Role and Importance of Cobalt Nutrition on Groundnut (Arachis hypogaea) Production

Two field experiments were carried out to evaluate role and importance of cobalt under different levels of nitrogen on nodules efficiency, growth, yield, minerals composition and chemical characteristics of groundnut plants. The experiments were conducted at Research and Production Station, National Research Centre, El-Nobaria Beheara Governorate, DeltaEgypt, under drip irrigation system during 2011 and 2012 seasons. The obtained results are summarized in the following: Cobalt significantly increased nitrogenase activity which was parallel and related to the increased nodules numbers, weights and its efficiency especially with both 100 and 75% nitrogen fertilizer. Cobalt gave the highest figures of all growth and yield parameters of Groundnut with 100% N followed by 75% N compared with the untreated plants. Growth and yield parameters of groundnut treated with cobalt and 50% N was not significant while cobalt with 25% N gave the lowest figures. Cobalt increased the efficiency of nitrogen fertilization, amendment reduce the recommended dose of about by 25% and resulted in superior pods and oil yields about by 25.6% and 18.84 with75% N Respectively, compared with 100 N without cobalt. Cobalt significantly increased the content of N, P, K, Mn and Zn as well as chemical contents especially with 100% and 75% nitrogen levels. Increasing cobalt in plant media reduced iron content, there are antagonistic relationships between two elements (Fe &Co). Finally, the addition of Cobalt to the soil, save 25% nitrogen and could be reduced the nitrogen environmental pollution and induced the agricultural cost for more money of farmers.