Changes in the soil content of organic carbon nitrogen and sulphur in a long-term fertilisation experiment in Czarny Potok (Poland)

The paper discusses fluctuations, including the underlying causes, in the organic carbon, nitrogen and sulphur content of meadow sward from a fertiliser experiment set up on a mountain meadow in 1968. The experiment included 7 fertilising objects with full NPK fertilisation and with control treatment. The area of the experimental plots was 42 m2 (6 m x 7 m). The experimental treatments involved the following fertilisation regimes: nitrogen alone, phosphorus alone, phosphorus and potassium, nitrogen (at two doses of application, and until 2004 in two forms: ammonium nitrate and urea), phosphorus and potassium. Since 1985, the experiment has been conducted in two series: unlimed and limed. Botanical composition and plant yield formed under experimental conditions strongly affected the soil properties. The following were determined in the soil: pH, hydrolytic acidity and total forms of carbon, nitrogen, and sulphur. Soil properties are important for sustainable agriculture and conservative livestock rearing. Changes in acidification were primarily caused by fertilisation with nitrogen, while liming conducted every 10 years significantly counterbalanced this negative effect. Mineralisation of organic matter caused by liming increased the total nitrogen content, hence a significantly narrower C:N ratio was observed. The C:N and C:S ratios cannot be treated as valid indicators of grassland management practice. The reason is the high dynamic of sulphur, nitrogen and carbon cycles caused not only by liming, but also by diversity in plant yield.