Organic matter characteristics, biochemical activity and antioxidant capacity of soil amended with different organic materials

Abstract

The influence of pelleted cow manure (PCM), peat, municipal solid waste compost (MSWC), wet olive husk compost (WOHC) and green waste compost (GWC) on soil biochemical activity, antioxidant capacity (trolox equivalent antioxidant capacity (TEAC)) and the level of soil organic matter was evaluated in a short-term laboratory study. Peat was the most acidifying material, followed by GWC and PCM, reflecting the acidic characteristics of the compounds present in the aqueous and alkaline extracts of the amendments. Organic materials caused a marked increase of total and water-soluble organic carbon, total N, water- and alkali-soluble phenols in soil, with values generally reflecting the amount of organic matter present in the amendments. The breakdown percentage of C added expressed as CO₂-C evolution for PCM was considerably the highest (18%) and for WOHC was considerably the lowest. The water-soluble organic carbon present in the amendments and soil total N acted as controllers of the rate of decomposition of organic C in soil. The highest TEAC was in peat soil, with 583.0 mM g⁻¹, followed by PCM soil (450.2 mM g⁻¹), while soils treated with compost had quite similar values (about 230 mM g⁻¹). TEAC was strictly correlated with both alkali- and water-soluble phenols and water-soluble organic carbon. The level of ATP in PCM soil at the 60th day of incubation suggests that the PCM is the most effective amendment for increasing the activity of microbial biomass in soil.

Keywords:

• compost
• peat
• cow manure
• short-term mineralization
• microbial activity
• soil antioxidant capacity

Acknowledgement

The authors wish to thank Dr. M. Agnolucci for providing them with the amendments.