Manures and the principles of manuring

by Charles Morton Aikman

Amount of Nitrogen recovered in Increase of Crop.

With regard to the amount of nitrogen recovered in the increased crop of mangel and roots when manured with different nitrogenous manures, it was found at Rothamsted, as an average of six years, that the following percentages of nitrogen were recovered: When nitrate of soda was applied, 60 per cent of the nitrogen it contained was recovered in the increased crop; when ammonia salts were applied, 52 per cent; when rape-cake was used, 50 per cent; and when a mixture of rape-cake and ammonia salts was used, 46 per cent.

It may be pointed out that the influence of season and climate on the composition of root crops is very great—greater, indeed, than on any other crop. Like oats, turnips grow better in Scotland than in England, the moister climate of the former country being more suitable for their maximum development, and hence the economy of maximum dressings in Scotland.

Norfolk Experiments.

In conclusion, a few words may be said on the Norfolk experiments, carried out under the direction of Mr Cooke for the purpose of ascertaining the best and most economical manure for mangels and swedes on different Norfolk soils. In most of these experiments it was found that superphosphate had not much effect in producing increase of crop in the case of mangels; that the best nitrogenous manure was nitrate of soda; and that on the whole it was not economical to apply farmyard manure at the rate of more than 10 tons per acre. It was further found that, although either potash or common salt gave a decided increase in weight of roots, it was not necessary to give both these manures at once, either of them being about as effective as the other.

Mr Cooke recommends the following manures as best suited for mangels—viz., 2 cwt. nitrate, 3 cwt. common salt, and 2 cwt. superphosphate. Upon certain soils peculiarly adapted to mangels, and in warm localities where larger crops than 25 to 30 tons per acre are habitually grown, it would probably pay to increase or to double the above quantity of nitrate of soda. Ten tons of farmyard manure may, if preferred, be substituted for all or a part of the nitrate of soda, or may even be used in addition to it, according to the resources of the farmer in respect of it, and the return he desires to get from the dung in the first year of application or in future ones. It is best to apply the nitrate of soda in two instalments—half at the time of seeding, and half as a top-dressing immediately after the first hand-hoeing of the roots. A third dressing may often be given with advantage a month later.

Manure for Swedes.

As a complete and economical dressing for swedes in Norfolk, Mr Cooke recommends 3 to 4 cwt. superphosphate, 1 cwt. sulphate of ammonia, and 1/2 cwt. of muriate of potash. Occasionally it may be found advisable to reduce the quantity of sulphate of ammonia, or to leave it out altogether; and in other cases the potash may be judiciously omitted. The entire mixture should be sown at the time of drilling the turnips. If farmyard manure is used—and if used it should be applied in a well-decomposed state—no other manure than 3 cwt. of superphosphate will be required.

Highland Society's Experiments.

Valuable experiments have been carried out on the subject of manuring of turnips by Dr A. P. Aitken, for the Highland and Agricultural Society of Scotland. The following are some of the results to be gathered from these experiments. The effect of a dissolved phosphate as compared with a ground phosphate is to produce a turnip of less feeding value. Superphosphate had a better effect when applied in April than when applied with the seed in June. It was further found that when the nitrogenous manure was given entirely in the form of nitrate of soda or sulphate of ammonia, the latter produced a denser and sounder turnip. Lastly, with regard to the application of potash, it was found that the best way was to apply it several months before sowing. The effect of potash manures is to increase the amount of turnips, but to retard the ripening of the bulbs. The effect of excessive potash manuring is to greatly injure the crop.