Research Article
The Effect of Minjingu Phosphate Rock and Triple Superphosphate on Soil Phosphorus Fractions and Maize Yield in Western Kenya
Table 6
Sequentially extractable soil P fractions (mg kg−1) at Khwisero in the season.
| Treatment | Resin-Pi | NaHCO3-Pi | NaOH-Pi | HCl-Pi | NaHCO3-Po | NaOH-Po | Sum of fractions |
| (1) Control | 13 | 10 | 85 | 10 | 59 | 297 | 474 | (2) Tithonia | 15 | 13 | 85 | 11 | 72 | 284 | 480 | (3) TSP + urea (50 kg P ha−1) | 15 | 12 | 106 | 10 | 63 | 295 | 501 | (4) TSP + tithonia (50 kg P ha−1) | 17 | 12 | 103 | 10 | 58 | 298 | 498 | (5) MPR + urea (50 kg P ha−1) | 17 | 10 | 101 | 10 | 54 | 307 | 499 | (6) MPR + tithonia (50 kg P ha−1) | 20 | 15 | 93 | 13 | 60 | 283 | 484 | (7) TSP + urea (250 kg P ha−1) | 46 | 30 | 158 | 13 | 76 | 288 | 611 | (8) TSP + tithonia (250 kg P ha−1) | 59 | 38 | 165 | 12 | 78 | 300 | 652 | (9) MPR + urea (250 kg P ha−1) | 46 | 23 | 134 | 20 | 62 | 293 | 578 | (10) MPR + tithonia (250 kg P ha−1) | 44 | 24 | 145 | 24 | 67 | 323 | 641 | s.e.d. | 6.5 | 3.2 | 13 | 2.1 | NS | NS | 25 | CV | 8 | 10 | 12 | 10 | 8 | 11 | 9 |
|
|
TSP: triple superphosphate; MPR: Minjingu phosphate rock; s.e.d.: standard error of difference between means; CV: coefficient of variance.
|