Effects of Disc Ploughing on the Morphological and Physical ...

3.0 RESULTS AND DISCUSSIONThe result <strong>of</strong> the effects <strong>of</strong> the treatment on the morphological and physical propertiessoil <strong>of</strong> furrow slice is presented in Tables 1, 2 and 3.There was no significant difference (P ≤ 0.05) among the variables. The effect <strong>of</strong> thedisc on parameters as obtained in Table 1, show no significant difference (P ≤ 0.05) betweenbefore and after disc ploughing on the soil samples studied. The bulk densities at the threesites show that Mugulbu has the highest mean <strong>of</strong> 1.32, followed by Moduva with 1.27 andLamorde is the least with 1.20 but statistically they are not significant (P ≤ 0.05) based onthe Duncan’s Multiple Rank Test (DMRT) as presented in Table 2.TABLE 1: Effect <strong>of</strong> disc ploughing on the variablesLegend: BD = Bulk density, PD = Particle density, PPS = Percentage pore space, INF = Infiltrationrate, WHC = Water holding capacity, SE = Standard errorTreatment BD PD PPS INF WHCBefor 1.29a 2.35a 44.80a 0.09a 44.07After 1.27a 2.35a 45.47a 0.16a 43.53aSE (±) 0.11 0.11 3.8 0.1 4.44There were no significant difference (P ≤ 0.05) in the interaction among particle density,infiltrability and bulk density, but a high significant difference (P ≤ 0.01) was recordedbetween percentage pore size, water holding capacity and bulk density both <strong>of</strong> which areinversely related as shown in Table 3.This work shows that bulk density was not affected by disc ploughing at the plough layer (0 –20cm depth). This may probably be because the soils were subjected to pulverisation whichloosens the surface soil. However, studies carried out on bulk density over a long timeindicated a positive correlation between bulk density and implement used below the workingdepth (30 – 50 cm) <strong>of</strong> the implement even as they lift and loosen the soil above. This is inline with the findings <strong>of</strong> Nuhu and Ibrahim (2006) that bulk density increased with increasein the number <strong>of</strong> tractor passes .Also, Ahmad et al. (2008), reported similarly that ploughingwith the same implement at the same depth for a long time affect soil physical propertiessuch as bulk density and porosity.In terms <strong>of</strong> particle densities, the results obtained from Lamorde (2.36 Mg/m 3 ) andMugulbu (2.50 Mg/m 3 ) show no significant difference (P ≤ 0.05) between the samples;however, the soil obtained from Moduva (2.14 Mg/m 3 ) has a significant difference (P ≤ 0.01)as indicated by Table 2.TABLE 2: Performance <strong>of</strong> disc ploughing on the variables at different sitesSite BD PD PPS INF WHCLamorde 1.20a 2.36a 49.90a 0.10a 44.30aModuva 1.27a 2.14b 38.40b 0.09a 42.20aMugulbu 1.32a 2.50a 47.10a 0.02a 44.90aSE (±) 0.11 0.11 3.80 0.10 4.44Figures with the same letters are not statistically significantThere were no significant interaction (P ≤ 0.05) between bulk density, water holding capacityand particle density, but a significant interaction existed between percentage pore size,infiltrability and particle density as shown in Table 3.In this study, particle density <strong>of</strong> the soils <strong>of</strong> the furrow slice was found to be unaffected bydisc ploughing since the values obtained before and after ploughing were constant (2.50mg/m 3 for both Lamorde and Mugulbu, and 2.00 mg/m 3 for Moduva). This result may beexplained by the fact that particle density is the same as the specific gravity <strong>of</strong> the soils <strong>of</strong>the actual soil particle or mineral material, excluding the pore spaces. The values obtainedwere within the limit <strong>of</strong> 2.0 – 2.5 mg/m 3 , This result is in concur with those reported byBrady and Weil (2007) that the particle densities <strong>of</strong> most mineral soils vary between thenarrow limits <strong>of</strong> 2.0 – 2.75mg/m 3 .