Relations between the number of measuring points for soil temperatures beneath film mulch and the mulch effect at the upland field.
1996
Suzuki H. | Ohshima T. | Seo R. | Koesmaryono Y.
Soil temperature effects beneath film mulch at the soybean field were studied in relation to the number of measuring points as regards soil temperature. The soil temperature sensors were of he thermo-junction type, and 10 sensors were buried 10 cm deep in experimental plot. Two mulching materials were mainly used. One was black polyethylen film (0.03 mm thick) with planting holes (7.5 cm dia.), and the other was a transparent one. Experimental plots, 12 in total, were designed by combinating the mulch materials, with plants and without plants. 1) When the multiple regression between the soil temperatures at 10 cm depth, meteorological factors, soil moisture and plant height were examined, the results showed that one point soil temperature was different from that of 10 soil temperatures. 2) Representative soil temperatures in the plots were calculated from the one point measurement for soil temperature to that of 10 points. Among those calculations, most frequencies were almost constant even though the number of measurement points were increased. However, the range of distribution varied. For instance, the range of the 10 points was half the width of that for one point. 3) During the early growing period, horizontal deviations of soil temperatures at 10 cm depths were larger than that of the late growing period. It showed that evaluating the soil temperature among some plots with plants was not so easy.
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