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.

TreatmentpHExchangeable acidity (cmol kg−1)Exchangeable Al (cmol kg−1)
4 WAI16 WAIΔ pH4 WAI16 WAIΔ ex. acidity4 WAI16 WAIΔ ex. Al

(1) Control5.164.67−0.490.240.28 0.040.08 0.09 0.01
(2) Tithonia (60 kg P ha−1)5.414.35−1.060.210.23 0.020.01 0.00−0.01
(3) FYM (60 kg P ha−1)5.364.71−0.650.210.24 0.030.01 0.00−0.01
(4) MPR (60 kg P ha−1)5.344.75−0.590.240.27 0.030.03 0.00−0.03
(5) TSP (60 kg P ha−1)5.204.73−0.470.250.26 0.010.06 0.06 0.00
(6) BPR (60 kg P ha−1)5.204.73−0.470.320.29−0.030.10 0.08−0.02
(7) Tithonia (20 kg P ha−1) + MPR (40 kg P ha−1)5.774.75−1.020.210.21 0.000.03 0.00−0.03
(8) Tithonia (20 kg P ha−1) + (TSP 40 kg P ha−1)5.324.61−0.710.250.25 0.000.04 0.00−0.04
(9) Tithonia (20 kg P ha−1) + BPR (40 kg P ha−1)5.394.38−1.010.240.31 0.070.05 0.00−0.05
(10) FYM (20 kg P ha−1) + MPR (40 kg P ha−1)5.364.82−0.540.230.25 0.020.03 0.00−0.03
(11) FYM (20 kg P ha−1) + TSP (40 kg P ha−1)5.334.74−0.590.240.27 0.030.02 0.03 0.01
(12) FYM (20 kg P ha−1) + BPR (40 kg P ha−1)5.364.61−0.750.240.28 0.040.02 0.04 0.02
(13) Tithonia (20 kg P ha−1)5.284.33−0.950.230.24 0.010.07 0.00−0.07
(14) FYM (20 kg P ha−1)5.214.68−0.530.240.26 0.020.02 0.00−0.02
(15) MPR (40 kg P ha−1)5.334.78−0.550.230.27 0.040.04 0.00−0.04
(16) TSP (40 kg P ha−1)5.204.70−0.500.250.29 0.040.07 0.00−0.07
(17) BPR (40 kg P ha−1)5.214.68−0.530.280.31 0.030.08 0.08 0.00
SED0.10N.S.N.S.0.014N.S.0.018
CV %2.05.640.00

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.