PRACTICAL IRRIGATION.

Dominion, Volume 5, Issue 1350, 30 January 1912, Page 10

PRACTICAL IRRIGATION.

« : MANURES. .(By-John MTleagu«o' HI. '• (Copyright.) W« have mentioned in previous articles tho chief organic'and tho chief inorganic substanccs that form crops. Each crop extracts large quantities of both from the soil, and tho substanccs thus extracted must be restored to tho soil in at least equal quantity, otherwise the soil will bo impoverished, and fail to grow desirable crops. To get some idoa of the quantities so extracted from the soil, let us take two inorganic substances extracted from tho soil by an acre of various farm crops; and the quantities of two organic substances in each 100 pounds of some farm crops: 1 Substanccs Extracted From the Soil. InoTganic. An acre of each crop extracts from the soil: Phosphoric acid. Potash. Crop. lb. lb. Mangels ................ 49 -262 Turnips 33 U8 Beans 31 81 ' Potatoes 27 7G Rod clover hay ...... 25 87 Wheat 22 . 28 , Swedes 21 '. 79 Barley 20 31 Oats 19 38 Meadow hay 12 50 Organic. In each 1001b. Starch. Gluten. Crop. ■ lb.' 11. Rye 65 10 Barley 65 10 linshellod oats 51 13 , Indian corn G8 . . 10 ' Eice 78 5 ; Buckwheat 60 9 Beans '.. 50 22 Hay .......' 58 12 Potatoes 20 2 If all the substances, organic and inorganic, wero given in terms of pounds weight, that are extracted from the soil by farm crops,, the total', amount and ■ weight Svould be great. It appears from this table that: ... ... (1) If a crop of "mangels be grown, much potash and phosphoric acid will be extracted from the soil. (2) If rye or barley be grown, much starch and gluten or their equivalents will be extracted from tho soil. It thus nppears that where farm crops are grown, the substances extracted from the soil must be returned to it, in at least quantity equal to that extracted. A manure is any substance, or mixture of substances,' added to the soil in order to restore its natural fertility, lost by cropping,: or to increase its . productive- 1 'ness. A reference to tho tables given 6hows_ that each crop carries off largo Quantities of the ingredients of the soil. Nor is this the only way in which these substances are extracted from the soil. When rain falls, and cither runs off the surface or sinks through tho soil, 'it carries away portions of tho substances that form the soil. These are carried by drains, by streams, or by rivers, to the ocean. Hence" it is that all these substances,' being available for the growth of maririo plants, seaweed forms - ! a-'■ very valuable manure. Nitrogen is an important natural gas," and is the dilntant of , the oxygen. gas of the atmosphere. Three-fourths of' the mass of the'atmosphere is elementary nitrogen, and it pert vades. the whole animal and vegetable kingdoms. It will not support combustion, nor-can it, in'many cases, be taken up directly by plants and utilised. Yet it plays an important part in building up nitrogenous organic matter. Nothing so £t^qji ( gffectS'the productiveness as nitrogen" when it is supplied, to plants in a form in which it can be assimilated by them. No other is so easily removed from the soil by water, and in tho'form of nitrates. Plants frequently do not possess the power-'of taking up the free nitrogen of the air by their leaves, and assimilating- it. It must, therefore, bo supplied by the Eoil, and this is dono in the form of the compounds of nitrogen, a constant source of supply being the nitric acid , and ammonia which descends on the land in the rain, hail, dew, and snow'. These get their supplies from the freo nitrogen gas, which forms the bulk of the atmosphere. Compounds of nitrogen : and other substances are: (a) Ammonia, ..(bj nitrates,.: (c) cyanides and others. Ammonia v is a compound of hydrogen and nitrogen; nitrates is a • generic - , torm for nitric-acid and its salts. The-gradual decomposition and fermentation of farmyard ■ manure gives a constant supply of nitrogen. When animal and vegetable matters containingnitrogen decay in the air, and in contact with limestone or with wood ashes, tho (d) nitrates of lime and (e) nitrates of potash are formed. In this way nitrogen, potash, phosphoric acid, and such like are first supplied to'the plant food laboratory in the soil, and then the food thus supplied and manufactured is absorbed and used by tho plant. These substanccs, as ,we have pointed out, get washed out of the soil, carried by streams and rivers to the oceaji, where they form vast beds. When the bed of the ocean is raised, these vast beds are' available for manure. In this way the huge deposits of nitre in Chile, the salt mines found all over tho world, the potash mines at Strassfnrt in 'Germany, and tho phosphato rock of Otago have been formed. Nitrogen is a very expensive manure. It may bo applied in a' more effective way. Leguminous crops, as beans, peas, tares, and vetches have the power when growing of extracting much nitrogen from the air. By applying potash, or some similar cheap manure, and growing peas or vetches on such land, large quantities ,of nitrogen will bo secured. If tho crop be ploughed into tho land, and allowed to decompose, a largo and immediate supply not. only of nitrogen, but of various organic manures will be added to the soil. Largo tracts of barren country have been rendered fertile in this way. When lime has been applied to peaty or swamp land, and the stagnant compounds have been converted into plant food, tho leading mineral substance, potash, is still absent. Potash salts, which is a cheap manure, applied liberally to peaty or swamp land, already limed, will largely increase its fertility and repay tho cost manifold. The quantity of each substance extracted by the crop varies with the different crops. Hence tho class of manure to apply to the eoil must be .determined largely by the crop to be grown. Many of these substances, such •as potash, may be present in tho soil in largo quantities, and yet not be available as plant-food. Potash euters largely into the composition of cabbage and mangels." Clny soils contain plenty of potash. Yet neither cabbage nor mangels may grow well on clay sails. Usually not a hundredth part of tho potash present in clay soils is available as plant-food. If common salt be sown broadcast, on clay soil, the solvent power of the rain water will bo increased manyfold, and a largelyincreased quantity of potash and of-other substanccs required for plant food will be set free. The large quantities of organic, and of inorganic, matter taken from tho soil by crops are restored to it by (a) vegetable manure, (b) animal manure, and (c) mineral manure.

Value of. Vegetable Manure. Those who understand the vast importance of vegetable manure, fully realiso the sad and wilful waste often seen when stacks of straw aro burnt. On heavy land, returned as straw, it would help to kcop the soil open, and allow the water and the nir to circulate freely. On lighter land, it would supply the oruanic "substances, of which such land is deficient, and. in view of the great necessifv for manure that will follow tho adoption of a system of irrigation, is host applied in tho shapd of fnrmynrd manure. The most important of the vegetable manures are grnts. clover =t.rnw, peat, and seaweed. Light and «ndy soils nro practically useless unvegetable or organic matter bo applied. Tlit value lo this class of land of growin? and ploughing in a crop of peas or vetches hn3 already been pointed out. If. afterwards, this land be laid down in grass and clover, the accumulation of vegetable matter from tho grass crop, in addition to the nitrogen and organic matter previously supplied, will seldom fnil to convert tno poorest soil into good .and fertile land. Should it be potsihlo to

do so, nil application of peaty soil, mixed with, lituo, to such soil is most valuublo. Tlio chief animal manures are tlio llcsh. blood, bones, and dropping of animals. Jn some eases the flesh ot animals 1* manufactured into meat meal guano, or which many thousand tons are used every year. The blood of slaughtered animals, mixed with other-refuse, dried, and used as a top-dressing for oats, wheat, or gra.ss is perhaps tlio most powertnl manure ot its class. Tlio bones of animals are crushed, and in the form of bone-dust, are profitably applied on light loamy land, boing especially useful and proiitable for turnip crops, or as a top-dressing for grass land. Both nnlk and cheeso contain bone earth, and when, on dairy farms, cattlo take this substance from the soil for years, the land becmnes specially deficient in this respect. .J) -this tokos place, only those grasses will grow which are in bono, earth. Jiyory ten gallons of milk contains nearly halt a pound of bono earth, lienco the great drain of this substance from the soil used for dairying purposes is apparent; and on such land it is necessaryJo apph bone-dust or bone-ash frequently, ana after such applications an increased now of rich milk results. Tho droppings of animals, mixed with peat, form a very valuable manure in the present of irrigation. The fluid droppings of animals nro especially rich in nitrogen, and should never be allowed to run to Y But, after all has been said, it should never be. forgotten that, chemists find substances in the ashes of plants, which tliey cannot find either in the soil, in the water, or in Hie air. For tho practical purposes of ■■■the farmer, the best plan to adopt to determine the best manure to apply to any soil, and the P ro l : " quantity of irrigating rater to apply to different soils and to different crow, is bv simple experiment. The farmer should never lose sight of these moat important fa (lfiand may be mined by applying irrigating water too freely. (2) Different soils require different quantities of irrigating water; and the quantity of water that will be beneficial to one soil, may ruin another soil. (3) Different crops require different quantities of irrigating water; and the quantity of water tlmt will bo beneficial to one crop, may rum another crop, (i) A manure that may be required for one class of soil may not bo necessary for another class of soil- (5) A manure that may be beneficial for one class of crop may not be of benefit to another class of crop. To Determine tho Best Manure. In order to determine tho best manure to apply to any crop; in what quantity; and the quantity ot irrigating water to apply, how often and at what times, it is not necessary ,to have elaborate experiment stations, or to incur great expense. First, it is necessary to conduct simple experiments on each class of soil represented in any given area —a county, or a province; and the county councils could easily and cheaply conduct the experiments; and in order to ensure uniformity of system, under the Department of Agriculture. It is only necessary to : lay out a series of fairly large experimental plots on each class of soil, as follows :—

The soil of different complete sets of plots rccoivos' different cultivation treatment. Tho manures are applied to the beds AJ, BK, CL, DM, EN. Five different manures, or more if tho number of beds be increased, may thus be applied to tho, beds; or, bettor still, four different manures, leaving one of tho beds unmanured, in order to determine tho value of tho ditferont manures more accurately. A board attached to each plot tells .tho quantity per acre of the specified manure, that was applied to each plot. The seed of any crop is then 6own, or the young plants placed in the plots, 1-8, 2-9, 3-10, 4-11, 5-12, 6-13, 7-11; and tho quantity of seed per acre is also stated on the board, which belongs to each plot, Any farmer by inspection of tho plots can determine what are the best crops, and the boards Will tell him the manure, and in what quantity per acre, as well as the quantity of seed per acre sown. It would be an easy matter to apply varying quantities of irrigating water at various times to the plots, and place theMj additional particulars on the board- attaohed to. each plot. The farmer . could then easily determine the quantities of irrigating water, the nnmber of waterings, and the best times to apply the water. The crops grown on these plots could be used for experiments regarding the various diseases such crops aro subject to and prevail in tho particular district; and 60 much of the information in every phaso as was of public interest and for the public benefit could be published by the Department of Agriculture. Isolated experiments are seldom of much value. All these particulars will vary with the class of soil, tho climate, the manure applied, and the crop grown. The futility and tho useless waste of public money in establishing an experiment station, or farm, or college, on any particular class of soil or land, or in any particular, climate, is apparent. Any farmer would readily assist tho County Council and tha Department of Agriculture in carrying out these experiment, and tho farmer would get tho crops gro-n-n on the plots. .With a permanent and constant supply of water foT irrigating, the exhaustion of tho soil will be moro rapid, and increased quantities of both organic and inorganic manures will be necessary. But with skilful irrigation better crops, with largely increased yields and larger profits, will result. But, once again, let us repeat that will demand increased mannring. Here are a few cx» amples of the increased yields that may result from skilful manuring -alone:— Plot A. Plot B. Plot O. Plot D. "On- 6cwt. 6cwt. 6cwt. manured, supcrphos- Buperphos- superphosphate. phate. lewt phale, lewt nitrate of nitrate of soda per soda, lewt. acre. sulphate of potash per acre. Produoe Produce Produce Prodnco per acre, par acre, per acre, per acre, roots only, roots only, roots only. Tons. cwt. qrs. Crop fail- 6 tons IS 8 tons 17 1J tons 16 cd to grow. cwt. 2qrs. cwt. lqr. cwt. lqr. Farmers may thus sec what may result from skilful "mannring. ' Tho corresponding results regarding, say, hay are:— Manures applied psr acre. 1. 2. 3. 4. No 2cwt. 2cwt. 2cwt. Nature manure, muriate muriate muriate of of pot- of pot- of potsoil. ash. ash, 2 ash, 2 cwt. en- cwt. superphos- perphosphate. phate, 1 cwt. nitrato of soda. cwt. qrs. cwt. qrs. cwt. qrs. cwt. qrs, All clay loam 30 0 56 8 42 0 46 0 Clay loam resting on clay subsoil 3d 0 42 0 48 0 51 0 Average results on various kinds of soil 20 1 27 2 27 3 3 8 0 The total net profite per acre which resulted from this manuring varied from t £l 13s. to .£3 l!)s. Tho nvcrago was .£2 10.=. per acre. It is hardly necessary to multiply instances of the profitable results which follow on skilful manuring. When unlimited quantities of irrigating water are available, but manuring is not both plentiful and skilful, the only possible result will be to exhaust tho soil more rapidly. Irrigation, with proper manuring, will convert the poorest soil into fertile land; will enable more profit to be made from a very small farm than could be niado from hundreds of acres without irrigation.