BETTER CROPS.

Dominion, Volume 2, Issue 527, 7 June 1909, Page 8

BETTER CROPS.

EXHAUSTED SOILS.- 1

.■;■;■■•;•:,\ ; the science: OF SUCCESS.;. -J; • j 'vThe. following is written for'THE Domeuon by Mr. A. B. Wood, agricultural chemist'fori Messrs; J. D.-Cruickshank":— -'■':> v : . '■■''.'':'■■ ■ "It is. becoming better, known in- New -Zealand .that the soil,'.no,matterihow productive 'in the pastj-.niust^by..the many crops.taken off come'to a ; state of exhaustion: "It has been, established ;long-ago "■ that: the- inorganic stituents, of plants, are solely derived from the: soil. Baron : Liebig'as. far. baok_as' 17,70 said,' '.'lt is. true, that the .diligent, tillage 'of jtho: ipaddocks, sunshine, and rainare the outward conditions, percepfiblo. to all' men, of .'. good 'harvest.V: Butthese, are- perfectly,': effect upon of'tho.'soiL'un-. less e'ertjam things hot so, easy.of .perception; •by ;the senses: are present; in the "soil, and 'these are the elements which■serye'for,npur-; :ishinentj' for the- production-of'.roots, leaves, and grain,.etc'., Plant food is always present,' in. mostsoils, but in such small,and unbalanced state-f-in- very small quantities.in proportion to tho,;mass .ofvsoil' iteolf.'--; : - '' ;V ; "" ■ ''•'"; "These elements' are .taken : from the soil daily in tih'e grain orj.in the flesh of tho'.ani.mals\ .'nourished. and. fattened by. iheso ', products, .and.experience shows that .the most 'productive paddock- 'under, this system, of; spoliation: muE# eventually, give, wayi .'.Thero ;is hidden in.-many, soils'* a ,jrtrg€> amount of. material which.a.farmer can lise/bnt'there-is-no reserve': of elements in the. bulk of .oUrlight: lands;. For years', the?plant' foods have been taken out. of; our soils,. and very little /effort has been,.made l : to';'^'e«rtx>re:them.by.;fef- , ■ - tilisers ' most suitable: to I ;fill;the -and/so i&tiongthen the links which, complete the circle of fertility.; !';.?:/ ■.;:': .':-"•' 1; '' ; -V,';:;'. 's/-\ What the Crops Need.;■■"•;,"■;,. ! ;! \ :'. ..',-'Who plantifobds-moit important,to''farm--ers 'are the following:—Phosphoric acid; combined witlifthejimo.of the Soil; to." form ph'os-, phate, which is' one.of-the perfected foods' which aH crops require: also. humuSi'-potash,' arid nitrates. .If one. of .the above .'important elements is 'absent,, or is, not, in: a state, of ''eat-;, '.ficiehcy,--the crop, will, suffer .and starve; '■' To increase the. store,of plant food so as to yield : profitably - cannot be'- done "all ■'■ at;' once,-■: but; must be a process of time; \.'. ;.:-''•.'■";'' , . ; "Principles to be remembered- by all farmers :—Oatsj.turnips, and barley.need plenty: of phosphates; mangolds plenty of: potash; wheat,.nitrates... Much of our heavy soils require lime, and when the .potash is locked up an;' application .of potash' salts will not only liberate some, .butiwill.supply the necessary potash..!;" v --;.;'; •■'.'./.'.' ' .-;'•'..'.:'".:• v -.,',-V V ■'■'; ■'•■ ''There/are a'few.:B.ignß;which,will'greatly assist the agriculturist to. ascertain tho con- : difcioh of his soil and to select tho most "suit-: able fertiliser'. -If -the country, is over-ridden: ..with'hawkweed and the'iherbage is of a pale , 'delicate.colour,'it is sadly in heed of nitrates; if .overVdonq"with tufts .of. cocksfoot .and coarse-growing'-grasses, the; soil is too. rich in, -nitrates ;.'■:.; if- . Yorkshire' .fog prevails, •'..-; with'.: sorrell,: :it : :, is,\ deficientin -lime; • should "clovers \ be absent ' there is a shortaga'of,phosphates arid potash:; The'careful feeding of the-better grasses and- ■ 'clover will,slowly-but'-;surely\crowd out the' : inferior herbage: good herbage .can only, be: maintained by keeping the\soil in':a. good -physical condition.'. ■'.'-.- '.-v ■':;..- '■■ .-.

HowPlantsJFeed.; . 7, v '"'[;. '' '' .''.''ln the now view which we'now, takeof the absorbing power of: soils, the question of the action of.'roots on ammonia ana potash 'is, greatly simplified/ These, being merely adhering to the surface of .the substances constituting ;tho,body-of tho soil, are r ;by ; ho means out of .reach of the. direct action ol .the roots of. plants'.; Tho roots come into contact with them by forcing their'way through the.soil, and take them up by special absorption,: in the.samo way as leavesiof plants do the. carhonic aoid from tho atmosphere. Tho diffusion of tho gases in the atmosphere is not.tho most active means of bringing carbonic acid'into contact, with tho leaves, al- . though 'we might suppose it capable of doing .'so.to a 1 slight extent.' The circulation of atmosphere; in'teing constantly disturbed by winds, accomplishes this .by rapidly bringing. tho nutritive substances', into 'contact. wltb the. leaves.';,..ln. tho soil tho roots,are con-; staritly in search of food. . ; But the food of plants exists in the soil in forms only slightly soluble'in water and totally incapable.of being dissolved by it and supplying the wants of pknts. It has heon proved long ago that plants are capablo of absorbing nitrogen from tho atmosphere direct, and that nitrogen docs not. act;■ unless phosphates are also present.The most important point to considor now is, , 'How can wo restore "the depleted plant'foods [to our.'-soil 1 so that the growth of crops may be perfected and yield an oxtra profit?' Wo can do this by up-to-date, methods as follow:— .- -

■ Drainage, an important factor, wo must, place first. Natural constituents of soil. The! proper uso of plough and preparation of seed ;bcd.' -.Correct rotation of crops. Rotation of manures, so that any rosiduo from former crops may be of benefit to the next crop! Attention, should bo also paid to tho various depths the plants •go in search of suitable food. : The difficulty of obtaining a proper return from tno land is often the fault of the farmor: some have peculiar opinions respecting. thq economics of agriculture. To deplorb.past .mistakes and sit down and allow matters to go! 'on as they like—making no effort to got totho root of failures to which tho scienco of manuring, if properly applied may lighten tbe burden of fanning—is not tho . shortest'road to successful faruring."