Mulching effect of plant residues on soybean [Glycine max] growth and soil chemical properties

The objective of this investigation was to analyze the mulching effect of plant residues on soybean growth and soil chemical properties. 1) The decomposition rate of plant residues applied as a mulch on the soil surface was higher in the order of soybean (Glycine max. L.) mugwort (Artemisia princeps P.) black wattle (Acacia mollisima) Japanese plumegrass (Miscanthus sinensis A.). 2) Soybean grew better with than without treatment with plant residue mulch. Moreover,the nodule weight, nitrogen-fixing activity per plant and specific activity (Nitrogen-fixing activity per nodule weight) also increased by mulching with plant residues. 3) Inorganic-N content was lower in the soil mulched with plant residues at 2 weeks after mulching, and it became higher in the mulched soil than in the untreated soil at 10 weeks after mulching. 4) These results indicated that the enhancement of soybean growth by mulching with plant residues was due to the increase of modulation and nitrogen fixation at the early growth stage, and improvement of soil fertility at the later growth stage