76 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



plenty of organic matter to furnish nitrogenous plant-food and 

 to favourably influence the supply of water. It is for this reason 

 that horticulturists find leaf-mould, pasture-turf soils, and 

 peat soils so beneficial for plant-growing. 



The total quantity of nitrates found in fertile soils is very 

 considerable. Table VI. shows the amount of nitrogen as 

 nitrates in drainage water passing through an unmanured soil 

 and a recently dunged soil. The quantities are given in pounds 

 per acre during each of the seasons of spring, summer, autumn, 

 and winter ; also the total amount for the whole year. 



TABLE VI. — Nitrogen as Nitrates in Drainage Water. 

 Quantities in pounds per acre. 



Seasons 



Unmanured soil 



Dunged soil 







lbs. 



lbs. 







19-5 



46-1 







13-5 



22-2 



Autumn . 





28-3 



38-2 



Winter . 





13-5 



17-4 





Yearly total 



74-8 



123-9 



The figures show that in the unmanured soil nearly 75 lbs. 

 of nitrates were produced in the year, whilst in the dunged soil 

 about 124 lbs. were produced in the year. In the unmanured soil 

 the largest production of nitrates was in the autumn, while in 

 the dunged soil the maximum amount was formed in the spring. 

 But it may be well to note that the whole of this nitrogen would 

 not be available to our ordinary cultivated crops, for the reason 

 that many of them only assimilate the spring or early summer 

 nitrates, the principal growth and power of assimilation having 

 ceased by the month of July. 



Vegetable crops, such as cabbage, beet, onions, turnips, 

 carrots, parsnips, celery, peas, &c, may still get hold of 

 summer-formed nitrates, but that produced late in autumn and 

 winter is of little use in so far as this applies to outdoor plants. 



The spring nitrification of the soil is, as a rule, quite in- 

 sufficient to meet the food requirements of early-sown spring 

 crops ; hence the advisability of using some stimulating manure, 



