Effect of coulters and depth control units of a seeder on sowing quality for precision sowing

ABSTRACT EFFECT of COULTERS and DEPTH CONTROL UNITS of a SEEDER on SOWING QUALITY for PRECISION SOWING Davut KARAYEL PhD in Agricultural Machinery Adviser: Prof. Dr. Aziz ÖZMERZİ January 2005, 150 pages This research was carried out to determine the effect of different coulters and sowing depth control units on seed distribution pattern, seedling emergence, emergence date and some physical properties of soil with reference to the precision sowing technique. Maize (zea mays L.) and watermelon (citrullus vulgaris) seeds were used for field experiments. The horizontal and vertical distribution pattern of seeds in soil was measured to determine seed distribution in soil. Seed spacing and deviation from row were measured to determine horizontal seed distribution pattern and sowing depth was- measured to determine vertical seed distribution pattern. A new method was used to.evaluate deviation from row and sowing depth together. The distribution area of seeds in vertical plane was measured using with new method. Mean emergence dates and emergence rate indices were calculated to determine emergence time of seeds. Soil moisture variation after sowing, soil disturbance and penetration resistance of soil were measured to determine effect of coulters to physical properties of soil. "IllThe best coulter was shoe type coulter according to seed distribution in vertical plane. Using side wheel as seeding depth control unit was improved the seed distribution in vertical plane especially for hoe type coulter. Therefore, the side wheels must be used with hoe type coulter for better seed distribution pattern. The best plant emergence rate was obtained with shoe and double disc openers. The least mean emergence date and the maximum emergence rate indices occurred when shoe and double disc coulter were used. The hoe coulter increased the soil moisture and soil moisture lost in seed zone after seeding. The hoe, single and double disc coulters pressed the soil at the seeding depth and seeded the seeds on pressed groove. KEY WORDS: Seeder, precision sowing, coulter, sowing depth, seed distribution, maize, watermelon. COMMITTEE: Prof. Dr. Aziz ÖZMERZİ Prof. Dr. Rahmi KESKİN Prof. Dr. Osman YALDIZ Prof. Dr. Ibrahim AKINCI Doç. Dr. Cengiz TOKER IV