ORCHARD TILLAGE. FERTILIZERS AND SHADE CROPS 9 
the land than wheat and most farmers know from experience that 
continued cropping to most farm crops leads to disaster. The day of 
reckoning does not come quite so soon, perhaps, with mismanaged 
orchards but it is none-the less certain. The fact that trees grow to 
great size and live for many years in forests,^ does not apply to 
growing apples, unless, perchance, they are grown for cider. The 
quicker the fruit grower realizes that each crop of fruit makes large 
inroads upon the available supply of plant food the quicker will he 
awaken to the fact that scrupulously clean cultivation is not all there 
is in the handling of orchard soil. 
There are 38 elements which enter into the make up of a plant; 
10 of this number are essential to its proper growth. These elements 
are as follows: Carbon, hydrogen, oxygen, nitrogen, sulphur, phos¬ 
phorus, potassium, calcium, magnesium, and iron. Normal develop¬ 
ment of a plant is impossible if a single one of these elements is absent. 
Only three of this number are considered, ordinarily, in the fertilizing 
of soil; namely, nitrogen, potassium and phosphorus. 
Nitrogen is essential to vigorous growth in plants and an over¬ 
supply in the soil often promotes a rank growth of twigs and foliage 
at the expense of fruit production. 
Potassium or potash is especially important in fruit growing since 
it aids in developing color and is the base in combination with fruit 
acids. It also forms more than 50 per cent, of the ash of fruits and 
constitutes a large proportion of the ash of the wood of fruit trees. 
Phosphorous is not so important in fruit growing as in grain produc¬ 
tion as it enters largely into the composition of seeds. But it is an 
essential constituent of tree and fruit and aids particularly in the 
proper ripening of the latter. 
These substances are supplied in various forms in commercial 
fertilizers and it would seem to be a simple matter to supply any one 
or all of them as the individual orchard seemed to demand. Such 
manures are used very extensively by orchardists in the eastern states, 
but so far as we know commercial fertilizers have not been tried in the 
orchards of Colorado and we hope that their use will not become 
necessary for many years to come. In any event, freight rates are so 
high as to make their use almost prohibitive, and then, the benefit 
to be derived from their use under Colorado conditions is problemati¬ 
cal as the following experience would indicate. 
Potato growers feel that they should grow two crops in succession 
after turning under alfalfa sod. The second crop, however, is rarely 
as good as the first and is very often produced at a loss. To one who 
is familiar with farming methods as practiced in the East it would 
seem to be a simple matter to bring up the yield of the second crop by 
an application of commercial fertilizers. Accordingly a series of acre 
plots were laid off in a potato field at Greeley to which commercial 
fertilizers were applied. High grade nitrate of soda, sulphate of 
potash and phosphoric acid in the form of dissolved bone meal were 
secured and applied separately and in various combinations. These 
experiments were carried through four years and at the end of that 
