Autor:innen:
Henrik Füllgrabe | Biogeochemistry of Agroecosystems, Georg-August-University Göttingen, Göttingen, Germany | Germany
Tobias Stürzebecher | Biogeochemistry of Agroecosystems, Georg-August-University Göttingen, Göttingen, Germany
Sandra Spielvogel | Soil Science, Christian-Albrechts-University Kiel, Kiel, Germany
Iris Zimmermann | Soil Science, Christian-Albrechts-University Kiel, Kiel, Germany
Yijie Shi | Soil Science, Christian-Albrechts-University Kiel, Kiel, Germany
Katja Holzhauser | Institute of Crop Science and Plant Breeding, Christian-Albrechts-University Kiel, Germany
Debjyoti Ghosh | Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research, Halle, Germany
Callum C. Banfield | Geo-Biosphere Interactions, Eberhard-Karls-University Tübingen, Tübingen, Germany
Michaela A. Dippold | Geo-Biosphere Interactions, Eberhard-Karls-University Tübingen, Tübingen, Germany
In intensive farming systems, most of the nutrient uptake by plants occurs from the topsoil. If the topsoil dries out due to more variable rainfall events and more frequent droughts as consequence of climate change, subsoil nutrient resources may be essential for future plant nutrition. In the RootWayS project, cover crop mixtures from deep rooting species together with shallow rooting partners from three different functional plant groups (clover, grass and brassica) were tested to enhance the root growth of maize into the subsoil, via re-use of root channels. The field experiment was located on a loamy Luvisol in Northern Germany. The aim of this study is to determine the amount of nutrient uptake of maize from the topsoil (0 – 30 cm), upper subsoil (30 – 60 cm) and lower subsoil (60 – 90 cm). Therefore, a pipe-in-tube injection system for nutrient tracers (15N-NH4+/15N-NO3-, Sr, Rb and Cs) was used. The total maize-uptake of N was 14% to 33% of the applied N tracer, with the lowest amount in the control, and the highest amount after the grass/brassica mixture. This suggests that winter cover crops generally enhance the efficiency of mineral N uptake in the following maize cropping season. Moreover, we observed a significant larger nutrient tracer uptake from the subsoil (30-90 cm depth) for maize grown after mixture 1 (red clover, white clover, tall fescue, ryegrass) and mixture 3 (oil radish, summer rapeseed, tall fescue, ryegrass) compared to maize grown on the control plots. In relation to the total tracer uptake from all three depths, maize grown after the clover/grass mixture (22% for N, 43% for K and 45% for Ca, respectively) and maize grown after the grass/brassica mixture (31% for N, 45% for K and 44% for Ca) achieved the highest uptake percentages from 30 – 90 cm depth. We conclude that the efficient soil exploration by roots of cover crop mixtures supports maize roots in reaching the subsoil and thus promotes the subsoil nutrient uptake of the main crop maize. Particularly, cover crop mixtures containing Poaceae seem to have a beneficial effect on subsoil nutrient uptake. We conclude that the observed better subsoil nutrient access of maize after cover crop mixtures containing Poaceae is either an effect of root channel re-use by primary and seminal maize roots, or an indirect effect arising from Poaceae root exudates and degradation intermediates diffusing into the soil and increasing subsoil nutrient availability.