get out on pasture, the total amount of manure is dropped in the confinement area. Unless properly and carefully handled, the opportunity is excellent for creating a sanitation hazard or an aesthetic nuisance, or both. There is a decided trend toward more and larger confinement-type livestock enterprises. There is also a marked trend toward discounting the fertilizer value of manures and regarding them solely as wastes to be disposed of in the most expeditious manner. Where the animals are housed and allowed to "loaf" on pavements, there is growing practice of "flushing" the pavements with water and handling the manure as a liquid. This method of handling is less disagreeable and often less laborious and costly than shoveling by hand or scraping with a tractor-mounted blade, but it presents problems in disposing of the liquid manure. The practice of allowing the liquid manure to drain to a remote spot behind the barn or in the pasture is not acceptable from a sanitary or aesthetic standpoint in an area that is becoming urbanized, as are many of our formerly rural areas. Subsurface absorption, similar to domestic sewage, has been tried but has two disadvantages. It requires (1) periodic removal of solids from the settling tank, and (2) an absorbent soil, which is not always available. In the arid Southwest, where irrigation is practiced, the liquid manure is sometimes applied to crops to supplement the irrigation water. The A disposal method increasing in favor in many areas is the "lagoon" or "stabilization pond." In this method the flushings are piped to a relatively inconspicuous location and allowed to accumulate in a shallow, open pond, usually referred to as a lagoon (fig. 14). lagoon has been used successfully for a number of years to handle sanitary sewage from rural and small urban communities, but its application to the farmstead for handling liquid manure is recent. It is not an aesthetically appealing type of facility and is often unsightly and odorous. It is also a potential health hazard. In an effort to develop information on improved methods and equipment for disposing of farmstead wastes, the USDA has recently initiated research on a small scale, in cooperation with the University of Maryland, to determine the biochemical oxygen demand (BOD) of the various types of livestock manures and to study the performance of a number of experimental lagoons. A brief report of the project is presented. Studies are in process to develop improved means of disposing of organic farmstead wastes, principally manures. Present effort is being centered on the lagoon or stabilization or oxidation pond. Confinement housing of livestock is leading farmers to remove manure and other wastes from livestock areas by flushing with water rather than by shoveling or scraping. This creates appreciable volumes of water-carried manure, which can create sanitation problems if they are not disposed of satisfactorily. The hazard is particularly acute where metropolitan population centers are expanding into formerly agricultural areas. Lagoons have been used successfully for disposing of sewage from numerous rural communities. Preliminary investigations of the relative BOD of sewage and animal manures indicate the probability that design criteria can be developed for successful manure lagoons. FIGURE 14.-The "manure lagoon" is becoming increasingly popular on the modern livestock farmstead. It is economical and convenient but a potential sanitation and aesthetic hazard if not properly constructed and operated. Lagoons are not usually esthetically appealing and their contents constitute a potential health hazard. Cost figures have not been developed for lagoons, but the chore labor requirement for flushing manure from livestock areas is considerably less than for shoveling or scraping. The volume of liquid manures produced on farmsteads will probably continue to increase and the metropolitan expansion into agricultural areas will probably continue so that the handling problem will become more acute. House heating USE AND APPLICATIONS OF SOLAR ENERGY Hesselschwerdt (16) described a solar collector for space heating in the MIT house, where a 1,200-gallon water storage tank supplied heat during periods of no collection. Floor area of the MIT house was 608 square feet, the collector area was 400 square feet. The collector supplied about 50 percent of the total heat requirement. Efficiency of collection of useful heat averaged about 30 percent and collection temperatures varied from about 100° to 160° F. Within the past few years two modern residences have been constructed in the vicinity of Washington, D.C., each with a large solar collector and storage system. The solar systems have provided nearly complete heating for these houses. Supplementing heat pumps A vinyl fluoride plastic film is being used on a solar collector for storage and to supplement a heat pump being used to heat a rural residence in Kansas. The solar-supplemented system consists of vertical south-facing collectors, a rock bed storage, associated electric controls, and an air-source heat pump. A 14-percent increase in overall heating performance has been observed (fig. 15). Grain drying Grain drying requires large quantities of air at a temperature only slightly above ambient. These are ideal conditions for flat-plate airtransfer solar heat collectors, since their efficiency increases with increase in rate of air movement, while their exit air temperature is reduced. The intermittency and varying intensity of insolation would not be a great problem in grain drying because the drying could be stopped whenever the insolation was below the threshold value for the collector. The collector could be an integral part of the drying bin or could be portable. Chemical dehydration of air for grain drying could be accomplished by using solar heat to reactivate the chemicals. When the air is passed over or through the chemicals, some of its water vapor is absorbed or adsorbed by the chemicals. Heating the saturated chemicals liberates the moisture, which may be vented to the outside air. If two batches of a granular chemical dessicant such as silica gel or activated alumina are used, one batch could be removing moisture while a second batch was being reactivated by heat from a flatplate air-transfer solar heat collector. A solar plastic collector to heat outside air for drying milo in 1,000bushel bins has been used in Kansas. A 45-percent reduction (over natural air drying) in the blower energy required was obtained (fig. |