POTATOES

King Country Chronicle, Volume XII, Issue 1174, 15 February 1919, Page 6

POTATOES

(Paper read by Mr. J. llcverlcy, Assistant Agriculturist, Department of Agriculture. »t the Teachers' Farm School at Kuakura.)

The potato (Solatium tuberosum) is a farm crop ptu«n tor its tutars, which arc used for human food, for feeding <>tmk. and for the manufacture of starch ami alcohol. Tta genus Milanum comprise* ataut 10UQ species, scattered throughout the world. Only about 20 of them arc tuber hearing, and only six of these arc considered distinct species. Of these six only Solonu'n tuberosum is known agriculturally. The potato is perennial by means of its tubers. The tuber is an under, ground stem; it bears buds which are commonly culled eyes, and when planted tends'to* produce plants similar to its parent; hence tubers are used for perpetuating a variety, and such are generally designated "seed tutars,*" »ir 'Seed." Nest to rice, the potato is the most extensively grown and the most valuable crop in the world. Wo have had proof of this during the war. FOOD VALUE. In a bulletin issued by the United States Department of Agriculture the Mlewing statement appears: "The m«x*t important groups of constituents in foods arc protein (nitrogenous matter), fats, and carbohydrates (starches, sugars, etc). The potato is essentially a starchy food, and eaten alone it would furnish a very one-sided. liadly balanced diet, but when eaten with meat. eggs, fish, etc.. which are essentially nitrogenous foods, an evenly balanced diet, which is most conducive to health and vigour, is secured. In experiments on the digestibility of potatoes by man. carried on by the Minnesota Experiment Station, it was found that 71.9 tier cent. of protein and 93 per cent, of the earW Imitate.* were digested or assimilated, tn these experiments the potatoes were eaten with some eggs, milk and cream. so the conditions were about normal." «Alt VESTING THE CHOP.

It would ta well to deal firstly with the harvesting and storing of the potato crop ** thi* season of the year is afi* pru>a«-Iting tfipidly. Degeneration i> brought atant quicker by storing seed potato?* improperly than any "other can*e. The death of the haulm is tta signal for digging the main crop. Fcr the early market potato growers do not wait for this, but an? governed l»y tie market price and the siae of the tutars. As long a* any portion of the haulm is grwn tta tutars can continue to grow, nnd the longer tta haulm is kept green &nd free front blight the tatter the crop will ta. Experiments have shown that more than one-third of the merchantable rrop is made during the last month of growth. In harvesting the crop it pays In handle potatoes; e.»refully. ns any injury afleet» their keeping qualities. It is quite n mistake »o allow potatoes; 10 Mand in sacks for any length of time in the open field, where lifting, as the edible tntars get green and unnaturally heated if the weather is hot, and wtan cartins them to the store ttay got bruised. Far tatter is it when lifting the crop for the pickers to have baskets and emnty tta contents into a cart moving along with them. With a stand cart and a eo-e.trt the work proceeds without any lot* of time. STOKING.

When tta load or potatoes arrives at the clamp or pit or potato cellar it should ta backed into position and tipred. The clamp or pit should never ta more thnn five feet wide at the base —perhaps tta best width for the tase of a potato chmp is 4ft Gin with a height of 3ft. After the potatoes are tippesl, they should ta placed into position with a siippet. This tool shot els up the potatoes without dam»ge when King .->« tta ground, and with a sippet the side> of a clamp ore formed. As soon as the potato clamp is a few yards long a start should be made to cover the sides with a straw. The straw should ta strong and clean, and should ta placed on the sides to n thickness of at least four inches. After the two sides are covered straw should ta placed on the apex of the triangle or the top and tanl over. It is best not to cover tta sides all over with soil immediately, but to leave spaces here and there for the heat to escape. In a few days the sides may ta covered with soil, leaving about 12in of straw ai the top uncovered. It is not necessary to cover the top with soil unless very "severe frosts are experienced during the winter. Never put potatoes on clamps or pits on the same place in succeeding years. In this way sources of infection from decav, including germs, may ta avoided to a" certain extent. Avoid covering potatoes with wet straw, and do not forget that potatoes should ta ripe if they are pitted. When a potato is ripe and lifted in fine weather, clamped upon dry and well-drained soil, and not in too considerable a bulk and well covered with straw and ventilation jirovided, there ought to tie no cause for complaint or source of loss. Darkness and low temperature are primary requisites in the successful storing of potatoes through the winter, tn harvesting, as well as in storage, potatoes should ta exposed to the light -is little as possible. When potatoes are allowed to green they become useless for i-ittiiwry purposes, and some authorities *»y poisonous. Warmth encouragt-s sprouting, which reduces the value r.f potatoes tath for planting and eating. I have stated that a low temperature ts neeessary in storing potatoes. The temperature should ta an even one of •T-Vbg. F. and not more than 4ndeg. F. f ;idvUe » temperature within these limits Tlie free/.in,' |«oint of potatoes i:; F. tn countries where low Oruiieraturcs are experienced during nfnt»t, pitting potatoes in the manner F h.,ve d«'*eritad atave ground is the rhe:»pe!»t and most satisfactory. It is not rfaiotcd that this method is suitable for the wanner parts of New Zealand—the reverse.

On account of its liiilk and perishable nature, which makes storing a difficult problem, the potato crop cannot 'k» thrown on the market in large quantities when the main crops are lifted. The market would In* glutted and tin- price would hill below the cost of production For thi«* reason potato {growers should find that |wtnto warehouses would enuhU- them to take advantage of the market: really a potato warehouse is an indispensable part of a large potato grower's equipment. If there is no danger of water during the season po* Utoes require storing, the basement type is the best. If there is danger of u;»t»r the l«asemeiit floor should lie raised ;tf>ovi' the danger line . At. inexpensive potato cellar may bo m;»»le hv merely excavating a trench five • >r sis feet deep and eight feel wide, and .1; »ong ,-is is needed. When the crop is hirv.sted the cart or dray is tipped on the side of the cellar. Never pile potatoes more than five feet deep. Always tutke a cellar in a line with the prevailiris; air eurrents. The roof should be eiven a pitch merely sufficient to shoot w.-»tcr nod :tve sufficient strength- A 4e»r.|i gutter or ditch should lie dug

.-■long eithi r side to carry away water .»hi-«l l>y tta roof. Up-to-date cellars or underground pits aro constructed so that air may pass through at night, and if the weather is hot dossed up during the clay. I have heard of an instance where potatoes were stored in an old m?ne tunnel and remained good for two years. A current of air passed through the tunnel and the temperature remainMi ataut 40deg. F. For storing small quantities of potatoes a kerosene tin may ta used—three sides can lie cut at the top to form a ltd. It holds ataut 281b when full. Dig Pig a trench 3ft or so deep and loin wide, so that a kerosene tin will lie lengthways. Place the lid close up to the bank side so that the lid mar be kept closed, and this will prevent rats doing damage. Cover the top with a sheet of galvanised iron sheeting. This is a very convenient method »f storing n few special potatoes, and where there are several varieties which have to be kept separate for seed purposes. I have gone fully into the subject of storage, a:« so many authorities on potatoes do not go into the matter very deeply and pay more .ittention to mamirial experiments.

SELECTION OF SEED POTATOES When the potatoes are ripe enough to keep, but liefore they are dug, and when the haulm is still green and in good condition, is the time to select potatoes to be saved for seed. Go into the potato field and look for strong, healthy tops, and see if the soil is being well raised up by the growing tubers. If yon place a stake at each root selected, the lifting can lie done later or as so.vi as sufficient selected roots have bcon secured.

There is no tatter way of selecting potatoes than bv taking seed from the jierfcct roots. Seed should ta selected onlv from roots producing first-class marketable potatoes, in the growing of which there is little waste of plant food. Tlie l rue breed characteristics of a tnricty can ta maintained by selection. PLANTING. When selecting potatoes it is ns well to know something about the quantity required to plant an acre. If potato row> arr- 2Sin apart there will ta 28 rows in 22 vards. «nd 280 chains qf rows ' n one acre—that is, 6160 yards to plant. s|kh<(xl il ISin apart, it will require 12.320 1(1 tars to plant one acre; if the tuliers weigh two ounces each, 14cwt of recti is required. The same weight of seed is required if largo tubers (4oz) ars ait in half. It is tatter to plant cut tutars at i ace and to place the cut surface uppermost when planting. The cut set is not so likely to decav, and if there are sprouts they are not knocked off in the covering. The Journal of the Hoyal Horticu 1 - tural Society states that covering the cut surface "with plaster of Paris gave the liest results as to Wright of crop, •oilphur tainjj also good. Lime was found to ta injurious. The Journal also says that cutting tubers tends to reduce the total crop. The prevalent idea that unless the seed tuber "decays,' the resulting crop is likely to ta small, •s generally true, and the cutting atvny the basal part or the heel of the tuber is said to ta an aid to dccay,but this was not borne out in the experiment. It was also found out that where the tillers were cut, those that were cut immediately tafore planting gave a better return "than those which were cut some time previously. Where the seed of a variety is limited, a larger yield will ta obtained if the sets are cut, but the averoge return per plant will not ta so large. A*, regards the size of seed it was found that tubers weighing between 2o« and 3o« wcr» tho most economical and reliable. It was also found that _ the greater tha space given to the individual plant the greater the yield of that plant would ta, but from the greater numtar of plants on a given area the greater thy total yield of that area would ta; but if it is desired to raise a large quantity from a small numtar of seed tuliers. the tutars must ta planted far apart. In my own experiments I have found that the greatest yield per acre is obtained when the sets are planted 12in apart; as the distance increases between the sets the yield decreases. If early crops are required it is good practice to sprout the tutars, taing careful to get short, sturdy sprouts which are not knocked off by planting. Another advantage to be gained h\ sprouting potatoes is that all the tutart affected with spindle-sprout disease may ta picked out, as when these are planted blanks will ta found. Light and air are necessary to get short, sturdy sprouts. When there is no fear of spindle-sprout disease, it is tatter to put nnsprouted potatoes in for the main crop. Potatoes will not sprout if stored under a low temperature. Is there any value in greening seed potatoes tafore planting? The practice of greening is resorted to as a rule when crops intended for seed purposes s.re lifted when the skins slip—that is, tafc.ie they arc ripe, and the skin is not s«t. If tutars are greened they should ta on the ground and not ta turned to gtt-en on tath sides. There is no harm done in greening seed potatoes if the potato moth is not a taut; that point must ta considered. I quite think thjt the practice of greening sometimes receives the credit which is more properIv due to the immature condition mi which the sets for planting were raised in the previous summer or autumn. The maturity of the seed seems to have an important tanr ; ng on productiveness. Potatoes not quite mature frequentlv g?ve the larger yield. The potatoes in Scotland never fully mature, they ar.; often cut down by frost in the autumn, yet Scotland is at the present time the potato seed-lied of the world. From evctv Continental State, from North and South America. Africa and Austral aiia glowers are sending for Scotch seed. Much in the same way do we send to the South Island of New Zealand when we require a change of seed in the North Island. CHANGE OF SEED.

In :uy experience the lienefit of u change"of seed is marked. It should rump "from a colder climnte and a distance away; no* necessarily from the South Island, as seed from a high altitude or a late district makes a go»wl change for the drier and earlier districts. When you have a good line '"• potatoes don't let it deteriorate. Select *<•£(! even - year, and lift it for seed whilst the" haulm is still green. Keep it cool, as I have said l**fore. When going in for the early market it is not advisable to plant large seed, smaller tubers will produce the earlier rrop. In Inle wet districts, or where the land does not come into a friabland nice working condition vi-ry early in the spring, jt is advisable to l*»x tin* s«>ed. Sprouted seed may l>c planted later, and then lie just as early as ifthcy had l>een planted in the liest condition a month liefore. There is thus a relief to the pressure of spring lalmur, and a|«to a relief to the farmer's mind io know that he need not battle with sticky land. Hoxing seed is a great bother, but is there not some bother attached to oil farm operations. Seed should not

be boxed all winter, the sprouts get too Jong—that is to say, for the main crop. It is tatter to put potatoes to sprout about two months before they are requited for planting, and keep them in the cool store until then. In every instance where boxing seed potatoes had been experimented with in Ireland there, was a distinct gain of from one to two and a-half tons per acre in the late varieties. If the sprouts get knocked off fresh ones will appear, but they are not as vigorous as the first ones. Under rough and ready methods of planting, and where the land is under an indolent method of tillage, it is best to put un. sprouted potatoes in. It is always advisable to test the germination of seed potatoes. Put a small quantity in a warm dark place to sprout two months before planting time to see if they all sprout well. Look carefully for tubers with sprouts almost as thin as cotton. Such tutars are affected with spindle sprout diseases, and wherever one is planted there will be reduced profits. DOTATION. Where should the potato come in a rotation? Certainly after a legume, 01 a pasture broken up in which clovers have formed part of the herbage. Fourfifths of the atmosphere consists of nitrogen,, and the potato grower who has an eye for business need not buy it from a merchant when the legume will collect it for him. The legume possesses the extraordinary power of taking nitrogen from the air and storing in the soil for succeeding crops what it does not require for its own use. Potatoes are not hard on the soil—that is, they do not remove large quantities of its fertility, as many farmers in certain dis. ricts of England follow potatoes with autumn-sown wheat. Quite as good crops of grain have been grown following potatoes as from summer fallow. In Jersey, an early maturing spring wheat often follows the early potato crop, and it is not uncommon to see the Jersey mangel being sown immediately the crop of potatoes is off the land. A rotation I know of as having been successful was lucerne four years, then potatoes fifth year and the sixth year wheat. When Marltarough lucerne seed can ta taught at Is (3d per lb, and 1511: sown per acre, it is not a costly crop to grow so far as seeding is con cemed, and where lucerne docs well, potatoes also do well. The heaviest crop of potatoes ever raised at Moumakahi followed lucerne. Peas and vetches are good preparatory crops for potatoes. If no provision for next year's potato crop has been made, crimson clover may be sown at once and ploughed or dug in during the winter. Taking the average of results for experiments covering two years for potatoes and four years for maize, it has taen shown in the United States of America- thar. when barley and legumes were grown as preparatory crops and ploughed in, that the average increase due to nitrogen added by legumes on the same land was 65 bushels of potatoes per nore and 10 bushels of shelled maize per acre. Thirty years ago the average vield of potatoes "in France was about three tons' per acre. In 1892, 110 French farmers who followed the advice given by Professor Aime Girard, succeeded in growing more than 10 tons per acre. So far as I know, three tons per acre and 30 tons per acre are the ascertained limits. One asks one's self, which of the two requires less labour in tilling, planting, cultivating and less expenditure in manure? Thirty tons grown on ton acres, or the same thirty tons grown on one or two acres. Under good cultivation and following a legume, it is possible to get 30 tons per acre. T'll tell you how to set about it. Space the rows 26 inches apart, that will give you 30 rows chain. Space the sets in the row 12 inches apart. You will then require 19,800 sets to plant an acre. If the sets weigh 2oz each you will require 1 ton 2cwt 111b cf seed to plant an acre. lam estimating the average vield per plant to be 3.41b: 19.800 plants x 3.41b gives 30 tons per acre. Some of my seedlings this year have yielded more than 3.41b per foot of row.