Carbon Dioxide Flux in a Soil Treated with Biosolids Under Semiarid Conditions

Abstract

The restoration of degraded land using biosolids provides a well known means of recycling these organic residues. In semiarid ecosystems they can enhance the chemical and physical properties of the soil and stimulate soil microbe growth and activity, leading to increases in soil fertility and quality. However, the respiratory activity in biosolids-treated soil may contribute to an increase in atmospheric CO2. Few studies examining CO2 emissions from biosolids-amended soils in semiarid climates have been conducted under field conditions. The aims of the present study were to determine the effect of applying different amounts of biosolids on the soil organic matter content and respiratory activity of a semiarid, abandoned agricultural soil. The CO2 fluxed from the soil surface (kg CO2 ha−1 d−1) was measured using a portable analyser. Soil temperature and soil water content were measured in the first 5 cm of soil. The results show that a large proportion of the organic matter incorporated into the soil via the biosolids was easily biodegradable in the first three years following its application. In addition, biosolids application generally increased soil CO2 emissions, although in a manner not proportional to the quantity applied. Differences in soil humidity were associated with differences in soil CO2 flux over the year. The soil water content was the major factor affecting soil respiration; a strong correlation was found between these variables. Soil respiration activity could serve as a useful index of soil biological activity, allowing the decomposition of biosolids under field conditions to be monitored.