Does long-term application of mineral fertilizers improve physical properties and nutrient regime of sandy soils?

In modern agriculture, mineral fertilizers are considered to be a significant enhancing factor. They promote soil fertility, particularly in sandy soils. Farmers should be aware of the effects of fertilizers on the soil environment. Here, we report the results of three long-term experiments with durations of 25, 41 and 94 years conducted in a sandy soil at the experimental station of the Warsaw University of Life Sciences – SGGW in Skierniewice, Poland. The soil physical properties and nutrient regime were monitored under a set of experimental treatments: Control – no fertilizer, NPK – NPK fertilizers, CaNPK – CaNPK fertilizers in the 41-year and 94-year-long experiments, and FYM – farmyard manure as control, FYM+NPK – farmyard manure+NPK fertilizers and FYM+CaNPK – farmyard manure+CaNPK fertilizers in the 25-year-long experiment. Only the 41-year-long experiment showed a significant decrease in bulk density by 7% under NPK treatment compared to control. Total and available P increased significantly across experiments and fertilization treatments compared with the corresponding controls, most remarkably in the 41-year-long experiment. In the 94-year-long experiment, total Ca and Mg rose by 168% and 45% under CaNPK treatment, respectively, relative to the control. Total organic carbon increased considerably across experiments. Similarly, total N and S increased in NPK treatment significantly by 67% and 56%, respectively compared with the control in the 41-year-long experiment. Overall, the highest number of correlations between soil physical properties and nutrient content was determined in the 94-year-long experiment. The obtained results show positive effects of FYM on the content of soil nutrients.