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No-tillage management is rapidly increasing in many places in the world because of serious soil risks occurring cultivated croplands.However, in most of the no-tillage management, intensive weed control is still a factor of soil degradation.Keeping weeds in cropland will enhance soil biological activities and ecosystem functioning of both above-and below-ground ecosystems.Late Masanobu Fukuoka (the author of One straw revolution) proposed, "natural farming"(no tillage, no chemicals, no wceding), as a sustainable agricultural method.Some Japanese farmers modified his method and are getting excellent harvest with minimum labor.They try to minimize tillage and keep weed all the time, thus weed are controlled by hand cutting to avoid excess competition with crops.We investigated soil fungal (T-RFLP method) and faunal biodiversity (microarthropods and earthworms), soil structure (water stable aggregates) and carbon sequestration at natural farms with different management history and operation years in central part of Japan.Due to the minimum disturbance to soil and a plenty supply of organic matter from weeds (litter and root) increased soil carbon contents was observed in the upper layer of soil.Earthworm casts enhanced water stable aggregates in the soil.Soil biodiversity was higher in the natural farming than conventional tillage: more fungal OTU and earthworm species were found in the natural farming plots.Same relationship was confirmed in experimental plots established recently in two universities.Increase of above ground plant species richness and biomass enhanced soil biodiversity, biomass and soil carbon,and this in turn supported plant growth without addition of fertilizers.Natural succession happening at cropland is well controlled by hand cutting of aboveground part of weeds.From ecological viewpoint, both nutrient cycling and species interactions support relatively good growth of crops with minimum pest attacks.