Effects of long-term fertilisation on soil agrochemical properties.

The study was aimed to examine the impact of different long-term mineral fertiliser rates and nutrient ratios on the accumulation of mineral nitrogen, phosphorus and potassium in the soil, migration of these nutrients into the deeper soil layers, as well as on the changes of different forms of phosphorus and on applicability of Mehlich-3 method for measurement of plant available phosphorus and potassium concentrations in the soil. Research was carried out at the long term experimental site (established in 1971). Experimental site’s soil type is moraine sandy loamy Epicalcari-Endohypogleyic Cambisol (CMg-n-w-cap) with the following ploughlayer’s characteristics: near k neutral (pH 6.8–7.1), low exchangeable soil acidity, high cation exchange capacity, high base-saturation, moderately rich in humus (2.2–2.4%, Tyurin method), low phosphorus content (57–90 mg kg-1), low potassium content (109–112 mg kg-1). According to the mean data for 2005–2008, as a result of the long term (38 years) regular application of NPK fertilisers, the spring and autumn content of mineral nitrogen (KCl extraction) in 0–30, 30–60 and 60–90 cm layers of soil depended on the nitrogen fertiliser rates, nitrogen, phosphorus and potassium fertilisation ratio and climate conditions. Regular nitrogen fertilisation at a rate of 111 kg ha-1 on the P96K96 fertilisation background increased the concentration of Nmin. in 0–60 and 0–90 cm soil layers inappreciably (by 1.37 and 1.17 mg kg-1); the increase was larger (3.43 and 3.58 mg kg-1) when nitrogen fertiliser rate of 222 kg ha-1 on the background of PK fertilisation was applied, and in the case of the application of 222 kg ha-1 nitrogen fertiliser rate without PK fertilisation the increase was 6.33 and 5.17 mg kg-1, respectively. [...]