The writer made these studies with a view to find out reasonable puddling method by mechanical power, and also to define the interrelation between the sizes of harrowed clods and the growth of paddy plants in an ideally builtup soil structure that would give the richest harvest, by making researches into the plant growth in each stage, the statistical samples of harvested crops, the degree of aggregation, and so forth, together with the vicissitude in each of these subjects.
It was disclosed that clayey-loam clods ranging from 0.5cm to 1cm and light-clay clods from 1cm to 2cm give best results, and that the number of aggregations is clearly proportionate to the growth of plants and forthcoming harvest.
It was witnessed that the highest degree of aggregation was brought about during the prime of the growing period, and the lowest during the milky stage. It was also ascertained that the ignition loss and E
h of soil are related to the changes in the degree of aggregation.
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