad survey to document plant species richness using an intensive, multi scale sampling method. We also wanted to learn whether environmental (soils or climate) or land management variables could help explain patterns of species richness. A total of 17 farms, encompassing 37 pastures, were sampled in New York, Pennsylvania, Vermont, Maryland, Massachusetts and Connecticut during July and August 1998. We positively identified a total of 161 different plant species across the study region. Species richness averaged 31.7±1.1 on pastures. Infrequent, transient species that were mostly perennial and annual forbs accounted for ∼ 90% of the species richness. Except for a subjective rating of grazing intensity, land management methods were not good predictors of species richness. Over time, it appears that grazing neither reduces nor increases species richness in pastures. Of the environmental variables measured, only soil P explained a significant amount of the variation in species richness. Soil P was inversely related to species richness at the 1m2 scale. Percent SOM was positively associated with species richness at this scale, although weakly. At larger spatial scales, we suggest that patterns of species richness are best explained by the species diversity of soil seed banks, or seed rain, and stochastic recruitment of these species into existing vegetation.

Diversification and ecosystem services for conservation agriculture: Outcomes from pastures and integrated crop-livestock systems

Conservation agriculturalsystems relyon threeprinciplesto enhance ecosystem services: (1) minimizing soil disturbance, (2) maximizing soil surface cover and (3) stimulating biological activity. In this paper, we explore the concept of diversity and its role in maximizing ecosystem services from managed grasslands and integrated agricultural systems (i.e., integrated crop–livestock–forage systems) at the field and farm level. We also examine trade-offs that may be involved in realizing greater ecosystem services. Previous research on livestock production systems, particularly in pastureland, has shown improvements in herbage productivity and reduced weed invasion with increased forage diversity but little response in terms of animal production. Managing forage diversity in pastureland requires new tools to guide the selection and placement of plant mixtures across a farm according to site suitability and the goals of the producer. Integrated agricultural systems embrace the concept of dynamic cropping systems, which incorporates a long-term strategy of annual crop sequencing that optimizes crop and soil use options to attain production, economic and resource conservation goals by using sound ecological management principles. Integrating dynamic cropping systems with livestock production increases the complexity of management, but also creates synergies among system components that may improve resilience and sustainability while fulfilling multiple ecosystem functions. Diversified conservation agricultural systems can sustain crop and livestock production and provide additional ecosystem services such as soil C storage, efficient nutrient cycling and conservation of biodiversity.

Seedbank diversity in grazing lands of the Northeast United States.

We evaluated the species composition of soil seed banks from 9 farms (36 pastures total) located in the northeast United States. Our objective was to quantify the soil seed bank composition of pastures managed for intensive grazing and hay production. Seeds from pasture soils were allowed to germinate in a greenhouse under natural light conditions. Seedlings were identified as they germinated, and the experiment was concluded after 4 months. Germinable seed was dominated by annual (40%) and perennial (23%) forbes most of which contributed little useful forage for cattle. Perennial grasses (11%), except for bluegrass (Poa pratensis L.), were largely absent from the terminable seed bank, while legumes (19%) were more abundant. Seed bank species composition showed little similarity (44%) to the existing vegetation. Exceptions were bluegrass, white clover (Trifolium repens L.), and common dandelion (Taraxacum officinale Weber ex Wiggers). These species were abundant in both the germinable seed bank and existing vegetation on most pastures. Overall, our study suggests that seed banks in these northeast pastures support abundant white clover and bluegrass seed, both of which are important forages for cattle. Soil seed banks, however, will not supply a diverse assemblage of useful forages. If a manager seeks to establish diverse, mixed-species pasture, then re-seeding pastures with desired mixes may be the best option. DOI:10.2458/azu_jrm_v53i1_tracy

Crop Management of Switchgrass

Management of switchgrass for bioenergy and forage share some commonalities, of particular interest in bioenergy crop production is: (1) rapid establishment of switchgrass to generate harvestable biomass in the seeding year, (2) highly efficient management of soil and fertilizer N to minimize external energy inputs, and (3) harvest management to maximize yields of lignocellulose. Bioenergy cropping may entail management for multiple services in addition to biomass yield including soil C sequestration, wildlife habitat, landscape management, and water quality protection. Management is a critical factor especially as land classified as marginal or idle land will be emphasized for bioenergy production to reduce conflicts with food production. Marginal land may also be more risky. To date, there has been no long-term commercial production of switchgrass on a large scale and there is little in the way of hands-on, practical farm experience with switchgrass managed as a bioenergy crop. In this chapter, we lay out the key best management practices for switchgrass as a bioenergy crop including establishment, soil fertility, and pest management.

Well-managed grazing systems: A forgotten hero of conservation

Ecologically sound grazing management is an underused and underappreciated conservation tool in the eastern United States. We contend that significant policy and educational barriers stand in the way of expanding the use of this conservation tool. Well-managed pasture systems combine vigorous perennial vegetation cover, reduced pesticide and fertilizer inputs, and lower costs of production using ecological approaches to generate ecosystem services for society, as well as economic sustainability for the producer. The majority of currently available conservation policy tools were designed to address either rangeland grazing situations in the western United States or conservation cropping in the eastern United States. To promote well-managed pastures in the eastern United States, resource managers and government agencies struggle to adapt programs that are really designed for annual row crop systems. Additional educational and technical assistance resources are needed for promoting well-managed pasture-based farming in the region. This paper summarizes the potential of well-managed pasture systems to provide ecosystem services, provides thoughts for discussion on the barriers to adoption of such systems in the eastern United States, and offers some solutions to move such systems forward through policy and educational efforts. These ideas were first presented at a symposium as part of the 2011…

Temperature and Precipitation Affect Steer Weight Gains Differentially by Stocking Rate in Northern Mixed-Grass Prairie

Abstract Cattle weight gain responses to seasonal weather variability are difficult to predict for rangelands because few long-term (>20 yr) studies have been conducted. However, an increased understanding of temperature and precipitation influences on cattle weight gains is needed to optimize stocking rates and reduce enterprise risk associated with climatic variability. Yearling steer weight gain data collected at the USDA-ARS High Plains Grasslands Research Station at light, moderate, and heavy stocking rates for 30 years (1982–2011) were used to examine the effects of spring (April–June) and summer (July–September) temperature and precipitation, as well as prior-growing-season (prior April–September) and fall/winter (October–March) precipitation, on beef production (kg · ha−1). At heavier stocking rates, steer production was more sensitive to seasonal weather variations. A novel finding was that temperature (relatively cool springs and warm summers) played a large predictive role on beef production. At heavier stocking rates, beef production was highest during years with cool, wet springs and warm, wet summers, corresponding to optimum growth conditions for this mixed C3–C4 plant community. The novelty and utility of these findings may increase the efficacy of stocking rate decision support tools. The parsimonious model structure presented here includes three-month seasonal clusters that are forecasted and freely available from the US National Oceanic and Atmospheric Administration up to a year in advance. These seasonal weather forecasts can provide ranchers with an increased predictive capacity to adjust stocking rates (in advance of the grazing season) according to predicted seasonal weather conditions, thereby reducing enterprise risk.

Extent of Kentucky Bluegrass and Its Effect on Native Plant Species Diversity and Ecosystem Services in the Northern Great Plains of the United States

Abstract Kentucky bluegrass, a nonnative species, has invaded rangelands in the United States and is currently present in most rangelands across the Northern Great Plains. Despite its accelerated expansion, the consequences of Kentucky bluegrass on the diversity of native plant species and on ecosystem services remain largely unknown. We synthesized the available data related to Kentucky bluegrass and how it affects native plant diversity and ecosystem services. We found that invasion may bring negative consequences to ecosystem services, such as pollination, habitat for wildlife species, and alteration of nutrient and hydrologic cycles, among others. To maintain the flow of ecosystem goods and services from these rangeland ecosystems, range science must adapt to the challenge of introduced, cool-season grass dominance in mixed-grass prairie. Based on our findings, we identify research needs that address ecosystem changes brought on by Kentucky bluegrass invasion and the corresponding effects these changes have on ecosystem services. We are dealing with novel ecosystems, and until we have better answers, adaptive management strategies that use the best available information need to be developed to adapt to the invasion of this pervasive invasive species. Nomenclature: Kentucky bluegrass, Poa pratensis L. Management Implications: Maintaining the flow of ecological goods and services instead of unrealistically managing for the past under changing cultural and climatic conditions (i.e., urbanization, climate change, and increased atmospheric nitrogen deposition) has become a reality. This has increased the need to implement adaptive management and new research approaches. Managing these novel ecosystems requires adjustment to timing and application of traditional management tools, such as grazing, fire, deferment, and rest, as well as bringing the collective knowledge and resources of government and educational and private sectors to bear. We need to be open to changing our traditional management practices and working on improving the flow of goods and services provided by natural areas.

Pastureland Conservation Effects Assessment Project: Status and expected outcomes

The Conservation Effects Assessment Project (CEAP) is a multiagency scientific effort to quantify environmental outcomes of conservation practices applied to private agricultural lands. The program is anticipated to help shape future conservation policies, programs, and practices. The integrated landscape approach will focus on enhanced ecological resilience and sustainable agricultural production, both of which are essential to maintaining livelihoods and meeting global food needs (Nowak and Schnepf 2010). Principal components of CEAP include (1) detailed syntheses of scientific conservation literature; (2) a national assessment of conservation effects on ecosystem services; and (3) detailed investigations of conservation practices at various scales, including paddock, landscape, and water-shed levels. The CEAP effort on grazing lands began in rangeland in 2006 (Weltz et al. 2008) with a synthesis of the scientific literature on key rangeland conservation practices (Briske forthcoming). A CEAP effort on pastureland, primarily in the eastern and central United States, began in 2008. A literature synthesis documenting the science behind key conservation practices (Nelson forthcoming) revealed that scientific support exists for most conservation practices on pastureland, but critical knowledge, data, and technology gaps remain, including the following: Comprehensive assessments of effects of grazing management on a broad suite of…

Pasture monitoring at a farm scale with the USDA NRCS pasture condition score system

The Pasture Condition Score (PCS) system, developed by the USDA Natural Resources Conservation Service, is a monitoring and assessment tool for pastureland enrolled in conservation programs. Ten indicators of vegetation and soil status are rated on a 1 to 5 scale and are summed to give an aggregate score, which is interpreted for management recommendations. Information is lacking, however, on how PCS results vary within and among environments and farms. We applied the PCS on two farms in Pennsylvania (one dairy, one beef), two dairy farms in New York, and an organic dairy in Maryland. All pastures (25 to 63 per farm) on each farm were evaluated according to PCS methodology in spring, summer, and autumn of 2004, 2005, and 2006. Aggregate PCS scores ranged from 30 to 40 (indicating some improvements were needed to pasture management) and were relatively stable within management recommendation categories across seasons in 2004 and 2006. The PCS scores in 2005, however, plummeted (below 25 to 30—indicating major management changes to prevent degradation) on the Pennsylvania and Maryland farms because of drought. Pastures used for heifers and dry cows or as wintering areas often had lower scores than other pastures. Typically, these pastures were on less productive soils, steep slopes, and were stocked intensively. There was much overlap among individual score categories for some indicators, which suggests that fewer but broader score categories (e.g., low, medium, high) would simplify the system for farmers. The monitoring workload could be reduced by assessing representative subsets of pastures managed similarly or in similar landscape positions instead of all pastures on a farm.