Effect of Vermicompost Biofertilizer and Plant Density on the Yield and Yield Components Soybean in Khorramabad

In order to investigate the effect of vermicompost biofertilizer and plant density on yield and yield components of second crop soybean (summer crop) in Khorramabad, this experiment was conducted at the research farm of the Islamic Azad University of Khorramabad Branch in the summer of 2012. This experiment in form of factorial including four levels of vermicompost fertilizer (control, 5, 10 and 15 tons per hectare) and four plant density (50, 25, 16/6 and 12/5 plant per square meter) was conducted in a randomized complete blocks design with three replications. The results indicated that the vermicompost biofertilizer was significant on the grain yield, harvest index, number of pods per plant, one thousand- grain weight and number of pods per square meter at five percent probability level. The effect of density was significant on all traits except seeds number per pod, one- thousand grain weight and harvest index and the interaction of these two factors was significant on the grain yield, number of pods per plant, number of seeds per plant and number of pods per square meter. The comparison of means showed, with the increase in the use of vermicompost fertilizer, the grain yield was increased so that use of 15 tons per hectare produced the highest grain yield (2231 kilogram per hectare) and use of five tons per hectare of vermicompost produced the lowest grain yield (1682 kilogram per hectare). Also, with the increase in plant density, the grain yield was decreased, so that the density of 50 plants per square meter, produced the highest grain yield (2302 kilogram per hectare) and the density of 12/5 plants per square meter, produced the lowest grain yield (1628 kilogram per hectare). In general and with regard to the obtained results, the highest grain yield was achieved in the use of 15 tons per hectare of vermicompost and in the density of 50 plants per square meter.