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this direction, we have endeavored to keep a very complete record of the physical conditions that have existed as regards temperature, moisture, rain-fall and sunshine, likely to affect the growing crops, and also to study the existing conditions, as well as the needs, of our soil.

POT EXPERIMENTS WITH COTTON.

Some preliminary work was started in the spring to determine the needs of our soil, in regard to plant-food, for a maximum crop of cotton. Twelve one-gallon, tall candy-jars were filled with fine gravel to a depth of one inch (400 grams); on this was placed a thin layer of cotton and 4,000 grams (8 lbs. 141 oz.) of our soil (top 6 inches). An open glass tube reached down to the gravel for ventilation. Each jar had a jacket of white canton flannel, lined with dark stuff, to exclude the light and heat, as far as possible, from the sides of the jar. Various fertilizers were added to the soil of most of the jars, as is seen in the table. A track was arranged so that the plants could be wheeled under the roof of a porch during stornis and at night; but proper care could not be taken of them, and the results were, in a measure, unsatisfactory.

The results given in the table seem very small, but when either the area of the surface or weight of the soil at the disposal of each plant is considered, the yield would, we believe, compare favorably with the average obtained in field culture.

It was desirable to know the amount of water which was, under favorable circumstances, transpired by a cotton-plant, as a control on our study of the crop and of the soil, in the field. To this end the amount of water given to each plant was carefully weighed for a period of 29 days, and a description of the plants, just before and after this, is given in the table. The figure at top of p. 90 is from a photograph of the plants taken Sept. 14.

The results thus placed on record being only preliminary, will not be further discussed at this time.

In the same cut are copied two photographs of tobacco taken May 28th and June 11th, from plants in water culture in solutions of different strengths, as indicated on the bottles. This

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set of reproductions from our photographs will give the general reader a better idea of the work which can be done in the planthouse than many pages of description would give.

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EXPERIMENTS ON THE AMOUNT OF WATER TRANSPIRED BY COTTON-PLANTS.

9
4
10

12
8
5

7
00
Date. No. of Jar,

6

10 +3
1

Nitrogen.
Nitrogen. Nitrogen. Nitrogen.
Fertilizer added, None. None. None.

Nitrogen.
Nitrogen.
None.
Potash.

Potash.
Potash.

Potash.
Potash.

Potash.
Phos, acid. Phos, acid. Phos, acid. Phos, acid. Phos, acid. Phos, acid.

8 6-16

1414
14 1-16

127
12 7-16

1472

1122

10% No plant. No plant. Aug. 18 Height of plant, 834 1012

17

4 12

18

11
12

18
10 12
No. of leaves,
10
4

2
2
3

3
No. of forms,
Water lost in 29

10434

15534
125
3434

10874
14224

144
10124 10074 101 39

9334
days, 02.,
Average loss per

544
5

374
5
312

372
194
day,
114

12
13
15

142
Sept. 14 Height of plant,
11

1672

1544
1192

11
15
16

13

16

10
21
13

12
No. of leaves,
10

3
No. of forms,

1
2

4
4

1
2

2

2
No. of bolls,

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Mean temperature of the air for the 29 days, August 17th to September 14th, inclusive, 73.4o.
Mean daily sunshine for the same time, 6 hours 30 minutes.
Seeds did not germinate.
Plant was early injured by an insect (?) from which it did not entirely recover.

16

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ON SOME PHYSICAL PROPERTIES OF THE SOIL.

GENERAL CONSIDERATIONS ON SOIL TEMPERATURES.

In the study of the temperature of the soil the aim should be, at present, not so much to determine the variations in temperature of the soil at different depths, but to try to establish the relation of the soil to heat, which can only be done by a study of the temperature at the same instant of time of the soil at different depths, and their relation to each other. If the relation of the soil to heat is once determined for a particular soil, it will, in connection with the amount and distribution of the rain-fall, and the consequent moisture of the soil, and the moisture in the air, prove of value to the farmer.

We should know what amount of heat we receive from the sun, and the amount and rapidity with which a part, at least, will be radiated from the earth, or given off into space. Not all the heat which reaches the surface of the earth is transmitted to the lower depths, by any means.

The surface of the ground has frequently reached one hundred and thirty degrees on the Farm, while the soil three inches deep has never been over ninetyfive degrees. That is to say, speaking practically, thirty-five or forty degrees of the heat which actually reached the soil at noontime did not descend three inches, being lost or converted into other forms of physical force. Part of the heat that reaches the surface of the earth is employed in heating the air, part in heating the successive layers of the soil, part in evaporating the moisture of the soil, and part is directly radiated into space. The question is, how much is available, as heat, or temperature, to the crop? Two soils may be exposed to exactly the same amount of heat, with practically the same amount of rain-fall, and yet the two soils just below the surface will have notably different temperatures. This difference in the relation of the soil to heat must be due in great part to the physical condition of the soil, and is, doubtless, of great importance in one way or another to the farmer, and should be more fully understood. This relation, if established for the typical soils of the State, would be of great value to agriculture.

We made some interesting observations on this point on the farm of Mr. Fielding R. Knott, near Oxford. The soil was one of the finest of Granville county tobacco lands, a very fine and compact gray sand. It was on July 28th, during a spell of quite warm, dry weather. The soil thermometers were duplicates of our own, and had been carefully compared and corrections made. The temperature of the soil on which tobacco was growing was observed frequently through the day. Some of these observations are given and compared with those taken at the same time at the Experiment Farm.

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The highest temperature of the surface of the soil at the two places was practically the same, 131.8° at 1 o'clock at the Experiment Farm, and 131.5° at 2 o'clock near Oxford, and the mean of the three observations given in the table differ only

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