Changes in soil pH and phosphorus availability during decomposition of cover crop residues

Abstract

The aim of this study was to determine the effect of winter cover crop (CC) residues on soil pH and phosphorus (P) availability. Three incubation assays were performed in pots using two CC: vetch (V) (Vicia villosa Roth.) and oats (Oa) (Avena sativa L.). Soil samples were taken from 10 sites at 0–20-cm depth. The rate of residues were 0 (D0), 10 (D1), 20 (D2), 30 (D3), and 40 (D4) g dry matter kg−1 soil and the soil sampling was after 10, 20, 30, 60, 90, and 120 days of incubation. Soil pH, extractable P (Pe), and soil organic matter (SOM) and its fractions were determined. The pH increase was correlated with the rate applied (D1 < D2 < D3 < D4). No differences were found for pH comparing V and Oa residues with low residue rates. Soil pH changes were dependent from initial pH and SOM fractions in different soils across the incubation period. The multiple regression models showed that the pH changes were dependent on initial pH level and SOM fractions with a high R2 (0.81). CC residues and its quantities produced different changes on pH – especially at the beginning of the incubation – which influenced the P availability.