12 Colorado Experiment Station 
application of 3 acre-feet of water in the experiments given did 
not appear to have any influence upon this condition that 1 acre- 
foot did not have. I have seen this condition present to just as 
great an extent in the so-called dry-land wheat as in irrigated 
wheat. 
THE EFFECTS OF PLANT FOOD 
We endeavored to find out what the effects of the individual 
plant foods, usually considered necessary for the growth of crops, 
are. It is well established that the plant foods of first importance 
are only three in number and if these be present in the soil in I 
sufficient quantities, the other necessary elements of plant food 
can be considered as also present in sufficient quantities. We 
know that this is true of practically all of our Colorado soils. 
The three important elements are potassium, phosphorus and 
nitrogen. Our soils are not excessively rich in phosphorus and 
total nitrogen. I say total nitrogen because there are two kinds | 
of nitrogen, organic and inorganic, and we get these together in 
our ordinary analysis. So far as our present problem is concerned, 
we can consider the organic nitrogen as of no use to the wheat 
plant. The total nitrogen present in our soils is usually very 
moderate. Still our crops do not show by their color or the manner 
of their growth that there is any shortage of nitrogen. As our 
soil already contains enough plant food to grow good crops, the 
only way that we could study the effect of these foods on the 
plants and their seed, on the field scale, was to apply enough to 
exaggerate the effects of each one, and compare the results with 
a check plot, which received no fertilizer. In this manner we 
obtained a most definite answer to the question which we have 
stated, i. e., why some of our wheat is yellow and soft. This 
condition is quite frequently designated by the specific name 
yellow-berry. 
INCREASE IN NITROGEN PRODUCES HARD WHEAT 
We applied the nitrogen in the form of sodic nitrate, chile- 
saltpetre, and found that with the application of 250 pounds of this 
salt to the acre, put on at the time of planting, we changed the 
character of the wheat produced to a small-grained, flinty, hard 
wheat, with a decided increase in the amount of gluten over that 
grown without it. This was the answer to one side of our ques¬ 
tion, namely, how to produce hard wheat. The answer to the 
other part of the question, What makes the wheat yellow, mealy 
and soft? was just as plain, for the potash increased the yellow- 
berry very greatly in each of 45 different experiments. 
