With non-inversion tillage, the soil is not ploughed, but only loosened. This has a positive effect on soil life: there habitat is not disrupted every year. A stable soil life ensures a good soil structure and better soil fertility, which leads to an airy soil and increases the water retention. Therefor the soil can absorb more water in wet periods and this water is longer available in dry periods.
Interesting links:
Project Leve(n) de bodem (Dutch)
Fuel Consumption calculator (German)
Publication about soil fertility (German)
Machinery for non-inversion tillage (English)
Different methods in reduced tillage (Greenotec) (French)