128 CROP GROWING AND CROP FEEDING 



organic matter of the clover and manure applied to the corn crop in a three 

 year rotation, all the nitrogen the wheat will need; and we need but con- 

 sider the needs of the crop as regards the phosphoric acid and potash, and 

 to ascertain what the needs of the soil are as regards these. The maturing 

 of the seed of the plant draws more heavily on the phosphoric acid in the 

 soil than it does on the potash, and hence the relative greater importance of 

 the phosphoric acid in the fertilizer. Then, too, we find that in order to get 

 best results from an application of potash it is essential that it be accom- 

 panied by a due proportion of phosphoric acid, since neither potash nor 

 phosphoric acid will have as good effect applied alone as in combination. 

 With nearly all the cereal grains it will be found that phosphoric acid is the 

 controlling factor in any mixture. But in clover the proportion of potash 

 is considerably larger than that of phosphoric acid. Then in devising a fer- 

 tilizer for the wheat crop on which we propose to sow clover it will be wise 

 to regard the needs of the clover for potash, and supply it; for we may rest 

 assured that the soil will hold on to it for the clover, even if the wheat does 

 not need it. A crop of two tons of clover hay per acre will require for the 

 hay alone 82.82 pounds of nitrogen, 15.2 pounds of phosphoric acid and 88 

 pounds of potash. The nitrogen it will get largely from the air, but the 

 potash must be in the soil. In this we take no account of what is in the 

 roots and stubble, as that goes into the soil, but the amount of potash in the 

 hay is seen to be large, and must be supplied to make the best crop. 



THOROUGH PREPARATION OF THE SOIL AS IMPORTANT AS FERTILIZERS FOR 



WHEAT. 



A hard lump of phosphatic rock may lie in the soil for generations 

 and produce little effect on the vegetation. But let that rock be pulverized 

 to an impalpable powder, and scattered through the soil, and the effect will 

 soon be apparent. In a similar manner, a hard lump of soil may have in 

 it a store of plant food, but the roots of the plants cannot get at it ; and the 

 lumpy character of such soil renders it liable to dry out rapidly and thus 

 prevent the proper solution of the plant food that may be in the soil, either 

 naturally or applied in the fertilizer. 



While deep plowing is as essential to wheat growing as to that of any 

 other crop, the fine, searching roots of the plant require that the soil should 

 be in a completely comminuted state, and well settled, so that the plant food 

 can be released; and capillary attraction set up in the soil to keep up the 

 regular supply of moisture from below. If wheat is sown in a dry soil dur- 



