A field experiment was carried out at Agriculture Research Station of King Abdulaziz University, Jeddah, Saudi Arabia to study the effect of fine particles, tillage system, and polyacrylamide application rate on the soil penetration resistance during the two seasons (2015/16 – 2016/17). Experimental design was split-split plot with four replications. Main plot included two percent of fine particles, (A = 25.2 silt + clay) and (B = 38.5 silt + clay). Sub-main plots included three tillage systems; no-tillage (NT), moldboard plowing with rotor tiller (CT1), and chisel plowing with disk harrow (CT2). Sub-sub plots were three polyacrylamide (PAM) rates; 0, 10 and 20 kg ha-1. Both locations were cultivated by wheat crop for two consecutive seasons. Results revealed that tillage system affected soil penetration resistance. Penetration resistance results revealed the existence of compacted layer beneath the tilled depth in all treatments in both locations. However, its hardness in location A was higher than in location B. The CT1 treatment had the highest value of cone index; however, the penetration resistance of CT2 and NT treatments was similar. High rate of PAM application improved penetration resistance especially with CT2 tillage system.
