This study investigated the effects of tillage system and fertilization on the distribution
and availability of phosphorus in different soil particle-size fractions. Samples were
collected from the long-term field experiment TillComp at three depths (0–10, 10–20
and 20–30 cm) under two tillage systems–conventional tillage with ploughing (CT) and
no-till (NT)–and four fertilization treatments: unfertilized control, mineral NPK
fertilization, compost, and a combination of NPK and compost. Following ultrasonic
dispersion, soil samples were separated into three particle-size fractions (< 20 µm,
20– 50 µm, > 50 µm), and total phosphorus (TP) and plant-available phosphorus
(AL- P) were determined in each fraction. TP content was highest in the < 20 µm
fraction, whereas the < 20 µm and > 50 µm fractions showed comparable AL-P
contents, both being statistically significantly greater than the 20–50 µm fraction.
Tillage system had no statistically significant effect on phosphorus content within
individual fractions, but NT induced more pronounced vertical stratification: AL-P
content in the 0–10 cm layer was 2.6-fold higher under NT than CT. Compost
fertilization significantly increased AL-P and the AL-P/TP ratio (21.5 %), compared to
only 9.6 % under mineral fertilization. No significant synergistic interaction between
NT and compost was detected.
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