Soil microbiota and nematodes respond differently to application of organic and inorganic fertilizers in grassland columns. Organic fertilizer columns

Phosphorus (P) and sulfur (S) are vital for living organisms and are widely used as fertilizers in agro-ecosystems. However, mineable reserves of P are finite and atmospheric supply of S has drastically reduced leading to plant nutrient deficiencies. Soil columns with Lolium perenne were setup in a greenhouse and fertilized with an inorganic fertilizer (NPKS and micronutrients), cattle slurry (organic), or urea (P- and S-free control). L. perenne rhizosphere of the slurry treatment had significantly higher abundance of nematodes, bacterial-feeding nematodes, mycorrhizal colonization, cultivable heterotrophic bacteria, phosphonate- and sulfonate-utilizing bacteria, arylsulfatase activity, available P and Variovorax asfA gene copies compared to the inorganic and urea treatments. Phosphatase activities, and gene abundances involved in organic P and S transformations (phoD, phoC, Burkholderia asfA, Polaromonas asfA) were similar in all treatments. Grass dry matter yield, shoot uptake of N, P and S were significantly higher in the inorganic treatment compared to the urea and slurry treatments. Slurry and inorganic fertilizer treatments had significantly different bacterial, alkaline phosphatase-producing bacteria, fungal, AM fungal, and nematode community structures compared to the urea treatment. These shifts correlated significantly with grass dry matter yield, uptake of N, P and S, bacterial abundances, mycorrhizal colonization, bacterial-feeding nematode abundance and enzyme activities. Next generation sequencing of the bacterial and nematode communities showed a significant separation of the slurry treatment from the urea and inorganic fertilizer treatment. Our findings suggest that organic treatment favoured the soil microbiota and nematodes involved in P and S cycling.