Simulating urban waste compost effects on carbon and nitrogen dynamics using a biochemical index

Area of Science:

• Soil Science
• Environmental Science
• Agronomy

Background:

• Urban waste composts (UWCs) are used as soil amendments, necessitating models to predict their impact on soil carbon (C) and nitrogen (N) dynamics.
• Accurate modeling requires laboratory incubation data for parameterizing soil organic amendments, which is time-consuming.
• Simulation models are crucial for managing UWCs and understanding their effects on arable fields.

Purpose of the Study:

• To evaluate a biochemical index based on Van Soest organic matter fractions for parameterizing soil C and N dynamics models.
• To compare the predictive performance of the biochemical index method with standard laboratory incubation data.
• To assess the efficiency of using a biochemical index as a substitute for laboratory incubations in soil amendment modeling.

Main Methods:

• Utilized the NCSOIL deterministic model for soil C and N dynamics.
• Collected data on C mineralization and inorganic N dynamics from soil mixed with UWCs and farmyard manure.
• Employed a biochemical index derived from Van Soest fractions for model parameterization.

Main Results:

• NCSOIL accurately predicted nitrogen mineralization-immobilization patterns but underestimated CO2 release for less stable amendments.
• Parameterization using the biochemical index resulted in significantly larger prediction errors in only 10% of cases.
• The biochemical index explained 62-66% of the variance in decomposition rates and C:N ratios of compost organic matter.

Conclusions:

• The biochemical index provides an acceptable fit to experimental data and is a viable substitute for laboratory incubations.
• This index effectively parameterizes organic amendments in C and N models, improving management of UWCs.
• Using a biochemical index streamlines the process of predicting compost effects on soil C and N dynamics.