Research Article
Effects of Organic and Inorganic Materials on Soil Acidity and Phosphorus Availability in a Soil Incubation Study
Table 5
Effect of organic and inorganic materials on soil pH, exchangeable acidity, and exchangeable Al for the Kakamega soils in the incubation study.
| Treatment | pH | Exchangeable acidity (cmol kg−1) | Exchangeable Al (cmol kg−1) | 4 WAI | 16 WAI | Δ pH | 4 WAI | 16 WAI | Δ ex. acidity | 4 WAI | 16 WAI | Δ ex. Al |
| (1) Control | 5.16 | 4.67 | −0.49 | 0.24 | 0.28 | 0.04 | 0.08 | 0.09 | 0.01 | (2) Tithonia (60 kg P ha−1) | 5.41 | 4.35 | −1.06 | 0.21 | 0.23 | 0.02 | 0.01 | 0.00 | −0.01 | (3) FYM (60 kg P ha−1) | 5.36 | 4.71 | −0.65 | 0.21 | 0.24 | 0.03 | 0.01 | 0.00 | −0.01 | (4) MPR (60 kg P ha−1) | 5.34 | 4.75 | −0.59 | 0.24 | 0.27 | 0.03 | 0.03 | 0.00 | −0.03 | (5) TSP (60 kg P ha−1) | 5.20 | 4.73 | −0.47 | 0.25 | 0.26 | 0.01 | 0.06 | 0.06 | 0.00 | (6) BPR (60 kg P ha−1) | 5.20 | 4.73 | −0.47 | 0.32 | 0.29 | −0.03 | 0.10 | 0.08 | −0.02 | (7) Tithonia (20 kg P ha−1) + MPR (40 kg P ha−1) | 5.77 | 4.75 | −1.02 | 0.21 | 0.21 | 0.00 | 0.03 | 0.00 | −0.03 | (8) Tithonia (20 kg P ha−1) + (TSP 40 kg P ha−1) | 5.32 | 4.61 | −0.71 | 0.25 | 0.25 | 0.00 | 0.04 | 0.00 | −0.04 | (9) Tithonia (20 kg P ha−1) + BPR (40 kg P ha−1) | 5.39 | 4.38 | −1.01 | 0.24 | 0.31 | 0.07 | 0.05 | 0.00 | −0.05 | (10) FYM (20 kg P ha−1) + MPR (40 kg P ha−1) | 5.36 | 4.82 | −0.54 | 0.23 | 0.25 | 0.02 | 0.03 | 0.00 | −0.03 | (11) FYM (20 kg P ha−1) + TSP (40 kg P ha−1) | 5.33 | 4.74 | −0.59 | 0.24 | 0.27 | 0.03 | 0.02 | 0.03 | 0.01 | (12) FYM (20 kg P ha−1) + BPR (40 kg P ha−1) | 5.36 | 4.61 | −0.75 | 0.24 | 0.28 | 0.04 | 0.02 | 0.04 | 0.02 | (13) Tithonia (20 kg P ha−1) | 5.28 | 4.33 | −0.95 | 0.23 | 0.24 | 0.01 | 0.07 | 0.00 | −0.07 | (14) FYM (20 kg P ha−1) | 5.21 | 4.68 | −0.53 | 0.24 | 0.26 | 0.02 | 0.02 | 0.00 | −0.02 | (15) MPR (40 kg P ha−1) | 5.33 | 4.78 | −0.55 | 0.23 | 0.27 | 0.04 | 0.04 | 0.00 | −0.04 | (16) TSP (40 kg P ha−1) | 5.20 | 4.70 | −0.50 | 0.25 | 0.29 | 0.04 | 0.07 | 0.00 | −0.07 | (17) BPR (40 kg P ha−1) | 5.21 | 4.68 | −0.53 | 0.28 | 0.31 | 0.03 | 0.08 | 0.08 | 0.00 | SED | 0.10 | N.S. | | N.S. | 0.014 | | N.S. | 0.018 | | CV % | 2.0 | | | | 5.6 | | | 40.00 | |
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WAI: weeks after incubation; FYM: farmyard manure; TSP: triple superphosphate; MPR: Minjingu phosphate rock; BPR: Busumbu phosphate rock; N.S.: not significant; SED: standard error of difference between means; Ex: exchangeable.
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