Catch crop root formation and its impact on nutrient carry-over in agricultural systems

Diana Heuermann, Dagmar Böhmert

Catch crops are fast-growing species cultivated between two main crops. Amongst other positive impacts on the agricultural system, e.g. reduction of soil erosion, increase of soil organic matter, pest and weed control, the inclusion of catch crops in a crop rotation aims at reducing nutrient losses via their incorporation into their biomass and at carrying over scavenged nutrients to the following crop.

As the nuturient uptake efficiency of a species depends to a large extent on its root system architecture we study the vertical root biomass distribution of different species (white mustard, phacelia, bristle oat and Egyptian clover) at two experimental sites in Germany. Thereby we tackle also the question if a mixed cutivation leads to the occupation of distinct vertical niches via a qPCR-based root biomass quantification method using species-specific primers. So far, fast -developing species, which build the largest root and shoot biomass in pure stands, repressed the biomass formation of slower-developing catch crops and were even able to increase their per capita root biomass in mixed stands. The root biomass pool of the mix has thus a high relevance for nutrient capture by catch crops. Current experiments investigate the impact of neighbouring species and of soil nutrient pools on root system architecture in different field-grown catch crop species.