Effects of Different Soil Amendments Application on Soil Aggregate Stability and Soil Consistency under Wetting and Drying Altered Planting System

ABSTRACT

How to address improving degraded soil has become an increased concern for agricultural production. Biomass ash is used for remediation of degraded soil and improvement in soil structure. To investigate the responses of aggregate stability and soil consistency by biomass ash and other amendments, a pot experiment with a degraded soil and seven treatments including a control (CK), no fertilizer or amendment; only N-P-K fertilizer (F); N-P-K fertilizer with lime (FL), lime and zeolite (FLZ), biomass ash (FBA), biological fertilizer (FBF) and peat ash (FPA), respectively, were conducted. Stability of soil aggregate, water-holding capacity, and soil consistency was analyzed within a lettuce-water spinach-lettuce planting system. Results showed that amendment additions significantly raised the fractions of >0.25 mm soil aggregate. Applications of biomass ash reduced the percentage of aggregate destruction (PAD) by 45.07%-59.97% and reduced the value of fractal dimension (D) by 1.79–2.16 during whole cultivation period, indicating the stability of soil aggregates. Soil organic matter (SOM) plays a key role in soil consistency because of significant relationship between SOM and soil consistency indicators including plastic limit (PL), liquid limit (LL), plasticity index (PI) and liquidity index (LI). While, hydrodynamic characters and potential low clay content occurred in the soil treated with biomass ash during high moisture conditions. These findings suggest that the application of biomass ash improved the stability of soil aggregate, which improved the structural stability of degraded soil but may pose a risk to soil erosion by water force.