March i, 1886.] THE TROPICAL AGRICULTURIST. 



635 



does not leave any after-beuetits ; but the good effects 

 of the Intter are found to extend over so me three or 

 our seaso is. 



Passing ou uow to notice the various experiments 

 in detail, we come first to those tried on permanent 

 meadow laud, Twenty different plots of grass land 

 are under investigation; the present being the thirti- 

 eth seasoo to which the experiments have extended. 

 The operations comprise the use of a mixture of a 

 small proportion of ammonia salts (the mixture of 

 sulphate and muriate) with farmyard manure; of each 

 singly ; and of superphosphate of lime — made by mix- 

 ing ilK) lb. of bone ash with 150 lb. of sulphuric acid 

 tsp. gr. V700) and water — with and without ammonia 

 salts, also with the addition of sulphates of potash, 

 sods, and n)asnesia. Silicate of soda and cut wheat- 

 straw were also used in some of the mixtures; and 

 some plots were left unraanured. 



The art of manuring is sometimes defined as giving 

 back to the soil that which is removed by the plants ; 

 but these experiments show that it is of a much more 

 complex description. If this idea is correct, it should 

 follow that land left uumanured would show a grad- 

 ually decreasing yield. This appears to occur to some 

 small extent ; insomuch that land to which manure 

 was not applied yielded rather lower results in the 

 second ten years than in the first. One plot left in 

 this condition yielded an average annual production 

 of 22^ cwt. of hay per acre during the first ten years, 

 and 20 cwt. in the second ten years ; another plot 

 yielded 25 cwt. per acre for the first period, and 22^ 

 for the second. But this variation between one period 

 and another is not so great as that noticeable in some 

 of the manured plots. One very instructive experi- 

 ment bearing on this point is that tried ou plot 18, 

 which was treated with a mixture supplying the quant- 

 ity of potash, soda, lime, magnesia, phosphoric acid, 

 silica, and nitrogen contained in a ton of hay, as 

 ascertained by analysis. It is very natural to suppose 

 that this would be ne plus ultra of manuring ; but, 

 although an increased yield was obtained, the result — 

 o3J cwt. as the average annual production per acre 

 during a period of ten years — is very low in compari- 

 son with other results. 



Turning to the advantages gained by the use of 

 sulphate, it appears that although, when the ammonia 

 salts are used singly, these results are not so good 

 as those following the use of a corresponding quantity 

 of nitrate, the former is superior to the latter when 

 mixed with other substances. The best results ob- 

 tained — 6.^7 cwt. of hay per acre per anuum — resulted 

 from the use of a mixture of the sulphate of potash, 

 soda, and magnesia, suiJerphosphate, ammonia salts, 

 and silicate of soda. The effect of leaving out the 

 ammonia salts from this mixture was very marked ; 

 the yield being reduced to somethiug like one-half. 

 The ammonia salts also have a marked effect iu in- 

 creasing the value of farmyard manure. Using singly 

 14 tons per annum of this material gave a yield of 

 425 cwt. ; but the addition of the comparatively small 

 quantity of 200 lb. of ammonia salts increased this to 

 49.^ cwt. — some 12 or 13 per cent. Only in one case 

 (No. 14) does the use of nitrate of soda in a mixed 

 manure approach the results afforded by the ammonia 

 .salts. In this case a production of 60^ cwt. is ob- 

 t.ained ; but all the other nitrate mixtures fall very 

 far short of this. 



The experiments 011 barley show that farmyard 

 manure gi\es the greatest production, and that the 

 ammonia salts yield slightly lower results, when utilized 

 as a source of nitrogen, than the nitrate of soda. 

 M'hen used for wheat, however, these salts occupy 

 a better position, and compiire fairly well with the 

 nitrate. Some excellent results were obtained by em- j 

 ploying a mixture of ammonia salts, superphosphate, 

 ami one or more of the sulphate of the fixed alkalies. ' 

 With regard to oats, broadly the results are about 

 the same as these obtained with wheat. Ammonia 

 salts and niti-ate, respectively used singly, are about 

 on a par ; and the former show a slight a'iv.intage 

 when used in mixtures of the character above indic- 

 ated. It is important to rem»n)ber that 400 lb. of 



ammonia salts are equal, in respect to nitrogen, to 

 550 lb. of nitrate ; and these are the relative pro- 

 portions maintained throughout the experiments. 

 Taking the value of nitrate at £10, the ammonia salts 

 are therefore worth £13 to .£14 per ton. Vulue for 

 value in the market, then, ammonia salts are superior 

 to nitrate for grain crops. Generally speaking, the 

 utility of a nitrogenous manure iurespect to grain is 

 very marked ; the crops being freqtieutly doubled by 

 its use. 

 A set of experiments was tried with oats, using 

 i the mineral manure as before, but only half the 

 quantity of nitrogenous manures, A considerable 

 diminution in yield was the result ; but it is remark- 

 able that, under these circumstances, the ammonia 

 salts secured better results than the nitrate. The 

 unmanured land yielded an average of 13| bushels 

 of oats per acre per annum. The effect of using 

 200 lb. of ammonia salts per acre was to more than 

 double this yield ; the result being 28^ bushels. The 

 use of a corresponding proportion of nitrate — viz., 

 275 lb. — secured a return of 26^ bushels. The results 

 from the mixed manures are still more remarkable. 

 When nitrivte was used as the source of nitrogen, 

 the results were no better thau those seciu-ed by the 

 use of ammonia salts singly— viz., 2SJ bushels ; but 

 when ammonia salts were u.sed, the yield was 3S 

 bushels. The mixture which secured this result con- 

 sisted of 200 lb. of sulphate of potash, lOfi lb. each 

 of the sulphate of soda and magnesia, 3.^ cwt. of 

 superphosphate, and 2o0 lb. of ammonia salts. The 

 effect of leaving out the ammonia salts (all the other 

 ingredients being used) was to render the manure 

 perfectly valueless; the result obtained being only 13j 

 bushels, or rather less than the yield from the uu- 

 manured land, 



A difficulty was experienced iu the application of 

 the nitrate on these plots, and possibly was the cause 

 of the experiments noticed in the preceding paragraph. 

 ■\Vhere the nitrate had been applied, year after year, 

 the land was so wet that it could not be brought 

 into favourable condition for sowing, although more 

 work was applied to the land ; and the plants in con- 

 sequence came up very irregularly. In one season a 

 heavy fall of snow a week after sowing caused many 

 of the plants ou the nitrate plots to perish from 

 standing surface water. Tlicse difficulties, due to the 

 deliquescent character of the uitrate, to a large extent 

 account for the low results obtained from this sub- 

 stance, as above noted. The user ot nitrate is evidently 

 under .some difliculty iu respect to drainage. If the 

 land treated with the salt is iusuflicieutly drained, it 

 retains moisture so obstinately as in some cases to 

 kill the young plant; aiul if ample drainage is jiro- 

 vided, there is tho risk of its runuiug oil' to waste 

 before it has done its work. 



The results obtained with bean.s, peas, clover, kc, 

 are rather difficult of explanation. The mineral con- 

 stituents used as manures (more particularly potash) 

 increased the produce very much during the early 

 years, and to a certain extent afterwards, when the 

 season was favourable. Ammonia salts produced but 

 little effect, notwithstanding that a leguminous crop 

 contains two, three, or more times as much nitrogen 

 as a cereal one grown under similar conditions as to 

 soil, &c. Nitrate of soda produced more marked effects. 

 But when the same description of legumiuous crop 

 is grown too frequently ou the same land, it seems 

 peculiarly subject to disease. It appeared that ordinary 

 garden soil yielded hotter results with these crop" 

 than arable laud with every jxjssible assistance iu the 

 way of manures. 



Turning to the experiments ou roots, it is notice- 

 able that the ammonia salts were used with some 

 advantage as a cross-dressing for turnip crops, when 

 mixed with rape cake. When used in this way in 

 conjunction with farmyard manure, superphosphate, 

 and mineral manures, the ammonia salts secured much 

 better results than either nitrate of soda or sawduf ■".; 



saturated with nitric acid. The greatest yield 



.1 the 



tnmips-S tons Ifi cwt. of roots and 29 ewt of _l^;j^«^y°^J 

 WAS obtained by usmg farmyard manure, with ^j ^fovelnb•r 



