70kg/ha/y. Sugars as well as phenolic compounds are chemoattractants of rhizobacteria [99, 100]. Carbohydrates alleviate negative effects of wood ash on enchytraeid growth and abundance, possibly by correcting an imbalance in the bacteria: fungi ratio, which is increased by addition selleck bio of wood ash . Glucuronic, galacturonic, and alginic acids (main constituents of bacterial exopolymeric substances) play a role in stabilisation of heavy metals such as Cr (VI) in soil under acidic or slightly alkaline conditions . The ratio of carbohydrate C/polyphenol C in soil hydrolysates is used as an indicator of soil organic matter quality , and the ratio of total carbohydrates/K2SO4 extractable total N appears to be a good predictor of N mineralisation and microbial biomass N .
Adsorption of carbohydrates, such as glucose or fructose, on alumina interfaces is characterised by an adsorption isotherm of a typical L-type, and an adsorption mechanism based on dipolar interaction has been suggested . The adsorption was pH dependent and was affected by anions (Cl?, SO42?, and PO43?) and cations; fructose appeared to be better adsorbed than glucose. Pentoses (arabinose and xylose) are not synthesised by microorganisms and are constituents of plant biomass. On the other hand, galactose, mannose, rhamnose, and fucose are of microbial origin [14, 104] and up to ca. 16mg/g soil organic carbon from a range of different soils was ascribed to microbial sugars . According to Oades , the ratio of galactose plus mannose/arabinose plus xylose is low (<0.
5) for plant-derived sugars and high (>2) for microbial sugars.Amino sugars represent major constituents of microbial cell walls and hydrolysable soil organic matter. Free amino sugars represent a small part of the dissolved organic C and N pools . Muramic acid, glucosamine, mannosamine, and galactosamine may be used as an indicator of microbial origin of soil organic matter [108, 109]. Glaser et al.  reported that total amino sugar and muramic acid in soil microbial biomass varied between 1 and 27mg/kg soil, while microbial biomass made a negligible contribution to total amino sugar concentration in soil. Glucosamine and galactosamine were found in the highest concentrations in different horizons of forest and prairie soils (up to 5200mg/kg soil) [108, 109].
Carbohydrates from soil microbial biomass were reported by Joergensen et al.  to account for 17% of total carbohydrate C, and the content of microbial biomass carbohydrates correlated well with microbial biomass C . Carbohydrates are extracted from soil using cold or hot water, 0.5M K2SO4, 0.25M H2SO4, 1M HCl, 0.5M NaOH, or 4M trifluoroacetic acid [13, 105, GSK-3 111, 113, 114]. Adesodun et al.  and Ball et al.  reported extraction of the lowest carbohydrate fraction (3%) using cold water, 10% by hot water, 12% by 1M HCl, and 75% by 0.5M NaOH.3.1.