idea of supplying field crop laboratory material which had formerly been carried on by the 

 Department of Agronomy of the University of Nebraska. Without the use of ideas from these 

 two sources, the work as presented in this manual could scarcely have been possible. 



Most of the laboratory exercises presented in this manual have passed through several 

 mimeographed editions, and have been used in one or more of the following Nebraska 

 schools: Teachers' College High School, Lincoln; School of Agriculture, Lincoln; School 

 of Agriculture, Curtis. 



Laboratory instruction as here outlined is designed to accompany classroom instruction. 

 A division of time that will probably fit most schools is as follows: 



(1) Classroom Work— Three single periods per week. 



(2) Laboratory Work — Two double periods per week. 



The exercises should afford ample laboratory work for a period of at least thirty-six 

 weeks. Should the instructor desire to give but eighteen weeks to laboratory study, he will 

 be aided in his choice of work by the asterisks preceding names of exercises given in the 

 table of contents. The instructor will observe that the manual is divided into exercises 

 according to subject matter, rather than the time allowed for a laboratory period. Some of 

 these exercises will require at least two laboratory periods, a few, less than one. 



In order to give the student some aid in preparing a brief record of work covered in 

 the laboratory, the authors have indicated by the use of Arabic numerals and small letters 

 those parts calling for diagrams, drawings, or written record. A few exceptions to this rule 

 will be found where blank forms are given as an aid in assembling and recording a variety 

 of related data. 



In the appendix will be found a list of laboratory supplies for the complete course based 

 upon the needs of a laboratory section of twelve students. The name and quantity of each 

 supply is accompanied by the approximate price. The use of laboratory supplies as suggested 

 in the appendix does not preclude the use of material which may be secured locally. In fact, 

 the use of the supplies called for in the manual should, by establishing a sort of scale, make 

 local material more useful than would otherwise be the case. For example, the study of the 

 various samples of wheat from different parts of the United States should give the student a 

 broad, general idea as to the effect of rainfall, evaporation, temperature, length of growing sea- 

 son, etc., upon wheat. With this general idea clearly realized, the student should have a much 

 better comprehension of the wheat in his own locality than could possibly result from a study 

 of local wheat alone. The same is true of corn and other important field crops. Again in the 

 case of soils, if the student is to gain a fair idea of the effect of texture upon the physical 

 properties of soil, he must have some carefully chosen materials to serve as standards for 

 study. It is not an easy matter for the average teacher to select and prepare good sam- 

 ples of sand, silt and clay for laboratory use. With a small supply of standardized material, 

 secured from a reliable source, he may make a more accurate study of soil texture in his 

 own locality than would be possible with material chosen and prepared at random. The 

 same is quite true in the study of humus content, acidity and alkalinity of soils. 



Realizing their own limitations and appreciating the fact that this is one of the first at- 

 tempts to organize laboratory exercises and supplies in general agriculture, the authors feel 

 that the work leaves much to be desired and will greatly appreciate suggestions and criti- 

 cisms from teachers and scientists who see possibilities of improvement. 



For help received in preparing these exercises the authors feel under obligations to 

 Prof. N. A. Bengston, Dr. R. J. Pool and Prof. S. B. Gass, of the University of Nebraska, 

 and Supt. C. V. Williams and Prof. E. Rail, of the University of Nebraska School of Agri- 

 culture at Curtis. Other acknowledgments accompany lesson material and photographs in 

 place. 



E. H. 

 Lincoln, Nebr., July, 1914. R. R. S. 



