Effect of continuous cropping on autolysis period of darkness seedling test
1996
Hashimoto, T. (Hokkaido National Agricultural Experiment Station, Sapporo (Japan))
To distinguish a microbial flora between continuous cropping soils and rotary cropping soils, an autolysis period of a darkness seedling test was examined. Soil water content was adjusted to 60%. Two surface-sterilized seeds were planted to 20 gram moist soil in sterilized test tubes. The tubes were incubated at 27 degree in darkness. Autolysis of seedling was checked at suitable time intervals. The average autolysis period was calculated from 20 to 40 replicates. Brassica campestris L. var. perviridis (Komatsuna; a kind of chinese Cabbage) or Brassica oleracea L. var. italica Plenck (Broccoli) was used for the darkness seedling test. Eleven-year continuous cropping o9f adzuki bean resulted in a significant shortage of the autolysis period of a soil sample collected on August, but neither those on May nor on October. Soil fumigation significantly deceased microbial population and elongated the autolysis period in a sugar-beat continuous cropping soil. Three-year continuous cropping of Broccoli resulted in shortening significantly the autolysis period and increasing in bacterial, fungal and protozoan populations. Above results suggest that an autolysis period of the darkness seedling test may be helpful to develop a biological soil test
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