Soil aggregation and water holding capacity of soil amended with agro-industrial byproducts and poultry litter

Abstract

Soil organic matter (SOM) addition has been shown to be effective for improving physicochemical and hydrological properties, but its effectiveness may be improved if amended with certain agro-industrial byproducts with cations and high carbon. This study was conducted to determine the quantitative effect of poultry litter (PL) amended with inorganic agro-industrial byproducts on aggregate and hydrological properties of a sandy loam soil. Poultry litter (PL) unamended or amended with quicklime (CaO), flue gas desulfurization gypsum (FGDG), Al2 (SO4)3·18H2O (alum), cement kiln dust (CKD), crushed ag lime (CaCO3), or biochar was applied to a sandy loam soil and incubated at room temperature for 30 days. Aggregate stability and water retention of the mixture were measured after the incubation. Amending PL with all byproducts, relative to the unamended PL, increased the stability of 0.25–2 mm aggregates and mean weight diameter (MWD) of aggregates. But only Ca-rich byproducts increased macro-aggregates (> 2.0 mm) stability by as much as 21.7%. The C-rich biochar reduced macro-aggregate (> 2.0 mm) stability by 18% compared to the PL alone. All byproducts increased soil field capacity (FC) and plant available water (PAW), and Ca-rich byproducts decreased water content at permanent wilting point (PWP), while biochar greatly increased water content at PWP. All Ca-rich byproducts increased PAW by an average of 49% over no Ca byproducts. Our results overall showed that Ca-rich inorganic byproducts, some of which are commonly applied to agricultural soils, are effective PL amendments for improving soil aggregation and water holding properties.