324 



THE TROPICAL AGRICULTURIST, 



[October i, 1882. 



Virgin soils usually contain all the elements required 

 and in safficieut quantity to render any further addition 

 urmecessary, and they can usually be cropped for a con- 

 siderable time before any appreciable decline in the pro- 

 duce is noticeable. If the same plant is grown year after 

 year, and the produce is continually being removed, the 

 decline makes itself manifest in a shorter time, since the 

 soil will become exhausted of one or more of the con- 

 stituents necessary for the structure of that plant, which 

 may have beeu present in undidy small quantity originally. 

 It is better, therefore, not to grow one kmd of plant 

 on the same soil continually, but to change it after the 

 first year for another which has a different composition, 

 and which therefore would exhaust the soil of other ele- 

 ments, or at all events, the same elements in different 

 proportions. This is the reason that rotation of crops is 

 practised. For instance, mangolds and swedes require 

 the .same compounds in almost the same proportions in 

 several cases; They each require large amounts of sodium 

 and potassium compounds in proportion to others, and 

 therefore it would be unwise to cultivate them in the 

 same soil for following years. Those salts whish become 

 deficient could certainly be added, but still unless every 

 compound taken by the plant were replaced in proper 

 quantity there would be exhaustion of the soil and a 

 poor produce. 



It is clear that we cannot go on indefinitely removing 

 Baits from the soil, and there consequently comes a time 

 when no species of plant will thrive on the impoverished 

 land, and here chemistry steps in to again make the 

 soil fertile. 



Before the time of Sir Humphrey Davy, farmers in this 

 country had altogether worked by rule of thumb ; they 

 had used no fertilizers whatever, except perhaps the 

 dung of the animals on the farm, and through continually 

 robbing the laml of its necessary constituents, and not 

 replacing them, it was getting into an impoverished state. 

 Scientific information was for a long time disregarded, 

 and it took a great deal of time and trouble to drive 

 into the farmers the benefits of scientific farming. Indeed, 

 the British farmer still, in many instances, asserts his 

 national obstinacy by refusing to consider anything of a 

 scientific character as worthy of his serious attention. 

 Happily, however, he is not altogether deprived of the ad- 

 vantages of science, since he closely watches his neighboui', 

 who probably does beheve in science, and when the results 

 are more favourable than his own, he often copies the 

 method of obtaming them, although he stiU denies the 

 assistance of science. He thus reaps the benefit indirectly. 

 Scientific farming was established on a firm basis in 1840, 

 when Liebig pubUshed his 'Agricultural Chemistry,' and 

 for the first time publicly announced his theory that all 

 the salts taken from the soil by crops must be returned 

 to it in the same quantity. He put the matter, which 

 had hitherto been in a very unsettled state, in a clear 

 form, and traced the Ufe and constitution of the plant 

 to its elements in a manner as convincing as it was new. 

 Scientific farming consequently received a great impetus, 

 unfortunately to be again checked, as the farmers found 

 that the increase in the crops, in many cases, did not pay 

 for the fertilizers they had been advised to add. 



Liebig considered that the inorganic salts only required 

 replacing in the soil, and that the plant derived all its 

 organic elements from the atmosphere. Lawes, however, 

 showed the cause of the failure of the exclusively rnineral 

 fertilizer by proving that plants were not able to assimilate 

 the nitrogen contained in the atmosphere, and that there- 

 fore some compound containing nitrogen must be added 

 to the fertilizer. This admixture was found to give ex- 

 cellent results, and finally established agricultural chemistry 

 as a science. It is now only exceedingly stupid farmers 

 who scoft' at scientific farming, and most of them, to a 

 greater or less extent, avail themselves of its advantages. 

 There are still some who are sceptical, but I should 

 think that the majority of these are people who have 

 been swindled by unscrupulous dealers in f ertihzers. Although 

 farmers have been considerably educated of late, they 

 require to be a little more so. 



They have been educated, or driven, to the conclusion 

 that they must use fertiUzers, but they require educating 

 to the further extent that before they buy they should 

 know what the soil is short of, and then know that 



they are getting the fertilizer which will supply those 

 elements which are deficient. 



I am afraid that farmers, in buying a fertilizer (often 

 the ^vrong one), are sometimes atrociously swindled by 

 some manufacturers or their agents, by being supplied 

 with rubbish not worth a tithe of what is charged for 

 it. But such is the peculiar idiosyncrasy of the British 

 farmer that he will rather buy his pig in a poke for, 

 say £100, than pay about a guinea to look at it, and 

 by so doing save perhaps £75. I mean by looking at 

 his pig, that on buying he should have an independent 

 analysis made by a competent chemi-st, and then he will 

 know that he is getting the stuff he has paid for. 



Happening to pass through a farmyard several years ago, 

 I noticed a quantity of superphosphate of lime lying under 

 a shed, and I asked the farmer, whom I knew, what he 

 had paid for it. " £10 per ton," was the answer. I next 

 asked him if he bought it on analysis : he replied in the 

 negative. From the appearance of it I judged it to be 

 of very inferior quality, and, for CLuiosity, took a sample 

 and analysed it, with the following result: — 



Water 13S6 



Organic matter* 17'94 



Soluble phosphate of lime 2*70 



Insoluble phosphate 21"49 



Gypsum 3074 



Sand 8-28 



Oxida of iron, etc 499 



lOO'OO 



I forwarded the result of my analy.sis to the farmer, 

 and told him that I did not consider it worth more than 

 £1 15s per. ton, and that the price charged for it was 

 a gross imposition. He confronted the manufacturer with 

 my analysis, and this person accepted, on the face of 

 this, £10 for the lot, which was over 6 tons. I met the 

 farmer about a year ago. He told me that he had bought 

 no more stuff from this man, but was dealing with 

 another firm. I said, " Of course you are getting this 

 lot analysed?" He repUed, "Oh, no, I did not think it 

 worth while ; they seem to be a respectable firm." The 

 faith of that man in human nature was so touching, that 

 I said no more, but formed my own conclusions, which 

 were not very flattering to the individual in question. 



Then suppose the farmer goes to an honest manufact- 

 urer or dealer, aud gets what he orders at a fair market 

 price. Unless he knows what the soil is .short of, he is 

 very Ukely wasting his money in buying an article which 

 the land does not want. If, say, he wants to grow carrots, 

 potassium salts will probably be deficient. It is of no use 

 his buying phosphates, salt, etc., and manuring the land 

 with these (if these substances are already there in sufficient 

 quantity); as long as the deficiency in the potassium 

 salt is not made up, so long will the soil yield poor crops 

 of carrots. It is, therefore, of the utmost importance 

 that the farmer should know what the crop takes from 

 the soil, and what the soil has already in it, or at all 

 events, leave it to someone who does know these things, 

 and knows how to replace any deficiency. 



I have known farmers who have had hme recommended 

 to them as a manure. Lime, in its place, is certainly an 

 excellent manure, especially on stiff, clayey, or sour ground. 

 These farmers tried the lime, aud found at first, a natural 

 increase in the crops. But they went on repeating the 

 same application year after year, until now they are 

 really doing the crops harm. 



For instance, a wheat straw with excess of lime in its 

 constitution is much more brittle than the normal straw, 

 and is therefore not able to withstand the beating and 

 levelling effects of win<l and rain. Normal and healthy 

 wheat may be quite flattened by heavy raii^s, but such 

 is the elasticity of the straw that it will grailually recover 

 its vertical position. A limy straw on the contrary, if 

 flattened, breaks off, aud consequently dies, and rots 

 away. As with the animal, so with the plant. If a man 

 takes too much carbon ami hydrogen, in proportion to nitro- 

 gen, in his food, he becomes inconveniently stout, and if 

 he takes too much nitrogen, he is also inconvenienced. 

 Again, it is necessary that the food should be suppUed 



* Containing nitrogen 

 Equal to ammonia 



■10 per cent. 

 ■12 



