484 BOARD OF AGRICULTURE. 



and speaks strongly in favor of clover as a preparatory crop for 

 wheat. 



Nitrate of soda, an excellent spring top-dressing- for wheat and 

 cereals in general, in some seasons fails to produce as good an 

 effect as in others. In very dry springs the rainfall is not sufficient 

 to wash it properly into the soil and to distribute it equally, and in 

 very wet -seasons it is apt to be washed either into the drains or 

 into a stratum of the soil not accessible to the roots of the young 

 wheat. As therefore the character of the approaching season can- 

 not usually be pi'edicted, the application of nitrate of soda to wheat 

 is always attended with more or less uncertainty. 



The case is different when a good crop of clover hay has been 

 obtained from the land on which wheat is intended to be grown 

 afterwards. An enormous quantity of nitrogenous organic matter, 

 as we have seen, is left in the land after the removal of the clover 

 crop; and these remains gradually decay and furnish ammonia, 

 which at first and during the colder months of the year is retained 

 by the well known absorbing properties which all good wheat soils 

 possess. In spring, when warmer weather sets in, and the wheat 

 begins to make a push, these ammonia compounds in the soil are 

 by degrees oxidized into nitrates ; and as this change into food, 

 peculiarly favorable to young cereal plants, proceeds slowly but 

 steadily, we have in the soil itself, after clover, a source from which 

 nitrates are coiitinuously produced ; so that it does not much affect 

 the final yield of wheat whetlier heavy rains remove some or all of 

 the nitrate present in the soil. The clover-remains thus afford a 

 more continuous source from which nitrates are produced, and 

 greater certainty for a good crop of wheat than when recourse is 

 had to nitrogenous top-dressings in the spring. 



The remarks respecting the formation of nitrates in soils upon 

 which clover has been grown, it should be stated, do not emanate 

 from mere speculations, but are based on actual observations. 



I have not only been able to show the existence of nitrates in 

 clover soils, but have made a number of actual determinations of 

 the amount of nitric acid in different layers of soils on which clover 

 had been grown ; but as this paper has grown already to greater 

 dimensions than perhaps desirable, I reserve any further remarks 

 on the important subject of nitrification in soils for a future com- 

 munication. 



