Effect of Different Levels of Vermicompost and Chemical Fertilizer applications on Some Physicochemical Characteristics of Soil and wheat (Triticum aestivum L. cv. Bahar) yield in Rotation with Sugar Beet

In order to study the effects of vermicompost and chemical fertilizers on soil physicochemical characteristics and wheat (Triticum aestivum L. cv. Bahar) yield, a field experiment based on randomized complete block design (RCBD) with 11 treatments and 4 replications was conducted in Mahidasht Agricultural Research Station during growing season of 2013. Treatments included, T1: application of 50% NPK chemical fertilizer, T2: application of 50% NPK plus 3 tons ha-1 of vermicompost, T3: application of 50% NPK plus 5 tons ha-1 of vermicompost, T4: application of 50% NPK plus 7 tons ha-1 of vermicompost, T5: application of 100% NPK, T6: application of 3 tons ha-1 vermicompost, T7: application of 5 tons ha-1 vermicompost, T8: application of 7 tons ha-1 vermicompost, T9: application of 3 tons ha-1 vermicompost plus crop fertilizer requirement minus equivalent amount of chemical fertilizers in 3 tons vermicompost, T10: application of 5 tons ha-1 vermicompost plus crop fertilizer requirement minus equivalent amount of chemical fertilizers in 5 tons vermicompost, T11: application of 7 tons ha-1 vermicompost plus crop fertilizer requirement minus equivalent amount of chemical fertilizers in 7 tons vermicompost. The lowest value of pH (7.7) was achieved by application of 7 tons vermicompost (T8) which decreased 5.39% compared to chemical fertilizer treatments. Also, the lowest bulk density (1.25 g cm-3), the greatest organic carbon percent (1.84) and the highest total porosity (57.16%) belonged to the application of 7 tons ha-1 vermicompost. Soil total nitrogen by application of 7 tons vermicompost was 80.45 and 72.52 percent higher than 50% and 100% NPK treatments, respectively. Results showed that application of 7 tons ha-1 vermicompost (T8) followed by T11 and T4 treatments showed the highest effect on soil physicochemical properties compared to other treatments especially chemical treatments. Also, the highest wheat yield was achieved by application of 7 tons ha-1 vermicompost plus crop fertilizer requirement minus equivalent amount of chemical fertilizers in 7 tons vermicompost (T11) and followed by application of 5 tons ha-1 vermicompost plus crop fertilizer requirement minus equivalent amount of chemical fertilizers in 5 tons vermicompost (T10).