35° 



THE TROPICAL AGRICULTURIST. 



[October i, 1882. 



-»- 



To the Editor of the Ceylon Observer. 

 NITRATES IN AGRICULTURE: 



THE PAST AND F0TURB OP COFFEE PLANTING — LOSS 

 FROM BURNING WEEDS. 



August 2Sth, 1882. 



Deak Sir,— In his closing remark in your issue of 

 22ud inst. — " aud further that it is not to the loss 

 of nitrates that we are to look for the explanation 

 of our present short crops." — " W. D. B." does not 

 directly tux me to the contrary, and this remark may 

 not have been esppcially, or in this sense, directed 

 against my previous letters. But it is a point I am 

 anxious not to be misunderstood on. Nothing I 

 have said can be fairly construed into implying this. 

 On the contrary, the widespread and persistent short 

 crops of late years, I as fully feel, are to be attributed 

 to other causes. This is the more manifest in the 

 face of shortcomings, even when cattlo dung has been 

 liberally applied. All I have supposed, and venture 

 still to s.iy, is that, as in the case of, I believe, every 

 other cultivation, nitrogen ia a most important element 

 both in the economy of the plant and for the develop- 

 ment of the bean. The same can no doubt be said 

 with equal truth of phosphoric acid, potash, lime, 

 &c. Does not M. Ville in other words tell us so ? 



But to turn the tables : " W. D. B." 's letter would 

 almost permit the inference that he regards nitrogen 

 as an item of comparatively small importance, or that 

 it is forced on us naturally, in our excessive rainfall 

 80 liberally — a sufficiency of the latter being absorbed 

 as it is — that the subject is at least one proprietors 

 need not feel anxiety on or trouble their heads about ! 

 Now — without referring to Hughes or the many other 

 agricultural scientists, who, even before they knew of 

 losses that may be attributable to nitrification, laid 

 stress on the importance to us of abundance of niirogen, 

 ■ — it is here I cert.aiuly cannot agree with him : that 

 after a series of years, during which little has been 

 removed by crop, or in soil known meanwhile to be 

 rich therein, he is right in confining manuring oper- 

 ations to the application of phosphoric acid, potash. 

 &c. In fact, whatever his soil is deficient in, in what 

 the chemists would call " an elegant form," I fully 

 believe. But wait a wee! It stands toreasnn that, 

 given 4 lb. of beef — though it may amply suffice for 4 

 days — if you will allow your dog to steal half of it, you 

 must lower your conditi-m on insufficient ration?, or 

 at the end of the second day piirchase fresh supplies. 

 And so, depend on it, jour correspondent will find. 

 With but shori crops, and as long as the soil con- 

 tains abundantly an unexhausted store of nitrogen, 

 extraneous supplies would be waste, and may for a 

 long time be found unnecessary. But let, as I hope, 

 and it would so far lead us to anticipate, his present 

 system of manuring result in continued crops of 7 

 to 8 cwt. per acre, my belief is that he will find 

 the supply insufficiently maintained by the small pro- 

 portion of the amount nature offers through the me- 

 dium of rainwater which he cares to accept under 

 the present system as it stands. He will then see 

 the necessity of devising means to do, as I said : 

 " clean rob every drop that falls of all its riche.s." 

 And further than this, unless by some means an 

 entire check be placed on losses by nitrification, I 

 venture to believe that it won't be many years before 

 he is in the market for heef (nothing in reality better 

 for the purpose !) — or shall we say white castor cake 1 ! 

 Further, if, as I confess I infer, he has such au entire 

 confidence in the superabundant amplitude of our 

 natural supplies of nitrogen, it leads up to a conclu- 

 Bion that the high value hitherto set on cattle man- . 



ure (and especially cake fed) is little better than a 

 popular delusion, for. though it be true that it contains 

 phosphoric acid, potash, &c., in fair quantity, nitrogen 

 is, or I am wrong, its dominant element of fertiliz- 

 ation, and the one on which its value has been con- 

 sidered predominantly to rest — a conclusion I don't 

 think many of our most experienced planters will 

 readily accept ! I grant though that I have often 

 thought that, if, by the application of gypsum, or other- 

 wise the ammonia in it could be fixed, a very great 

 saving in the cost of application (transport) might be ef- 

 fected—on the presumption that this would permit of 

 the manure being dried, thus ridding it of a very 

 heavy portion of its extraneous matter in the form of 

 sterile moistm-e. I believe it is right to say that M. 

 Ville disapproved cattle manure only as bein;; a ci!(m«y 

 manure ; aud that he attached no less importance to 

 nitrogen in abundance, I think the following extract 

 shews conclusively: — "Professor Ville found that the 

 conditions most favorable to fertility consisted in the 

 union of 4 substances, nitrogenous matter, calcic 

 phosphate, potash, and lime, to which he has 

 given the name of normal manure. His experi- 

 ments with these materials were most interest- 

 ing. Without manure at all, the soil produced 

 12 bushels of wheat. With chemical manure, 

 but without nitrogen, the yield was 18 bushels. 

 Treated with nitrogenous matter but without mineral 

 the yield was 22 bushels. But treated with normal 

 manure the yield jumped up to 50^ bushels per acre ! " 

 It is adverse to sound argument, and to resolve a 

 discussion into a waste space and paper, to attach mean- 

 iugs to a writer that caunot be fairly construed from 

 his words. I would therefore carefully guard against 

 implying that "VV. D. B." attaches no importance to 

 nitrogen ; but that he does seem to be over-confident of 

 the magnitude of our natural supplies, or too lightly 

 regards the necessity of conserving those supplies ; 

 that he does not apparently consider that, if the days of 

 abundant harvest return permaneuttj, any losses in this 

 direction will have lo be made good at their equivalent 

 value artificially, if I interpret his views rightly. 

 Your correspondent may be right but I think not. It 

 is true I did not take the power of suction exercised by 

 ciivored-in drains into account, and, if it be a power, 

 this truly would point to less loss bv a system of open 

 drains. But it must be remembered that, in the 

 Rothamstead experiments, drains but 20 niches deep 

 earned off the largest quantity o'f nitrates; and he can- 

 not surely mean that none but the surplus surface water 

 passes into uncovered Ariaaa ; that a large quantity does 

 nut in times of heavy rain filter through the soil into them, 

 or that Ibis water contains no appreciable proportion 

 of nitrates ? Again, allowing that the nitrates do .all sink 

 down into the subsoil, is he justified in assuming that 

 they remain indefinitely, or for a sufficient length of 

 time, within access of the roots ? I make no assertion 

 to the contrary but are there not stronger reasons for 

 supposing so in the case of a free soil? Can "W. D. B." 

 say that on digging out old bushes he has found the 

 roots to a depth he would, judging from Mr. VVaring- 

 ton's experiments, believe sufficient, aud in sufficient 

 numbers, to take them all tip again as required ? Or 

 on a stiff, clayey soil, presuming that this does absorb 

 and retain the nitrates near the surface, does not the 

 manner in which the roots of a well-grown young plant 

 are often to be found confined within the hole cut for 

 it, as in a flower-pot, lead to a doubt whether the 

 roots of even an old tree can get at them in such a 

 soil with sufficient readiness? Convert it into a free 

 soil by cultivation, digging, &o., without some counter- 

 check, you at once open the door to their escape ? If it 

 be true a- to the power of cLiy soils to hold nitrates or 

 check nitrification, it may account for their often great 

 fertility when worked up and sweetened by limn, draining 

 &c, That " W. D. B. " sets no too high a value on 



