Research Article
The Effect of Minjingu Phosphate Rock and Triple Superphosphate on Soil Phosphorus Fractions and Maize Yield in Western Kenya
Table 4
Sequentially extractable soil P fractions (mg kg−1) at Khwisero in the first season.
| | | Resin-Pi | NaHCO3-Pi | NaOH-Pi | HCl-Pi | NaHCO3-Po | NaOH-Po | Sum of fractions |
| | (1) Control | 7.4 | 7.4 | 72 | 9.4 | 57 | 322 | 475 | | (2) Tithonia | 8.4 | 7.7 | 72 | 10 | 56 | 398 | 522 | | (3) TSP + urea (50 kg P ha−1) | 11 | 9.2 | 72 | 10 | 52 | 327 | 481 | | (4) TSP + tithonia (50 kg P ha−1) | 15 | 11 | 84 | 10 | 57 | 329 | 506 | | (5) MPR + urea (50 kg P ha−1) | 11 | 8.8 | 71 | 11 | 52 | 328 | 482 | | (6) MPR + tithonia (50 kg P ha−1) | 12 | 7.9 | 71 | 11 | 52 | 327 | 481 | | (7) TSP + urea (250 kg P ha−1) | 43 | 25 | 135 | 12 | 57 | 356 | 628 | | (8) TSP + tithonia (250 kg P ha−1) | 50 | 29 | 116 | 11 | 60 | 354 | 620 | | (9) MPR + urea (250 kg P ha−1) | 39 | 16 | 109 | 21 | 58 | 345 | 588 | | (10) MPR + tithonia (250 kg P ha−1) | 33 | 16 | 101 | 21 | 54 | 337 | 571 | | s.e.d. | 6.6 | 2.8 | 11 | 1.5 | NS | NS | 22 | | CV | 8 | 12 | 11 | 12 | 10 | 13 | 10 |
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TSP: triple superphosphate; MPR: Minjingu phosphate rock; s.e.d.: standard error of difference between means; CV: coefficient of variance.
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