Synergism of nitrogen uptake from soil and symbiotic fixation of atmospheric nitrogen in increasing total nitrogen in soyabeans (Glycine max)
Ruschel, A.P.; Ruschel, R.
Pesquisa Agropecuaria Brasileira, Agronomia 10(11): 37-40
In a glasshouse trial, the effect of inoculation and of different N sources on nodule number and wt., symbiotic N fixation, nitrogenase activity and N content in soyabean was studied. Nodule wt. decreased with application of ammonium sulphate, ammonium nitrate or potassium nitrate, but not with urea. Although nodule number decreased with addition of N, no inhibition of nitrogenase activity was noted. Plant dry wt. at 45 days of age showed no difference due to inoculation, but inoculation increased total N and N percentage in above-ground plant parts in all treatments. Increase in total N indicated a synergism of inoculation and fertilizer N.