Long-term effects of tillage and fertilization on pH and sorption parameters of haplic Luvisol

The influence of different tillage and fertilization practices on changes in soil pH and sorptive parameters of loamy haplic Luvisol was evaluated in a long-term field experiment (established in 1994, in the locality of Dolná Malanta, at the experimental station of the Slovak University of Agriculture in Nitra). The field experiment included two types of soil tillage (conventional tillage – CT and reduced tillage – RT) and also three treatments of fertilization (1. Co – control, 2. PR+NPK – crop residues together with added NPK fertilizers, and 3. NPK – with added NPK fertilizers). The soil was sampled from all treatment sites throughout 1994-2011. The results showed a statistically significant influence of tillage and fertilization on pH and sorptive complex of haplic Luvisol. The values of pH were higher (by 4%) in RT than in CT. The sum of basic cations (SBC), cation exchangeable capacity (CEC) and base saturation (BS) were all higher in RT, by 11%, 8% and 3% respectively, than in CT. In NPK (by 16%) and in PR+NPK (by 20%) the values of hydrolytic acidity (Ha) were decreased in comparison to the control. On the other hand, SBC was elevated. This led to the increase of CEC and BS. Conventional tillage and application of crop residues together with NPK fertilizers increased pH by 0.06 and 0.03 units per year, respectively, which means that the pH in the soil increased by14% and 8%, correspondingly, between 1994 and 2011. In CT and in PR+NPK, an increase of SBC occurred at an average rate of 3.17 and 1.93 mmol kg-1 year-1, respectively. A positive correlation between the content of soil organic carbon (TOC) and Ha (r = 0.334, P ≤ 0.01, n = 54), as well as a negative correlation between TOC and BS (r = -0.307, P ≤ 0.05, n = 54) were determined only in CT.