Dissolved organic carbon and bioavailability of N and P as indicators of soil quality

Abstract

Soil quality has become an important issue in soil science. Considerable attempts have been made to define soil quality, but a general concept has not yet been accepted by the scientific community. The selection of quantitative indices for soil quality is extremely difficult, and a considerable number of chemical, physical, and biochemical properties have been suggested as potential indicators of soil quality. Because soil organic matter (SOM) can be associated with different soil chemical, physical and biological processes, it has been widely considered as one of the best soil quality indicator. Land use can significantly influence dynamics of organic carbon and N, P, and S cycle. However, changes in total soil organic carbon (SOC) contents in response to land use may be difficult to detect because of the natural soil variability. In the short to medium term, biological properties and readily decomposable fractions of SOC, such as dissolved organic carbon (DOC), are much more sensitive to soil management than is SOM as a whole, and can be used as a key indicator of soil natural functions. Despite the fact that labile C accounts for a small portion of the total organic matter in the soils, DOC is the most mobile and important C-source for microorganisms, and can easily reflect the effects of land use on soil quality. Although several methods are used to characterize DOC, the factors influencing mineralization and bioavailability of elements associated with organic matter (N, P, and S) remains unclear. Future research should focus on the processes that govern DOC and nutrient dynamics and how they affect soil quality.

Agricultural use of treated sewage effluents: agronomic and environmental implications and perspectives for Brazil

“…Regarding soil quality and C conditions after TSE irrigation, it is suggested that the evaluation of dissolved organic carbon (DOC) will become more essential because DOC is more sensitive to changes in the environment than soil organic carbon as a whole (Silveira, 2005). Also studies on the effects of SAR in TSE on soil parameters such as Na contents, clay dispersion and hydraulic conductivity are of future interest especially for Brazilian soils.…”

Effects of peat drainage on labile organic carbon and water repellency in NE Poland

“…It is considered as an indicator of soil resistance to negative anthropogenic and natural factors (Šlepetienė et al, 2010) and can be divided into labile and refractory carbon forms (Lützow et al, 2007). Labile fractions of organic carbon (microbial biomass C, fractions of dissolved organic carbon, hot water-extractable carbon [HWC]) can respond rapidly to changes in C supply (Zhang et al, 2006) and therefore are suggested as good indicators of the effects of land use changes on soil organic matter quality (Silveira, 2005). The hot water extractions provide quantitative data on the predictions of the mineralizable C (Körschens et al, 1998;Sparling et al, 1998).…”

Liming and Ionic speciation of an Oxisol under no-till system

“…In areas under the NT system, the presence of relatively high concentrations of organic ligands in the soil solution, due to the increment in organic matter, can reduce aluminum toxicity (Hue et al, 1986) and help mobilize cations (Tack & Verloo, 1995). When compared to the soil total organic matter, the more readily available fraction, such as the dissolved organic carbon (DOC), is more sensitive to changes caused by soil management in the short and medium terms, being, therefore, used as a fundamental indicator of soil quality or of changes in native conditions (Silveira, 2005).…”