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A Soil Hygrometer for Irrigated Cane Lands of Hawaii 1
Author(s) -
Heck A. Floyd
Publication year - 1934
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1934.00021962002600040003x
Subject(s) - hygrometer , cane , agronomy , agricultural engineering , library science , environmental science , mathematics , computer science , geography , engineering , meteorology , biology , biochemistry , sugar , humidity
The sugar planter in Hawaii is continually beset by the problem of when to irrigate and why. The characters of Hawaiian soils, together with those of the cane plant, make the answer to-this question somewhat uncertain. It has been found that when the moisture content drops to a certain point the cane practically ceases to grow until it receives additional water. The moisture content of the soil at which growth slows up varies with the different soils and also with different varieties of cane. When a soil is saturated with water its affinity for water is satisfied, and under these conditions will show no additional attraction for water. As the free water disappears by drainage and the soil becomes drier, it exhibits an attraction for water in inverse relation to the amount of water which it contains. This is not a straight-line function of the moisture content, but as the soil becomes drier its attraction for water increases much more rapidly than the moisture decreases. It has been found that when this attraction of the soil for moisture reaches a point equivalent to from 25 to 40 cm of mercury, it is difficult for the plant to obtain water sufficiently rapid for active