The results of the investigation in 1960 in Shinden-bara Fukuoka prefecture were reported in this journal vol. 23, No. 1, 1961. This paper reports about the results of investigation of soil physical and chemical properties and the growth and the yields of wheat in 1961 and 1962.
Most of this region are sticty, brown clay soil. The trouble for root development was caused by the soil compaction. The investigation were carried out to determine the lasting effects of pan-breaking for one or two years after the mechanical treatment. The results are as follows:
(1) The peak value of soil penetration are ranging from 70 to 100kg appears at the depth of 10cm below the surface. The value at the depth of 43cm is comparably low (10 or 20kg). It means the lasting effect by the chisel of pan-breaker.
(2) The layer of compacted soil is distributed at the furrow bottom (depth of 15cm below the surface). By the operation of drill opening, covering, cultivating, and ridging, the compaction increased.
(3) The soil is very hard. The apparent specific gravity at the untreated plot is 1.3 to 1.4, and 1.23 to 1.25 at the treated plot. The maximum value of soil porosity treated by the chisel is 53 percent.
(4) PH value of top soil is 4.3 to 5.7. The rate of organic matter in the soil is 8 percent. The humus is not contained. Therefore, it needs liming and farm manure spreading.
(5) The yield of wheat at the treated plot is 226 to 344kg. The yield was about two times of the rate at the untreated plot. Especially, the wheat above the subsoiling shows better cropping than the others.
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