عنوان مقاله [English]
Background and objectives: Due to risks and pollution of chemical fertilizer, need to reduce the usage of them and find the ecological approaches to provide the necessity of nutrition sources for crops. One of the is the usage of the reasonable pre-sowing plants. The present study was conducted to evaluate the effect of the pre-sowing treatments and nitrogen levels on qualitative characteristics of silage corn.
Materials and methods: This research is performed during growing season 2013-14 at the Agricultural Research Station of Islamic Azad University of Karaj, Iran. The experiment was conducted as a split plot based on a randomized complete block design with four replications. Main factors include pre-sowing treatments in 4 levels (Perko PVH, Buko, Manure and Fallow) and sub factors also included nitrogen levels (120 and 240 and 360 kg ha-1, utilized urea source). Perko PVH and Buko belong to Brassicaceae family that if they back to the soil they can increase the oraganic matter. Seeds (sc 704) were planted by pneumatic machine under 12 plants m-2. At the end of the season, qualitative and quantitative characteristics, including dry matter digestibility, water soluble carbohydrates, crude protein, acid detergent fiber, neutrals detergent fiber, total Ash and forage yield were determined. Data analyses are done by using SAS (Version 9.1.3) statistic software mean comparison was done using the LSD test at probability level of 5%.
Results: Variation analyses illustrated that the effect of pre-sowing treatments was significant (P≤0.01) on dry matter digestibility, neutrals detergent fiber and forage yield so that in all traits, Perko PVH and Buko treatments were the best ones to compare with fallow and manure. The highest forage yield was observed by Perko PVH Pre-sowing treatments (78.23 ton ha-1) and the least forage yield for the manure treatment was (63.71 ton ha-1). The effect of nitrogen levels on dry matter digestibility, neutrals detergent fiber and forage yield had a significant difference (P≤0.01), so that with the increasing use of nitrogen, the rates of that traits increased. The Interaction effect of pre-sowing treatments and nitrogen levels was significant on a water soluble carbohydrates, crude protein, acid detergent fiber and Total Ash (P≤0.01), somehow in Karaj region the suitable component was Perko PVH treatment by using 240 kg ha-1 nitrogen fertilizer. That's the highest percentage of crude protein was recorded pre-sowing of Perko PVH and for 240 kg N ha-1 was 9.07% and the lowest percentage of crude protein was related to the manure treatment and 120 kg N ha-1 are 4.6%.
Conclusion: According to the results of this research, the combined usage of organic fertilizer with nitrogen fertilizer, enhances the quantitative and qualitative characteristics have been studied in corn silage. Hence, by use of the organic fertilizers, meanwhile considerably reducing the chemical fertilizer consumption and consequently reducing the environmental impacts are. The results showed that perko and buko treatments have positive and significant effect on qualitative and quantitative parameters of corn silage and the reaction of corn silage to pre-sowing product is different. In general can say that by cultivation the pre-sowing crops and return the their remnants to the soil leads to soil fertility and consequently improve the quantity and quality of corn silage and can be considered as one of the ways to achieve sustainable agriculture.