“Single Value” Soil Properties. A Study of the Significance of Certain Soil Constants. IV. A Further Note on the Technique of the “Box” Experiment

One of the previous papers by Coutts(1) in this series has directed attention to the value of the data obtained from what is now generally referred to as the perforated box experiment devised by the present writer and Raczkowski(3). In a further paper Coutts(2) has described an improved and simplified technique, which gives results that are either identical with the old method (pore space) or else related to them by simple linear expressions (water retention; volume expansion or “swelling”). As Coutts’ procedure is now being followed at Rothamsted, and is likely to be taken up by other workers, it appears desirable to record some hitherto unpublished data bearing on the technique of the method, obtained at Rothamsted some years ago by Prof. Ohga (S.M. Educational Institute, Mukden, Manchuria) and dealing with the effect on the results of the degree of packing to which the soil is subjected. The original method, followed by Coutts in its essential details, is to add the soil in small quantities, tapping the box on the bench after each addition, until the box is nearly full, at which stage the filling is completed in the manner described in the original communication.