Aliphatic, Cyclic, and Aromatic Organic Acids, Vitamins, and Carbohydrates in Soil: A Review

Table 1

Dominant organic acids in soil of different ecosystems.

Management	Dominant organic acids	Ratio aliphatic/cyclic plus aromatic acids	Concentrations	Sampling	Increase/decrease with depth	References
Pinus sylvestris L., Quercus  robur L., Picea abies (L.) H. Karst., Betula  pendula Roth., Fagus sylvatica L., and Abies alba Mill.	Citric, acetic, formic, oxalic, malic, butyric, propionic, malonic, lactic, tartaric, succinic, shikimic, and propionic acid	4–157	Up to 5820 μM*	Whole profile	Mostly decrease, sometimes increase with depth	[6, 20–22, 36–41]
Lupinus polyphyllus  Lindl., Agropyron repens  L., Juncus effusus  L., Juncus inflexus L., and Juncus 253⋅10^3 articulatus L.	Citric, acetic, formic, lactic, and oxalic acid	4–10	Up to 1 μmol/g soil	A-horizon	—	[23, 42, 43]
Contaminated soils (industrial, agricultural)	Oxalic acid	—	Up to 3 μmol/g soil	—	—	[44]

 *Dissolved organic matter was extracted from the fresh A horizon soil samples using double-deionized water with a solid/volume ratio of 1 : 2.