Determining the phosphorus needs of soils
1923
Truog, E.
The use of the field plot method of determining the phosphorus needs of soils is greatly limited in a region like Wisconsin, because of the great natural variation in the soils and marked differences of treatment given. A less expensive and more rapid method is greatly needed. A step in this direction has been made by devising a rapid method of determining the total phosphorus content of soils. The interpretation of the phosphorus content must be made with great care and judgment. Other factors, namely, climate, kind of soil and subsoil, reaction of soil, crops to be grown and economic conditions must be taken into account. Too little attention has been given to these factors in this connection. The relation of other limiting factors, especially lack of potassium and lime must always be considered. A tentative table, giving minimum percentages of total phosphorus deemed adequate for general farming in Wisconsin under different soil conditions, is given.
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