Exercises in soils and fertilizers for vocational agricultural schools, no. 7 [1919]

EXERCISES
IN
SOILS AND FERTILIZERS
FOR
VOCATIONAL AGRICULTURAL SCHOOLS + No.7
Agricultural Educational Series No.3 +
PUBLISHED BY THE
STATE VOCATIONAL BOARD
ATLANTA, GA.
M. L. BRITTAIN. EXECUTIVE

EXERCISES
IN
SOILS AND FERTILIZERS
FOR
VOCATIONAL AGRICULTURAL SCHOOLS
..
No.7
Agricultural Educational Series No.3
PUBLISHED BY THE
STATE VOCATIONAL BOARD
ATLANTA, GA.
M. L. BRITTAIN, EXECUTIVE

FOREWORD.
By the provisions of the National Vocational Education Law, enacted February 23, 1917, the State Boards are charged with the duty of approving METHODS OF INSTRUCTION in schools of secondary grade. This bulletin, therefore, on Exercises in Soils and Fertilizers is the third of several bulletins on instructional problems which the State Board proposes to issue in the near future.
The exercises suggested in this bulletin have been prepared by request by John T. Wheeler, Professor of Agricultural Education at the State College of Agriculture. Mr. Wheeler has been assisted by other members of the Department of Agricultural Education and faculty of the State College of Agriculture.
R. D. MALTBY, State Supe1'visor.
2

INTRODUCTION.
The exercises contained in this bulletin have been brought together in this form to meet the demands of the teachers of secondary agriculture in this State. These exercises, are prepared to meet the demands of some of our teachers in service.
This bulletin is not intended in any way to serve as a manual for secondary pupils. Its only purpose is to serve as a guide to those teachers who need some direction in developing class and laboratory exercises in Agriculture.
In outlining these exercises, suggested lesson topics, materials, apparatus, and some references have been included. The lessons follow very closely those suggested by the Georgia State Vocational Board in the State Course of Study, and the references noted under each lesson are to text and reference books which are already in most of the schools. At the end of this bulletin a more complete group of reference books is given, and the teacher is urged to obtain as many of these references as possible to supplement the references in each lesson and exercise.
A list of materials and apparatus for carrying out the exercises of the first years work will also be found following the list of reference books.
3

TO THE TEACHER
The teacher is warned against blindly following the order of these lessons, and attempting to do all of the exercises herein suggested. The teacher is also warned against accepting these exercises as a final word as to what he should do or have his pupils do. These exercises simply suggest the type and kind of activity in which pupils should be engaged. The teacher will also need to keep clearly in mind the capacity of his pupils and the seasonableness of the material presented in order that these suggested exercises may be of the greatest help to him.
Do not attempt to hurry the pupils over the work. Be sure that they have clearly in mind the problem or problems involved in the exercise before they attempt it. When an exercise is completed, be sure that each pupil has the right idea, that he understands the underlying principle, and that he sees the application of the principle to agricultural practice. Caution is particularly necessary in regard to exercises that take several days or a month before conclusions can be drawn. When an exercise of this kind is completed, the teacher should again raise the problem in the minds of the pupils. He should carefully go with them over the procedure and data, and bring them to a point where they can grasp the whole situation, get the right idea, draw some conclusions and make the applications.
The principles discovered or emphasized by these exercises, together with definite conclusions, and applications should serve both as a basis for the pupil's permanent notes and for his further reading and study.
4

EXERCISES WITH SOIL
LESSON XXV.
Soil Formation
References: Soils and Fertilizers, Lyon; Elements of Agriculture, Warren, Chapter V.
EXERCISE 44. To study soil formation and gather soil samples in a given locality.
Materials needed: Soil auger, knife, rock samples, (shale, limestone or marble, quartz, sandstone and granite), water and hydrochloric acid.
Procedure: (a) With the soil auger examine the top and sub-soil at various places; note the difference in texture and color, show how the soils in a given spot are probably formed. Explain what agencies have been at work in forming this soil; classify the soils studied according to formation, sedentary or transported.
(b) From a study of the pebbles and stones along streams, and those found on upland fields, note the effects of running water. Make a collection.
(c) Visit a field that is poorly terraced or one that has badly washed places, note how the water has carried away the loose top soil and is now wearing into the hard sub-soil. Note where the coarser portions of this soil has been deposited. Where are the finer portions?
(d) Find some exposed rocks or boulders and note the effect of weathering upon them. You should be able to find places where the rock is being rapidly transformed into soil.
5

(e) Compare top and sub-soil of hillside and bottoms in texture, color, fertility, etc.
(f) Point out and demonstrate the relation between rock composition and soil composition in regard to physical and chemical composition. If all the soil were removed from the surface of the earth, how long would it take to replace it by weathering?
(g) Make a study of the rock particles found along a local stream and of the laboratory collection to discover their composition and physical characters. The pupil should be able to readily name the several rock formations. Their composition, color, hardness, solubility (in water and hydrochloric acid) and the nature of the soil formed from each should be carefully studied and noted.

EXERCISE 45. To take soil samples for mechanical and chemical analysis.

MateTials needed: Soil auger, spade, dozen or more pint fruit jars or other soil containers, labels, a piece of strong new muslin or oil cloth 10 inches square, pocket rule.

PTocedure : Clean all of the vegetable growth from the spot where the sample is to be taken; spade a hole into the soil to determine the depth of the surface layer: with the spade make slices of even thickness at all points, place one or more of these slices on the cloth and examine; note color, texture, etc.; place in a jar and label "Surface Soil No.1". Clean away the surface soil and bore into the sub-soil to a depth of 20 or 24 inches, examine as before and place in a jar and label "Sub-soil No.1". The next sample will be numbered 2, etc.

Samples should be made in this way of as many of the soil classes and types as the community affords. These samples must be carefully labeled and kept for the next laboratory exercise.

The pupil should keep records on the following points:

I

1---

Texture

No. Sample

Where obtained

1 Color
I I I I

1 Coarse
I I I I

Fine

I Medium
I I I 1

6

LESSON XXVI.
Physical Characteristics of Soils
References: Soils and Fertilizers, Lyon, Chap IV., and exercises.
EXERCISE 46. Examination of physical character of soils.
Materials needed: Each pupil should be provided with two 250 c. c. beakers; six 500 c. c. beakers or pint fruit jars; a stirring rod; and soils-one fine and one coarse.
Procedure: (a) Put 175 c. c. of water in each of the 250 c. c. beakers; place a label on each beaker so that the top edge of the label is at the surface of the water; on these labels number the beakers "one" and "two". Put 350 c. c. of water into the six larger beakers or fruit jars and label as above, numbering them "three", "four", "five", "six", "seven", and "eight" respectively.
Take 15 gram portions of the soils to be studied. The samples should be air-dry, and of widely different texture-one coarse sandy soil and one a fine loam or clay soil. These samples should be placed in a beaker and treated over night in about 75 c. c. of water and 5 c. c. of strong ammonium water. This is done to break the soil lumps up into their natural soil structure. This solution should be stirred several times before using.
(b) When ready to proceed, stir the soil solutions for several minutes and treat each sample as follows:
Wash the soil solution into the 250 c. c. beaker "number 1"; fill to the 175 c. c. mark; stir briskly for three minutes; let stand for thirty seconds, then pou:r. into beaker "number 2", being careful not to transfer the sediment. Now, fill both beakers, "No. I" and "No.2", to the mark; stir for three minutes, and then let stand for thirty seconds; pour the liquid from "Nos. 1 and 2" into "No.3" ; fill these three beakers to the mark, stir, let stand thirty seconds and pour liquid from "Nos. 1 and 2" into beaker "No.4", and from "No.3" to "No.5". Fill "Nos. 3, 4 and 5" to the mark, stir, let stand thirty seconds, and pour into beakers "Nos. 6, 7 and 8".
7

Dry the sediment in all the beakers except Nos. 6, 7 and 8, by placing them over a low gas flame. Transfer the sediment from "No.2" into "No.1". This coarse material represents the sand of the soil sample. Place the sediment of "Nos. 3, 4 and 5" together. This represents the silty portion of the soil sample. The clay is in the beakers "Nos. 6, 7 and 8". Much of the clay remains in suspension in the water, and cannot, therefore, be dried and handled. However, the suspension should be poured off, and some of the sediment dried for handling.
Weigh the dry sand and silt portions in dishes of known weight. Determine the weight of clay by subtracting from the total weight of the sample the sum of the weights of the sand and silt.
Study these three sizes of soil particles, noting how the amounts of each differ in different soils. Note carefully the nature of clay as shown in the water suspensions. Keep some suspensions for a day or so and note whether or not they clear. (See exercise 77, 2-c.)
2. (a) While the above work is being done, a moisture determination should be made as follows: Weigh out two 10 gram samples of air-dry soil, one each of surface and sub-soil from the samples used in the above exercise; place it in dishes of known weight; heat over burner at about the boiling tep1perature for an hour; weigh; continue to heat until the weight becomes constant. The loss in weight is due to a loss of water. Find the loss in terms of tp.e percentage of original weight. Which loses the greater amount of water, the surface or the sub-soil? Explain.
(b) Continue to heat these samples of surface and sub-soil until they become red-hot and look like ashes; cool and weigh again. To what is this further loss due? Does the surface or sub-soil lose most?
(c) Examine some grains of the soil samples you are studying under a hand' lens. Place a small amount of dry soil from your sample upon a slide, moisten with a drop or two of water and examine under the microscope. Note the color, size, and
8

shape of the grains. The dark colored materials clinging to the soil particles is organic matter. Can you see in this exarninatibn that soil particles are held together by organic substances?

(d) Bring together the data gotten above and classify the soils as follows:

Sample Number

Percentage Loss of
I. W a t e r

I Loss Due to Organic I I I I Matter

ClassifiSa~d Weight We~ght cation of

WeIght Clay

Sllt SampIe

I
_ _ _- +I
I

I

I

1

---:_

I

I

i

Point out correlation between size of partiCles ahd amouht of water found in air-dry soils; color and amount of organic matter in different soils and in surface and sub-soils; compare surface and sub-soil as to the amount of clay, etc.

LESSON XXVII.
Classification of Local Soils
References: Soils and Fertilizers, Lyon, Chapter IV; Elements of Agriculture, Warren, PP. 76-84.
EXERCISE 47. To study and classify soils in the field.
Materials Needed: Soil auger, cloth for examining samples.
Procedure: From this study pupils should become familiar with the principal classes (and types) of soils in a given community and be able to recognize them. The teacher will, therefore, have to know in advance where this trip can best be made so that the pupil will come upon the common local classes of soils. If possible sandy soils, sandy loams, clay, clay loams or sandy clay loam, peat, sub-soils, etc., should be studied with reference to the following points:
9

1. Color (when wet and ..when dry). 2. Feel-gritty or smooth. 3. Size of particles-coarse, medium, fine, 4. Moist-crumbles or single grain. 5. Wet-sticky, very sticky, crumbly. Now classify, as "sandy clay loam"; or, if you are considering the type: "plainfield sandy clay loam", etc.
LESSON XXVIII.
Local Soil Map
References: Soils and Fertilizers,. Lyon, pp. 43-45; State Geological Survey Maps and County Soil Maps when available.
EXERCISE 48. A study of soil maps and reports.
Materials Needed: Soil survey reports in the form of maps of various counties are prepared by the Bureau of Soils U. S. D. A. in co-operation with the Georgia State College of Agriculture. These maps may be obtained from the College, or from the Congressman of your District or from your U. S. Senator. A State geological map should be provided. The State geological maps can be had for five cents each from S. W. McCallie, State Geologist, Atlanta, Georgia.
Procedure: Each student will make a study of the soil map of his own county or of some nearby county. A county soil map ~hould be procured and the following points noted:
(a) Formation: Locate your county on the State geological map. What is the formation of the land in that area? What is the nature of the rock formation of the county?
(b) Topography: Be able to describe the outstanding topographical features of the county assigned. If your map has contour lines, what contour interval is used?
(c) Industry and Transportation: What are the principal industries in the county? What railroads cross the county? Are the wagon roads good?
10

(d) Soils: How many types of soil are in the county? Classify the types in your immediate neighborhood as follows:

,-------,----------,---------,--- ------~-----

Soil Type

Class

Series

Origin

LESSON XXIX.
Relation of Soil Texture to Soil Structure
References: Soils and Fertilizers, Lyon, pp. 37-43 and exer~ cises.
EXERCISE 49. To show the effect of puddling on soils, and the results of working land too wet.
Materials Needed: Dry clay soil, some pie tins or shallow tight wooden boxes.
Procedure: (a) Put equal amounts of the same kind of soil in each of two tins; wet the soil in one tin until it is well moistened but not puddled; to the other dish add enough water to make the soil sticky, then stir into a paste; set both in the sun until dry, note the results. Explain. How does puddling injure soils?
(b) Take three other tins; place clay in one, sand in another, a loam soil in the third; put enough water on the clay soil to make it sticky, add the same amount of water to the other soils; stir all briskly, and set in the sun to dry. Note results. How does working soil when it is too wet affect its texture? May some classes of soils be worked sooner after a rain than others? To what is this due?
EXERCISE 50. To show how soil that has a tendency to puddle may be aided by proper handling.
11

Materials Needed: (a) Clay soil, air-slaked lime, very fine barnyard manure, large pie tins, 4-inch flower pots or quart tin cans.
Procedure: Place equal amounts of the same kirid of soil in each of three tins; wet all with equal amounts of water until sticky; stir into the soil in the first tin 5 tablespoonfuls of lime; stir into the soil in the second tin two handfuls of fine manure; stir the soil in the third tin but do not put anything into the soil; set in sun to dry. WhE:!n dry exathin~ and crumble in the hand. Which is the hardest? Which breaks up most easily? What is the effect of lime ori clay soil? Does manure keep the soil in better physical condition. Explain.
(b) Take some more of the same soil as used in (a) part of this exercise and fill three flower pots three-fourths full; add to the first pot a good handful of fine barnyard manure and mix well; add to the second pot 6 tablespoonfuls of lime and mix well; do not put anything in the soil of the third pot; add equal amounts of water to each pot and treat each pot the same until the third pot becomes very sticky by stirring; set in the sun to dry. Which soil is the hardest? Explain the effects of lime and manure oil the tilth of soils; May soils having planty of organic matter be worked sooner after a rain than soils low in organic matter? Can sod land be plowed earlier in the spring than stubble land? Why? What effects has lime on clay soil?
LESSON XXX.
Capillary Water in Soils
References: Soils and Fertilizers, Lyon, PP. 61-66.
EXERCISE 51. To observe the capillary rise of water in different soils.
Materials Needed: Six soil tubes at least 30 inches long and rack for holding, cheese cloth, and the following soils: coarse sand, very fine sand, sandy loam, clay loam, muck, peat; threefoot ruler.
12

Procedure: First, tie cheese cloth over bottom of tubes; fill the tubes with the several soils to within two inches of the top (compacting after each 10 inches of soil has been added by dropping two inches on a book) and place them in the rack; if each tube has a separate pan, all pans should be filled with water at the same time and kept at the same level.
Each pupil should record his observations as follows:

Kind of Soil Coarse Sand

1 1-- 5 Min.
I
II

Height of Water

1 20 Min. I 1 hour I 2 hours . I 24 hours

1

--I-

1 I

-

-

-

-

-

-

-

-

-

-

-

-

I
!

-

-

-

Fine Sand

I

1

I

1

Sandy Loam, etc. I

I

I

Which soil takes up water at the most rapid rate, the fine or coarse? Which soil is able to raise water to the greatest height?

EXERCISE 52. To demonstrate the amount of capillary water that is held by different soils.
Materials Needed: Some short soil tubes or student lamp chimneys, cheese cloth, crock, shears, and the following soils: coarse clean sand, some "poor" unproductive fine soil, rich dark loam, some sand mixed with manure (eight parts sand and two parts very fine manure, weigh out).
Procedure: Securely tie the cheese cloth over the small end of the lamp chimney or over one end of the soil tubes, weigh and record the weights; fill three-fourths full of the different soils indicated above; set in a crock of water so that the water is a little higher than the soil in the chimney, leave until all show free water on top (note the time required for the water to reach the top in each case.) Explain. When all are wet on top remove and set on a shelf to drain; cover the top with an evaporating dish to prevent evaporation; after 24 hours weigh, and compute the amount of water that has been retained by each soil. This computation should be in terms of the percentage of increase in weight. Note particularly the difference in water held by the clean sand and the sand and manure? Does a fine soil hold more film water than a coarse soil? Explain. What effect on the water holding capacity of soil does organic matter have?
13

LESSON XXXI.
Relation of Rate of Leaching to Texture
References: Soils and Fertilizers, Lyon, pp. 66-67 and exercises.
EXERCISE 53. To study the rate of percolation of water through soils of different texture.
Materials Needed: Soil tubes with racks and tank, six 500 c.c. beakers, graduate cylinder, cheese cloth, one-fourth inch rubber tubing, soil-clay, loam and sand.
Procedure: Cut a disc of cloth to fit bore of cylinders; place the cheese cloth in bottom of each tube; fill the tubes with the above soils to within one inch of the overflow drain; put sand in two tubes, loam in two tubes, and clay in two tubes; put a thin layer of cotton over each tube to prevent the running water from washing deep holes into the soil; now, place the tubes in the racks and connect the overflow pipes; fill the supply tank and put it in place; put 500 c.c beaker under each tube to catch the water.
Note time of applying the water and also the time when it begins to flow through each tube. After the flow becomes constant in all the tubes measure the amounts of water percolating through each soil during 15 minutes; repeat the measurement three times and take the average amounts. Compare the amount of water percolating through each kind of soil. What can you say as to the relation of size of soil particles to the rate of percolation? What type of soils will leach the least?
Note: Glass soil-tubes or lamp chimneys may be used in this exercise. Place cheese cloth over bottom; fill to within two inches of top with different soils; add water to keep surface covered; note amount of water added and time it takes to run through in each case. Measure the amount running through each soil for fifteen minutes, record in terms of cubic centimeters of percolation per hour in each soil. What can you say as to the relation of size of soil particles to the rate of percolation or leaching?
14

EXERCISE 54. To study the available moisture in different classes of soils.
Materials Needed: The following soils: sand, loam, clay; sixinch flower pots or other container; some corn or small tomato plants.
Procedure: Fill one jar with each of the above soils; transplant one of the seedlings into each pot, using the same kind and size of plant in each pot; get the plants well started by keeping watered and under favorable conditions; stop watering them and keep watch to see when one of the plants begins to wilt. As soon as a plant wilts empty out the dirt and thoroughly mix, place a 10 g. sample in a dish of known weight and heat it to a constant weight over a burner at a boiling temperature. Calculate the loss of water. Repeat this procedure with each soil as soon as the plant in the dish wilts. Wilting indicates that the soil is not giving to the plant enough water to sustain life. Which soil has the most water in it at the time the plant wilts? What can you say as to the power some classes of soils have to give up their water to plants? Which class of soils above studied will best support plants in time of drought?
LESSON XXXII.
Loss of Soil Water by Evaporation
References: Soils and Fertilizers, Lyon, pp. 73-78; Chart showing evaporation of water from soil.
EXERCISE 55. To study the loss of soil water by evaporation under field conditions.
Materials Needed: Soil auger, and piece of heavy cloth about eighteen inches by eighteen inches.
Procedure: (a) Notice the moist surface of compacted spots on a newly worked field, as the tracks of men and mules. Why are these spots more moist than the loose surface? Why do farmers often roll land after sowing small seed like grass seed, millet, clovers, etc?
15

(b) Find a field that has both a cUltivated crop and land that has no crop on it and has not been broken the present season. Examine the top layer of soil on both the cultivated and uncultivated land. Note the texture, the moisture content. With the auger get samples of soil from the following depths on both cultivated and uncultivated land: six inches, ten inches, eighteen inches and twenty-four inches. Place these samples on the cloth and examine them carefully for moisture content and physical condition. Compare each time samples from the same depths. What is the effect of cultivation on moisture content? Compare vegetation of the same kind on both cultivated and uncultivated land. Explain the differences.
(c) Examine in the same manner soils from a field that is not cultivated but which has a crop on it, and soils from adjoining land that has no crop and not cultivated, and soils from adjoining cultivated field. Take and compare samples as above. Do you find any difference in moisture content of the soils at different depths? Why would you expect the soil with an uncultivated crop to be dry in comparison with the cultivated soil? How does the apparent moisture content of the two uncultivated soils compare?
LESSON XXXIII.
Object and Effect of Tillage
References: Soils and Fertilizers, Lyon, pp. 42 and 74-80.
EXERCISE 58. To show the effect of a dust mulch on conservation of soil moisture.
Materials Needed: 4 one-gallon crocks and silt or sandy loam soil.
Procedure: Weigh, label and record the weights of the crocks; fill each crock three-fourths full of silt or sandy loam soil; set on the scales and adjust amounts of soil until each crock contains same weight of soil; to jar No.1 add 1000 c. c. of water
16

(2.2 lbs.) ; from jar No.2 remove about one inch of soil, add 1000

c. c. water; after water has soaked in, sprinkle on the dry dirt

which has been removed; treat jar No.3 as jar No.2, and pack

the mulch layer until firm; treat jar No.4 as No.1, and add on~

half-inch layer of chopped straw; now weigh and record total

weights. Expose all jars to the sun and weigh every twenty-

four hours and record weights for a week as follows:

.

Tot~l

I Iper
Weight After Exposure .. Total LossCoefnt

I I Contamer Weight 1 day 2 days 1 4 days 15 days 1--6--d-a--y-s Loss AWdadteedr

I

I

I

'rJar No. 1 I

I I

I

I

i

I

I

I

IJar No. 2 I

I

1 I

-

-

-

I I

I
i

IJar No. 3 I

I I

I

I

!

I

I
I

I

IJar No. 4 I

I I

I

I

I

I~I-

I
I I
I

-

-~

I

I

I

- - 1 - - i --

I
- - - ---~! -

--

I

---1--- ---

I

I

I

I

I

I

I

Do you find a difference in the amount of water lost from the

jars? Which jar has lost least? Which one has lost most? Ex-

plain the difference. How is a mulch formed under field con-

ditions? What happens to the dust mulch when it rains? Why

cultivate after every rain?

EXERCISE 59. To study the effect of a break in the capillarity of a soil in or below the seed-bed.
Materials Needed: Lamp chimneys or glass soil tubes, some finely chopped straw, loam soil.
Procedure: Tie some cheese cloth over the ends of two glass soil tubes or lamp chimneys; put about one foot of soil in one tube or chimney; place about 6 inches of soil into the other tube or chimney; now put about one and one-half inches of finely cut straw on top of this soil, and add five inches more of soil. Place both tubes in a shallow pan of water, and note results.
Why doesn't the water rise through the straw? What would be the effect if a large quantity of coarse vegetable material were plowed under just previously to planting? What remedy would you suggest?
17

LESSON XXXIV.
Effect of Drainage on Soils and Plant Growth
References: Soils and Fertilizers, Lyon, pp. 78-80.
EXERCISE 60. To study under field conditions, the effect of poor drainage on plant growth, and on the soil.
Materials Needed: Each student should be provided with a good trowel.
Procedure: (a) If possible, visit a field of alfalfa (or some other naturally deep-rooting plant) which has a low spot or basin in it; take up a plant from a high, well drained spot by first digging around it with a trowel to the depth of several inches, then pull steadily straight up until the plant gives way. Try until a good specimen is obtained. Now, carefully remove a plant from the lowest part of the field. Compare the plants in vigor and root development noting particularly the depth of rooting. This m~y be done with any perennial plant with good results. How does poor drainage affect the root development of plants?
(b) Now, visit a poorly drained field (not a swamp) and compare the soil of the poorly drained portions with the soil where the drainage is good in regard to physical conditions; compare the plant growth as in (a). How does drainage affect the tilth of the soil? Can plants obtain food from clods and holes? Why do plants grow poorly on badly drained land?
(c) If it is possible visit a swamp and note how trees and plant roots stay close to the surface of the ground. How would these trees and plants fare if the water table were to be lowered by drainage? Explain. What happens to a crop on poorly drained land when a drought suddenly comes upon it? Why do plants that are grown on well drained soil better withstand dry weather?
18

EXERCISE 61. To demonstrate the effects of poor drainage on the soil and on plant growth.

Materials Needed: Two one-gallon crocks, some good sandy clay loam, corn or some of the small grains.

Procedure: Make sever~il holes through the bottom of one crock, place about two inches of coarse gravel over the bottom and then fill to within three inches of the top with sandy clay loam; fill the second crock to within three inches of the top with the same kind of soil but do not provide for drainage; add the same amounts of water to both crocks until the undrained croek shows standing water on the surface.

As soon as the soil in the drained crock is dry enough to work, plant three or four kernels of corn in each crock at the depth to which corn should be planted in the soil in question. Add the same amounts of water to both soils each day (let the amount be determined by the needs of the plants in the well drained crock).

Keep a soil thermometer in both crocks-the bulb should be about two inches below the surface. Keep a record of temperatures and plant growth every six days for a month according to following scheme:

Crock Number

2 2 2 2 I I
1 I I1

I
1I

II
II 1 I

II ~-1-2-1

I II

I II

II

I

1

I II

I II

11-1- \

Date

-1 II

I II

II 1

. - - . - 1I- 1II11 ---:--~-II-I-II I -

II I .. -11-1

I

Temperature

I

'I

1 II

I II
I II

II II 1

Height

I il I II

I II

I

I

I II

\1

II

,

II

Color

I II
I II

II I II
Ii I II

I 11

I II

At the end of thirty days, cease watering the plants and place in the sun. Note the effect upon the plants in each crock after a week without water.
19

Now remove the plants from the pots and carefully examine the root systems. In which pot did the roots go deeper? Will a crop grown on well drained soil withstand a drought better than one grown on poorly drained soil? Explain. What effect upon the temperature of the soil has poor drainage? Will low soil temperature aid or retard plant growth? What are the most important evil effects of poor drainage on soils, on plant growth?
LESSON XXXV.
Methods of Drainage
Refe1'ences: Soils and Fertilizers, Lyon, pp. 80-85; N. C. Bu!. 234; Texas Bu!. 188; Wis. 229; F. B. 524.
EXERCISE 62. To install a farm drainage system. (May omit.)
Materials Needed: Shovel, drain scoop, tile hook, a tile spade and instrument for leveling.
Procedure: 1. A preliminary study of the land to be drained should be made to determine (a) the courses of poor drainageamount of fall, sources of water, conditions of sub-soil, etc., and (b) suggest a remedy-tiling, open ditch, etc.
2. Now, the services of a drainage engineer from the Agricultural College should be consulted in order that the best possible results may be obtained.
3. When a definite plan has been determined upon, the grading and tiling may be done by the class or as a project. At least the class should be brought in actual contact with a drainage project, and do the various operations necessary in tile drainage.
The references given above will be found of much value in these exercises.
20

LESSON XXXVI.
Effect of Organic Matter on Physical Condition of Soil
References: Soils and Fertilizers, Lyon, pp. 51-54.
EXERCISE 63. To study the effect of organic matter on the water holding capacity of soils.
Materials Needed: Very fine manure, clay loam soil, lamp chimneys, cheese cloth.
Procedure: Tie cheese cloth securely over the small end of two lamp chimneys; fill one chimney three-fourths full of clay loam; to the second lamp chimney add the same amount of the same kind of soil and fill nearly full with very fine manure. Now, empty out the contents of the chimney containing the manure and thoroughly mix the soil and manure; refill the chimney with the mixture, weigh both chimneys and record weight; add water to both soils by placing them in a crock of water and allowing them to absorb all the water they will hold; when free water appears on the surface of both soils, take from the crock and allow to drain for several hours, and weigh again. Which soil has absorbed the most water? To what is this difference due?
Note: This exercise may be continued by keeping the chimneys covered to prevent evaporation. Weigh again after several weeks. Which soil retains the most moisture? What is the effect of organic matter on the water holding capacity of a soil?
EXERCISE 64. To demonstrate the effect of color upon the temperature of soils.
Materials Needed: Flat shallow boxes; soot, lamp black or coal dust; slaked lime or chalk dust; soil, and thermometers.
Procedure: Fill two boxes nearly full of soil, and shake down equally firm; add to one a thin layer of lime or chalk dust; add to the other box a thin layer of the black material. Place both boxes in the sun and insert thermometer bulbs in both boxes
21

about one inch beneath the surface of the soil; take readings every two hours until after sun-down and record results.

~~flck
White Soil

I II temp.

I
time

IIII

temp.

II t i m e

IIII

temp.

I
[ time

IIII

temp.

II time

III

I
temp1 time

I

I

II I II I II I I I

I I II

I II

I II

I

II--[~

I II
I I II I I II I I II

II II II I

I 11--1-11--1-11-1--

I II

I II

I II I

I II

I II

I II I

Make a similar test under field conditions.

EXERCISE 65. To study the absorbent power of soils.
Materials Needed: Rich fine garden loam, a bucket of farm yard manure, and tin can with perforations in bottom.
Procedure: Nearly cover the manure with water and let it stand over night; pour off the colored water into beakers. Place the finely pulverized soil into the tin can and firm well; pour the colored liquid slowly upon the soil and continue until it leaches through. Compare the color of the leached water with that added.
Where has the coloring matter gone? Is the surface soil enriched by its absorbent power?

LESSON XXXVII.
Organic Matter and Soil Fertility
References: Soil and Fertilizers, Lyon, pp. 54-57.
EXERCISE 66. To show the effect of raw sub-soil on plant growth.
Materials Needed: Fertile surface soil and its sub-soil, two large flower pots.
Procedure: Fill one pot with the fertile top soil to within two inches of the top; fill the second pot with sub-soil; plant
22

some corn in each pot. Care for both pots in exactly the same manner. After the corn is up keep record of growth and vigor for a month. Record results each week as follows:

I
i Pot

1

2 IIIi 1

II 2 II 1

II 2 II 1

2

I

II

I!

II

I i Color

II

1'I

II

II

Ii

I

I

II

I Growthl

II

I

I

il

I

I

II

I Date I

II

I

I

II

II
II
III! --~--:-----; II II

Do you notice a difference in the vigor of the plants in these potS? To what is it due? Why is sub-soil not so fertile as surface soil? Is it a good practice to increase the depth of plowing too much at one time? Why? How should sub-soiling be done?

Make observations of this principle under field conditions if possible.

LESSON XXXVIII.
Relation of Soil Organic Matter and Soil Bacteria
References: Soils and Fertilizers, Lyon, p. 54 and Chap. IX; any soil bacteriology.
EXERCISE 67. To observe the nature of micro-organisms of the soil.
Materials Needed: Compound microscope with oil immersion and other objectives, Abbe condenser and plane mirror, slides, cover glasses and stains.
Procedure: (a) Chop some dry hay into short pieces about an inch long; put it in a beaker and cover well with water; let stand for a day or two in a warm room. Take a drop of this water and examine under the microscope, using cover slips. Under the lower power objectives many living organisms can be seen moving about.
23

Now, examine with the oil immersion objective. Many forms should be seen. The smallest ones are bacteria, the larger one protozoa, the smallest of the animal kingdom. Bacteria are plant forms.
(b) Make and examine in the same way fusions of fresh horse manure, sand and rich garden soil. Place fifty grams of the above materials in water, stir thoroughly for several minutes, and let stand for two days, examine as in (a). Where do bacteria live? Can you see them with the unaided eye? Explain their presence in the soil and their work there. Are all bacteria of use to man? Name some that are not.
Note: Further examination of this material can be made by preparing and staining some slides with carbol-fuchsin, methylene blue, gentian violet, and iodine. No cover slips will be needed for examination of stained material.
Did the solution from the sand have as many bacteria in it as were found in the horse manure or garden soil? What can you say as to the relation of organic matter in the soil and the bacterial content?
LESSON XXXIX.
Soil Acidity
References: Soils and Fertilizers, Lyon pp. 55 and 112-118.
EXERCISE 68. To study the acidity of some soils in the community.
Materials Needed: Blue litmus paper, soil samples from the home farms of the pupils, soil pans and small wooden sticks for stirring the soil, a Truogg Soil Tester.
Procedure: (a) Place a good handful of soil in a soil pan; add (distilled) water and stir until a mud-ball can be made; press the mud into a firm ball with the hands, and break the ball in halves, place a strip of blue litmus paper on one of the
21,

broken surfaces of the mud-ball; (be careful not to let the litmus paper come in contact with the hand) press the ball together again and leave for five minutes. If the paper has pink spots or has reddened entirely, the soil shows an acid reaction.
(b) Make an acid test with a Truogg Tester to determine the amount of lime necessary to counteract the acidity. Directions for using the Truogg Tester are supplied with each testing apparatus. (Wis. Exp. Station Bulletin 249.)
(b) Make an acid test with a Trougg Tester to determine the

LESSON XL.
Some Factors Influencing the Temperature of Soils

References: Soils and Fertilizers, Lyon, Chap. X.

EXERCISE 69. To study the effect of exposure and slope on soil temperature.

Materials Needed: Four shallow wooden boxes, soil, and thermometer.
pJ'ocedure: Fill four boxes with any soil that is fairly dry; raise one edge of one box of soil so that it makes an angle of about fifteen degrees with the ground and expose it toward the South, place another box with the same exposure but at an angle of thirty degrees, leave the third box flat on the ground; expose the fourth box to the north at an angle of thirty degrees. Insert a thermometer in each box and record temperatures every two hours until sun-down as follows:

Box Time

_ _ I
3_o3_~

~ooN

I

Flat

Temp.

Time
Temp. 25

How is the temperature of the soil affected by slope? Exposure? Make a similar study under field conditions.
EXERCISE 70. Field trip to study the effects of color, drainage, slope and exposure on soil temperature.
Materials needed: Soil thermometers, dibbles, and note books.
Procedure: There are four groups of conditions to be tested. For the first observations place one thermometer on a well drained bottom, the second on a well drained gentle slope and a third on a well drained more abrupt slope, and note the exposure. Set the second group of three thermometers under like conditions but on different exposure. The third group of temperature readings should be taken on poorly drained soil on bottom land and on slopes. A fourth group of tests should be made on soils of as widely (Iifferent color as possible, but slope, exposure and water content the same. Record data as follows:

I

I

I

I

I

----it
I

Can you detect the effect of slope on soil temperature? To what degree does exposure affect the soil temperature? Why does color of soil affect soil temperature? Why does wet soil keep colder than dry soil?

LESSON XLI.
Erosion
References: The Mangum Terrace in Relation to Efficient Farm Management B. P. I. Circ. 94; also B. P. I. Cire "A" 78; Terracing U. S. D. A. Bul. 512; Terracing Farm Lands, Farmers' Bulletin 997.
26

EXERCISE 71. To layout a terracing system (see U. S. D. A. Bulletin 512 and F. B. 997.)
Materials Needed: A good farm level, stakes and hatchet.
Procedu1'e: (a) Make a trip to study local practices in terracing. Visit a field where an efficient method of terracing is being used. With the level, arrive at the fall of the terraces; note their width and height, and how they were constructed. Visit another field where poor terracing has allowed washing. Compare the two systems, and discover wherein the second system has failed.
(b) Now, the class should be ready to layout a terracing system on one of their home farms, or on the school farm. This should be done under the direct supervision of the instructor or some other competent person. For procedure and home-made devices see F. B. 997.
LESSON XLII.
Phosphorus as a Plant Food
Refe1'ences: Soils and Fertilizers, Lyon, Chap. XII; Ground Phosphate Rock, Ga. Ext. Arc. 42; Commercial Fertilizers Composition and use Farmer's Bulletin 44.
EXERCISE 72. To study the relative solubility of common phosphoric acid fertilizer materials.
Materials Needed: Commercial acid phosphate, bone meal, mixed commercial fertilizer, floats, di-calcium (referted) phosphate, filter paper, funnels.
Procedure: (a) Weigh out five gram samples of each of the materials at hand; place in beakers, add 100 c. c. of water, stir for ten minutes, filter. (Note: Do not wash the residue on to the filter paper.) Heat the filtrate to boiling, add 40 c. c. molybdic solution; let stand over night and observe results. A yellow
27

color indicates phosphoric acid. Can you see a difference in the amount of yellow precipitate in different beakers? Do you get a precipitate in all cases? Which of these materials is apparently most soluble in water? Which least?
(b) Another method may be tried as follows: Weigh out five gram samples of each of the available materials; place on a filter paper previously fitted to a funnel. Pass 500 c. c. of water through each sample; put the residue and paper in an evaporating dish of known weighi, dry and burn the paper; weigh again. Calculate the loss from solution? Which sample has lost most 'f Which one has lost least?
Test filtrate for phosphoric acid as in "a".
EXERCISE 73. To prepare acid phosphate.
Materials Needed: Raw bone meal, three-inch porcelain evaporating dish, glass rod, strongest sulphuric acid, a strip of board.
Procedure: Put five grams of the bone meal into the evaporating dish; add slowly with constant stirring four grains of strong sulphuric acid; stir with a strong glass rod. (Note: This stirring should be done in the open air or at a window. Do not breathe the fumes.) Transfer the mass to a board. and set aside. After three days test for solubility as in the last exercise.
Is raw bone meal soluble in water? Is the product of this exercise soluble in water? Explain.
EXERCISE 74. To show the action of soil acids on the solubility of di-calcium phosphate.
Materials Needed: Di-calcium phosphate, and ammoniumcitrate solution.
Procedure: Place.5 gram samples of the di-calcium phosphate in each of two beakers; to one add twenty c. c. of water, to the other add twenty c. c. of ammonium-citrate solution; warm both beakers; note results. May acid in the soil aid in causing mineral plant food in fertilizers to become available?
28

LESSON XLIII.
Sources and Uses of Nitrogen as a Plant Food
References: Soils and Fertilizers, Lyon Chapter XI; Farmers' Bulletin 44; Nitrogenous Fertilizers Obtainable in thE! United States; Farmers' Bulletin 37.
EXERCISE 75. To study the relative solubility of some com.:. mon nitrogen fertilizer materials.
Materials Needed: Sulphate of ammonia, nitrate of soda, dried blood, leather, hoof or hair, pepsin, hydrochloric acid, filter paper, and funnels.
P1'oceclure: (a) Weigh out ten grams each of sulphate of ammonia, nitrate of soda, and dried blood; place on a filter paper fitted into a funnel; add equal amounts of water to each sample; test filtrates for nitrates (place some of the filtrate in a test tube; add a bright crystal of iron sulphate (ferric sulphate) ; then pour 3-5 c. c. of strong sulphuric acid down the tube while holding it at 45 degree angle. The brown ring indicates nitrates). Have all samples dissolved equally well? Is the nitrate test equally distinct in each case? What can you say as to the relative solubility of the nitrate of soda, sulphate of ammonia, and dried blood? Which will give their food most readily to growing plants?
(b) Make up the following solution: two grams of commercial pepsin in a liter of water (an ounce of pepsin to three ,pints) ; add one c.c. of strong hydrochloric acid.
Place five grams each of the following materials in a small bottle or a 200 c.c. erlenmeyer flask: dried blood, leather scrapings (hoof or chopped hair can be used instead of leather; add 100 C.c. of the pepsin solution to each bottle, keep in a warm place for 24 to 36 hours with occasional stirring. At the end of this time note the relative amounts of materials remaining undigested? What can you say as to the solubility of organic nitrogen in the form of hair, hoof, dried blood, etc. found in commercial fertilizers.
29

LESSON XLIV.
Sources and Uses of Potassium as Plant Food
References: Soils and Fertilizers, Lyon pp. 179-180; Farmers' Bulletin 44.
EXERCISE 76. To study the relative solubility of potash fertilizer materials found on the market.
Materials Needed: Muriate of potash, sulphate of potash, kainite, kelp-ash, ground felspar.
Procedure: Weigh out a two gram sample of each of the substances available; place on a filter paper previously fitted into a funnel; add 500 c.c. of water to each sample and note which substances are readily soluble and which are relatively insoluble or slowly soluble.
Which of these substances will give up its food elements most easily to plants?
LESSON XLV.
Lime and Other SoH Amendments
References: Soils and Fertilizers, Lyon, Chapter XIV; Lining of Soils, Farmers' Bulletin 77; Relation of lime to Agriculture, Md. Ext. Bulletin 2.
EXERCISE 77. To identify and learn the nature of different forms of lime.
Materials Needed: Some fresh quicklime, ground limestone, hydrate or water slaked lime, landplaster or gypsum, soil that gives acid reaction, litmus paper, clay s::>il, ammonia water, and large bottle.
Procedure: 1. Indentification: (a) Quick-lime is easily detected by its reaction and the formation of heat when in contact with water.
30

('b) Ground limestone can be distinguished from quick-
lime from the fact that it gives no reaction with water. It can be distinguished from other forms of lime by its fine granular structure.
(c) Hydrate of lime can be distinguished from ground limestone from the fact that the hydrate of lime is soluble in water.
(d) Landplaster can be easily distinguished from all other forms of lime from the fact that it does not give a reaction with hydrochloric acid as does the ground limestone. Land plaster is also tasteless and can be distinguished from the hydrate by this fact.
2. The nature and uses:
(a) Dampen a small portion of each of the forms of lime available; test with litmus paper. Which forms give the most decided test for alkalinity? Do all forms give an alkaline test?
(b) Take some acid soil and make a litmus test for acidity as in exercise 68 "a" divide the mud ball into halves again; to one half add twenty grams of hydrate or quick lime and thoroughly mix the lime with the soil. Now test both portions again with both red and blue litmus. What effect has lime upon soil acidity?
(c) Place ten grams of clay soil in a large bottle; add 100 C.c. of water and a few drops of ammonia to throw the clay particles into suspension; shake thoroughly for fifteen or twenty minutes, and allow to stand for at least three hours before using. (This exercise can be finished on the following day, but the soil and water should be shaken several times in the meanwhile). When ready to proceed, pour the suspension into a glass cylinder and add a half teaspoonful of finely powdered lime hydrate and shake well. Note the action of the clay particles in suspension. What effect does lime have on the structure of clay soils?
NOTE: Exercise 68 (b) should be repeated in this connection.
31

LESSON XLVI.
Composition and Value of Commercial Fertilizers
References: Soils and Fertilizers, Lyon, Chapter XV.; Elements of Agriculture, Warren, pp. 129~135.
EXERCISE 78. Home mixing of fertilizer: Make up a ton of 2-7-2 or any desired mixture; Home Mixing of Fertilizers, U. S. D. A. Year Book, 1918.
Materials Needed: Nitrate of soda (15 percent), acid phosphate (14 percent), muriate of potash (50 percent).
Procedure: Put the proper proportions of the above materials together on a tight floor and mix as follows: Place about one-half of the acid phosphate on the floor in an even layer, then add all the nitrate, distributing it evenly over the first layer, now, add the remainder of the phosphate material in a 18yer, and over this distribute the muriate. If a filler is used, place it over the top layer of muriate. Mix with flat shovel by turning each shovelful so that it falls off the side of the shovel. Work over three or four times in this manner. There is no set way of working these elements together, but the above method insures a good mixture.
Is it cheaper to mix your fertilizer at home? Is it necessary to use filler? What are the advantages and disadvantages of using fillers?
Computation*-Assuming the fertilizer needed to be 2-7-2. the following computations are necessary; (Note: Always get percentage composition and prices of substances from your local dealer.) If two per cent of nitrogen is required, it will take .02 of 2000 lbs. or 40 lbs. of nitrogen, and if the nitrate of soda is 15 % nitrogen or .15 nitrogen, it would take as many pounds of nitrate as 40 -+- .15, or 258 lbs. For 7 per cent or .07 of the mixture to be phosphoric acid, it will require .07 of 2000 lbs.,
*NOTE: See computation cards issued by the Georgia State College of Agriculture.
32

or 140 Ibs. phosphorie acid, and computing as above 140 -0-- .14 =

1000 Ibs. of acid phosphate needed and in like manner it is found

that 80 Ibs. of muriate is needed, the results tabulated are as

follows:

40 .15 258 the number of Ibs. nitrate of soda .

140 .14 1000 the number of Ibs. acid phosphate.

40 .50

80 the number of Ibs. of muriate.

Total Weight 1338 Ibs. 2000-1338 = 662 Ibs. of filler needed to make up a ton.

EXERCISE 79. To study the water-soluble material in a commercial fertilizer.
Materials Needed: A commercial fertilizer, filter paper, and funnel.
Procedure: Put two grams of the fertilizer in a filter paper fitted into a funnel; pass 500 c. c. of water through the sample. Place the residue and filter paper in an evaporating dish of known weight, and burn. Weigh and compute loss due to soluble substance. The results obtained by several pupils should be compared. What is the nature of the insoluble material? Commercial fertilizers may vary in the amount of soluble material from thirty to eighty per cent.
Test the filtrates for nitrates. (Exercise 75-a) ; Phosphorus, (Exercise 72-a).

LESSON XLVII.
Results of a Given Fertilizer on a Given Crop
Refe1'ences: Soils and Fertilizers, Lyon, Chapter XVI; Farm Practice in the Use of Commercial Fertilizers in the South Atlantic States. Farmers' Bulletin 398; also Farmers' Bulletin 44.
EXERCISE 80. To observe the effects of various fertilizers on plant growth and crop production in the community.
33

Materials Needed: Note book and pencil.

Procedure: (a) The teacher must make a community survey of crops and fertilizer practices, before he can attempt this exercise. With a little trouble the teacher can find examples of some of the following results: A given fertilizer on certain crops, such as alfalfa, clover, peanuts, etc.; the effect of certain fertilizer mixture on cotton, corn, potatoes, etc.; nitrate of soda on wheat, oats, etc.; cotton seed meal on various crops. When these examples have been found and the class brought to the field to study the situation, it is always best to have the farmer explain the condition and results to the class. This exercise can and should be made a very important and instructive field trip.

(b) Assign to each student the task of studying the kind and amount of fertilizer used on their home farm during the past season.

Arrangement of data on fertilize:-s used.

-I Brand or I

I

I

I Yield I

1

I Source I Composition 'Am't Used I Crop I per Acre IRecommendedl

~I~~-I-

1

1

,-

I

I

-1-I - - - II

11 '------1;.'----+1I ---------;1I

1I -----+--1I - - - - ; - 1I ---+-II-~-+II- - - iIl-- - - - - - i ,I

I

1

I

I~------!I----+I----!I

-I
1

I 11_

-

-

-

-

-

'

-

I
1

_

-

-

-

I
-

'

-

1

_

'I
-

-

-

-

-

'

-

-

-

-

-

-

-

-

I
-

These reports should be discussed in class and helpful sug-

gestions made.

LESSON XLVIII.
Machines and Methods of Applying Fertilizers
References: Soils and Fertilizers, Lyon, p. 214.
EXERCISE 81. To study the different types of fertilizers distributors and their adjustments.
34

Materials Needed: The various machines that are used and sold in your community for applying fertilizers.
Procedure: The teacher may well arrange for this exercise with the local farm implement dealer, or with some farmers who have these machines in actual operation. The general construction and adjustments should be studied and understood.
LESSON XLIX.
Value and Nature of Farm Manure
References: Soils and Fertilizers, Lyon, Chapter XVII; Elements of Agriculture, Warren, pp. 135-147; Barnyard Manure, Farmers' Bulletin 192; also States Relation Service Bulletin 30.
EXERCISE 82. Observe the results of heating in manure pile.
Mate1'ials Needed: Some ammonium carbonate, test tubes and burner.
Procedure: Ammonium carbonate is formed in manure piles. Place about two grams of ammonium carbonate in a test tube; dampen a narrow strip of red litmus paper and suspend from the bottom of an inverted beaker, hold the inverted beaker over the test tube; heat gently and observe the odor given off, and note the change in color of the litmus paper. To what is the odor due? What is the effect of allowing manure to heat in the pile? How could you test a manure pile for escaping ammonia?
EXERCISE 83. To study the effect of mixing lime or ashes with nitrogenous fertilizers or manures.
Materials Needed: Ammonium sulphate and carbonate, nitrate of soda, a fertilizer containing nitrogen, some fresh hen manure, lime, and wood ashes.
Procedure: (a) Mix a small amount of each of the salts containing nitrogen, with an equal amount of quick lime, moisten.
35

Can you detect the odor of ammonia? What important plant food element is escaping? Test the commercial fertilizer in thE' same way. Should lime be mixed or used with nitrogenous fertilizers?
(b) Mix some quick lime with a bucket of fresh hen manure, dampen and cover for an hour; remove the cover and note the odor. Make a test with damp litmus paper.
(c) With another bucket of hen manure mix a quantity of wood ashes and treat as in (1) above. Is it a good practice to use ashes or lime in quantities about the hen roost? Snggest f'nme materials that may be used.
Note: It may be necessary to let the test in "b" and "c" remain over night to get a good reaction. In case no odor is given off, make a litmus for escaping ammonia.
LESSON L.
Care of Farm Manure
References: Soils and Fertilizers, Lyon, Chapter XVII; Elements of Agriculture, Warren, pp. 135-147; F. B. 192; also States Relation Service Doc. 30.
EXERCISE 84. To study a method of preventing the escape of ammonia from manure piles.
Materials Needed: Ammonium sulphate, test-tubes, and burners.
Procedure: (a) Place.5 gram of ammonium sulphate in a test-tube; apply heat gently as in exercise 82. Do you detect any odor? Does ammonium sulphate give off ammonia when heated? Could you save the ammQn~a which escapes from a manure pile, if you could convert it into ammonium sulphate?
(b) Mix.2 gram of amm'onium carbonate with about two grams of gypsum (land plaster, or calcium sulphate), moisten,
36

place in a test-tube and test as above. Is ammonium given off in the presence of a quantity of moist gypsum? Calcium has a greater attraction for carbon than it has for sulphur, and so it trades places with the ammonia found in the ammonium carbonate thus forming calcium carbonate and ammonium sulphate. If gypsum is added to the manure pile, what takes place chemically? How does this preserve the nitrogen of the manure?
(c) Using acid phosphate proceed as in (b) and draw conclusions.
EXERCISE 85. To show the effect of excluding air on the loss of nitrogen from manure.
Materials Needed: Two two-quart fruit jars, fresh, fine horse manure, road dust, cow urine.
Procedut'e: Loosely fill two two-quart jars three-fourths full of the fine fresh horse manure; add to each jar equal amounts of cow urine (not absolutely necessary) ; leave one jar in a loose condition; compact the other and add water to exclude the air and place about one-half inch of soil over the top. Suspend a piece of moist red litmus in each jar, being careful not to have the paper touch the contents of the jar. Cover and observe results. Keep the litmus paper moist from time to time. How may manure be handled to prevent large losses of ammonia? In practice, how can this best be done on your farm?
LESSON LI.
. Farm Manure Survey
References: Soils and Fertilizers, Lyon, pp. 227-231; Elements of Agriculture, Warren, pp. 140-144.
EXERCISE 86. Field trip to observe the care and condition of farm manure.
Materials Needed: Soil thermometers, litmus paper, note book and pencil.
37

Procedure: (a) Horse manure-Place a thermometer in the loose portion of a heap of horse manure, place another thermometer in a compact portion of a horse manure pile. After twenty minutes record temperatures.
Open with a fork a manure pile that is hot, and hold a strip of moistened red litmus paper in the hole. (Do not let the paper touch the manure.) Note any change in color of the paper. Escaping ammonia turns red litmus blue. What causes "fire fang"? What harm results from heating?
(b) Make like tests and observations about the cow barn or stable. Note particularly whether or not all the liquid manure is being saved, and whether leaching is going on.
Why is cow manure not hot? Would it be a good practice to mix cow manure with horse manure? Explain.
(c) Visit a hen house and make the following tests and observations. How is the accumulated hen manure stored? Make a litmus test for escaping ammonia. Can you smell ammonia?
Can you smell ammonia about the roosting place? Is lime being used about the hen house? Are wood ashes being mixed with the hen manure?
What happens when hen manure heats? When lime is mixed with hen manure? When wood ashes are mixed with hen manure? Explain.
(d) Each pupil should be required to make a report of the trip. This report should show the kind and condition of the manure observed; first good or bad practices were observed; and recommendations for remedying any bad practice.
The pupils should be required to study the conditions and practices employed on their home farms and make recommendations for correcting any bad practices in the care of farm manures.
LESSON LII.
Green Manures and Cover Crops
References: Soils and Fertilizers, Lyon, Chapter XVIII; Farmer's Bulletin 278.
38

EXERCISE 87. (Exercise 86 and 87 should perhaps be worked out on the same field trip). To study the effects of green manuring on soil.
Materials Needed: Spade and a cloth on which to examine the soil.
Procedure: (The teacher must know in advance the soil management of the field to be studied. The farmer should also be consulted.) On a piece of land that has been "brought up" or its physical and chemical condition improved by green manuring samples of the soil should be examined for color, etc. Its general productiveness should be known. The soil on this field and its productiveness should be carefully compared with adjacent fields which have had no green manure.
Let the pupils get from the farmer his opinion about green manuring.
Some of the soil from the two fields studied might be taken to the laboratory and tested for organic content.
EXERCISE 88. To study the effect of uneven distribution of manure or fertilizer on a crop.
Materials: Nitrate of Soda, large box (4 x 4 feet) of subsoil, or a plat of soil of low fertility.
Procedure: The soil in the box should be at least six inches deep, and the surface should be level. Plant the box or plat with oats or some other small grain. Place a few small lumps of the nitrate salt in a small circle (one foot radius) in the center and at each end of the box or plat; leave the remainder unfertilized. Water by sprinkling. After the grain is well up, note the unevenness of growth. This unevenness can be well seen in cow pastures, etc.
Does the fertilizer or manure move from place to place very much? What can you say about the necessity of placing manure or fertilizer evenly over a field for an even growth of crop?
If the results of uneven manuring can be noted in the field this exercise may not be attempted. In a pasture is a good place to observe the facts in the case.
39

LESSON LUI.
Soil Management References: Soils and Fertilizers, Lyon, Chapter XIX. EXERCISE 89. Visit a well managed farm and let the pupils have the benefit of the farmer's experience as given by himself on soil management. The following practices should be noted and discussed: Crop rotations, tillage and tillage tools, drainage and terracing, fertilizers and farm manures, etc. The teacher should make special arrangements with the farmer for this important visit. Note: See Georgia State Vocational Board Bulletin 6, for list of equipment in soil work.
LESSON LIV.
Restoration of Worn-out Soils References: Renovation of worn-out soil; Farmers' Bulletin 406; also Farmers' Bulletin 245. EXERCISE 90. If it is possible to find a farm in your community that has been in poor condition and has been brought back to productivity, give the pupils the benefit of hearing from the farmer as to how he has been able to do this.
40