Abstract
The characteristics of the six different agricultural soil from Michigan were as follows. Colwood and Capac soil were loam, Gilford and Ceresco were sandy clay loam, Sission was clay loam, and Spinks was sandy loam. pH of Gilford sandy clay loam was 6.6 whereas that of the soil ranged $5.4{\sim}5.9$. Gilford sandy loam found to contain a relatively higher amount of organic matters as compared to other soils. Furthermore, the numbers of bacteria in Gilford sandy clay loam were significantly higher than those in other soils. The populations of fungi in Gilford sandy clay loam and Colwood loam soils were significantly greater than those in other soils. On the other hand, the densities of actinomycetes in Gilford sandy clay loam and Ceresco sandy clay loam soils were significantly different from those in other soils. The population of anaerobic bacteria varied depending on the soils; Ceresco sandy clay loam, Capac loam, Colwood loam soils have higher numbers of bacteria, whereas Gilford sandy clay loam was very lesser than the other soils. In the $^{14}C-glucose$ respiration by soil microorganisms after 10 hrs, the respiration rate was decreasing in the order of Ceresco sandy clay loam, Spinks sandy loam, Colwood loam, Sission clay loam, Capac loam and Gilford sandy clay loam. Germination of test propagules on natural soil soil was $0{\sim}5%$, and it was germinated $90{\sim}98%$ on autoclaved soil and PDA. The propagules differed in thier germination response to nutrients added to the soils. In general, more nutrients were required to promote germination on Capac loam and Gilford sandy loam soil than Spinks sandy loam soil. Especially Mortierella n. sp. required more nutrients for germination to obtain the same ratio as Helminthosporium victoriae.
공시(供試)한 6개지역(個地域)의 토성(土性)은 Colwood와 Capac이 양질토(良質土)이고 Gilford와 Ceresco는 사질식양토(砂質埴壤土)이며 Sission은 식양토(埴壤土)이고 Spinke는 사질토(砂質土)이었다. 토양산도(土壤酸度)는 Gilfold사질식양토(砂質埴壤土)가 6.6이고 기타는 $5.4{\sim}5.9$의 범위로 나타났으며 유기물함량(有機物含量)은 Gilford토양(土壤)이 제일 많이 함유하고 있었다. 일반세균수(一般細菌數)는 Gilford토양에서는 다른 토양(土壤)에서 보다 통제적으로 많았고 사상균수(絲狀菌數)에서도 Gilford와 Colwood토양(土壤)이 다른 토양보다 통계적으로 더 많았다. 방선균(放線菌)의 밀도(密度)를 보면 Gilford와 Ceresco의 토양(土壤)에서 많았고 혐기성(嫌氣性) 세균(細菌)의 수(數)는 Ceresco, Capac및 Colwood에서 많았으며 번대로 사질식양토(砂質埴壤土)인 Gilford에서는 적었다. $^{14}C-glucose$를 첩가한 토양(土壤)에서의 미생물(微生物)의 호흡량(呼吸量)은 Ceresco, Spinks, Colwood, Sission, Capac 및 Gilford의 순(順)으로 적었다. 공시균주(供試菌株) Helminthosporium victoriae(# 418)와 Mortierella n. sp.에 대한 자연토양(自然土壤), 살균토양(殺菌土壤)및 glucose와 peptone을 농도별(濃度別)(mg/g 토양(土壤))로 첨가한 토양(土壤)에서의 발아율(發芽率)을 보면 자연토양(自然土壤)에서는 $0{\sim}5%$이고 살균토양(殺菌土壤)에서는 $90{\sim}98%$이었다. 토양(土壤)에 첨가(添加)된 영양물(營養物)의 농도(濃度)에 따라 공시균(供試菌)의 발아(發芽)정도는 달랐다. 일반적으로 Capac과 Gilford에서는 Spinks토양(土壤) 보다 발아(發芽)에 필요한 영양물(營養物)을 더 많이 요구(要求)하였으며 특히 Mortierella는 H. victoriae보다 발아(發芽)에 있어서 더 많은 량(量)의 영양물(營養物)을 요구(要求)하였다.