June, 1910.1 



518 



Scientific Agricuture, 



Nitro-bacterine, therefore, falls into 

 the same category as Moore's cultures 

 of nodule-forming bacteria. The latter 

 were dried on cotton wool, and distri- 

 buted by the U. S. Department of Agri- 

 culture many yeais ago. But the distri- 

 bution was abandoned, because it was 

 impossible to preserve the bacteria in 

 that way, and therefore the cultures 

 were valueless. When nodule-forming 

 bacteria are dried they die, and for that 

 reason nitro-bacterine cannot contain 

 any. 



ARTIFICIAL MANURES. 



(From the Madras Agricultural 

 Calendar, 1909.) 



Plants remove certain mineral sub- 

 stances from the soil which they utilise 

 as food, and it is upon the presence of 

 these substances that the fertility of a 

 soil largely depends. The amount of 

 them in the soil is limited, and sooner or 

 later, if no provision is made to replace 

 those removed by the crops, the residual 

 amount of one or more is insufficient for 

 the needs of the plants, and impover- 

 ished crops result. The supply of plant- 

 food in the soil is kept up by adding 

 farm-yard manure or artificial fertilizers 

 or by green-manuring, etc. 



Unlike farm-yard manure which sup- 

 plies all the different kinds of plant-food 

 required in the soil, artificial manures 

 supply only one or at most two of these 

 substances, and it is necessary to make a 

 judicious selection in order to correct 

 the deficiencies in the soil. For example, 

 the application of phosphate to a soil in 

 need of potash would merely result in 

 loss to the cultivator. 



Many artificial manures are liable to 

 be washed out of the soil by rain or irri- 

 gation water, and others are destroyed 

 by the action of micro-organisims, so 

 that there is great danger of loss if more 

 is supplied to the soil than is necessary. 

 Only tliat portion of the fertilizer which 

 is recovered in the crops is of value, and 

 the residue must necessarily remain until 

 the next crop is on the ground, repre- 

 senting so much capital which returns 

 no interest. Under these circumstances, 

 the object to be aimed at in applying 

 artificial manures is to supply sufficient 

 food to the soil to satisfy the require- 

 ments of the succeeding crop only. In 

 other words it is to feed the crop and 

 not to enrich the soil. A well-chosen 

 artificial fertilizer should act promptly 

 and decisively on the crop to which it is 

 applied. 



Artificial fertilizers are spoken of as 

 either " slow " or 41 quick " acting, accord- 



ing to the length of time over which 

 their effect is felt by succeeding crops. 

 Thus superphosphate is quick-acting and 

 its effects are chiefly felt by the crop 

 immediately following the application, 

 but bone-meal is a slow-acting manure 

 as it only gradually becomes available 

 as plant-food and its effects are felt over 

 several successive years. In this con- 

 nection it must be remembered that the 

 same amount of plant-food applied in 

 the form of superphosphate or bone-meal 

 has only the same total effects on the 

 crops, and that with bone-meal the only 

 difference being that in the case of bone- 

 meal it is spread over a number of years, 

 during which the capital represented by 

 it is bringing no return and much loss 

 may occur. 



Considerable skill is required in the 

 application of artificial manures both as 

 regards time and method; but in this the 

 properties of the fertilizer may be taken 

 as a safe guide. The easily soluble 

 quick-acting manures are preferably 

 applied when there is a prospect of a 

 vigorously growing crop to make use of 

 them. For example, nitrate of soda 

 should never be applied until there is a 

 crop on the grouud, as there is great 

 danger of its being washed out of the 

 soil. The same applies to ammoniacal 

 fertilizers, for, although the soil has a 

 strong retentive power for it, it is soon 

 converted into nitrate and washed out. 

 The fact that soil retains ammonia make 

 the application of this preferable to 

 nitrate for wet lands and in wet 

 weather. 



Phosphatic and potassic fertilizers are 

 retained by the soil and their time of 

 application may be determined by 

 their convenience ; superphosphate, for 

 example, is commonly drilled in with the 

 seed or broadcasted the same day as 

 sowing. Slow-acting manures like bones, 

 basic slag, etc, may be applied many 

 months before sowing. 



On light open soils possessing little 

 retentive power it is better to use 

 slightly soluble manures in preference to 

 soluble manures which would easily be 

 washed out. 



Artificial manures do not provide any 

 organic matter for the formation of 

 humus and consequently in soils natur- 

 ally poor in this constituent, like many 

 Indian soils, long coutinued applications 

 of them lead to a reduction of the humus 

 and a consequent alteration of the con- 

 dition of the soil. This change may 

 have serious effects on subsequent crop- 

 pings. Undoubtedly the best method to 

 use artificial manures is in conjunction 

 with bulky organic substances such as 



