Annual plowing is helpful in controlling weeds, but it can also be detrimental to earthworms in the soil. In a now 24-year long-term trial in the dry¬lands of southwest Germany, it was investigated how the intensity of tillage (plow 30 cm deep vs. goose share culti¬vator 15 cm deep) and the implementation of a green manure every 3rd year within the crop rotation (with vs. without) affects earthworm population. The follo¬wing two questions were the main focus: (1) Does the earthworm population suffer over time due to the low humus regene¬ration capacity of the beet-cereal crop rota¬tion with straw removal and without organic fertilization? (2) Can the negative effect of low humus-regeneration capacity be compensated by earthworm-promoting measures such as no plowing and green manuring?
In the 9 years from the first to the second campaign, earthworm biomass decreased by about 30 % (mean across all variants). With one exception, earthworm biomass was always lower in the plowed soil than in the corresponding cultivator variant. For endogeic earthworms, plowing - especially in combination with green manure - was even rather positive. Generally, earthworms benefited more from green manuring than from reduced tillage
