Effects of soil conditioners on physical properties of soils in relation to the growth of peach seedlings

Abstract

1. Experiment was made in order to know the effects of soil conditioner upon the physical properties of soil in relation to the growth of peach seedlings. 2. The total shoot growth of peach seedlings under broadcast treatment (Aerotil) without deep tillage was superior to the other treatments at the early stage, but the seedlings on the deep tillaged plots applying manure made the most growth at the later season. With respect to the total shoot length at the end of the growth, seedlings on the deep tillaged soil mixed with soil conditioner made far more growth than the control treated with neither cultivation nor soil conditioner application. It is doubtful whether these results are due to the effect of soil conditioner or of deep tillage itself. As for the difference between concentrations of A-22, seedlings applied with the concentration of 0.1% showed more growth than that of 0.01%. 3. After the leaf fall, fresh weights of top and root were measured. Seedlings on the deep tillaged plots applying manure made the best growth and the broadcast treatment without deep tillage was the next. On the other band, seedlings in the control plots made markedly less growth than the other treatments and the difference of trunk cir-cumference was highly significant. Root penetration could not be observed under the soil depth of forty centimeters in the control plots and broadcast plots. Therefore, broadcast treatment without deep tillage is expected to be effective, especially in the case of making seedling stock during only one year, but it is doubtful if this effect continues thereafter. 4. The soil class of the experimental field is loam and the total pore space and air capacity of the subsoil layer was about 50% and 3% respectively. Deep extension of the root was almost impossible under these conditions, therefore the later effect of deep tillage will be considerably great. Total pore space of the plots treated with 0.1% A-22 are appeared to be slightly more than the others, but the differences between the various treatments deeply tillaged is insignificant. There was no definite difference between different treat-ments about the soil moisture and soil aggregation. For the practical use, considering both price and effect, it will be concluded that the soil conditioner application is not a very profitable method for orchard soil improvement. However, as mentioned above, the soil conditioners will be effective and profitable when they are applied on the soil surface of nursery field to prevent the crust formation on the surface soil.