Effect of residual fertilizer N, lime and Bradyrhizobium inoculum on groundnut yield, N uptake and N2 Fixation

Groundnut (Arachis hypogaea L.) is known to be effective in symbiotic N2 fixation, but uncertainty remains concerning the magnitude of this process, especially when this crop is grown under acid conditions with different N management systems. This study was conducted to determine the effect of previously applied fertilizer N and previously applied lime rates on groundnut yield, 15N concentration, total N uptake and N2 fixation. Previously applied N rates were 0, 80, 160 and 240 kg N ha‐1 as NH4NO3 to main plots or labelled‐N rates of 0, 40, 80 and 120 kg NO3‐N ha‐1 to microplots as NH4 I5NO3. The lime was previously applied at the rates of 0 and 2 Mg ha‐1 to the preceding maize (Zea mays L.) crop. The effect of inoculum was also investigated. Nodulating isoline, groundnut cv Chalimbana seed was treated with Bradyrhizobium peat inoculum containing Bradyrhizobium sp. (inoculant strain TAL 1000) 105 cells per seed. Non‐nodulating isoline PI 109839/NC AC17090 (NFN‐43) and nodulating isoline Chalimbana were gr...