Relationships between quality and quantity of soil labile fraction of the soil carbon in Cambisols after liming during a 5-year period

Abstract

The labile fraction of soil organic carbon (SOC) in terms of its quantity is a sensitive but dynamic indicator of the reactive agent in soils. If it is to be considered as a feature of soil quality, the value of its quantity should be completed by data on its quality. It can be expressed by the value of the rate constant of microbial oxidation k bio of this fraction or by data on chemical stability during hydrolysis or oxidation. If the quality of SOC labile fraction is not determined, at least the ratio of C MIC : C org should be given. The adjustment of soil acidity increases the microbial activity of soils, therefore the quantity of SOC labile fraction decreases and at the same time k bio decreases proportionately to the increasing stability of soil organic matters. During a 5-year period after the liming the soils acidify again and this process passes the faster the lesser their ion exchange capacity and buffering are. The quantity of the labile fraction of SOC raises again, its stability decreases and k bio raises again. The conversion pH value has secondary relevance.

Fractionation of Soil Organic Matter into Labile and Stable Fractions

“…In general, the less stable the organic matter, the more it contributes to soil fertility. Therefore, many authors consider the content of the labile fraction of SOM as a sign of potential soil fertility [16,[20][21][22]. However, not only the labile fractions of SOM are important.…”

A Method of Measuring the Degree of Organic Matter Degradability

“…This is the reason why these authors used a biochemical method for the investigation of oxidation kinetics and measured the rate of a decrease in biochemical oxygen demand (BOD) in an Oxi Top Control Merck vacuum system designed for BOD measurement. The rate constant K bio was able to reflect the intensity of soil organic matter transformation more appropriately (Kolář et al 2011). …”

“…We wanted to contribute to a solution of this problem by comparing the kinetics of biochemical oxidation based on K bio determination with determination of anaerobic degradability D COD (Kolář et al 2006) when a patent was granted to this method (Kolář et al 2011). …”

The effects of soil management practices on soil organic matter changes within a productive vineyard in the Nitra viticulture area (Slovakia)

“…Labile SOC pools such as water-extractable organic C, hot water-soluble organic C, potassium permanganate oxidizable organic C, and organic C fractions of different oxidizability are considered to respond to agricultural management more rapidly than total organic C (Blair et al 1995;Benbi et al 2012). As such labile fractions of SOM are used as sensitive indicators for soil management and land use induced changes in soil quality (Kolář et al 2011;Benbi et al 2015;Shang et al 2016). Small changes in total SOM are difficult to detect because of its high background levels and natural soil variability.…”