Long-term cattle manure application to saline-sodic soil increases maize yield by decreasing key obstacle factors in the black soilregion of Northeastern China

Poor soil physical properties, serious salinization and low soil nutrients are the limiting factors for crop yield in saline-sodic soil. Long-term cattle manure application is an important measure that can affect the physicochemical properties and increase the maize yield of saline-sodic soil. This experiment included five treatments according to the history of cattle manure application: a control treatment with no cattle manure (CK) and treatments with cattle manure application for 14 years (14a), 17 years (17a), 20 years (20a), and 25 years (25a). The results indicated that compared with the CK treatment, long-term cattle manure application to saline-sodic soil resulted in significant increases in soil organic matter (SOM), soil total nitrogen (TN) and available nutrients at the 0-20 cm and 20-40 cm depths (p<0.05). The soil physical properties improved significantly, and cattle manure application significantly decreased the soil bulk density (ρ_b) and soil density (ρ_d) and increased the soil total porosity (f_t) and water-holding capacity (WHC). With the number of years of cattle manure application, the soil pH, electrical conductivity (EC), exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR_1:5) decreased significantly, and the maize yield gradually increased over time from 8690 kg/hm² in the CK treatment to 14690 kg/hm² in the 25a treatment. There were significant differences among all treatments (p<0.05). The results showed that long-term cattle manure application decreased the soil ρ_b and saline-alkaline properties, which was the main factor that affected the maize yield in the saline-sodic soil, especially for soil ρ_b.