**3.3 Effect of fertilizers on soil cation exchange capacity**

The cation exchange capacity (CEC) is a very important soil property for nutrient retention and supply and acts as a bridge between soil and plant [30]. **Table 3** presents the characteristics of soil CEC on two-kind of crop growth (radish and komatsuna). The results shows that all treatment of fertilizer (compost and struvite-K) with two-kind of crop growth were higher than control (soil only). However, the highest results seen in treatment of struvite-K with 0.3% percent ratio of soil for both of crop growth. This is indicated that struvite-K is effective as supplying of nutrient sources which have higher macro nutrient such as phosphate, magnesium and potassium. This is agreement with [31] who found application of phosphate fertilizer increasing of soil CEC after 40 years of application. This can be explained that phosphate, potassium and magnesium is the most important factor affecting on soil CEC.
