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.
LIMITATIONS OF AUTO-IRRIGATORS FOR CONTROLLING SOIL MOISTURE UNDER GROWING PLANTS.
An accurate, convenient method for controlling soil moisture under growing planits would be of obvious advantage to the experimenter attempting to grow plants under uniform conditions, as well as to the physiologist who may wish to study the effect of varyiing soil moisture on plant development. Since the time of the original suggestioin by LIVINGSTON in 1908 (3), various forms of auto-irrigators have been proposed for this purpose. Porous clay cones were later developed by LIVINGSTON (4) to overcome difficulties ascribed to poor contact between the soil and the porous water-supplying surface of the early cylindrical cups. LIVINGSTON, HEMMI and WnSON (5) used tenisions up to 40 cm. of mercury and state, "The moisture conditions of the soil are now among the environmental conditions most susceptible of control and satisfactory measurement." Tensions of 60 to 65 cm. of mercury, equivalent to 8 or 9 meters of water, were considered to be maximum for satisfactory irrigator performance. HENDRICKSON an1d VEIHMEYER (1), with an unstated water supply tensionl, were unable to mainitain uniform moisture distribution with irrigator cones, but found a layer of moist soil near the irrigator surface filled with absorbiing roots. Uinder such conditions growth of plants might easily give indications of controlled low soil moisture which actually were only responses to a restricted rooting zone. A substantial imiprovement in apparatus design was made with the development of double-walled irrigator pots by KORNEFF (2), RICHARDS (6), WILSON (14) and RICHARDS and BLOOD (7). Compared with porous irrigator cylinders or cones, these units maintain a larger fraction of the soil mass in proximity to and in good contact with the irrigator surface. WIGGIN (11, 12) has published results from a study of double-walled irrigators from the samiie source as those described by WISON (14). He states that, "Soils can be held at an approximately constant percentage of soil moisture anywhere within a range from below the wilting point for plants to a condition of soil saturation." His data, however, hardly justify this conclusion for he reports, " The greatest difference found between the water content of the soil in the outside layer and the center of the pot was 4.2 per cent.; the greatest difference between the top and bottom layers of soil, 5.1 per cent. The variation in the water content of the soil . . . is therefore
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.