UNIVERSITY OF CALIFORNIA 
 
 COLLEGE OF AGRICULTURE 
 
 AGRICULTURAL EXPERIMENT STATION 
 
 BERKELEY, CALIFORNIA 
 
 CIRCULAR 306 
 
 May, 192G 
 
 A GENERAL PURPOSE SOIL AUGER 
 AND ITS USE ON THE FARM 
 
 STANLEY W. COSBY 
 
 In any investigation of the soil, particularly one concerned with 
 the production of crops, it is highly important to examine the subsoil 
 zones in which root development occurs and to determine the presence 
 of conditions favorable or unfavorable for plant growth. For such 
 an examination it has been found most desirable to make use of some 
 soil sampling tool (such as the one described herein) that is effective 
 for the purpose, readily used, and easily transported. 
 
 TYPES OF SOIL AUGERS 
 
 Several types of soil sampling tools have been designed, among 
 the more important being the "worm" augers, "post-hole" augers, 
 and the "soil tubes." Each of these tools appears best suited for some 
 specific purpose. The soil tube is used primarily by the scientist and 
 investigator who must have accurate and uncontaminated soil samples 
 for laboratory study, while the post-hole auger has been found best 
 suited to sampling certain of the very dry and coarse soils. The worm 
 auger (fig. 1) has proved under a wide range of field conditions 
 to be the best general purpose auger and one that is particularly 
 suited to the farmer's use. In soil survey work by the federal and 
 state governments this auger is used almost exclusively and it has 
 become known as the ' ' Bureau of Soils ' ' type of auger. 
 
 This auger is being offered for sale at the present time by several 
 manufacturers at prices ranging between seven and twelve dollars. 
 A blacksmith, or anyone handy with tools, can make such an auger 
 from the directions given below. 
 
DIRECTIONS FOR MAKING A SOIL AUGER 
 
 /"PiPE 
 
 \ 
 
 ■Bit 
 
 -Weld 
 
 A" Pod 
 
 The side cutting edges and the screw point (A and B in fig. 2) are 
 removed from a li/o-inch carpenter's standard wood bit and the pitch 
 of the worm, between C and D in figure 2, is made slightly steeper. 
 In making the latter change the bit is heated and drawn out on the 
 round point of the anvil, a process that tends to make it somewhat 
 fish-tailed in shape (fig. 3). Finishing touches 
 can be given with a file. 
 
 The square-tapered, upper end of the bit is 
 then removed and the shank welded to a six-foot 
 length of % or %-inch steel rod. The handle at 
 the top is best made by attaching two 6-inch 
 pieces of 1-inch pipe to the rod with an ordinary 
 Tee-coupling. 
 
 The auger may be made in two or more sec- 
 tions for greater convenience in carrying it from 
 one place to another by putting in a sleeve- 
 coupling at each joint, as shown in figure 1. This 
 coupling should be strong; the hexagonal wind- 
 mill pump rod connection has been found most 
 satisfactory for this purpose. A short section 
 near the ends of each rod may be slightly flat- 
 Aero motor tened to make it easier to grip with the wrench 
 "i* iSleevi when uncoupling the auger. The threading on 
 the ends of the sections should extend for a 
 sufficient distance to permit jamming the ends 
 together within the coupling. When the auger 
 is thus screwed tightly together it will withstand 
 considerable strain in "backing-out" without 
 uncoupling. It is not advisable to drill a hole 
 through the coupling and the rod for a rivet or 
 pin, as it weakens the rod and is unnecessary if 
 the auger is properly made. 
 
 HOW TO USE A SOIL AUGER 
 
 In boring a hole with this type of auger, the 
 
 surface trash and loose soil should be removed 
 
 to prevent it from falling into the hole. Twist 
 
 the auger vertically downward about six inches, 
 
 place the feet close to the auger on each side 
 
 and pull straight upward, at the same time 
 
 giving the auger a quarter turn to the right to 
 
 break free the core of soil. To remove the soil 
 
 from the auger, hold it near the point of 
 
 COC/PUNG 
 
 r "Pod 
 
 Tee 
 /Coupling 
 
 ^m 
 
 f/6. J. /fssen^c/ 
 
balance with the right hand, place the thumb and first finger of the 
 left hand at the tip of the bit and twist the entire anger with the 
 right hand. This will canse the bit to turn through the fingers and 
 drop the soil into the left hand. In particularly dry soils it may be 
 necessary to pour a small amount of water into the hole to moisten 
 the soil and permit the ready removal of the sample. Do not twist 
 the auger too deeply before removal, as in heavy soils it may prove 
 impossible to pull out a deep core. In very tough soils better progress 
 can be made by boring in a half turn of the auger, pulling this up an 
 inch or two to cut it loose, then boring in again, thus filling the worm 
 with soil without having to break it all loose with one effort. 
 
 /="/<£ 2 - WOOD BIT 
 
 F/6. 3 - SOIL BIT 
 
 SOME FARM USES FOR THE SOIL AUGER 
 
 The soil auger is adapted to a great many uses on the farm. These 
 range from a detailed inspection of land Avhich the farmer contem- 
 plates purchasing or a study of soil conditions for the laying out of 
 his fields and orchards, to the acquisition of soil knowledge on which 
 to base his various cultural methods and irrigation practices. 
 
 Although the surface of the soil may have a uniform appearance, 
 the subsoil frequently shows marked variation within short distances, 
 either in a vertical or horizontal direction. This is particularly true 
 in the case of our stream-laid soils. In the more recent depositions the 
 vagaries of the depositing streams have produced numerous strips and 
 bodies of soil having wide textural differences ; a very heavy clay sub- 
 soil strata may adjoin a coarse sandy or gravelly remnant of a former 
 channel which has been covered by later depositions. In our old 
 alluvial soils, marked changes in subsoil textures are not so abrupt 
 
in a horizontal plane as they are in a vertical direction, the initial 
 differences due to deposition having* been largely obscured by later 
 modifications due to weathering. Generally this period of modification 
 has produced a much heavier-textured subsoil, one that may be very 
 compact and relatively impervious to the penetration of moisture and 
 plant roots. The more extreme developments of these processes have 
 resulted in the formation of the hard cemented subsoil zone, com- 
 monly known as "hardpan." The various subsoil conditions are 
 seldom apparent from surface indications and yet their presence has 
 a profound influence on the production of crops. 
 
 In purchasing a farm, the intelligent buyer will endeavor to secure 
 extensive information concerning it and to evaluate this in terms of 
 crop-profits. The most reliable and economical method of securing 
 information regarding the soils consists of a systematic series of 
 borings over the entire property in order to determine the soil and 
 subsoil characteristics. Such borings will show the soil variations and 
 may be used subsequently in the construction of a map, or lay-out, 
 to determine the location of the different crops to be planted. This 
 will lead to the crops being situated on those soils which are best 
 suited to their production. 
 
 On a farm which has already been developed, the soil auger is a 
 valuable aid in cultural practices, particularly in the case of irri- 
 gation. By a study of the moisture conditions both before and after 
 irrigation, information can be secured to determine the time of 
 application of water and the most desirable method to follow. The 
 farmer can ascertain the depths to which the water is penetrating and 
 avoid the undesirable features of too shallow or of too deep a distri- 
 bution, making the application according to the root-depths of his 
 crop. He can vary his applications in different parts of his orchard, 
 or field, according to the local soil variations. By a frequent obser- 
 vation of the moisture in his soil, he can maintain it more nearly at 
 the desirable point than by judging from surface indications, or by 
 a rule-of-thumb schedule. 
 
 Over-wet soils, high water tables, and the need for artificial 
 drainage can be readily determined with this tool. Many other uses 
 might be suggested, such as studying small areas where failure of 
 crops may be due to some previously undiscovered subsoil condition 
 or moisture variation, or determining the proper location for various 
 farm structures, wells, pits, and other excavations. 
 
 This type of soil auger is light, easily carried, and rapid and easy 
 in operation, features that are essential if the tool is to be used as 
 extensively and continuously as is necessary in controlling irrigation 
 and interpreting crop responses to soil conditions.