LESSONS ON POTATOES FOE KUKAL SCHOOLS. 15 
tions in connection with potato crops are being carried out and note 
general conditions of fields, crops, and tillage.) 
Correlations. — Correlations in language will be suggested in the 
matter of written or oral reports on field trips and observations made 
in the study of the farm practice of the district in rotations. 
Drawing: The construction of the charts suggested under illus- 
trative material will afford practice in drawing. 
Arithmetic: Problems on yields of potato crops on both rotation 
plan and the continuous cropping plan will be suggested in the study 
of this lesson. 
LESSON VIII. 
Subject, — Soils — kind, preparation, fertilizers, etc. 
Problem. — To study kinds of soils suitable for potato growing, 
their preparation and fertilizing. 
Sources of information. — Farmers' Bulletins 365, 386, and 407; 
bulletins from State college of agriculture. 
Illustrative material.— -Collect soil samples from the potato farms 
of the district; bottle and use in class for comparison. Collect in a 
like manner the various commercial fertilizers used for potatoes. 
Clip and mount pictures from farm papers, circulars, etc., showing 
soil preparation such as plowing, harrowing, applying fertilizers, etc. 
Class exercise. — Characteristics of potato soil: Rich, well culti- 
vated, one that will conserve moisture and retain soluble fertilizer, a 
light sandy loam to be preferred to a heavy retentive soil. While 
excellent crops are frequently grown on heavy clay soils, the lighter 
soils will usually produce smoother, more even potatoes with bright 
skin and eyes of medium depth, and usually mature the crop at an 
earlier date. 
1. Prepartion of the soil: Object of soil preparation — to provide 
for a rather weak root system, correct faults of local soil and climate, 
reduce the tillage after planting as much as possible. 
2. Time of plowing — winter or fall plowing more desirable, espe- 
cially where the soil does not run together and the slope is not steep 
enough to cause washing. This lessens the spring work and some- 
times makes earlier planting possible. 
3. Depth of plowing varies with the soil, usually from 8 to 12 
inches unless subsoil is too> near the surface. 
4. Fertilizers: Object of fertilizing — potatoes require a complete 
fertilizer on most soils. Commercial fertilizers. Rotation. Green 
manuring. What objections to use of barnyard manure? Wlien 
should lime be used? Methods of applying fertilizers to the potato 
crop. 
Practical exercises. — Make a study of the types of soil in which 
potatoes are grown in the district. Which is most common? How 
