Sawdust composts in soil improvement
As indicated in a previous paper 2) the use of wood wastes in soil improvement has received considerable attention lately. Composting seems to offer large possibilities for avoiding the adverse effects of fresh sawdust and to utilize the potentialities of sawdust as a soil builder in the best fashion. The literature on composting of various waste products has been listed and reviewed very comprehensively i n t w 0 recent publications 1). The investigations rePorted here are preliminary tests of methods of composting sawdust and tests of the resulting materials on plant growth in greenhouse pot cultures.
Sawdust composts in soil improvement
The experimental work here reported is a continuation of the pre• liminary tests of methods of sawdust composting reported previouslY 5), Results are given of further pot culture tests with plants in composts mentioned there after longer periods of decomposition. Information also was sought on effects of treatment with highpressure steam on sawdust-manure mixtures and on effects of varying proportions of sawdust to soil on plant growth.
Apparatus for studying water-relations in potted plants
The apparatus here described was developed to obtain information on the flow and distribution of water in soil as effected by the moisture-absorption of plant-roots. It was desired also to obtain information on the operating characteristics of double-walled irrigators which were developed for the purpose of securing automatic control of soil-moisture for potted plants. 
 
Apparatus and experimental procedure—The essential details of the apparatus are snown in Figure 1. The irrigator-pot was suspended from a scale-beam and a pen attached to an extension of the beam was used to give a continuous record of the weight of pot. The 200-pound capacity scale-beam gave a pen-deflection of 0.67 cm for a change of ten grams in weight of pot and chart-errors due to friction-effects were less than one 0.1 cm. Shifting the small weight on the scale-beam provided a convenient means for checking the deflections-sensitivity and for bringing the recording pen back onto the 9-cm range of the disc-chart. The soil-cavity of the pot was 10 inches in diameter at the top and 14 inches deep and the cut-away section i n Figure 1 shows the double-walled construction. Two spouts were provided a t the top of the pot for making water-connections. A glass air-trap was attached to one o f these to provide visual indication that the interwall-cavity remained completely filled with water. The section-view AA shows how the supply-water connection to the other spout was made with flexible tubing on the fulcrum-axis of the scale-beam.