SOILS. 13 



pounds of timothy hay per day, when he is doing hard work; calculate 

 the cost of such a feed for one year; determine the value of fertilizer 

 requirements contained in the manure and find difference between cost 

 of feed and value of manure. 



Experiments. 



1. Horse manure was lightly packed in a box and left exposed to 

 the weather from March 30 to September 30, with the following results : 

 Analyzed and weighed 



April 25. September 30. 



Gross weight 4,000 1,730 



Nitrogen : 19,6 7.79 



Phosphoric acid 14.80 7.79 



Potash 36.00 8.65 



What was the per cent of loss in gross weight and in each of the 

 elements given? 



2. At the same time and in the same way, cow manure was treated 

 with 300 pounds of gypsum, with the following results : 



Gross weight 10,000 Ibs. 5,125 Ibs. 



Nitrogen 47 Ibs. 28 Ibs. 



. Phosphoric acid 32 Ibs. 26 Ibs. 



Potash , 48 Ibs. 44 Ibs. 



What was the per cent loss? To what do you attribute the differ- 

 ence in loss between problems 1 and 2? 



Field Studies and Soil Experimentation By the School. 



Each school should be supplied with reports or bulletins from 

 the state in which the school is located, giving the results of the 

 station's work in soil fertility and fertilizer experiments. 



1. Make a collection to illustrate the different kinds and sizes of 

 particles into which rocks have been ground or broken up by the 

 forces of nature, such as stones, gravel, coarse sand, medium 

 sand, fine sand, very fine sand, silt, and clay. 



2. Have a collection of the three leading types of farm soils made 

 up of the different soil constituents. The three leading types 

 are sandy soils, clay soils and loam soils. 



3. Examine soil particles under a strong microscope, magnifying at 

 least 500 diameters. Make observations as to color, size, smooth- 

 ness, shape, stickiness. Spread out a small portion of the dry 

 soil on a glass plate and examine carefully with a magnifier. 

 What minerals can you recognize? What percentage seems to 

 be sand? Clay? Humus? 



