Research Article
Effects of Organic and Inorganic Materials on Soil Acidity and Phosphorus Availability in a Soil Incubation Study
Table 6
Effect of organic and inorganic P amendments on Olsen P (mg P kg−1) at Bukura and Kakamega in the laboratory incubation study.
| | Treatment | Bukura | Kakamega | | 4 WAI | 16 WAI | Δ Olsen P | 4 WAI | 16 WAI | Δ Olsen P |
| | (1) Control | 7.3 | 8.9 | 1.6 | 3.2 | 4.3 | 1.1 | | (2) Tithonia (60 kg P ha−1) | 13.1 | 14.7 | 1.6 | 8.2 | 9.6 | 1.4 | | (3) FYM (60 kg P ha−1) | 16.0 | 16.5 | 0.5 | 9.5 | 10.0 | 0.5 | | (4) MPR (60 kg P ha−1) | 13.4 | 16.3 | 2.9 | 6.9 | 8.0 | 1.1 | | (5) TSP (60 kg P ha−1) | 18.2 | 17.7 | −0.5 | 9.8 | 10.1 | 0.3 | | (6) BPR (60 kg P ha−1) | 11.0 | 11.5 | 0.5 | 4.5 | 6.0 | 1.5 | | (7) Tithonia (20 kg P ha−1) + MPR (40 kg P ha−1) | 14.1 | 13.9 | −0.2 | 7.9 | 6.3 | −1.6 | | (8) Tithonia (20 kg P ha−1) + (TSP 40 kg P ha−1) | 17.4 | 15.8 | −1.6 | 8.9 | 8.6 | −0.3 | | (9) Tithonia (20 kg P ha−1) + BPR (40 kg P ha−1) | 12.4 | 12.6 | 0.2 | 4.4 | 5.1 | 0.7 | | (10) FYM (20 kg P ha−1) + MPR (40 kg P ha−1) | 15.0 | 15.7 | 0.7 | 7.4 | 9.3 | 1.9 | | (11) FYM (20 kg P ha−1) + TSP (40 kg P ha−1) | 14.5 | 17.7 | 3.2 | 8.0 | 6.0 | −2.0 | | (12) FYM (20 kg P ha−1) + BPR (40 kg P ha−1) | 13.1 | 16.1 | 3.0 | 5.9 | 5.8 | −0.1 | | (13) Tithonia (20 kg P ha−1) | 11.2 | 13.9 | 2.7 | 4.6 | 7.3 | 2.7 | | (14) FYM (20 kg P ha−1) | 12.7 | 15.6 | 2.9 | 5.7 | 7.5 | 1.8 | | (15) MPR (40 kg P ha−1) | 12.5 | 14.9 | 2.4 | 6.3 | 6.6 | 0.3 | | (16) TSP (40 kg P ha−1) | 14.2 | 16.6 | 2.4 | 6.7 | 7.3 | 0.6 | | (17) BPR (40 kg P ha−1) | 9.8 | 9.6 | −0.2 | 4.4 | 5.6 | 1.2 | | SED | 0.9 | 1.3 | | 0.7 | 0.7 | | | CV % | 9 | 11 | | 10 | 10 | |
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WAI: weeks after incubation; FYM: farmyard manure; TSP: triple superphosphate; MPR: Minjingu phosphate rock;
BPR: Busumbu phosphate rock; SED: standard error of difference between means.
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