The study comprised a random experimental design of a wood ash treatment program similar to fertilizer applications that are typically carried out in the study area. In 2003, four experimental plots of size 35 x 35 m2 were established in quadruplicate. The experimental treatments were as follows: control (no treatment); WA [addition of 4.5 Mg dry matter (DM) ash ha-1], and WAP (addition of 4.5 Mg DM ash ha-1 plus 0.1 Mg P2O5 ha-1). In 2004 and 2005, the WA experimental plots were again treated with 4.5 Mg DM ash ha-1 (Fig. 6.2). It is important to

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Table 6.2 Chemical analysis of the horizons in the soils developed on lutites and migmatites Color pH (H2o) pH (KC1) OM (%) C/N (%) S (%) P (mg kg~! Ca ) (mg kg-1) К (mg kg-b Mg 1 (mg kg-1) CECe (cmolc kg-1) Cations (bases %) Lutites Ahl 10YR3/3 4.8 4.1 10.3 31.2 0.08 3.3 38.4 42.8 14.8 21.3 6.4 Ah2 10YR3/4 4.7 4.2 6.9 18.2 0.04 4.6 24.4 29.6 10.6 7.6 9.8 Migmatites Ahl 10YR3/2 4.7 3.8 7.3 19.3 0.02 4.7 39.1 32.1 10.6 10.7 14.8 Ah2 10YR3/2 4.6 3.9 4.4 22.0 0.02 3.8 23.6 22.3 8.5 10.7 14.8 OM organic matter, CECe effective cation exchange capacity

Fig. 6.1 emphasize that the phosphate fertilizer was only applied to the plots in 2003. The phosphate fertilizer (0-29-0) is partially disaggregated, and P release is therefore slower than from commercial fertilizers (e. g., superphosphate). This fertilizer is appropriate for acid soils and enables the amount of P applied to the soils to be monitored over time.