EXPERIMENT STATION BULLETINS. 



497 



combined with the free use of the disc and fall plowing, wherever possible, 

 are very important practices. Soils that are high in organic matter and 

 are not deficient in lime are far less difficult to maintain in a well granulated 

 condition or in good tilth, than are those that are deficient in these. 



Ferlilizaticn. The chemical composition of these types show an abundant 

 supply of plant-food elements with the exception of phosphorus. Though the 

 supply is abundant it should not be overlooked that the plentiful elements 

 should in no way be wasted but maintained or increased. 



Nitrogen. Without doubt the cheapest means of maintaining the supply 

 of nitrogen is by the production of leguminous plants. When such crops are 

 turned back to the land or fed to stock and the residue and manure properly 

 cared for and applied to the soil they may add a large amount of this 

 element. 



Fig. 8. — Small grains produce well on the silt loam soils when well drained. 



afford evidence of fertile soils. 



The farmsteads usually 



Good rotations will include at least one legume every fourth year. _ The 

 standard rotations for heavy soils are given in figures. When the price of 

 seed is not too great, the sowing of clover with wheat and oats, the same to 

 be turned under in the autumn is good practice. Such systems and the high 

 nitrogen content of these soils make the use of commercial nitrogen un- 

 necessary except in small amounts in some cases to assist in early growth. 



Phosphorus. The element phosphorus commonly spoken of as phosphoric 

 acid, the supply of which is somewhat limited in these soils, is contained 

 largely in the seed or grain of crops. Where grain farming is practiced, as 

 it is on these types, we can logically draw the conclusion that large amounts 

 of phosphorus are removed from the soil. It is true some of this valuable 

 element is returned to the soil by means of crop residues and manure but the 

 amount so returned on the average farm is small in comparison with that 

 which is taken away by the crops.* Where barnyard manure is applied 



*For suggestions concerning the use of phosphates send for Popular Bulletin 284, Michigan 

 Agricultural Experiment Station. 



63 



