(1)

The processes involved in deformation, internal strength and stability of soils with long-term application of fertilizers (organic and inorganic sources) remain poorly investigated and hence understood, particularly in agricultural systems under subtropical climatic conditions. We investigated how long-term fertilizer management with organic and inorganic amendments in no-till crops affects the microstructural stability of a sandy Alfisol under oscillatory shear. The study was conducted in southern Brazil on a 17-year completely randomized block experiment with five fertilizer treatments: pig slurry (PS), cattle slurry (CS), pig deep litter (PDL), mineral fertilizer (MF) and control, i.e. unfertilized (CL). Soil samples were collected from two layers (0-5 and 5-15 cm) for physical and chemical analyses and evaluation of soil rheological properties under oscillatory shear at two matric potentials (0 and -10 kPa). Organic matter accumulation in soil provided by the PDL and CS fertilizers resulted in higher soil stability and elasticity under oscillatory shear, especially in the 0-5 cm layer. Conversely, MF and PS enhanced the soil susceptibility towards deformation under transient stresses, mainly in the 0-5 cm layer under saturated conditions. The PDL significantly increased soil shear resistance under low-shear strain conditions. Significant differences ceased under high-shear strain conditions, though PS and MF yielded at significantly lower strains. Hence, under subtropical conditions, long-term application of organic fertilizers with fibrous components promoted soil microstructure strengthening, reducing soil susceptibility to erosive processes and compaction.

来源平台：SOIL USE AND MANAGEMENT