This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Assuming that the soil contains the food supplies already tabulated, the only way to bring them within the reach of any crop is by a rational system of supplying organic manures (see p. 145) and by deep cultivation. This is apparently a costly method, but it is really more economic than the prevailing system, as we shall endeavour to prove. In these days there is a good deal too much quackery about supplying foods to plants in a chemical and more or less unnatural form. Growers are told they have only to give their soil a dressing of this, that, or the other special manure, and their crops will be increased a hundredfold. There is never a suggestion of cultivating the soil deeply (that would sound too laborious), and the natural condition of the soil itself is rarely taken into account; whether it be clay, sand, loam, or gravel the same manures are recommended in all cases and under all circumstances. The result in many cases is that the grower spends his money uselessly and thoughtlessly, and his crops are a failure instead of a success. Here and there, where the special manure happens by accident to suit the soil, good results are secured. The grower is delighted. He pins his faith to that particular brand, and uses it exclusively, until at length he finds that he has ruined his soil and lost his money. This system of cultivation is on a par with the methods of a man who seeks to keep himself in good health by the aid of somebody's much-advertised pills, without taking sufficient natural food or exercise. Sooner or later he becomes a physical wreck (like the soil), and the pills (like the chemical manures) no longer perform the miracles in his system they did when first used.
This view is borne out in a striking manner from the experiments on Wheat at Rothamsted, an account of which has been published by Mr. A. D. Hall in The Book of the Rothamsted Experiments, from which the following figures are taken: -
Averages in Bushels of Grain over
8 Yrs., 1844.51.
10 Yrs., 1852.61.
10 Yrs., 1862.71.
10 Yrs., 1872.81.
10 Yrs., 1882.91.
10 Yrs., 1892.901.
50 Yrs., 1862.901.
Farmyard Manure ......
Single Ammonium Salts and Minerals ......
Double Ammonium Salts and Minerals ... ...
Treble Ammonium Salts and Minerals ... ...
Double Ammonium Salts alone
Double Ammonium Salts and Superphosphate ...
Double Ammonium Salts and Sulphate of Soda ...
Double Ammonium Salts and Sulphate of Potash ...
Double Ammonium Salts and Sulphate of Magnesia
From these figures it will be seen that, while the yield per acre from farmyard manure steadily increased, except in one decade (1872.81), from 28 bus. of grain per acre to 39.2 bus., in every case of chemical manures except the "treble ammonium salts and minerals" there was a conspicuous and remarkable decline in the yield. All plots show a big drop for the decade 1872.81, "a period of notoriously bad seasons", as Mr. Hall states. A recovery then took place, but it was as marked in the "unmanured" plot, No. 3, as in some of the others. Indeed the unmanured plot recovered more effectually than did Plots 5,10, and 11. Comparing the average yields over the period specified, it will be noticed that while farmyard manure shows an increase from 28 bus. in 1844 to 39 bus. in 1901, all the others show a decrease, with the exception of the plot that had been manured by " treble ammonium salts and minerals". The drop in yield is so remarkable that it is worth while to state it in tabular form, thus: -
50th Year ...
In Plots 2, 3, and 10 the experiments commenced in 1844; all the others commenced in 1852. Plot 2 received farmyard manure, and shows an increased yield of 112 bus. per acre. Plot 3 was "unmanured", and at the end of fifty.eight years shows a decline of 4.9 bus. per acre. It will be noticed, however, that this decline is greatly exceeded in the chemically manured Plots 10, 11, 12, and 14, which show a drop of 6.7, 89, 67, and 85 bus. respectively; while Plot 6, which received single ammonium salts and minerals, only beat the "unmanured" plot by the skin of its teeth - 4.1 against 49. Out of eleven plots, therefore, it appears that four plots (Nos. 10, 11, 12, and 14) had a much larger decrease in yield than the "unmanured" plot; while four others (Nos. 5, 6, 7, and 13) were almost as bad as the plot that had received no manure at all.
Taking the highest yield - that produced by the application of farmyard manure and the treble ammonium salts and minerals - the yields of 392 bus. and 38.5 bus. are by no means remarkable. They are both under 5 qr. to the acre, so that at £2 per quarter the return is only about £10 per acre for the grain. To this must be added the sale of the straw, averaging from 34 to 40 cwt. per acre, making the gross return about £12 to £14 per acre. From this must be deducted the cost of labour and manures, rent, rates, and taxes, so that farming and manuring on the Rothamsted principle would appear to be a very precarious business. The cultivation seems to be of the poorest description; in fact it can hardly be described as cultivation at all. "The usual practice", says Mr. A. D. Hall in his account of the experiments, "is to scuffle the land immediately after harvest, and remove the weeds; the land is then ploughed 5 or 6 in. deep; the mineral and other autumn.sown manures are sown and harrowed in, after which the seed is drilled." One can imagine the condition of the soil 6 in. from the surface after fifty years of such "cultivation". It must be almost as hard as rock, and impervious to rain, air, or roots.
To obtain some idea as to what Wheat really could do if cultivated on horticultural instead of agricultural lines, the writer carried out the following experiment at Ealing in 1910: Ordinary English Red and White Wheat obtained from a flour mill - 200 seeds of each - were sown at a foot apart each way on March 14. They germinated on April 9, and caused some amusement owing to their scanty herbage and lonely appearance. By August the plants had tillered and grown fairly well, but were not considered satisfactory, although they averaged 2 1/2 to 3 1/2 ft. in height. On September 24, the plants being sufficiently ripe were cut, and the following results were tabulated: Out of the 400 plants, about 40 failed altogether, that is 10 per cent. The best plant had 83 stems, and bore 45 ears of corn, the gross weight of the plant being 2 lb. Other plants had 50 stems and 37 ears; 39 stems and 36 ears; 37 stems and 17 ears; and the very poorest had 24 stems and 11 ears, and a weight of 1 lb. The average per plant for the whole crop was 466 stems, 292 ears, and 1.45 lb. Taking an acre of wheat grown on these lines, there would be about 40,000 plants, producing an aggregate of about 2,000,000 stems and 1,200,000 ears of corn, having a gross weight of nearly 26 tons, of which 19 tons may be regarded as straw, and 7 tons as corn; or over 31 qr. of wheat per acre. By tilling the ground deeply and well on true horticultural principles, there is no doubt but that far larger supplies of wheat - two, three, and four times as much - could be obtained from the acreage already under that crop. The cost of producing it would be increased naturally, but taking an average of four years' cultivation and manuring, it need not exceed an average of £9 10s. per acre per annum, apart from cutting. The cost of cultivating wheat on horticultural lines, as indicated above, and the receipts, may be estimated as follows: -