Nitrogen uptake, recovery and use-efficiency in forage oat (avena sativa l.)

Abstract

Study was conducted to investigate effects of different levels of nitrogen on nitrogen content, uptake, recovery and use-efficiency of forage oat. Two-third of five levels of nitrogen (0, 40, 80, 120 and 160 kg ha-1) in the form of urea (CO (NH2)2), was applied at planting time and the remaining one-third - 30 days after sowing on soils with pH 7.3, 238 kg ha-1 available nitrogen, 0.7% organic carbon, 47.3 kg ha-1 available phosphorous and 284.37 kg ha-1 exchangeable potassium. It was found that total nitrogen uptake by the crop and the nitrogen content in plant tissue significantly increased (P < 0.05) with successive levels of nitrogen applied up to 120 kg ha-1 ; whereas, the apparent recovery and the use-efficiency declined significantly (P < 0.05) with successive levels of the applied nitrogen. The implication is that the efficiency of fertilizer use is inversely related with level of application and that of the uptake and content in plant tissue and dry mater yield of the crop. In the present study optimum level for maximum rate of yield increment could not be more than 120 kg N ha-1 . The decrease in recovery and use efficiency was reflected in yield only at a rate higher than the optimum level.