What Roots are Worth

Manawatu Times, Volume 61, Issue 144, 20 June 1936, Page 12

What Roots are Worth

Swedes 8s 6d; Mangels 6s 8d Per Ton

The article on roots’ values given below is by Dr. H. E Woodman, School of Agriculture, Cambridge University, Britain.

The values given the roots in the heading above, are their worth to-day, compared with barley landed on the farm in the Manawatu district. The assumed cost of barley is 4s bushel.

Value Per Acre. Very fair. Local crops of mangels return about 45 tons por acre, and at Gs 8d per ton this yield is worth £ls an acre when pulled and carted out to the feeding paddock. For swedes a 25 ton crop would be a typical fairly good crop. At Ss 6d ton this returns £lO 12s 6d an acre, ready to feed off. These figures provide food for thought. Both crops require a year’s use of the ground. An acre of good farm land will return about £5 worth of grass in a year. Deducting this “rent” from the crop returns, we find that swedes give £5 12s Gd and mangels £lO an acre gross profit. From this must be deducted tire cost of crop growing—the ploughing, cultivation, seed, sowing and in the case of mangels, the weeding. A Modest Profit. In (he cast of swedes, the growing cost would not be great, say £2 an acre. This gives a nett profit of £3 12s Gd an acre, with a 25-ton crop. Mangels, owing to the weedings and thinning, are a more costly crop, per acre. An estimate of £0 would be a modest one. This shows a nett return of £4 an acre from a 45-ton crop. In neither case is fertiliser charged to the crop. This is to keep the crops on a parity with grass. The crops have already been debited with ground rent of £5 an acre. The growing cost includes all labour and plant used, as well as seed. Some Conclusions. With a relatively fine margin of profit to work upon, it follows that a poor crop must result in a true loss. The growing costs arc not overstated; indeed, reasonable efficiency is required to keep to these costs given. Very high yielding crops, would, of course, show a substantial profit, for they cost little, if any more, than do average ones, in their cost per acre. The high yield diminishes the rental and growing cost per ton, and this raises the profit margin. If successful crops are not raised, the land is best loft in grass. This, wellhandled. top-dressed, harrowed and properly grazed, will give a substantial and sure return. By special autumn topdressing, with ammouiated super, grass-lands can be very good providers even during the winter and early spring. Dr. Woodman’s Article.

Roots, on account of their high water and low fibre content, are classed with the succulent foods; they are in reality “watered” carbohydrate concentrates. White turnips are the most watery of the roots, containing as much as 914 per cent, of water, and therefore only SA per cent, of dry substance. Mangels co.ue next, the different varieties ranging from 10 to 13 per cent, of dry substance, while swedes vary from 10 to 14 per cent. Roots or No Roots? It was the bulky nature of roots, consequent on this hign water content,, that gave rise to the controversy of a fow years ago, sponsored in his inimitable way by Principal Boutour, about the desirability or non-desirabiliiy of including roots in the rations of dairy cows. This historic controversy served to clear the air, and it is now agreed that roots are an eminently suitable ingredient of the cows’ winter dietaryprovided they are used in moderation, say from 30 to 50 lbs. per head daily. They add a desirablo succulence to the winter rations, and, by virtue of their high content of vitamin C, particularly in the case of swedes, serve to keep up the amount of this ant.i-scurvv factor in milk during winter, when dairy cows frequently have no access to the vitamin supply of pasturage. Food Material in Roots. In order to gain a clear idea of the nature of the food material in roots, and to understand the part they are albe.io play in the feeding of livestock, it is necessary to consider fifie composition and nutritive value of the actual dry food material contained in them. The necessary data are given in the accompanying table, where, for purposes of comparison, similar figures are also given for potatoes, barley- and marrow stem kale:—

The figures show clearly that the nature of the food material in turnips, mangolds and swedes is very similar. Further, this food material strikingly resembles that in potatoes and a typical cereal such as barley. All these foods are exceedingly rich in carbohydrate, but poor in protein, oil and mineral matter. No less than with cereals, the particular function of roots and potatoes is to supply digestible carbohydrate. When using them iu the feeding of live-stock, it is of importance that the foods constituting the rest of the ration should be such as to furnish the requisite minerals and protein that are lacking in the roots. Indeed, much of the albuminoid in rools and potatoes is not in the form of protein at all, but of simple nitrogenous substances of distinctly lower feeding value. Inferior to Potatoes and Cereals. It will be sceu from the staren values iu the table that the food material in swedes is more valuable than that in turnips or mangolds, but that all the roots are inferior in this respect to potatoes and cereals. This is in part due to the different character of the carbohydrate, the bulk of this constituent in roots being sugar, whereas in potatoes and cereals it takes the form of starch. Kellner, iu his classical investigations, has shown that sugar mis omy about three-quarters the productive value of starch when consumed bysheep and cattle. Worth in Terms of Cereal. The figures explain why roots are able to take the place of cereals in the ration. When cereals are commanding a high price, the farmer witu a guou supply of roots can view the fact with some degree of equanimity, knowing that his roots will furnish him with a large part of the carbohydrate he requires for feeding purposes. On the basis of the starch values, it can be shown that 1 ton of swedes, containing S 8 per cent, of water, is equal to about 2 1-G ewt. of barley, and 1 toil of mangolds, containing 89 per •cent, of water, to 1 3-5 cwts. of barley. A Price Difficulty. From this it may be argued that if the cost of production of 1 ton of mangolds is less than the price of 1 3-5 cwts. of barley, or the cost of producing 1 ton of swedes is less than the price oi 2 I-G cwts. of barley, it should pay the farmer to grow swedes or mangolds, as the case may be. The difficulty of this method of reasoning, however, lies in forecasting the price of barley. A second line of argument would be to compare the cost of production of roots with their food values on the farm, which, on the basis or trie unit prices of protein equivalent and starch equivalent at the time of writmg, work out at 8s and Us per ton of mangels (89 per cent, water) and swedes (88 per cent, water) respectively. Swedes Versus Marrow Stem Kale. The figures in the table for marrow stem kale are taken from the results, as yet unpublished, of an investigation carried out at Cambridge last winter by my colleagues, Dr. K. E. Evans and Mr. A. Eden, and myself. They reveal the striking fact that one ton of the dry food substance in marrow stem kale is very nearly equal in starch value to one ton of the dry substance in swedes. Advantage of Kale. Where, thereiore, a swede crop has the high dry matter content of about J 4 per cent., 1 ton of such swedes may be taken as equal to 1 ton of kale, but in the case of swedes of lower dry matter content, the advantage lies win the kale. For example, one ton of marrow stem kale, averaging 13.8 per cent, of dry matter, would bo equal to about 1 1-5 tous ol' swedes containing only 11J per cent, of dry matter. It may also be pointed out that marrow stein kale is decidedly superior to swedes as a source of protein equivalent and of minerals, particularly of lime and chlorine.

Constituents in 100 lbs. of Dry Substance of Pood. M.S. Tps. Mels. Sws. Pot s. r.ly. lbs. Kale lbs. lbs. lbs. lbs. Jb.v. Albuminoids „ .. .. 11.8 8.8 11.5 8.8 10.1 15.4 Oil . 8.3 0.8 1.7 0.1 1.8 8.4 Carbohydrates .. .. 67.1 7S.4 70.5 82.S 70.8 4H.6 10.6 5.8 10.4 5.8 5.o IS.3 Mineral flatter .. .. 8.1! 6.7 6.1 4.2 5.0, 13.3 Protein Equivalent .. 4.7 8.5 6.1 8.6 7.5 10.1 Starch Equivalent .. 52.0 52.0 61.0 75.0 S5.0 05.0