Gardening Notes

Hutt News, Volume 2, Issue 46, 24 April 1930, Page 9

Gardening Notes

ABO%T^ MANURES.

The object, of manuring is to supply -plaints with those: sufrstaflnces,which, thfly 'need for tlieit growth arid "which they

I cannot obtain in. sufficient quantities 'jrjfom ;na&i¥aii resoti*<Se¥.rf'. besides, a -xatiftnai i^ftU&ationv vof (manures tends also t.o. .imp*roye.vthe .physical, condition '" ' i:" ' '"'-' ; vj

' Manures may be divided into two inainr classes—-natural or absolute, and artificial ox relative. To the. firet en tegdry belong farmyard manure, compost, green manure, etc.' They all cqfttf.in organic matter, and supply plants wit,h.ali plant foods thougih in varyiikg proportions. Substances like superpho'spliate, ammonium sulphate, potash salts .qtc, belong to the second category. They are mostly axtme|al jprod'uetb, with specific properties/; and are valued 'as such; They contain plant foods in an easily available form, and hence 1 arises the necessity of their being mi a state of fine division so that they might \}-i evenly distributed without . much difficulty. ,/ob.eir a£pscatio)i has always a specific object M View; sucSi jas the production of substances particularly rick in proteids, eaTboniiydrates, etc. A-? they .most frequently 'supply one pUmt food, they are called relative mania es. Such are the principal nitrogenous, phospfoetic and potash, manures.

On most of the farms of the world, farmyard manures .forms the basis for a system of rational manuring. It is •highly valued because at once or in a relatively short time, it ...improves the piiysicftl .condition bf the soil in such a way that the same result cannot be produced by the application of any artificial manures> and creates favourable conditions for the activity of the micro^ organisms in the soiL The working or action of farmyard manure is therefore thiee-fold—chemical in that it supplies plant food, physical in that it improves th». texture of the soil, and biological in that it increases the activities of

thi micro-organisms

All these varioiis effects of farmward in«nure are not always equal. They vary according, to the nature and feeding of the animals, the litter applied, tfci'. state of decomposition, and the method of preservation.

In green manuring, certain quickgrcwing and nitrogen assimilating plants are ploughed into the soil with the object of enriching it in nitrogen and humus-forming material. It is meant either to replace or supplement farmyard manure with this difference— that only new quantities of •nitrogen and organic ' matter are added to the soil. This art of manuring the soil seems to have been known in Europe already before 20.00 years. Writers lon agriculture inancient times have warmly recommended the,method, Leguininous plants, like lupiiii and cow-pea, aTe the ones best suited for. the purpose. Green manii^ing^s.;'specia'lly suited to farms on which there are not enough animals to produce the necessary manure. It is particularly: useful on light, sandy ' soils, W'hicJ^are j generally poor in humus.

GTeen manures can be grown in various, ways, either as principal crop or before or after the principal crop. It is only on very lrg&t, sandy soils that it 4 canpbe grown advantageously as the principal crop. *

The oil-cakes, th<)ugihv!fhey contain ail the;plant foo^s, are valued •specially for. their .nitrogen eojitents. They are usually' the by-products from oil mills. Like the other organic manures, they are also of slow decomposition. They, too, supply organic matter" to the soil, .and small quan/tities of phosphoric acid f an'J potash, as well as maniiT^; they are first' fed vtcweafctelei and :rfihe excreta of the-/anima,ls. is used as manure. Not

nvnch of the 'fertilising value of the oil 'cake-is lost when it is thus first passed through animals and rthen used as manure. . Naturally, it is not every kind Of cake that can be used as cattle food for the purpose of producing manure. Such, for instance; as castor cake, eaii be used for feeding purposes only after ■the harmful ingredients have been Tern oved by ohemicalr processes.

Manures such as tiiose described ab*ove can be-/Used'*with T comparative safety on almost eveiry kind of sbil. If they cnn do no decided good at times, they do not at any. rate do any positive harm. The ijext class of manures is

sometimes called "scientific" or "artificial" manures, for . the reason that their application is an art, or a knowledge .of natural sciences is helpful for the purpose. Not infrequently they are artificial products, too. They cannot be applied in the same way as the na-

tural manures to all crops and soils. Tli 6 demands of crop and the nature of 'the soil haye to be duly considered. Sometimes,, they contain small quantities'of. ofjber substances which are •haTmful to crops. ' "■..'■"■'

Sulphate of ammonia and nitrate of sbcla are the principal nitrogenous manures belonging to the second category; It is only on soils with a sufficient lime content thai sulphate of ammonia is likely to give the best results. Nitrate

of soda is a quicker acting manure than sulphate of ammonia, but has a tendency to spoil the tilth, ofl the-soil at times. It is only when the soil contains sufficient amounts of other plant foods that these manures give the tjest ; -results. •;•- . .' -..■.,. ,• ■■■:. ;.-.' .

Basic, slag, superphosphate and bonemeal are the chief phosphatic manures. Basic slag is a by-product of the steel industry in those parts of the world in which iron ores rich in phosphorus ,aye found. It was considered^ a waste pTOduet in the beginning,. and its useful ness .in agriculture was recognised only later on. Unless it is in the form, of a very fine powdery it is_ not iikely to give good results, and the firms supplying it do take good care to see that it is well powered before it is put upon.the market. ■ As it contains a fairly large amount of lime also, it acts beneficially pn *odir.p"§6r in lime as well. Even -heavy dOSeS Of it do not injure the soil n any way; nor does the phospthoTiJ acid get leached put. What is not used uo by crops in one season remains in t»he soil for succeeded crops.. ' _■

. Superphosphate is maaufactul-e^ by treating mineral phosphates or bonemeal "with suphuric acid. 'Being an acid manure, it is well suited for heavy soils. Its availability w&eh applied to soil rich in iron and aluminium still remains to be investigated. As it contains a lot of calcium siiiphate, the water-soluble phosphoric acid in it gradually becomes converted into triealcium phosphate and not easily available to plants. Hence some of its avail ability is lost w&en it is stored for a long time, but still it remains more easily available than the phosphoric acid in the soil itself. It is generally sold, not on its total phosphoric acid content, but on the contents of watersoluble phosphoric acid.

Bone-meal is another phosphatic manure, bait is not. so readily available to plants as basic slag or superphosphate. Its use was first, started in England, and as its value "became more and more recognised it was imported from t»he Continent in very large quantities. A cry was immediately set v thap* England was walking away with, the fertility of Continental soils, and that shie was irreverently ransacking all the old battlefields simply for the sake of bones.

It -has to be applied to the soil in fairly fine powder, and has to undergo some decomposition in the soil before it becomes available to plants. It is said to act better on soils which are not very rich in lime^ Simultaneous application of such manures as ammonium sulphate is ' said to favour its decomposition, and ience increases its availability.

Bocllf- phosphates, such as Christmas Island phosphate and Tric-hy nodules, aTe of comparatively slow availability,: even when they are^ applied in a state of fine p.owder. ' .j'.

Till quite recently,'Germany*haCffhe monopoly of potash salts. Their^ manurial value : was not known at first. la mines, w rhere rock-salt Was .chiefly looked for, the potash salts which had> first to be dug out .wera looked upon as .mere ballast .and trash. Later on when their value became recognised; tiey formed-the principal product .ofthe mines. v . .

They are put on the market in : vari* ous;.grades of purity. The more impure ones, with a low potash, content, are meant for places not faT from the mines. The pure salt, surih. as sulphate and chloride, are meant for places lying far away. The impure salts Shave to by.applied some time before crops are sown, so that the impuTities. might get leae>hed out of the soil, and not prove harmful to crops. Sue-h crops as potatoes and tobacco aTe very susceptible, especially to compounds of chlorine, anclhenche chlorides ought not be applied to them. It is generally the

sugar and starch producing crops that need dressijags of potash manures to thi- extend t^tl;they .oaan ia^"be supplied from natural sources^ in ..the.. SQ r jl. .Fye-^ fluent applications' M^polas&'lalis^ae-** plete the soil, of lime and hence/arises the need for liming at intervals. When applying artificial manures, it is r.ot only the crop j that, has to be'considered, but t-he nature of the soil and the whole course of rotation as well. They are meant to supplement farmyard manure in producing maximum yields from the soil, and not to supplant it. , Lasti but not least, the: quest'.>i as to how far they can be applied •witiSi financial success has to be caxe-.. fTiily considered and worked out.