38 
Bulletin 58. 
greater than the ratio of potash to phosphoric acid in the ash. The 
effect of the manure is probably to be found in the specific action of 
the nitrogen and the organic matter. I think that the analyses of 
the soil will tend to establish this view. 
§ 66. The nitric acid in the ground water in 1898 is more variable 
and much higher than it was in 1897, but on the other hand, the 
water level stood somewhat higher in 1897 than it did in 1898, 
the difference being about one foot. I think that the smaller 
quantity of water applied to the surface in 1898, either as irrigation 
water or as rain, tending perhaps to yield a more concentrated 
percolate, will not account for the greatly increased amount of 
nitric acid in the ground water, but that it is to be explained chiefly 
by the oxidation of the nitrogen added to the soil in the manure. 
§ 67. The total solids in the ground water in 1898 were 
higher, as a rule, than in 1897, but whether they were as much 
higher as the supply of water was less, I cannot say. I know that 
it does not hold good that the total solids in the water are larger in 
amount as the water is lower. The greater the depth of soil the 
water has to travel through, the less likely we are to find excessively 
large amounts of the total solids in the water. 
§ 68. In 1899 we had a larger amount of water as sub¬ 
irrigation water, and it may be doubted whether the total solids 
contained in the ground water should be used as a criterion of the 
effect of the manure, i. e., as a measure of the chemical changes 
induced by the manure. I regret that the relation here is so 
obscure and involved that it lessens the value of the results ob¬ 
tained, but our observations show that the total solids fell again in 
1899 to a lower point than they showed in 1897. 
Irrigation or heavy rains which fill the soil with water, raise 
the water level, and cause an increase in the chlorin contained in 
the ground water. The manure applied seemed to make the 
increase more pronounced and of greater duration. 
The analyses of the ground water in 1898 do not show a 
sufficiently marked difference to justify any further inferences than 
those based upon the nitric acid and chlorin. We shall discuss this 
part of our work more fully in the succeeding part of our study. 
§ 69. The effects upon the crop indicate that the manure 
applied produced not only mechanical effects upon our soil, but also 
chemical effects, both tending to improve its condition and elimi¬ 
nate the effect of the alkali in increasing the percentage of ash. But 
it is not clear what relation exists between the composition of the 
manure and the general effects produced. The observations made 
upon the effects of the straw, and the increased amount of nitric 
acid in the water (it is understood that this nitric acid is present in 
