DETERMINATION TO RESIDUAL N EFFECT OF LENTIL VARIETIES ON SUCCEEDING WHEAT N-15 ISOTOPE TRACING TECHNIQUE

Abstract

The field experiments were conducted to determine nitrogen fixing capacities of winter and summer lentil (Lens culinaris Medic.) varieties and the carry-over N effect on succeeding wheat, using N-15 isotope technique, under Central Anatolia dryland conditions. The use of labelled nitrogen provides a unique tool allowing to separately study the behaviour of fertilizer N, soil N and also to quantify the amount of biologically fixed nitrogen. First year, biological nitrogen fixation capacities of winter and summer lentil varieties were estimated by using N-15 methodology. Second year, carry-over of N from the legume residue to wheat was determined. According to first year results, the average of fixed nitrogen were found as 70.0 and 45.0 kgN/ha for winter and summer varieties, respectively. Second year, the average of carry-over N derived from soil values were found 43.0 and 17.0 kgN/ha for succeeding wheat when the previous legumes were winter and summer lentil varieties, respectively.