The Study Rate of Seeding and Seasond Urea Application In Rainfed Winter Wheat in Kurdest8n Province

Naterials and Methods: This study waS carried out in a split plot Design with 3 treatments in mainplot and 5 treatments in subplots in 4 replicate in Kharkeh Soil and. Water Research Station during four years period. (1985 - 1989). The factorial configuration of treatments are: (515253) x (TOT1T2T3L.) in which 51,52 and 53 are lOa, 150 and 200 kgs of seeding Rate treatme¬nts respectively, while TO control (without using urea), T1 application all urea (30 kgs) once in autumn before planting. T2 applicatio~ ,all urea once in spring, T3 application 1 urea in autumn preplanting and, 1/2 in spring before rain onset and T4 appliction 1/3 urea in autumn and 2/3 in spring. The seed-bed preparation conunenced with mouldboard plowing fatllowed by one or two time disking. The seed and fertilizer broadcasted then in corporated with soil by final disking, the seed variety was sardari which treated with PCNB fungicide before planting. The phosphorus source was triple super phosphate which 30 kgs of P20S was uniformly used in all treatments before planting in autumn. A complete sample woas prepared from 0-30 cm depth in each replication for necessary soil testa. Results and Discussiuns: the seed rate and urea application time were not statistically significant on crop yield in each year and throui.ta out fuur years compilation uf results but the effect of year was significant in 1% level. In the first and second years the appropriate amount and distribution of rainfall, contributted to a significant difference in crop yields in comparision with succeeding years. The prevalence along frost period in later years was the main reasion of crop failuce without any response to the fertilizer usage and application time. It can be concluded that: determining the appropriate season for nitrogen application and seeding rate ate very unreliable and mainly depends on erratic, uncertain and Bearse rains in arid and semiaud Mediterranean climate.