温床々土の理化学的性質について

抄録

The composts for raising vegetable seedlings in hot beds are generally prepared by mixing soil, manure, and fertilizers in proper proportion, and leaving them to mature in pile for more than a half year before using. Since we had no standard formu-lar for preparing the composts in relation to the proportion of soil, manure or the amounts of ferti-lizers to be added, the authors intended to know the physical and chemical properties of the exce-llent composts. Twentyfive samples were collected from the gardens raising good vegetable seedlings, and were analysed. The results of analysis showed the following facts.
1. One of the most important factors in rela-tion to the texture and other properties of the com-posts was the organic matter content (loss of ign-ition). The higher the organic matter content, the lower the specific gravity and the apparent specific gravity, and the higher the porosity, mois-ture equivalent, total nitrogen, and exchangeable, capacity (Figures 1-6).
2. The composts for raising cucumber seedlings contained higher levels of organic matter (more than 20 percent in loss of ignition), while the ones for tomatoes contained rather less (12.1_??_18.7 percent). The organic matter contents in the composts for egg-plants were variable, ranging from very low to high (6.5_??_22.8 percent).
3. Hydrogen-ion concentrations of the composts were in the range of pH 5.2_??_8.O, but most of them were in pH 7±1, or nearly neutral in their reaction.
4. Available phosphorous contents were deter-mined by the TRUOG's method and the BRAY's me-thod. The amounts of the available phosphorous found in the samples were in the range of 41 to 1, 110 ppm by the TROUG's method, and 198 to 917 ppm by the BRAY's method.
5. All of the samples except one contained mo-re than 1.0m.e. of exchangeable potassium, and three of them contained more than 10m.e. of it.
6. It was not clear how high of P or K levels were sufficient for the excellent growth of vege-table seedlings, but the amounts in some of the samples, at least, were so high, that they seemed to contain surplus amounts of fertilizers.
7. It was found that fairly large amounts of nitrate and ammonium nitrogen had accumulated in most of the composts tested.