Symbiotic N2-Fixation Estimated by the 15N Tracer Technique and Growth of Pueraria phaseoloides (Roxb.)‎ Benth. Inoculated with Bradyrhizobium Strain in Field Conditions

Abstract EN

This field experiment was established in Eastern Cameroon to examine the effect of selected rhizobial inoculation on N2-fixation and growth of Pueraria phaseoloides.

Treatments consisted of noninoculated and Bradyrhizobium yuanmingense S3-4-inoculated Pueraria with three replications each.

Ipomoea batatas as a non-N2-fixing reference was interspersed in each Pueraria plot.

All the twelve plots received 2 gN/m2 of 15N ammonium sulfate 10% atom excess.

At harvest, dry matter yields and the nitrogen derived from atmospheric N2-fixation (%Ndfa) of inoculated Pueraria were significantly (P<0.05) higher (81% and 10.83%, resp.) than those of noninoculated Pueraria.

The inoculation enhanced nodule dry weight 2.44-fold.

Consequently, the harvested N significantly (P<0.05) increased by 83% in inoculated Pueraria, resulting from the increase in N2-fixation and soil N uptake.

A loss of 55 to 60% of the N fertilizer was reported, and 36 to 40% of it was immobilized in soil.

Here, we demonstrated that both N2-fixing potential of P.

phaseoloides and soil N uptake are improved through field inoculations using efficient bradyrhizobial species.

In practice, the inoculation contributes to maximize N input in soils by the cover crop’s biomass and represent a good strategy to improve soil fertility for subsequent cultivation.