THE MAINTENANCE OF FER-TILITY.

Otago Witness, Issue 2856, 9 December 1908, Page 8

THE MAINTENANCE OF FERTILITY.

To the Canterbury Agricultural College Magazine for November — a most creditable production — Professor Lowrie contributes a. valuable paper on, the "Maintenance of Fertility" as follows: — This is a question of great importance to the farmer and to the State, for in proportion a3 fertility is understood and maintained judiciously the returns from the land will be increased. In the Dominion, speaking generally, the matter ia only now beginning to receive that careful consideration, which it deserves, but the explanation 13 patent. The land was acquired originally with the accumulated fertility of ag*s latent in it, and the pioneer farmer in exploiting it was led naturally to think of ihis land much as a miner thinks of his reef — something from which wealth has to be drawn in the quickest way practicable. Indeed, on much of the good land in Canterbury a process of exhaustion was justified, for the land was too fat to carry such pioneer crops as wheat to best advantage. The excessive growth of straw induced by the extreme fertility was not always followed by a corresponding yield of grain. In wet seasons the grain wae damaged through the crop lodging, and often a spring favourable to rank growth resulted in such luxuriance that when, a period of hot, dry weather supervened when; the crop was in ear there resulted a pinched or shrivelled sample. An end to this «tate of things was easily reached, but fortunately long before the land had been reduced by frequent cropping to that extreme degree of impoverishment witnessed, for example, in some parts of Australia and America, the practice of mixed farming extended, and more attention was devoted to live stock. The land in rotation was sown out with grass and clovers, and consequently rested or even reeuiverated. Then the development of the freezing industry brought a rousing influence, of importance the most far-reaching towards improvement in farm practice. The value of forage and root crop 3 as a means of increasing the carrying and fattening capacity of the farm became evident ; and as such crops demand readily available manures, the extension of the it cultivation became a means of replenishing the soil. But the end is not yet: it is well so far, and that only. The application of artificial manures, usually made — lewt per acre or thereabouts — to root and forage crops only, in this district at least, may be sufficient to maintain equilibrium in the soil at that position below full fertility which now obtains, but will not suffice to bring it back to the condition of fertility consonant with maximum profit. Some years of fairly generous manuring to cereals as well as Toots and forage crops will bo required to bring about that result, but when it is brought about it will be practicable to lower the manure bill to the limit sufficient to maintain equilibrium near full fertility and continue to realise on crops and pasture alike something near the limit of profit. If the subject of the maintenance of fertility were better understood, and if it were fully realised how far below the limit of its capacity much of the land is being maintained, there would not be seen so many farms being laboriously worked,' year in year out, and all the while not in condition or heart to respond to that work as far as the climate and physical characteristics of the soil \ allow. Undoubtedly one of the ways of \ meeting the high price of labour is to j provide that the result of that labour shall not be limited by the somi-exhau6tcd condition of the land on which it is expended. It will not be questioned, as things are now, that much of the land would better repay the labour spent on it were it put into better heart. Let it not be understood that liberal manuring would diminish the amount of working of the land, now considered indispensable: on the contrary, such manuring without good and sufficient working is wasteful, for the full value of the manure is only secured on land so , thoroughly worked that the crops can properly utilise it. Indeed, the fundamental importance of working the land well is not to be argued: it i 3 not likely to be questioned even, if it be recognised that the surface 6oil is the matrix of the activities of inconceivable numbers of ferments, bacteria or mieroseropic fungi ' (estimates of their number have been given as -ome millions per cubic inch of soil), ar.-d that some of these lowly forms of life exercise a most useful influence in the soil, and arc e«sntial to changes in its composition indispensable for the nutrition of plants. As it happens, just that condition which practice describes as a mellow tilth is best adapted to stimulate the i multiplication and general activity of these unseen myriad agents, which conform to the tame general laws of life, nutrition, and death as organisms higher in the scale of life, for in a good tilth moisture is conserved, and a circulation of air . essential to life i 3 facilitated. Further, as it is indispensable that some of the most valuable constituents of artificial manures be acted on or changed through the work of ferments before becoming nutritive to plants, it will be allowed that such working of the land a3 will increase the ferment activity will enhance the value to be derived from the manure. In a soil well worked the delicate rootlets of the plants , spread more freely and widely ; the solvent ] action of the root-sap and moisture is in- | creased, for the smaller the particles of soil the greater the surface exposed ; the ' movements of water, and consequently the I movements of air, are more freely allowed ; ' and the beneficial action cf the' swarming ' microscopic- oieanisma is increased. On the other hand, when the soil ha 3 been , puddled through being worked too wet or when it is water-logged through lack of drainage, or when the tilth is wanting, the healthy functioning of tlip roots is prevented and bacterial acthity is les=ened. Manuring, therefore, is not to be reckoned in any way a substitute for thorough working of the land, but rather a- means of realising the full value of such woiking. j In the matter of manuring al-o it I*. well \ i hat -our practice should be governed by the facts which modern research has elucidated in relation to the nitrification of organic matter, to the accumulation of nitrogen through bacteria in symbiosis with leguminous plant 3, and to the direct fixation of tno free nitrogen of the air by the soil itself through the agency of bacteria, as nitrogen is much the mot expensive element in manure, and it may bo piofitablc to secure a sufficiency of that ingredient by extending the area of leguminous crops and at the came time working the soil so w to aiake the most '

of the activity of the nitrifying fenrienta in bringing the organic matter of the soil — roots, leaves, dung, etc. — into available form. The explanation of the benefit accruing to the soil from the growth of such leguminous orops as peae, vetches, ! and clovers is found, as is now well known, in the nitrogen-restoring influence of bacteria associating with legumes and living in the nodules produced on their roots; but although the explanation was wanting until this generation, the (practical fact of experience, that great advantage to the soil invariably followed the growth of legumes, has "been common knowledge for ' ages. Virgil has it thus: | At least where vetches, pulse and tares bay« stood, And att*".ks of lupines grew a stubborn mood, Th' ensuing season in return may beer The bearded product of the golden year. The cultivation of clover needs noplead- ; ing: its value as a crop or as a constituent of our pastures 13 allowed unhesitatingly. But it is not co generally known that clovers can be greatly encouraged by the application of phosphates and lime, and in many cases by potash, and that a double benefit to the soil results from suoh applications. There is, firstly, an increased yield of forage; and, secondly, an increased i accumulation of nitrogen through the greater vigour of the manured plant. It may be confidently affirmed that when grasses and clovers are sown out with cereals suoh as barley or oats, it is profitable to apply with the cereal a dressing of superphosphate or basic slag. The increased yield of grain, especially barley, will pay handsomely for the manure; the carrying capacity and fattening value of the pasture will be found to be very appreciably increased ; in relation to milking 1 cattle, the higher percentage of clover, with 1 the consequent increase of albuminoids in ! the forage, "mil stimulate the milk yield ; and the land "will be improved in fertility directly from" the residtte of the manure applied, and indirectly by the increased accumulation of nitrogen. But something more can be done in the way of renovation of nitrogen over and above the , growth of clover. Peas and vetches, for example, are now much neglected crops, but if their value in irural economy was more justly estimated, I believe the area under each of these crops would be extended. Peas, on well-farmed land, return nearly as much per acre as wheat ; the crop is not much more risky ; the expense of harvesting is less now than it was a few years ago 7i before the simple pea harvester attachment to mowers was introduced ; the grain provides a very valuable constituent of farm rations, especially for growing stock i and the gain in nitrogen to the land which has carried pea 6 is equivalent to an application of at least 4cwt to scwt of nitrate of soda. To get full returns from peas, however, it is necessary to apply to the land scwt or thereabout of ground quicklime broadcast, and, say, 2001b per acre of superphosphate, or its equivalent of basic elag, drilled with the seed. Again, vetches deserve much more prominence on Canterbury farms than is given to the crop, and it is indeed difficult to account for its being so generally passed over nowadays or neglected. No doubt the risk of its persisting in the land through, reseeding and getting into the sample of wheat discounts it ; it shells out readily, and the harvesting is often troublesome, while the yield is generally low in terms of other crops; and the cost of the seed is often nearly prohibitive. But against these drawbacks there are sufficient advantages in the crop to justify well its more extensive cultivation. When sown in the autumn it will smother weeds and help to clean land from annuals ; it is one of th© best forage crops grown, being hardy, bulky, and nutritious ; it makes, when mixed with oats or barley, a valuable soiling crop to be cut for feeding in tho spring; when cut at the right time, andt saved in good condition, it furnishes firstrate hay; when mixed with some cereal it affords excellent early spring feed to be grazed by ewes; and it may be eown in the early spring with rape, when it will offer for early Jambs at weaning time a, fattening forage mixture unsurpassed. Let there be added to these merits its value in adding fertility to the land, and the case for the vetch is surely proven. On the college farm this year wo have had Italian ryograss following cape barley, cut for soiling. A few acres, extending across the middle of the field, grew barley and vetches mixed, and this year the Italian vye on this block compared with that where barley alone preceded ; the grass looked as if it had been heavily manured and tho manure limited to that area. There are few ways of recovering and improving tho fertility of the soil more prompt, effective, and economical than, growing vetches with a dressing of 2cwt per acre or more of superphosphate or -basic slag, according to the land, and feeding the crop on the land ; and, as has been indicated, for peas the result on the. soil will be greater if a few hundredweight of ground quicklime has been broadcasted as a preliminary. A heavy crop of vetches straight, however, hugs- the ground too closely, and for grazing it is better mixed with cereals such as oats, cape barley, or giant rye corn. Such mixture will yield enormous quantities of feed when generously treated with manure : it can be grazed lifted early enough to be followed with early-sown Italian ryegrass and clovers, or liften early enough to be followed with rape and mustard for autumn fe-ed, if th© season is fairly moist. Another very excellent practice is to sow rape and vetches in fhe 6pring sufficiently early to give the vetches a good chance. Drill the vetches with, say, 1201b of superphosphates, and cross-drill with rape and, say, lewt of freezing- works special kale manure, sowing thp rape quite shallow. I have not seen this mixture u^cd in Canterbury, but experience on tho college farm justifies 'ts being urged on the attention of farmers. Xo better lamb-fattening forage can bo grown, but the lambs should bs dropped in time for weaning about the middle of December to make the best uso of it. The velvet vetch (Vicia VUlosa) is to be recommended in preference to other varieties for bowing with rape. It grows much finer in the straw and stands grazing better, while yielding a good bulk of very palatable and nutritious forage. We have been growing this vetch for two years on the college farm, and it promises to meet the bill well. I believe there is also a very good case in favour of rape and vetches to be in February, if the season will allow, but the ordinary large Scotch tare is, I think, in this case to be preferred to the hairy or velvet vetch. Altogether

I would urge a more extended use of the vetch, and the growing of a- few acres for seed on every farm. The reseeding of tho land is only a slight consideration now where sheep are so prominent on every farm that the land carrying vetches for seed can always be followed by a forage crop, or Italian ryegrass to be grazed, aim) the seed shelled out can be got rid of accordingly. It is well within tbe mark to say that the gain to the land frorf vetches fed down in this way is wortb 30s to £3 per acre. In evidence that ihis estimate is on the safe side, I .will quote Moore, of the U.S. Department of Agriculture. "In Germany," he writes, "the number of pounds per acre of nitrogen added to the soil by legumes is estimated at 200. In the United States the average from 16 States is 1221b." Now, in the Dominion that amount of nitrogen cannot be bought in nitrogenous manures, such as nitrate of soda, sulphate of ammonia, or dried blood, for less than £4- to £6. Surely, therefore, there is good reason for urging this prac■tice as a means of replenishing our soils, and I am confident that within a few years it will be generally adopted; indeed, I have good reason for the belief that the more closely we get into line with Nature* and our natural conditions in farm practice, the more economically and more successfully can the farm be worked. Ferment activity, I indicated in detail in my article on wheat in the last issue of this magazine-, is more pronounced in the Dominion thai* British experience would lead us to anticipate, and it is for farmers to avail themselves most of this greatly benefiting, valuable, unseen natural agency. Let them feed th land with superphosphates and occasional, dressings of ground quicklime, and grow legumes sufficiently widely, and little need will arise to look round for nitrates — the most expensive of manures — on good farming land. On light land it may be advisable to us© nitrogenous manures as well as phosphates, and potasti s&lte xxi-eiy A-lso tmtov^ x*oxxLUZ*e3r&fci'v-& there. But tho question is easily settled in these days of drill husbandry and readily available manures. It needs no experimental farm for the investigation of a question of practical husbandry euch as this. SuTelj. every farmer can try blocks of four or five acres in his different fields with 'different mixtures of manures and different quantities, and the results will be readable to - him as he walks along the headlands. Tho information which chemical analysis of his soil might give him would be meagre and uncertain compared with such practical every -diy workable tests. Indeed, it may eve.i be Whispered that a farmer who has a good working knowledge of the composition, function, and utility of different! manures and a good practical knowledge of the working of land can work out his own guide lines most surely in this way 1 , as he knows thoroughly his land and its previous cropping history — an important matter in relation to' reports- of experiments.

So far as this farm goes, it is indicated that phosphate manures are most profitable* They feed tho plant and encourage the nitrogen-fixing bacteria, -and their influence on the crops 13 not so much affected by spells of dry weather. But, I doubt not» on a farja more exhaustively cropped than this, nitrogenous manures, such as dried blood or neat scrape or tankage from that freezing works, would be necessary; and in this ;elation I will say that I believe it could be better for the freezing companies and for the farmers if the companies put their manures on the marked

as-*guch, and left it to the farmer to .do such blending as met his individual requirements, or at least if at the freezing works "titried blood, bone dust, meat eSraps, and alimentary canal offal were offered as well as blended manures, and prices charged according to their value. It is well, indeed, a vital matter, for the farmer . to support the freezing works in buying their manures, -but it is scarcely for the works io prescribe for his land, and it will stretch his loyalty to have to buy in the blend \rhat he may not need, and pay the cost of blending, which he would -gladly and might to more purpose have done himself for his particular needs.

I will close this article by setting out in the -broadest and most general way the practice of manuring which experience on this farm seems to justify. Wheat. — One' hundredweight and a-half to 2owt per acre of superphosphate or basic 6lag. When growing wheat after wheat, superphosphate and dried blood 2 to 1, or superphosphate and special kale manure, half and half. Barley. — About 2001b of superphosphate. Peaa and Vetches. — One ' hundredweight and a-half to 2cwt of superphosphates mixed with wood ashes as far as this last is obtainable, and scwt of ground quicklime applied before sowing. .Turnips. — One hundredweight and a-half to 2cwt of superphosphate mixed with a little wood ashes, or lowt of superphosphate and £cwt to lewt of basic slag blended immediately before sowing ; or on very open, thin soils, jewt dried blood and l£cwt of superphosphate. B,ape. — Two -hundredweight of special kale manure— a blend of superphosphate, bonedust, and dried blood.

Mangolds. — Three hundredweight to 4<rwt per acre of a mixture of the following, in these proportions: — Dried blood 8 parts, superphosphate 3 parts, boned ust 4, kainit 4, and sulphate of pofash 1 part;" or in the case of mangolds after lea, kale manure and kainit 3 to 1, or thereabouts. . Such manuring will, in a very few years, bring a farm up to the very fullest fertility, when the amount applied can be gradually reduced to half the quantity or thereabout. Of course, many considerations ' must modify the applications, but chiefly the character of the cropping and the proportion of grass on the torn. Permanent pastures will respond profitably to a topdressing of basic slag. The manure bill on a fairm of 800 acres under the indicated practice will range from £150 to nearly £200 per annum, but the increased returns due to this outlay will amount to more than double these figures, and the farm trill be from year to year gaining in fertility.