Carbon and Nitrogen Mineralization and Humus Composition Following Municipal Solid Waste Compost Addition to Laterite Soils under Continuous Cassava Cultivation

Abstract

A glasshouse incubation experiment was conducted to study the carbon (C) and nitrogen (N) mineralization of municipal solid waste compost (MSWC) added at differential rates to a laterite soil where cassava has been continuously cultivated for the past 10 years. The rate of C mineralization from added substrates increased with increasing rates of addition of MSWC. Available N significantly increased with increase in the rate of application of MSWC. There was a decreasing trend in E₄₆₅/E₆₆₅ ratio of humic acid as we increased the rate of application of MSWC from 2.5 to 20 t ha⁻¹. The Cross Polarization Magic Angle Spinning (CPMAS) ¹³C NMR spectral analysis revealed that there are differences in the rate of humification of added MSWC, and application of MSWC at 15 t ha⁻¹ resulted in least humification with the greatest alkyl C, lowest aromatic C, and greater O-alkyl C content. The decomposition rate (R) was found to be greater for this treatment. The residual C in soil was found to increase over time coincident with greater rates of MSWC application, indicating increased C stabilization, which could improve soil quality.

Keywords:

• Carbon
• cassava
• ¹³C NMR
• fulvic acid
• humic acid
• humus
• nitrogen
• organic matter
• UV-visible spectroscopy