Mulching is a vital agricultural practice that affects soil moisture retention, temperature regulation, and overall soil health. Three grass mulching materials (Gamba (Andropogon Gayanus), Jema (Chrysopogan Zizanioides) and Kachala (Typha Angustifolia)) at four mulching depths (0, 5, 10 and 15 cm) were examined to assess their effects on soil moisture content, temperature, bulk density and porosity. The study was conducted on onion plots irrigated with sprinkler system at a constant operating pressure (100 kPa). The study was carried out at the irrigation field laboratory of the Yelwa campus of Abubakar Tafawa Balewa University, Bauchi. Data were analysed using SPSS software version 23. The results indicated a significant combined impact of mulch type and depth on all studied parameters, except for bulk density. Results showed that Kachala grass, particularly at 15 cm depth, demonstrated superior moisture retention capabilities with 16.8% moisture content, leading to optimal soil moisture levels for plant growth. While the lowest soil moisture (8.81%) was conserved under the control (Un-mulched plot). Soil temperature recorded beneath the mulch was lowest (19.1oC) under 10 cm Kachala grass, while the highest (28.0 oC) was recorded under 15 cm Gamba grass. Highest soil bulk density (1.78 g/cm3) was recorded under the control, while 15 cm depth of Kachala grass gave the lowest (1.5 g/cm3) value of bulk density. The highest value of soil porosity (46.8%) was observed under 15 cm Kachala grass and the lowest (34.2%) was observed under the control. In conclusion, grass mulching has a positive effect on soil physical properties under sprinkler irrigation system in the fadama areas of Bauchi, Nigeria.