Long-term organic material application enhances black soil productivity by improving aggregate stability and dissolved organic matter dynamics

Abstract

Understanding the long-term effects of organic material application on soil structure and organic matter dynamics is important for sustainable agriculture. We investigate interactions between organic materials, soil aggregates, dissolved organic matter (DOM), and crop yield after long-term (34-year) experimental field conditions. The effects of fertilization regimes on soil aggregates, DOM characteristics, and soil organic carbon from 0 to 20 cm and 20–40 cm depth, and their impacts on crop yield are explored for various treatments (no fertilizer, chemical fertilizer, and chemical fertilizer combined with low straw, high straw), and organic manure (OM)). Organic amendments increased proportions of soil aggregates > 0.25 mm by 2.5 %-5.4 % and soil organic carbon contents within aggregates by 4.5 %-21.2 %. The OM treatment had the highest mean weight diameter and geometric mean diameter. DOM concentration in soil aggregates increased by 11.8 %-42.7 % in organic material treatments, and shifted in composition. Fulvic-like and humic-like components increased and protein components decreased, suggesting a transition towards microbial-derived organic matter, enhancing soil humification and bioavailability. Analyses reveal DOM influences aggregate stability and carbon sequestration by changing fluorescence components and structure in soil layers. Straw treatments primarily improved crop yields by enhancing soil aggregate stability, and OM boosted yield. We demonstrate the benefits of applying different organic materials to soil to sustain agricultural productivity, improve soil structure, enhance organic matter quality and quantity, and increase crop yield, revealing ways to optimize organic amendment in different agricultural contexts for more resilient and productive farming systems.