عنوان مقاله [English]
Organic fertilizers such as vermicompost (VC) are an undeniable source of required nutrients of plants. This field experiment performed as split plot arrangement based a randomized complete block design with three replications in 2008. The main factors (vermicompost treatments) added to soil at six levels including 20 and 40 ton.ha-1, 20 and 40 ton.ha-1 plus (1/2) chemical fertilizer, chemical fertilizer (consists of 100 kg.ha-1 urea, 150 kg.ha-1 triple superphosphate and 100 kg.ha-1 potassium sulphate based on soil testing analysis) and control. Also, sub plots considered VC application periods (1, 2 and 3 years). Results showed that using VC and also fertilization year's factor significantly affected studied traits of rice. So, 40 ton.ha-1 VC plus 50% chemical fertilizer determined as the best fertilizer level, because the maximum content of biomass (12.43 ton.ha-1), tiller number, height, total number of grains in panicle (124.3), harvest index (41.41%) and yield (681.1 g.m2) and also the lowest percent of unfilled grain in panicle (15.52%) recorded in this treatment. Meanwhile, 40 ton vermicompost per hectare treatment had the highest panicle fertility percentage (94.08%). Increasing application periods regularly enhanced the content of studied traits. In addition, the maximum positive and significant correlation coefficient (r= +0.91**) existed between paddy yield and harvest index.