A landscape-scale and small-plot assessment of the nitrogen and non-nitrogen rotation benefits of pea

The inclusion of a pulse crop in a rotation often leads to higher seed yields for the succeeding cereal crop. This effect is known as the rotation benefit. It is not clear how much of the yield advantage is caused by factors related to soil N availability (N benefit) or those factors not related to soil N availability (non-N benefit). The major objective of this study was to quantify the N and non-N benefits of pea to a succeeding wheat crop. Pea-wheat and wheat-wheat rotations were established in two adjacent 1-ha areas in 1993 using a landscape-scale research approach. The same rotations were established in small plots at three sites.;Percent N;In the second year of the landscape-study, wheat seed yield was 982 kg ha;In the small-plot study sites, wheat seed yield was 43% (698 kg ha;The larger rotation benefit from pea in the landscape-scale study could be due to topographic variation not included in small level areas of a small-plot research site. Footslope and depressional areas can serve as the source of diseases and weeds for the entire field, and accentuate the expression of the non-N rotation benefit of pea to the succeeding wheat crop.