This experiment was carried out during the two successive summer seasons of 2008 and 2009 at  Private Farm in El-Mahala El-Kobra region Ghrabia Governorate, on potato plant  cv. Diamant to study the effect of potassium rates  ( 0,50 and 100 kg K₂O/fed) and humic acid  as soil application  ( 0, 2 and 4 kg/fed. as humate potassium)  as well as their interactions on growth,   nutrition  status and productivity of potato under clay  soil. Application of 100 kg K₂O/fed.  was the superior treatment for enhancing   dry weight of straw and tubers,  percentage  of N,P and k  and total uptake  by plant  as well as   total yield/fed. Treated of  potato plants with humic acid at 4 kg/fed. gave the maximum values of plant growth and plant nutritional statues as well as  yield and its components  with significant differences with 2 kg / fed. with respect to N,P and K (%) and  yield and its components.  The best interaction treatment for increasing yield and its components  was obtained by  fertilization of potato plants with 100 kg K₂O / fed. and  treated of plants with 2 kg /fed.  humic acid.