Effects of Atrazine on Urease in Soils with Different Fertilization

Effects of atrazine on urease in two t ypical soils wer e studied here.The t wo soils were treated by different dosages of a-trazine. We have discovered that ure ase activity was stimulated by lower concentration o f atrazine in the fir st days.However,the activity was restrained by higher co ncentration during the period of thi s experiment.There was a distinctly diffe rence on urease ac-tivity in different soils after treatment by application of atrazine at higher dosage.We also noticed that a l ong -term application of NP Kfertilizers combined with organ ic manure could significantly incre ase urease activity and the activity was less restrained than that in the soils that had be en applied with NPK fertilizers.