THE VEGETABLE GARDEN.

New Zealand Herald, Volume LXIV, Issue 19604, 5 April 1927, Page 14

THE VEGETABLE GARDEN.

[NITROGENOUS FERTILISERS. BY S.T.R. The intention of the writer in submitting this article is to give the gardener a better vision of this extensive subject and so help him to make a more judicious selection of fertilisers and manures which are to supply his crops with nitrogen. It is quite a common practice for a grower to depend on one fertiliser for all purposes where the supply of nitrogen is concerned. This is a great mistake. To take an example, many growers place great faith in blood and bone and use it for all crops at all times. This universal use of blood and bone is -wrong; for the requirements of every crop are not the same. However, it seems to be firmly rooted in the minds, of some gardeners that, because this particular manure was admirably suitable for one crop, and pushed that crop on wonderfully, it will produce results equally good when applied to another crop. If this notion can bo dispelled a part of the object in view will have been achieved. It will then be neecssary to give a list of fertilisers to be used in place of blood and bone where a change is desirable. The reason vtrhv any nitrogenous fertiliser "will not fulfil the requirements of every crop is that each one in not the game in every respect, and some differ an several respects. Some contain more nitrogen than others, and therefore are more suitable for crops requiring a large proportion of .nitrogenous food. Again, some contain' other foods besides nitrogen, and so are more suitable for crops requiring several foods. It would not, however, be altogether reasonable to use a certain nitrogenous manure which contained another food, also, if that other food were supplied in a separate fertiliser. It would be more economical, perhaps, to use a purely nitrogenous fertiliser. Nevertheless, it might be that the extra quantity of that certain food would be used also, but this can be determined only by experiment. This is another of the objectives of this article—to get the gardener to do some experimenting, and discover for himself which fertilisers are best suited for the purposes for which he requires them. Eapidity of Action. Another ■ respect in which nitrogenous fertilisers and manures differ is m regard to the rapidity of their action. Some act almost immediately, while others do uot have any effect on plants for some considerable time. The rapidity with which a fertiliser acts when applied must, therefore, become an importantfactor in the choice of any • nitrogenous manure. It would 'be of very little use to apply a slow-acting fertiliser to a quick crop which matures in a comparatively short space o'i time, for, most probably, the nitrogen would not be available for the crop before it had matured. Consequently, as far as that crop is concerned, the manure will be of very little if any, benefit. Cases similar'to this are not unknown; in fact, one may frequently come across such an instance, and, indeed, one might easily be an offender, though unwittingly, in this respect oneself. Thus it will be seen that the matter of supplying nitrogen to crops is not easy, nor one to be given little thought. Rather, it is one to be thought over carefully and given due consideration. Nitrogenous fertilisers may be divided into two groups, which are quite distinct from each other. The first group consists of the organic fertilisers, that is, those that have been derived from anything which at some time contained life. These organic forms of nitrogenous fertilisers supply nitrogen in a form which is not available to plants until it has gone through a certain process. This process is nitrification, which was described in these columns some weeks ago. The process by which the nitrogen contained in organic manures is rendered available is fairly long, and requires time. As a result of this the organic forms are: slow-acting. Notwithstanding their slow action they may be said to be as useful as the quicker-acting manures, for they last much longer. Inorganic Nitrogen. The second group contains the inorganic forms of nitrogenous fertilisers which are derived from substances which have never contained life. They are, in fact, chemical substances containing nitrogen. For the most part they are readily available to the plant, and hence quick-actir/g. In certain instances it is a feasible idea to use a slow-acting manure with a quick-acting one in conjunction. The latter supplies the crop with an abundance of nitrogen until the slow-acting manure is ready to carry on the supply. The first of the organic nitrogenous fertilisers is F.Y.M. These letters stand for ■ 4< farm-yard manure," which may be taken to include stable manure. This manure contains one-half per cent, of nitrogen. This may seem to be but a small quantity, but when its cost (which is very little if anything) is taken into account it will bs found that this is one of the cheapest nitrogenous manures. 1 think it may safely be said that this is the most popular of all nitrogenous manures used by the giardener. Wheu the quantity which is used is considered it will be seen that the crop receives as much nitrogen from this manure as it does from the small quantities of other manures which are used. The second in the group of organic nitrogenous manures is bonedust. This is also comparatively poor in nitrogen, containing 3£ per cent, of this food. Nevertheless bonedust is not chiefly a nitrogen ous manure for it contains approximately 42 per cent, of phosphate. This fact makes it mainly a prosphatie manure, but, aa it contains nitrogen also, it is included in the nitrogenous fertilisers. We now come to one of the most important commercial nitrogenous fertilisers, viz., blood and bone. This manure contains about 6g per cent, of nitrogen and in addition 26 per cent, of phosphate. Although blood and bone contains more phosphate than nitrogen, yet it is called a nitrogenous manure chiefly, and is very rarely counted as a phosphatic manure. It is hard to account for this fact, but it appears that the phosphate has been ignored to a very large extent, its presence being taken as something which is " given in " with the nitrogen. Being of the organic group, blood and bone is slow in its action, but becomes available for the use of the crop in regular quantities once nitrification has commenced, and those quantities are supplied over a fairly long period. Use of Blood and Bone. As with every manure, almost without exception, blood and bone has a use arid a misuse. The use of this manure is for crops which require a fair amount of nitrogen and which take a fair time to reach maturity. It may be applied at the time of sowing in the drill or a short time bafore when giving the ground its final prepartion. (Bonedust may be applied in a similar manner.) Neither of these is fiven by top-dressing. The misuse of lood and bono is when it is applied to cruciferous crops. As has been mentioned several times previously in these columns, blood and bone, in fact all organic nitro- i genous apparently encourages J that much-dreaded fungoid disease, club < root. rhat concludes the nitrogenous manures i organic class. There is one of ( which no direct mention has been made, I °^ ev ® r ' an( l that one is green manure. It i uinW 4U t,a u en v that this manure comes ( although 'it dn a< ! ing * of farm y ard manure. yard in ? eS 110 corne f lorn the farmWhic'h it.'i nftrr 15 and ' n the niSnure 111 j the crow £ * en . ls .,made available to j .justifies it* ;" n ,} S . 81mi!ar > and this fact Tha firit and ? n Undcr the heading. *h 9 may be rightly said. iertilWra £ mor g anic Ss a (fihemical .nK.t ni trate of soda, I "S"* 1 fcs» SLS?'»« »Mdi Is ex. i iKSsi? VE" 1 " •»]>- i •ts Urate of soda j ik

contains about 15 per cent, of nitrogen, which is in a form immediately available to the crop, i.e., as a nitrate. All nitrates are absorbed by plants without delay and are therefore quick-acting. They are most suitable for applying to growing crops as a top-dressing, and to crops which mature in a short space of time. Nitrates which are not used up immediately by plants are drained out of the soil fti the drainage water. Therefore the economical use of nitrate of soda is to apply it in small quantities at frequent intervals instead of in larger quantities, of which a certain portion is lost in the drainage water, at longer intervals. It may be calculated that the crop receives about twice as much benefit from the former method as it does from the latter. Sulphate of Ammonia. The second manure containing inorganic nitrogen is sulphate of ammonia. The nitrogen is contained in the ammonia part of the manure. Although it is soluble in water, sulphate of ammonia has yet to go through the second and third stages of nitrification bef6ro the nitrogen is available for the use of the crop. This makes it a slow-acting manure, but, notwithstanding this fait, it is a very important nitrogenous fertiliser. It is used very largely in fertiliser mixtures. It is applied "at the time of sowing, and is not suitable for top-dressing. The nitrogen content of sulphate of ammonia is 20 per cent, approximately. Nitrate of lime containing 13 per ce.nt. of nitrogen, calcium cyanamide or nitrohm with a nitrogen content of 20 per cen ~» and nitrate of ammonia containing 35 per cent, of nitrogen are the remaining inorganic nitrogenous fertilisers. are all manufactured from the air, which contains a very large proportion of the nitrogen gas. These three fertilisers aio, as yet, not used in New Zealand to any extent. Hence the writer has not enlarged on them. Even though the gardener may make a correct choice of fertilisers, he is not assured of complete success unless a further aspect of the subject is given consideration. Having decided on the fertiliser which is to be used there still remains one other thing to be decided by the gardener. This remaining decision concerns the quantity of the fertiliser to be used. In this connection there is a wide scope for experiment, and tbe gardener should not be slow to avail himself of such an opportunity.