| چکیده انگلیسی مقاله |
In order to study variations of organic carbon, nitrogen, phosphorous, potassium, iron, zinc, copper, and manganese available in soil in response to different wheat based rotations, an experiment was conducted for 5 years with completely randomized block design, with 8 treatments and 3 replications. Treatments were: T1- continuous wheat culture, T2- wheat, wheat, wheat, canola, wheat, T3- wheat, sugar beet, wheat, sugar beet, wheat,T4- wheat, potato, wheat, potato, wheat, T5- wheat, potato, wheat, canola, wheat, T6- wheat, sugar beet, wheat, potato, wheat, T7- wheat, corn, wheat , potato, wheat, T8- wheat, corn, wheat, sugar beet, wheat. Results showed that the amount of macronutrients in surface soil layer varied with rotation and number of years. The %OC and the residual macronutrients and micronutrients were affected significantly in 5 years: %OC was reduced, the residual N increased, the residual P remained constant, and the residual K decreased in 5 years. Also, the residual Fe and Zn increased while the amount of residual Mn decreased, but the residual Cu remained unchanged in 5 years. The amount of %OC and the residual macronutrients and micronutrients were affected significantly by different rotations. T1 rotation had the highest levels of %OC and the amount of residual N, Fe, and Zn and the lowest level of residual K. T2 rotation, too, had the highest %OC and residual N, but the lowest level of residual P, Zn , and Fe and the highest level of residual Mn and Cu. T3 rotation had the highest level of residual P. T4 rotation resulted in the lowest level of %OC and residual N. T5 rotation had the highest level of %OC and the residual N and K. T7 rotation resulted in the lowest level of %OC and residual N. T8 rotation had the highest level of residual P. |