Statement of Work.docx

Soil Analysis Statement of Work

The USDA ARS U.S. Sheep Experiment Station (USSES) Dubois, ID location needs to obtain soil sample analysis, including microbial and nutrient analysis.

There is a total of 190 soil samples that need to be analyzed for both the microbe community composition and abundance as well as selected soil nutrients. USDA ARS USSES will provide and ship the soil samples to the laboratory. 152 samples are already collected and the remaining 38 will be collected in September 2024. The results will be provided electronically by the contracted vendor.

The vendor must be able to provide both microbe and nutrient analysis for each sample using the preferred methods outlined below.

Microbes – preferred PLFA Preferred microbial approach is phospholipid fatty acid analysis (PLFA) similar to Buyer and Sasser (2012) to get biomass and composition of 5 broad microbial groups: saprophytic fungi, arbuscular mycorrhizal fungi, gram positive bacteria, gram negative bacteria, and actinomycetes. Samples should be extracted using a phosphate buffer in the Bligh-Dyer extraction. Lipid classes should be separated by solid phase extraction using silica in well plates. PLFA fractions should then transesterified to produce fatty acid methyl esters and analyzed by gas chromatography. Fatty acids should be identified using software and quantified. Fatty acids should also be summed into biomarker groups.

Nutrients The nutrient analysis we need for these samples include ammonium, nitrate, total nitrogen, and total carbon. Preferred methods for these are as follows:

· Ammonium (KCL extraction method)

· Nitrate (KCL extraction method)

· Total Nitrogen (dry combustion with combustion analyzer)

· Total Carbon (dry combustion with combustion analyzer)