6 
Coi^oRADo Experiment Station 
loam soil well supplied with vegetable matter and containing all 
the elements of fertility will give the best results both in yield 
and quality. The heavier types of soil have a tendency to puddle 
after heavy rains and after irrigation, which greatly impedes the 
development of the tubers. Potatoes grown on heavy lands are 
apt to be rough ana ill shaped. This is due to the fact that when 
the growing tuber comes into contact with hard and lumpy soil, 
it yields and grows in the direction of least resistance. 
Heavy soil, as a rule, is difficult to aerate, that is, to get a 
supply of air into the soil which is necessary for the normal 
development of the root system and the tubers. When there is 
no choice and potatoes have to be planted on heavy land, fall 
plowing and the turning under of green crops in the fall is helpful 
in loosening up the soil. Under a regular system of rotation, 
where alfalfa precedes the potatoes, the last crop of alfalfa should 
be turned under to increase the vegetable content of the soil, thus 
making the soil looser and more friable. 
FERTILIZERS 
Commercial fertilizers are not used to any extent in Colorado 
and for the present, at least, there is little call for their use. In 
general farming, where a regular system of rotation is followed, 
soil fertility and proper soil conditions are maintained by the 
])lowing under of alfalfa or clover, and, with the application of 
bnrnyard manures. In the non-irrigated sections, a longer system 
of rotation should be followed, together with the plowing under 
of any green crop that can be grown. Often a crop of weeds may 
be grown and turned under. The raising of livestock in the non- 
irrigated sections is now looked upon as necessary to success in 
order to provide the much needed fertilizers. 
One crop farming has proven a failure as a permanent type 
of farming in every section of the country. It not only robs the 
soil of its fertility, but it also burns out the vegetable matter and 
leaves the soil dead and unproductive. Rotten stable manure is 
the best fertilizer for potatoes in Colorado. Fresh stable manure 
should not be applied on the land immediately before planting, 
as it generally has too much straw in it and tends to dry out the 
soil, and, further, it takes a full season under our arid conditions 
for the strawy manure to decompose and during this period it 
does more harm than good. This is particularly true under dry 
farming conditions. Under irrigation, there is less objection to 
the use of strawy manures, as the decomposition is more rapid. 
The custom of applying fresh manures to the land in the 
fall and early winter is less objectionable, as it has a chance to 
be acted upon by the rains and snow before the crop is planted. 
