Effect of Soil Organic Matter (SOM) Content on True Particle Density and other Physical Properties of Sudan Savannah Entisols

The study aimed to determine the effect of long-term cultivation and soil organic matter (SOM) content on the particle density (Pd) and other physical properties of an Entisols in Usmanu Danfodiyo University Teachings and Research farm.. Soil samples were taken from six different spots (A, B, C, D, E, and F) at the depth of 0-15 and 15-30 cm. The field experiment was laid in RCB design and replicated three times each at a depth, totalling 36 samples. Purposive random sampling was used at 50 m intervals from one spot to another. The results show that interaction between sampling spots and sampling depths of the soil was significant (p<0.05) in terms of total porosity (TP), SOM content, bulk density (Bd), and Pd. Averagely, there was a significant (p<0.05) difference between 0-15 cm and 15-30 cm in terms of TP, Bd, and SOM content with the higher values of TP and OM observed in the 0-15 cm depth. The results show that spots near the shelterbelt (C and E) had higher OM, TP, and lower Bd and Pd. In terms of the textural class, differences were also observed among the sampling spots with C and E having sandy loam while the remaining spots had sand texture. Pd was higher in lower OM spots (A, B, D, F). The study revealed that whenever the standard Pd value (2.65 Mg m-3) was used to calculate TP of the soil, particularly spot C and E, it is being overestimated by 2-3%. It is therefore recommended that OM and crop residues should be incorporated and returned immediately after harvesting to help improve the soil properties. When soil is rich in OM, it is recommended that constant value (2.65 Mg m-3) should not be used to calculate its porosity, but rather the actual (measured) Pd of the soil.