712 IOWA DEPARTMENT OF AGRICULTURE 



The soils section is now worl^ing on a soil survey of the state and 

 analyses are beitig made of many samples representing typical soil areas. 

 These samples have been obtained with great care by the station men 

 using the most accurate means of sampling, and they are representative 

 of definite soil types. Thus, while it is impossible to analyze all the 

 soils of the state, the composition of representative soil types may be 

 ascertained and the soil areas mapped in detail. From these data and 

 experimental results obtained on the different soil areas information 

 will be available regarding the treatment advisable for any soil, the 

 crops best adapted to it, and the best method of management. 



These facts give all the information which the farmers need. The 

 analyses of the typical soil areas give the approximate composition of 

 their soils and the plant food deficiencies may be as closely determined 

 as would be possible for chemical analysis of special samples. 



In the ease of abnormal soils, however, where no typical analyses 

 are to be found, it may be advisable for the farmer to collect a sample 

 of soil, as will be described, and have an analysis for nitrogen, phos- 

 phorous and potassium, and possibly for calcium and magnesium made 

 by a commercial chemist. 



Using the analysis as a basis, field tests should then be made to 

 obtain definite information regarding the actual influence of different 

 fertilizing materials. 



Collecting Soil Samples. — In the few cases where samples of soil need 

 to be taken, either to be sent to the station for examination or to be 

 analyzed by a commercial chemist, care should be taken that they are 

 representative of the entire field and not peculiar merely to • the spot 

 from which they were taken. 



The places from which the samples are to be obtained need to be 

 carefully cleaned of grass and other vegetation. About twenty or more 

 different spots a few rods apart are chosen, all apparently representative 

 of the soil type, and borings are made to the depth of plowing. These 

 borings may be made by means of a regular soil auger, which is about 

 40 inches long and li/^ inches in diameter, the kind used by the station 

 men, or samples may be taken by means of a trowel or spade. 



The borings or samplings are then thoroughly mixed and placed in a 

 clean receptacle. A strong muslin sack may be used for mailing or ex- 

 pressing a sample of soil for an anaylsis or an inspection. The surface 

 samples are usually taken from the surface to a depth of 62/3 inches. 

 A second and a third sample are then taken in the same manner, one 

 of the subsurface soil 62^ inches to 20 inches, and one of the subsoil 

 20 inches to 40 inches. 



It is quite essential that all samples be taken as suggested, for soil 

 is very apt to be quite variable in composition and the samples should 

 represent definite soil areas. If they are not representative the results 

 of the analyses are of no value whatever. 



SOME TESTS WHICH THE FARMER CAN MAKE. 



From the results of the soil survey of the state, which has been men- 

 tioned, and the experimental data in connection with it, it will be possible 

 to make many definite recommendations regarding profitable methods of 



