The Effect of Minjingu Phosphate Rock and Triple Superphosphate on Soil Phosphorus Fractions and Maize Yield in Western Kenya

Table 3

Sequentially extractable soil P fractions (mg kg⁻¹) at Nyabeda in the first season.

Treatment	Resin-Pi	NaHCO3-Pi	NaOH-Pi	HCl-Pi	NaHCO3-Po	NaOH-Po	Sum of fractions
(1) Control	8.5	5.2	81	9.2	47	265	416
(2) Tithonia (6 kg P ha^−1)	8.5	5.6	75	9.2	44	274	416
(3) TSP + urea (50 kg P ha^−1)	9.5	6.9	85	9.7	47	291	449
(4) TSP + tithonia (50 kg P ha^−1)	9.6	8.6	77	9.7	44	268	417
(5) MPR + urea (50 kg P ha^−1)	8.4	6.2	76	8.2	43	285	427
(6) MPR + tithonia (50 kg P ha^−1)	9.8	7.4	84	11	45	275	432
(7) TSP + urea (250 kg P ha^−1)	28	27	143	9.6	46	281	535
(8) TSP + tithonia (250 kg P ha^−1)	29	27	125	10	47	299	537
(9) MPR + urea (250 kg P ha^−1)	27	14	99	11	43	288	483
(10) MPR + tithonia (250 kg P ha^−1)	26	16	103	12	44	268	469
s.e.d.	5.1	2.1	10	0.63	NS	NS	18
CV	11	8	13	12	10	11	7

TSP: triple superphosphate; MPR: Minjingu phosphate rock; s.e.d.: standard error of difference between means; CV: coefficient of variance.