August i, 1885.] 



THE TROPICAL AGRICULTURIST, 



lay 



although somewhat deaf to instructions upon anything 

 new, is yet prone to imitation and will soon pick up 

 the method ho sees the Polynesian adoptiug. 



If a column of the '' Na Mata " could be deroted to 

 spread the information abroad in the group concerning the 

 advantages of planting the yabia ruin, a couple of 

 years would find the whole native population in posses- 

 sion of one of the most valuable food plants in the 

 world, and for which it is claimed that it is the food 

 crop which can he cultivated at the minimnn of cost for 

 ieedt ctt the minimum of labour required fm' its cultivation, 

 and that it will produce the ma.rintuin of return and with 

 the greatest ceriainli/ of any other food crop known in 

 Fiji, and that is adaptable to both Polynesians and 

 Fijians. It may be added that as the tubers when dug 

 do not keep good for any length of time, the sweet 

 cassava cannot be looked upon as likely to supplant the 

 cultivation of the yam, but it may either be viewed as 

 a great addition to the food crops of the natives, and 

 likely to prove of the greatest value in those years 

 when the yam crop is ruined by hurricanes or droughts, 

 and when the cassava crop may still be relied upon. 

 It should be added that goats and cattle and pigs will 

 eat both the leaves and the tubers of the sweet cassava 

 greedily. Outtings of the sweet cassava can be obtained 

 from Mrs. Towsou, of Savusavu Bay.— J^i/i Times. 



MANURES. 

 The following, for which we are indebted to onr cor- 

 respondent, Wr. De Mar, is a paper which was read at 

 a meeting of the Massachusetts Horticultural Society, 

 and will be of interest to many of our readers resident 

 near the great fishing stations and fish markets of this 

 country. 



The Hon. James J. H. Gregory was introduced to the 

 meeting, and read a p.iper on '• Nitrogen." After an in1;i o- 

 duction, showing the very small quantity of mineral 

 matter in plants — a cord of wood, that might require two 

 yoke of oxen to draw it and woidd be of the bulk of 

 "100 bushels, yielding but a bushels of ashes, which the 

 driver might carry on his shoulder — and the sources of 

 this matter, he passed to the consideration of nitrogen, 

 which makes up about four-fifths of the air mass that 

 surromids the earth for a depth of about 50 miles, the 

 other fifth being oxygen. This gives unnumbered thou- 

 sands of tons of nitrogen, right at hand, but never 

 available, for human knowledge has not yet discovered 

 a way by which nitrogen can be economically got from 

 it for plant food. We have to depend for our supply 

 wholly on what plants and animals have incorporated 

 into their structure, using their waste in the form of 

 manure, dead remains, eitheir from land or sea, for onr 

 supply. The ammoniated liquor from the gasworks is 

 but the waste produced from the remains of ancient 

 forests which we burn as coal. 



■Wlien nitrogen is combined with hydrogen in the pro- 

 portion of three parts of hydrogen to fourteen parts of 

 nitrogen, we have ammonia, otie of the most common 

 forms, in which forms the waste of both animals and 

 plants, nitrogen is fed to onr crops. 



The other most important source of nitrogen is nitric 

 acid. This is a combination of nitrogen with oxygen ; 

 and nitrates, of which we see frequent mention in all 

 works on manures, are a combination of nitric acid 

 with soda, potash, and other materials called bases. It 

 is well to fix in the mind that, in changing nitrogen 

 to ammonia in any manure analysis, we must add about 

 one-filth to the quantity given. It appears to be the 

 settled conviction among men of science, as the result 

 of many experiments, that plants cannot take uj) pure 

 nitrogen directly from the air. The theory is that they 

 are able, in a greater or less degree, to get their 

 supply through the water that carries it in some form 

 in solution into the soil, and also from the air indirectly 

 by the soil first separating it from the air that per- 

 meates it. Still another source of natural supply for 

 plant growth is nitrogen in a latent condition, that has 

 accumulated in the soil, set free by the action of such 

 substances as lime and plaster. There is a general belief 

 among agricidturists that plants have ways of collecting 

 Btill but little known, while some extremists have gone 



so far as to declare that there is no necessity of feed- 

 ing nitrogen to onr crops, for they can of themselves 

 collect from natm-al sources all they require. There is 

 a growing belief that their power to supply their wants 

 from natural sources is greater than has hitherto been 

 credited to them. It is found also that different kinde 

 of plants have different capacities for taking up nitrogen. 

 Olover is an example, for though nitrogen enters largely 

 into its composition, it has such a capacity to help 

 itself to the good things which surround it, that it needs 

 but very little artificial help from the manure pile, 

 while wheat, though it needs but little nitrogen, is so 

 dainty a feeder that it insists on a large artificial sup- 

 ply from which it may pick out that little. 



In regard to the sources from which the practical 

 gardener can obtain nitrogen, Mr. Gregory first considered 

 hen manure which has by some been compared in value 

 to guano, but he regarded this as overestimated. He laid 

 down a grand principle, that no more nitrogen, phos- 

 phoric acid, or potash can be obtained from the manure 

 of any animal than is contained in its food. An ordinary 

 hen will eat about 2 bushels of maize a year, and the 

 larger breeds about one-half more. From this they must 

 take the material for about 125 eggs annually, a change 

 of feathers, keep up the animal heat, and make up the 

 growth of the body, besides performing the various 

 functions on which life depends. Now, subtracting what 

 is required for these purposes, the waste element in our 

 2 bushels of maize shrinks to very small proportions. 

 ■\Ve must also take into account the fact that the 

 dropping which we save are confined almost wholly to 

 those made during half of the twenty-four hours. By 

 analysis 2 bushels of maize contain, in nitrogen, potash 

 and phosphates, 4U cents iu value. From this standpont 

 it Avill be seen that the droppings of a hen for a year 

 cannot contain nearly the value sometimes claimed' for 

 them. For many years the essayist collected hen manure 

 at a cost of 1 dol. per barrel, tut afterwards reduced 

 the price to 73 cents, ai'd thought it at the latter price a 

 cheap manure until he tested it sine by side with an equal 

 value of guano. Moreover, it is a sticky mass ditticult to 

 handle, and it is worth any one's while to experiment, if it 

 were only to realise the advantage in the handling of any 

 commercial fertiliser over hen manure even in its finest 

 state. It is generally composted with nmck or dryi.sh 

 soil — three parts of muck to one of manure— and the 

 compost should be made as fine as possible. A rake is 

 the best tool to do this with if it is sticky, and it should 

 be turned over in three or four days, and a sLx-tined fork 

 is a good implement for this purpose. 



Sulphate of ammonia, a by-product where coal is 

 used for the manufacture of gas, is one of the principal 

 sources of nitrogen. It looks like rather coarse salt, and 

 ia often sold in huge casks weighing 1000 lb. or 1500 lb. 

 It is readily soluble in water, but does not waste in the 

 air. Nitrate of potash (saltpetre) is usually too costly a 

 source of nitrogi-n to make it available. Nitrate of soda 

 is a remaikably stimulating fertiliser, but if there is umch 

 rain it will waste before plants caii take it up. In dry 

 seasons, however, it is better and cheaper than sulphate 

 of ammonia, as the latter needs a degree of moisture to 

 make plant food; yet, on the whole, the latter is con- 

 sidered the better investment, for, first, it is not likely 

 to be lost in the atmosphere ; second, it is not too 

 soluble; and third, it lias the power of clinging to the 

 ingiedients of the soil. Clay will hold it persistently, 

 and even pure sand, when washed with water, will re- 

 tain a large portion of it. Its ammonia is easily changed 

 into nitric acid by ingredients in the soil. Nitrate of 

 soda is very liable to be adulterate<l with white sand or 

 broken quartz, and with common salt or the cheap potash 

 salts. The purchaser should see that it dissolves entirely 

 in water and does not taste distinctly of salt. Castor 

 oil pomace affords a supply of nitrogen, but it must be 

 kept from animals, as it is poisonous, and in sjireading 

 it care must be taken to go with the wind, as it is very 

 disagreeable to the eyes or mouth. Cotton seed meal 

 is better fed to stock, and the manure used, which will 

 lie nearly as rich as the meal before feeding. Gcciisioii- 

 ally spoiled meal can be fouud in the maiket, and this 

 as good for manure as the best, and is a very cheap 

 source of nitrogen and phosphoric acid, AV'ood aud horn 



