In use Protocols – Continuously updated
Particle size Analysis for Soil Texture – Hydrometer Method:
The hydrometer method applies Stoke’s law, which considers sedimentation of particles to be dependent on the particle diameter and settling velocity. A Bouyoucos hydrometer is used to determine the density (g L-1) of the soil particles settling at different times due to differences in their particle size and settling rates.
Particulate Organic Matter (POM) and Mineral Associated Organic Matter (MAOM)
Soil organic matter can be separated into particulate organic matter (POM, density < 1.6-1.85 g cm3 and size >53 µm) and Mineral associated organic matter (MOAM, size <53 µm, density >1.6-1.85 g cm3 ) fractions. Physical fractionation methods can be categorized into aggregate and particle fractionation, which isolates fractions based on size, density, or both. Several studies have used size fractionations to effectively separate the two functionally distinct SOM pools, POM and MAOM. They can help provide important insight regarding the formation and persistence of SOM.
Soil Electrical Conductivity – in water without extraction
Electrical conductivity provides a measure of the soil salinity – soluble salt content in the soil. Soluble salt can include cations ( Ca2+, Mg2+, K+, Na+, H+) and anions (NO3-, SO4-, Cl–, HCO3-, CO3-, OH–). The determination of EC in soil-water extracts is accomplished using a conductivity cell which measures the conductance of electricity through the solution between two metal plates in dSm.
Soil pH helps determine the availability of nutrients and other toxic elements present in the soil to the plants. The most common method of determining soil pH involves mixing soil and deionized water in a 1:1 (weight: volume) ratio and measuring using an H+ ion selective glass electrode.
This standard operating procedure (SOP) describes the measurement of potential soil enzyme activities using para-nitrophenyl (pNP) linked substrates that releases para-nitrophenol (pNP) when hydrolyzed by soil enzymes.
β-Glucosidase – Enzyme Analysis Method
Glycosidase enzymes are important catalysts in the production of labile C and energy resources by hydrolyzing complex sugars found in structural cells. These compounds are critical to the health of soil microbial communities and the carbon cycling of soil organic matter. β-glucosidases enzymes enable the degradation of cellulose compounds, which account for 15-30% dry weight of the primary cells walls of plant residue. β-glucosidases serve in the final step of cellulose decomposition, by hydrolyzing glucose chain fragments from cellulose to glucose.
Soil respiration is the process of carbon dioxide (CO2) being released from the soil. Sampling soil respiration can provide insight into carbon cycling and over all soil health. This sampling can also be used in the agricultural setting to evaluate management practices on soil carbon sequestration.