86 Fruitgrowing under Irrigation 



addition to this, nitrogen is required. If the soil is 

 well supplied with humus, the nitrifying bacteria in 

 the soil will supply a considerable amount of the 

 nitrogen that is needed, and in that case the large 

 amount of nitrogen that chemical analysis shows is 

 necessary for the successful growth and fruiting of 

 citrus, need not all be put back into the land in the 

 form of artificial fertilizers. Still, it is doubtful if 

 this sort of nitrogen supplies the trees with all the 

 food of this class that they require ; even on soils 

 containing a fair humus supply, and a dressing of a 

 couple of cwt. to the acre of nitrogenous manures 

 every second year will probably be needed on most 

 soils. 



METHODS OF APPLICATION. 



Different classes of fertilizers, may be applied at 

 various times of the year. Such slow-acting 

 manures as vegetable mould or bone dust, which 

 contain ingredients not easily leached out of the soil 

 by rain or irrigation, may be applied during winter 

 or early spring, as but little plant food would be lost 

 before the root activity commences. On the other 

 hand fertilizers containing highly soluble ingredi- 

 ents, such as most mineral superphosphates and 

 the various classes of nitrates, are best applied dur- 

 ing early spring or summer when the roots of plants 

 are active. Generally speaking, phosphates should 

 not be put into the ground later than October if the 

 current crop is to receive their full benefit, but 

 nitrates may often be advantageously applied, as in 

 the case of citrus, during summer as well as spring- 

 time. 



Manures may be put into the ground either by 

 being drilled in, broadcasted and ploughed in, or by 

 being scattered along the bottom of plough furrows 

 and ploughed in. Drilling in manures with the 



