Variations of horizontal distribution of soil temperature beneath film mulch at different depths [in soybean [Glycine max] and Japanese radish [Raphanus sativus] field]
1997
Larrea, P. (Kagawa Univ., Miki (Japan). Faculty of Agriculture) | Suzuki, H.
Horizontal distributions of soil temperature at different soil depths beneath the mulch film wee studied in relation to the meteorological conditions in soybean field and radish field. Mulching material was black polyethylene film (0.03mm thick) with planting holes (8cm, dia.). Four experimental plots were designed as follows: Co plot was not planted and not mulched, Cp plot was planted and not mulched, Mn plot was not planted and mulched, and Mp plot was planted and mulched. The observation was performed from April to December in 1994. (1) Correlation coefficients between average of 10 soil temperatures and their standard deviations at different soil depths in each plot were calculated. Differences of the coefficient between Co and Cp for soil layers of 0-10 cm did not show an obvious tendency, and other differences between Mn and Mp were small. The correlation coefficient between the average soil temperature and its standard deviation below 20 cm depth became small in all the plots and revealed that the influence of the average soil temperature on their standard deviation was lowered. (2) By 10 soil temperatures measured daily at 6:00 a.m. during experimental period, the soil temperature rising effect of much film became small as the depth of soil increased. On the relation of the vegetation and of daily maximum soil temperature, common tendencies about change of soil temperature were not gained. (3) Soil temperatures at 10 cm depths were compared between 2 plots with a fixed threshold, and the results were the same in comparison with statistical analysis. But the two results gained by the threshold and the statistical analysis did not coincide at other soil depths
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