The aim of this research is to study some factors affecting the hole diggerperformance in the sandy soil. The experiments were conducted in El-Kasasin Research Station in El-Sharkia Governorate. Auger diameters (250 mm) of the developed hole-digger were tested at different auger–speeds (75, 100 and 150 rpm), auger pitches (10, 15 and 20 cm), hole–depths ( 20, 30 and 40 cm), hole–spacing (5 m) and soil type (sandy) with moisture contents of 15, 22 and 32 % .
The obtained results can be summarized as follow:
The maximum hole productivity rate for sandy soil was 335 hole/h obtained with auger speed of 150 rpm, hole depth 20 cm, auger pitch 20 cm at moisture content 32 %. The penetration resistance of sandy soil at 15 % moisture content increased by 30 and 40.6 % as compared with of sandy soil at moisture content 22 % and 32 %, respectively. The maximum fuel consumption was 0.59 L/h was obtained with auger speed of 150 rpm, hole depth 40 cm, and auger pitch 10 cm. The maximum power requirements 1.91 kW was obtained with auger speed of 150 rpm, hole depth 40 cm, auger pitch 10 cm and moisture content 15 %. The minimum operation cost was 0.04 L.E/hole at auger pitch 15 cm and hole
depth 20 cm. Whereas, the maximum operation cost was 0.14 L.E./hole at auger pitch 10 cm and hole depth 40 cm. The operational cost using a hole digger attached to a power tiller decreased by 371 % compared with manual digging.