The influence of long-term fertilisation on phosphorus dynamics in the soil

A long-term experiment on agricultural plant fertilisation was carried out on a sandy loam Epicalcari-Endocalcari-Endohypogleyic Luvisol in Central Lithuania from 1971 to 2019. The aim of the study was to determine the influence of long-term use of mineral phosphorus (P) fertilisers and their interaction with nitrogen (N) and potassium (K) fertilisers on P fertiliser uptake, mobile phosphorus (P2O5) concentration and P balance in the soil, and to evaluate its relationship with P leaching from sandy loam soils. According to the data of the study, after 49 years different combinations of NPK fertilisers in the fertilised fields resulted in the variations of mobile P2O5 in the 0-20 cm soil layer: 62-71 mg kg(-1) without P-0, 280-351 mg kg(-1) with annual P-95 fertilisation and 503-614 mg kg(-1) with P-190, or 10 times higher compared to zero P application. Due to fertilisation with P, the total phosphorus (P-tot) concentration in the soil increased. The P balance showed that after 49 years of annual applications of P-95 to agricultural crops, 45.4-68.7 kg ha(-1) was incorporated, and when P-190 was applied, 131.0-160.3 kg ha(-1) was incorporated in excess of the need for this element by plants. The most inefficient uptake 5.4-11.4% P was observed after annual application of P-190 without the use of N and K fertilisers. The uptake increased to 27.3-32.6% when N216K190 fertiliser was applied together with P-95. With increasing rates of P fertilisers, P2O5 leaching from the soil 0-40 cm layer increased. Without P application, its annual leaching was as follows: in 1976-1998 - 0.43-0.77 kg ha(-1), in 1976-2019 - 0.82-0.90 kg ha(-1). This study was able to establish significant relationships between P fertiliser uptake and NPK fertiliser rates, between mobile P2O5 concentration in the soil and P balance, and between P-tot concentration in the soil and P balance.