The nitrogen and non-nitrogen rotation benefits of pea to succeeding crops

Abstract

The inclusion of a pulse crop in a rotation often leads to greater seed yields in the succeeding cereal crop. Two rotations were established at three sites in 1993 to examine the N and non-N rotation benefits of pea (Pisum sativum L.) to the subsequent wheat (Triticum aestivum L.) then oilseed crops. Wheat seed yield was 43% greater (rotation benefit) when preceded by pea rather than wheat, a consistent response among sites. Six to fourteen kg ha-1 of the extra 27 kg ha-1 of N accumulated by wheat in the pea-wheat rotation was derived from the additional N derived from pea residue. The additional soil N availability in the pea-wheat rotation, as indicated by the A-value, explained 8% of the rotation effect on seed yield (N benefit). The remaining 92% of the yield advantage in the pea-wheat rotation was attributed to non-N rotation benefit. The yield of the oilseed crop following the pea- wheat phase of the rotation did not differ from that following the wheat- wheat phase. The influence of growing conditions and cropping history on the magnitude of the N to non-N rotation benefits, and the contribution of different non-N effects, should be investigated further.