Effects of nutrient fertilisation on soil carbon and nutrient cycling in a long-term grassland experiment

This study addresses how longterm additions of nutrient fertilisers either in inorganic or organic forms might affect biogeochemical interactions in a permanent grassland subject to intensive management.<br><br>I found for example, that after a 10-month incubation period under field conditions, highest root mass loss (~43%) was associated with highest additions of organic animal slurries, whereas lowest root mass loss (~29%) occurred in inorganically N-fertilised and unfertilised- control soils.

Root mass loss was mainly driven by N-induced decreases in both root C:N ratios and Fungal-to-Bacterial (F:B) ratios. The study also demonstrates how 47 years of high organic p applications (through liquid manures) caused a 1,600% increase in soil P availability and > 400% increase in total soil P stocks (0-15 cm depth) when compared to control-unfertilised soils. Soils' ability to retain added P was quite remarkable whereby up to 62% of organic P and 48% of inorganic P annually applied since 1970 was retained in soils.