Organic materials quality to control soil aggregation: A meta-analysis

Organic materials (OM) are considered as potential soil amendment for its positive impact on soil physical properties such as soil aggregation. Aggregate stability is indicated by mean weight diameter (MWD), which is influenced by the OM quality components. However, OM quality components that control soil aggregation are inconsistent from individual study. The present study conducted a meta-analysis of 789 paired comparisons from 48 peer-reviewed publications to investigate how different types of OM coupling with their quality components can potentially influence soil aggregation. OM application significantly enhanced the aggregation by 148±18%, regardless of OM types (p < 0.001). There was a higher favorable influence of sugar-enriched easily decomposed organic material (EOM), which preferentially increased the aggregation by 314±96% and consequently, sugar showed a significant positive linear relationship with aggregation (p < 0.05). Cereal straw higher with cellulose and hemicellulose resulted in a lower aggregation by 152±62% compared to EOM, while a negative impact of cellulose on aggregation had found (p < 0.05). In addition, manure rich with lignin and aromatic C exhibited the aggregation response by 70±31%, and the regression analysis revealed that lignin and aromatic C suppressed the aggregation (p < 0.05). Moreover, aggregation was intensified in alkaline soil, while there was a greater impact in loam to clay soil with a higher initial SOC during OM application. The current meta-analysis demonstrates that OM application improve the soil aggregation, which can be accounted by their sugar, cellulose, lignin and aromatic C functional quality components.