Nitrogen Fixation 23 
so. A sample of this soil which was taken by the owner and deliv¬ 
ered to me contained 1.262 per cent of water soluble which con¬ 
tained nitric acid equivalent to 11.230 per cent of sodic nitrate, 
equivalent to 0.142 per cent of the air dried soil. If this sample 
had been taken to a depth of a foot, which it very probably was, 
how much would it mean to the average man? Very little so 
long as it is expressed in tenths of one per cent of the soil. It will 
mean more to him, perhaps, if we state that this is a piece of very 
bad land containing 5,680 pounds, 2.84 tons, of sodic nitrate or its 
equivalent of nitric acid in the top foot of soil. I found on this 
piece of land an excellent illustration of the mealiness which I have 
already mentioned several times. The adjoining piece of land on 
the north is in even worse condition than this, spots in it are barren. 
Another case •was observed in an alfalfa field under and near 
a ditch. We are prone to blame seepage for as many of our trou¬ 
bles as possible and I am personally no exception, but I am some¬ 
times conscious that I am trying to give a reason to avoid the 
labor of finding out a cause. In this spirit I judged the cause of 
the dead spots in this alfalfa to be due to seepage. * The ditch 
was there; there was water enough; the ditch was higher than the 
ground. Of course it was simply another case of seepage. I, how¬ 
ever, thought it might be well to prove this thing. On examining 
the ground and digging a hole of some depth my faith in my theory 
disappeared. I was not at all satisfied about the relation of seep¬ 
age to the death of the plants. I took a sample of the soil and 
found that 5.73 per cent of its weight was soluble in water and 
that this soluble part contained nitric acid corresponding to 27.259 
per cent of sodic nitrate or calculated on the air dried soil 1.522 per 
cent or supposing this soil to have been taken to a depth of four 
inches it means that there would be 20,290 pounds, 10 1-4 tons, on 
each acre. If one should spread 10 1-4 tons of Chile-saltpetre on an 
acre of ground we would not need to appeal to seepage to account 
for any unproductiveness of the soil which might follow. After a 
number of such experiences I have concluded that it is not wise to 
be too certain about the direct and universal effects of seepage. 
The same remark applies to the effects of alkali. I am quite con¬ 
vinced that I have not seen in Colorado a single instance in which 
it was even very probable that our ordinary alkali, not this so called 
“black alkali,” has of itself been the cause of the death of any 
plant. An excess of water in the soil, especially in cases where it 
continued for a long time, may have been. 
These occurrences are not confined to Colorado soils. Two 
samples of soil received from Brawley, California, were strongly im¬ 
pregnated with alkali and their aqueous extracts reacted for nitric 
acid with sulfuric acid and ferrous sulfate. Neither the size nor lo- 
