ResultsConcentrations of Sipain Ap + Arp horizons of paddyfields were significantly larger for Philippine than for Viet-namese regions (mean values of 141–322 vs. 20–51 mgSi kg−1; Kruskal–Wallis-ANOVA, p < 0.0001; Fig. 3). Fur-thermore, they significantly differed between the Philippineregions, with PH 1 > PH 3 > PH 2 (mean values of 322,203 and 141 mg Si kg−1; Wilcoxon–Mann–Whitney test;p < 0.001 for PH 1 vs. PH 2; p = 0.005 for PH 1 vs. PH 3;p = 0.002 for PH 2 vs. PH 3). In Vietnam, Sipaconcentra-tions were significantly smaller in VN 2 than in the otherregions (Wilcoxon–Mann–Whitney test; p values of 0.005 orsmaller), furthermore they were significantly larger in VN 4than in VN 1 (p = 0.003).Mean values of Sipaconcentrations in the top 20 cmof the mineral soil from sites of alternative land-use weresmaller than mean values of Ap + Arp horizons of paddyfields (Fig. 4). Significant differences between paddies