Long-term productivity of legume based crop rotations

Abstract

Crop sequences are known to influence both yield and quality of crops and legumes have the potential to replace or partially replace fertiliser nitrogen. There is a lack of available data on the long-term sustainability of legume based rotations in modern UK agriculture. This is being investigated in a long-term rotational trial with a stocked (traditional sheep grazed ley/arable system, managed organically) and a stockless (all arable system with no manure, managed organically). Annual grain yields of the organically grown oats in the stocked system were not significantly different from National List/Recommended List yields in NE Scotland for oats receiving 100 kg N ha−1. The highest yields of spring barley and spring oats occurred following a ley in the stocked system. Wheat was grown only in the stockless rotation but wheat directly after red clover had a higher yield than wheat after potatoes following red clover again as a result of differences in soil fertility. Grain had greater thousand grain weight and larger grain sizes occurring towards the end of the rotation when available nitrogen levels were likely to be lowest. This research shows the ability of legume based rotations to maintain productivity over time but also that rotation design can be used to manipulate grain yield and quality.