Biochanin A feed supplementation alters dynamics of trace gas emissions from lamb urine-amended soil.

Sustainable growth in livestock production requires reductions in trace gas emissions on grazing lands. Urine excreta patches are hot spots for accelerated emissions of carbon and nitrogen. Ruminant dietary supplementation with the isoflavone biochanin A (BCA) has been shown to improve cattle weight gain.

Tall Fescue and Genetics Influence Root-Associated Soil Fungi in a Temperate Grassland.

A constitutive, host-specific symbiosis exists between the aboveground fungal endophyte (Morgan-Jones & W. Gams) and the cool-season grass tall fescue ( (Schreb.) Darbysh.

Time in pasture rotation alters soil microbial community composition and function and increases carbon sequestration potential in a temperate agroecosystem.

Soil carbon (C) sequestration plays an important role in mitigating global climate change, and certain land utilization strategies can exert a pronounced effect on carbon storage. Land use practices, such as planting previously cropped lands into perennial grasslands, can increase soil C sequestration; however, the temporal response of soil C pools to such changes in land use are likely complex and not well quantified. In the current study, a space-for-time approach was used to assess the response of soil C sequestration and microbial community composition during a five-year grazed pasture rotation following three years of vegetable production on a central Kentucky farm.

Compositional differences in simulated root exudates elicit a limited functional and compositional response in soil microbial communities.

Inputs of low molecular weight carbon (LMW-C) to soil - primarily via root exudates- are expected to be a major driver of microbial activity and source of stable soil organic carbon. It is expected that variation in the type and composition of LMW-C entering soil will influence microbial community composition and function. If this is the case then short-term changes in LMW-C inputs may alter processes regulated by these communities.

Warming reduces tall fescue abundance but stimulates toxic alkaloid concentrations in transition zone pastures of the U.S.

Tall fescue pastures cover extensive acreage in the eastern half of the United States and contribute to important ecosystem services, including the provisioning of forage for grazing livestock. Yet little is known concerning how these pastures will respond to climate change. Tall fescue's ability to persist and provide forage under a warmer and wetter environment, as is predicted for much of this region as a result of climate change, will likely depend on a symbiotic relationship the plant can form with the fungal endophyte, Epichloë coenophiala.

Effects of multiple climate change factors on the tall fescue-fungal endophyte symbiosis: infection frequency and tissue chemistry.

• Climate change (altered CO(2) , warming, and precipitation) may affect plant-microbial interactions, such as the Lolium arundinaceum-Neotyphodium coenophialum symbiosis, to alter future ecosystem structure and function. • To assess this possibility, tall fescue tillers were collected from an existing climate manipulation experiment in a constructed old-field community in Tennessee (USA). Endophyte infection frequency (EIF) was determined, and infected (E+) and uninfected (E-) tillers were analysed for tissue chemistry.

Soil and plant water relations determine photosynthetic responses of C3 and C4 grasses in a semi-arid ecosystem under elevated CO2.

To model the effect of increasing atmospheric CO2 on semi-arid grasslands, the gas exchange responses of leaves to seasonal changes in soil water, and how they are modified by CO2, must be understood for C3 and C4 species that grow in the same area. In this study, open-top chambers were used to investigate the photosynthetic and stomatal responses of Pascopyrum smithii (C3) and Bouteloua gracilis (C4) grown at 360 (ambient CO2) and 720 micro mol mol-1 CO2 (elevated CO2) in a semi-arid shortgrass steppe. Assimilation rate (A) and stomatal conductance (gs) at the treatment CO2 concentrations and at a range of intercellular CO2 concentrations and leaf water potentials (psileaf) were measured over 4 years with variable soil water content caused by season and CO2 treatment.