594 



THE TROPICAL AGRICULTURIST. 



[February 2, 1885. 



not by being eaten. Again, it is entirely non-poisonous to 

 vertebrates. A friend told me that he ate a tablespoonful 

 with no harm even to his digestion. 



" I have found the powder very effective to kill many 

 insects, when dusted on to them by use of a dust-bellows, 

 or sprayed on to them when mixed with water — one table- 

 spoonful to two gallons of the liquid — by use of a Whit- 

 man pump or when the alcoholic extract is applied as a 

 spray. We kill our house-flies, by dusting on the powder. 

 We do this as we retire at night, and can sweep up the 

 dead or paralyzed flies the next morning. I prefer to kill 

 cabbage-worms, slugs, etc., by spraying with the liquid 

 mixture. I have not seen the article you mention, so can- 

 not say as to the correctness of its representations, but I 

 do consider pyrethrum a very valuable insecticide, especi- 

 ally the buhach, which is more apt to be pure and fresh. 

 \Yhile many of our worst insect pests are quickly killed 

 by use of this powder, I have found that some bugs and 

 a few beetles are proof against it. In all our use of this 

 substance, when dusted into close rooms like living-rooms 

 or chicken-houses, the dust comes in contact with flies, 

 lice, etc., and quickly kills. We must put it immediately 

 on the insects, as its virtue is soon gone." 



It is a common practice of dealers to keep this powder 

 in open boxes or barrels, but it is evident, from Prof. 

 Cook's experience, that pyrethrum so kept must soon lose 

 its active properties, — Farm mid Fireside. 



ASSIMILATION OF MANURES BY THE SOIL. 



BY SIB J. B. LAWES, BABT., LL.D., F.E.S. 



In a previous article I pointed out that when a soluble 

 salt of potash, or a soluble phosphate, was applied to 

 the soil, plants which required these substances could 

 take them up in large quantities, but that in the course 

 of time they became fixed in the soil, and then were 

 not so readily taken up by plants. 



In some of our pasture experiments we apply annually 

 500 lb. of sulphate of potash per acre ; two crops of hay 

 are removed each year, and when the season is favour- 

 able, the crops carry off more than the whole of the 

 potash contained in the manure. Of these two manures 

 it may be said, therefore, that when first applied they 

 are readily taken up by plants, and if not taken 

 up at once they form fixed compounds with the soil, and 

 remain at the disposal of vegetation for very long periods of 

 time. 



With regard to the various compounds of nitrogen, 

 we can find no simple formula which can be applied in 

 a similar way. It may be said of ammonia, as it exists 

 in salts of ammonia — and possibly of ammonia in all 

 forms — that the process of its nitrification goes on in the 

 soil in the absence, and quite independent of, vegetation 

 growing on the surface, and that the nitric acid formed 

 is — in the absence of vegetation, or unless taken up by 

 vegetation — washed out of the soil. 



Nitrogen in the form of ammonia, or nitric acid, and 

 more especially in the latter form, is of the greatest possible 

 importance from the fact of its furnishing our crops with 

 their chief, if not their sole, supply of this substance, but 

 at the same time it constitutes but a very small amount 

 of the nitrogen which exists in our soils or manures. 

 Nitrogen in combination with carbon, or what is generally 

 termed organic nitrogen, is the main source of fertility, 

 and in the form of cattle food, manures, farmyard dung, 

 bones, and similar organic compounds, it will constitute 

 one of the chief items in the tenant's claim for unexhausted 

 fertility. To separate the landowner's organic nitrogen from 

 that of the tenant, and not only to assign to the latter 

 the proper amount of his organic nitrogen, but also to fix 

 the period at which it will assume its active form, will 

 constitute one of the chief difficulties of those who under- 

 take the responsible office of arbiters. 



The period of time at which we may expect a substance 

 applied to the soil to form part of the crop appears to 

 be full of difficulties. We have recently been making 

 some investigations in regard to the rate at which nitrific- 

 ation takes place iu soils and subsoils, aud we find that 

 some of the leguminous plants have roots extending 5 or 

 6 feet, and even in some cases more than that, below the 

 surface. We find, further, that organic nitrogen, as well 

 as nitric acid, is to be found at these depths ; it is evid- 



ent, therefore, that the large amount of nitrogen which 

 these leguminous plants take up, even when "grown upon 

 soils where cereal crops would find very little, may prob- 

 ably have its source at the same depth. 



My observation leads me to think that organic manures, 

 and such manures as potash and phosphate, descend 

 slowly into the subsoil, and are in some degree out of the 

 reach of the ordinary ' roots of plants, except when special 

 climatic circumstances favour the extension of the roots 

 of wheat and grass into the subsoil ; and I can always calcul- 

 ate on a large grow* than usual of these plants in the 

 experiments where the surface soil has been purposely ex- 

 hausted of its mineral good. The descent of manure 

 mto the subsoil proceeds very slowly, and even where we 

 have applied 14 tons of dung per acre annually for forty years, 

 the second 9 inches of soil contains comparatively but a 

 small amount of increased fertility. 



It is the practice of gardeners io place the manure in a 

 trench between y inches and IS inches from the surface, 

 and thus ensure subsoil fertility. The seconds inches of 

 my garden soil, which has received no manure for more 

 than thirty years, and during that period has grown 

 about one hundred large crops of red clover, is still very 

 rich in nitrogen. It is evident, therefore, that to exhaust 

 a soil of its ascumulated fertility is not so easy a process 

 as many would suppose, even on agricultural foil, as in 

 the ordinary practice of agriculture to get the land into 

 condition, and then to remove that condition, occupies the 

 larger portion of a nineteen years' lease. 



The Agricultural Holdings Act was passed in order to 

 prevent the necessity of this reduction of fertility. The 

 Newcastle Farmers' Olub has boldly attempted to grapple 

 with the question of compensation by valuation, based 

 upon the manure value of different goods, while the 

 Chamber of Agriculture and Clubs iu other countries pro- 

 pose to contract themselves out of the Act by the pay- 

 ment of a certain portion of the cost of the food. This 

 latter process appears to be much more likely to lead to 

 litigation, as although such an agreement may be made, 

 it is only to be binding on the condition of its being 

 fair and reasonable. Possibly some day the fact will be 

 recognised that the • cost and the manure value of goods 

 have no necessary connection with each other, and then 

 some landowner or incoming tenant will require to be 

 bound by the agreement. — N. B. Agriculturist. 



COCONUT PRODUCTS. 



The paragraph we extracted in our last issue from the 

 Observer, regarding the fattening of horses on coconut 

 meal iu France, was inadvertently published without our 

 remarks. Our contemporary, in referring to the success of 

 the experiment of feeding up horses with the meal inquired, 

 Can the demand for Copperah in France be due to this fact ? 

 Probably it is, but we fancy the chief reason why Copperah 

 is in demand on the Continent is for the oil for Soap Manu- 

 factories. Perhaps few have noted the extent to which the 

 exportation of Poonae itself has grown in recent years. 

 Mill I'oonac used to be almost a drug in the market, as 

 cart drivers and others preferred Chekku Poonae for their 

 cattle, owing to its containing more oleaginous, that is 

 nutritive matter. Mill Poonae, from which a larger percent- 

 age of Oil had beeu extracted by more effective grinding 

 and greater pressure, was chiefly used locally as a manure, 

 and the demand for export was almost nil. We believe 

 Mr. Alexander Stevenson maintained for a long time 

 the fertility of his Dimbula properties by manuring them 

 with unlimited quantities of Poonae from his Kelani 

 Ganga Mills. His Firm now exports the better part of 

 the refuse which he used to send upcountiv; aud during 

 a recent visit to the Hulftsdorp Mills, which wc were 

 enabled to pay through the courtesy of Mr. G. B. 

 Leechman, we saw large quantities being packed iu gunnies 

 for export. The price at which the Poonae sells has more 

 than doubled — R45 per tou being now the price, as against 

 R20 in former years. According to the Customs Returns 

 for 1883, over 40,000 cwt. were exported that year, France 

 taking the largest quantity, viz., IS, 100 cwt. We 

 have little doubt that most of Ibis Poonae is used in the 

 preparation of cattle food, and in the feeding up of horses, 

 although we have heard that the voyage transforms some 

 of it to linseed meal as well ! The market for Poonae 



