POTATO MARKETING.

Otago Witness, Issue 2323, 8 September 1898, Page 4

POTATO MARKETING.

Every farmer ought to know that a crop will only do its best when the plant food ingredients are in abundance in the soil, or presented to it under the most favourable conditions and circumstances. Instances occur so often where satisfactory results are not obtained with fertilisers thai the faith of many farmers has been shaken in tlicm. The mere fact that the putting on of so many pounds of plant food does not treble or quadruple trie yield of the crop should not be taken as an indication that fertilisers do not; pay. Various influences have to be considered, and often one of them may be powerful enough to avert success. Put into the soil, fertilisers must pass into a liquid condition befcreitliey can be absorbed by the plants. If^owever, by the neglect of cultivation the soil is in a poor condition— he) rd and lumpy — it offers resistance to the growth of the roots, and they 'can neither absorb nor retain moisture necessary to plant growth, then, quite naturally, fertilisers cannot show their desired effects. Plants are like animals in the matter of feeding. If they do not get their food in the right bhape or in the necessary quantities it is only natural that they cannot attain to a full and vigorous production. It is necessary to impress upon potato growers this season, when there ia promised tho most extensive cultivation of potatoes ever known in the colony, the principle* essential to the success of the crop. It is almo&l certain thai tliere will be, so far as -market prices are concerned, an overproduction of potatoes ; but while pork continues worfcb say 3d per Ib, and co-opera-tive bacon factories would keep it at that and over, a potato grower — a fanner — will do his best to secure a good crop. But, ordinarily, the growing of a potato crop is regarded as a matter of simplicity itself, and the failures, almost universal, to obtain a yield of seven or eight tons per acre of marketable tubers* are, of course, attributed to other causes than insufficient manuring and tillage. Well then, everyday experiences are quoted as to the unprofitableness of tlie crop, but most of these " my-experi-ence ' scribblers should have their ears nailed to the barndoor posts, as was the old-time custom with farm vermin. And so it is that we submit an abstract of results of some experiments in potato growing in England and Scotland in 1896 and 1897, merely prefacing the details with the remark that the potato crop is regarded in many English and Scotch counties as a paying one to the farmer who knows how to turn it to account on his farm when market prices are low. As the Scottish experiments are more certain to obtain most consideration from fanners in Otago and Southland they are given precedence. Last year experiments were conducted under tho supervision of tlie Glasgow Technical College on the manuring of potatoes. One was conducted on the farm of Terreglestown and the other on the farm of Helensburgh. No farmyard manure was used, but of the three necessary constituents of farmyard manure nitrogen was supplied in tlie form of sulphate of ammonia, phosphoric acid in tlie form of mineral superphosphate, which, is one of the cheapest and most effective forms of phosphate, and potash, in tlie form of sulphate, and also of muriate of potash. The chief object was to find out what quantities oc these substances were necessary or could be profitably employed to grow a large potato crop where farmyard manure was not available. Professor Wright, in his report, refers to the difficulty of securing absolute accuracy of results in field experiments arising from inequalities of soils. This difficulty was increased where the land was in high condition, as it already contained a large quantity of the mammal constituents, but tliere was~iio certainty that these were equally distributed. As indicating the condition of the land on the two farms operated on, Professor Wright mentions tliat on Terreglestown the portion which received no manure whatever produced a crop equal to 7 tons 7cwt of dressed potatoes and lOcwt " chats " per acre ; a yield distinctly higher th-in the average for the who.le of Scotland for 1897, even with manure. On such lands no manure could produce such good results as they would have done on poorer land where they were more needed. In the first of the experiments an attempt was made to discover the best quantity of phosphate to apply. To each of tlie plots there was applied sulphate of jimmonia at the rate of 2£cwt per acre, sulphate of potash at the rate of 2cwt .per acre, and superphosphate in varying quantities. The returns were as follows : —

in the quantity of superphosphate had been steadily followed by an increase in the quantity of potatoes of saleable size and ifc was made apparent it had been a profitable addition. In the c.t&e of Drumfork the increase amounted to 15cwt, representing at £3 per ton a return of 45s for the 10s worth of additional superphosphate. The second part of the experiment dealt; with the quantity of ammonia that cotild be profitably applied, and tne following were the returns : —

were contradictory. The first increase in sulphate of ammonia reduced the crop and a still larger application increased it. But in the

case of Drumfork — thepoorer soil — there was a steady increase of crop with the increase in the quantity of ammonia. Professor Wright thinks that the Drumfork resiilt was correct, and that the failure of the ammonia to produce increased crop* on the second plot at Terreglestown was due to some exceptional cause. The third series of the experiments dealt with potash. The returns were :— -

In the case of Drumfork they found a steady increase in the yield of marketable potatoes as they increased the dressing of potash. The increase in every caso was sufficient to be very profitable, and the greatest increase as profit was obtained from the largest addition of pott.sh. In the second plot at Terreglestown — a rich soil — an irregularity was exX^erienced ; but between the first and third there was an increase of 25cwt potatoes for 2cwt potash manure — 75s for a cost of 18s, or a clear increase of profit of about £3 per acie. . Two other points of interest were dealt with in the experiment. The first was a comparison of the muriate of potash with the sulphate of potash. There was a third form, kainit, in which potash could be purchased in an artificial form. (Here we -would advise colonial buyers of kainit to insist on a guarantee of percentage of potash, for there are grades of kainit not worth cartage or railway freight.) Another manure was applied in the experiment — viz., Cape Cross or Damaraland guano. This was obtained from an immense and very rich deposit of guano recently discovered on the coast of Damaraland. It was applied at the rate of 12cwt per acre, and on Terreglestown the yield was 191cwt dressed potatoes, and lCxnvt small ; the total crop therefore being over 12 tons. On Drumfork the guano plot also gaA'e a larger produce, proving this to be an .effective guano manure. On the other hand the cost of the guano was 108s per acre, -whereas the cost of the other manures applied in the experiments in no case exceeded 70s per acre, the range being from 51s to 70s. Turning finally to the question of profit derived from the increase of ciop obtained by application of the various manures, the most productive plot on Terreglestown (that yielding 203cwt) gave as compared with the unmanured plot an increase of 56cwt of dressed potatoes, "which at £3 per ton represented an increase of value to the extent of 168s. The cost of the manure in that case ■was exactly 70s, so that they had a profit of £4 18s from the application of these artificial manures, and that dressing would give a profitable return po long as the price of potatoes did not fall below 30=; per ton. In reference to these experiments, Mr Wallace, the "occupant of Terrelstown, wrote that while he did not care to alter his system on the strength of one year's results, the experiment would causa him to put more potash into his potato mixture. He agreed with Professoi Wright that an increased quantity would pay, and 'that the mixture which he suggested (9cwt superphosphates, 3Acwt sulphate of ammonia, and 3cwt muriate or sulphate of potash) would probably give better results than any obtained in the experiment. At the same time they had to consider that they would not always have potatoes at £4 a ton. When his early crop was raised in July, they were marketed to give him 35s clear, and that was the best year he had had for a long lime. But if they were to go down to 265, 255, and even 2is, for which he had to &ell his crop after July 21, 1896, this very high manuring would never pay at all. In the experiments in Scotland described above nc farmyard manure was used ; in those conducted in Wiltshire in England, under the supervision of Professar T. H. M. Munro, instructed by the Agricultural Committee of the Wilts County Council, the object was to ascertain the results of (1) different manurial dressings ; (2) varying weights of seed ; (o; close and wide planting ; (4) deep cultivation by hand labour ; (5) change of seed ; (6) spraying with sulphate of copper solution. There was a continuance '.f • these experiments for five years, and tLe results were embodied in a comprehensive report issued by the Committee of the County Council. In the manujial experiments the crops were variously dressed with farmyard manure, no manure, complete chemical manure, and several incomplete chemical manures. The complete chemical manures were devised by Professor Mur.ro, and consisted of a mixture of sulphate of soda or jts equivalent in sulphate of ammonia — with mineral superphosphate and potash salts. Ths ingredients were so proportioned that

J the manure yielded on analysis 5.37 per cent, of nitrogen, 4.2 per cent, of soluble ' phosjihoric acid, and 4 per cent, of potash. The remarkably high yields on the unmamired plots — averaging over the five years no less than 13^ tons pei acre — militates somewhat against any effective comparison * of the results of the different manurial dressings employed. Although the average crop • of the live years' trials is in favour of farmyard manure (4cwt per perch), yet in two years out of the five the comiilete chemical manure (91b per perch) gave considerably the best return and at much less cost. The five years' average crop was at the rate of 17 tons lOcwt per acre with farmyard manure, and of 16 tons 18cwi per acre with the complete chemical manure. Bui the farmyard manure was from highly-fed cattle liberally supplied -with supplementary concentrateu foods. The report goes on to state that provided tho land is fairly good it does not seem expedient to use "more than Bcwt per acre of the complete manure, as the extra crop obtained after a larger dressing does not pay for the extra cost involved. The importance of a supply of nitrogen in any system of manuring potatoes is clearly illustrated in these experiments, the average yield obtained from siipplying dressings of potash and phosphates only being barely 14cwfc per acre in excess of that obtained without manure. There is thus a decided loss by the omission of nitrogen, the small return from the potash and phosphates alone being insufficient to cover the cost of the dressings.

Manures Applied : ' cwt superphosphate, 2c\vt sul pate of potash, and sulphate ofj ammonia as below. | Yield Per Acre. Terreglestowu Drumfoi'k. Dressed Small Owt. Cwt 378 19 172 16 187 21 | Dressed Small Cwfc. Owt. 112 29 143 30 156 25 ijcisul. of ammonia '■£ n Si In the case of Tregglestoivn the result;

ures J -X iei leJ >er 1 ere. 2Kwt fei'lphate ou ' " ammonia aiid2cwt ierrcslcs town Druinfork. sulphate of potash] . ancl supcrphos-j \ I phate, as below. .DresscdiSmall Dressed!Bmall I I I Cwfc. Cwt. Cwt. | Cwt. scfc superplio-pliate lf-i 32 V.iY 25 7ct „ ■ 172 H) 14.?, m SJcfc „ 181 I IS 352 25 In the case of Terresrlestown tlie increase

Manures Applied : cwt superphosphates, 2\cwt sulphate of ammo-, ni?, and potash aE below^ TerrcglestowD Drunifork Dressed Small D v esse<] Small CvTfi. Cwt. Cwt. Cwt. 17S J9 134 28 172 16 143 30 203 13 IBS BU cwt sill, of potash •cwt luwt „ CvTfi. Cwt. 17S J9 172 16 203 13