The long-term effects of cattle manure application to agricultural soils as a natural-based solution to combat salinization

Abstract Excessive exchangeable sodium and high soil pH result in structural destabilization of sodic soil. The long-term application of cattle manure is an important management practice that can affect the physical properties of sodic soil. Experiments were carried out using a randomized complete block design comprising five treatments according to the cattle manure application history: corn ( Zea mays L.) fields with annual manure application since 2011 (M2011), 2006 (M2006), 2001 (M2001) and 1995 (M1995) were used as the experimental treatments; manure was applied at a rate of 10,000 kg ha −1  yr −1 on an oven-dry weight basis, and corn without manure application was used as the control. The results indicated that long-term application of manure to sodic soil resulted in significant increases in soil porosity, water-holding capacity, and saturated hydraulic conductivity ( K s ) and a decrease in bulk density in comparison to the control treatment. In addition, manure application significantly increased macro-aggregate formation and the mean weight diameter (MWD). Based on stepwise regression analysis, the dominant independent variable that affected aggregate stability was water-stable aggregates (WSAs) of 0.5–1 mm, and the dominant independent variable that affected both capillary porosity (ƒ c ) and non-capillary porosity (ƒ n ) was WSAs of 0.25–0.5 mm. MWD, ƒ n and especially soil organic matter (SOM) were the dominant attributes that affected K s . It was concluded that improved soil physical properties are related to soil aggregation, resulting mainly from macro-aggregate formation, particularly WSAs of 0.25–0.5 and 0.5–1 mm. This is due to binding-agent production and increased SOM from annual manure application.