XIII. CULTIVATED CROPS - HERBAGE AND FORAGE CROPS (cont.)
Natural Meadow Grass
In proceeding to notice the crops most usually cultivated in Britain for green forage we shall begin with natural meadow grass. In the south-western parts of England abundant crops of grass are obtained by irrigation with water alone. Our remarks will here, however, be restricted to those situations where sewage from towns or villages is available. Wherever a few scores of human families are congregated together, and have their dwellings properly drained and supplied with water, there is an opportunity for manuring a considerable extent of meadow with the sewage-water accruing from them throughout the year. The celebrated meadows in the environs of Edinburgh are interesting illustrations of the value of such water for irrigating purposes, and of the astonishing bulk of rich herbage which can be obtained in the course of a year from an acre of land thus treated. From the thickness of the crop in these meadows, and the rank luxuriance of its growth, the grass must be cut before it exceeds ten inches height, as otherwise the bottom gets blanched and the grass rots out. The mowing begins usually in April and continues till November, so that by fitly proportioning the head of stock to the extent of meadow and having the latter arranged in plots to be mown in regular succession, soiling can be practiced throughout the season by the produce of the meadow alone. This practice is necessarily limited to situations where sewage-water is available. The following excerpts from a paper read before the Royal Scottish Society of Arts in January 1867, On the Collection, Removal, and Disposal of the Refuse of the City of Edinburgh, by Charles Macpherson, C.E., burgh engineer, to which the society’s silver medal was awarded, will explain this system and exhibit its results:_
The waters of the Craigentinny Burn, the Lochrin Burn, the Jordan Burn, are used in irrigating part of the lands adjoining the course of the respective streams. The waters of the Craigentinny Burn are used for irrigating about 250 acres; Lochrin Burn, about 70 acres; Jordan Burn, about 11 acres; and Broughton Burn, about 5 acres being 336 acres in all irrigated by the water flowing in these four natural outlets for the drainage of Edinburgh.
"The area within the city draining towards the Craigentinny Burn-to the meadows irrigated by the waters of which I shall confine these remarks-is about one square mile and a half in extent. From this district there flows about 20 cubic feet of spring-water perr minute; the surplus rainfall being the non-absorbed portion of 24 inches per annum; and the sewage from a population of 95,589 persons, according to the census of 1861, with a water supply of say 25 gallons per head. Of this population about 60,000 have the use of water-closets; and excrementitious matter from about 15,000 or 20,000 of the remainder finds its way to the sewers connected with the burn at the rate of about 265 feet per minute of sewage.
"Various kinds of soil are irrigated. The subsoil of the part of the meadows nearest the city is peat, with loam over it near the course of the burn; while to the northward it is naturally sad, but the sand has been taken away, and the ground made up with rubbish of buildings, &c., dressed off with soil. Further down the course of the stream the soil is reddish clay, or loamy clay, or sandy clay; while at the part of the Figgatte Whins adjoining the sea-shore it is pure sand, with a coating of rich loam, varying from 1 inch to 4 or 5 inches deep, entirely derived from repeated applications of the sewage, no soil having been ever spread over the sand. The deeper soil is nearest the channels for conveying the sewage to the land. The meadows on the farm of Lochend, at Restalrig, and at Craigentinny, have a slope transversely to the course of the stream, varying from the steepest part, 1 in 25, which is of small extent, to about 1 in 50, which is the slope of the greatest part of these meadows. The Figgate Whins were artificially leveled to allow of irrigation.
"The kinds of grasses grown are Italian ryegrass and meadow grass. The ryegrass requires to be resown every third year; but the meadow grass has not required resowing, not even on the Figgate Whins, which were sown about forty years ago, when the ground was first irrigated. Opinions differ as to which grass is best adapted for the purpose; but ryegrass seems to produce the heavier crops. The irrigated ground is let off in small plots or squares for the season to the highest bidder. The grass is cut by the tenant as required, so that the annual yield of any particular plot has never been accurately ascertained; but an average crop is considered to be from 30 to 40 tons per acre, in four cuttings. The first cutting takes place at the beginning of April, and the last at the end of September, the let of the ground expiring at 1st October. The time of cutting the intermediate crops depends upon the wants of the tenant.
"The whole grass is eaten by about 3100 cows-the number previous to the cattle plague-in Edinburgh, Newhaven, Leith, and Portobello; but after the fourth crop is cut, sheep are turned on some parts of the ground about the beginning of November, and remain for about a fortnight, should the weather be favourable. The sheep do not seem to thrive, however, although the food is plentiful. The grass has been found most suitable for feeding cows-the attempts to use it for feeding other animals having been found not to answer, and the cost of converting it into hay being proved to be such as to render the process unprofitable.
"The price paid for the plots varies considerably, the best being known to bring £40 per acre, while others are as low as £15 or £20. Last season, owing to the cattle plague, the former high prices could not be obtained. The best land produces the heaviest crop; but on the Figgate Whins, mere irrigated sand, the first crop is earlier in the season-a matter of such consequence that, although the annual yield is less, the rent paid for these plots is about as high as for the plots producing the heavier crop. The rental of the Figgate Whins previous to the irrigation was, I have been informed, about 20s. per acre; while, when irrigated, parts have been let for some years at £40 per acre. The only works having been the leveling of the sandy hillocks and formation of channels for the sewage-neither of them very costly operations-and the annual outlay being small, the increased annual value of that land may be stated at not much less than the difference between the two sums.
"It might be an interesting speculation to consider how far the cost of the works necessary for collecting and removing the sewage from the district of the city draining towards Craigentinny might have been defrayed by the advance of rent obtained by the disposal of the sewage in irrigating the land along the course of the stream. The cost of the whole sewerage works (including many of the branch drains) constructed within the district in the city which is drained to the Craigentinny Burn, may be stated at £96,000. Assuming that the annual rent of the 250 acres irrigated was £5 per acre on an average previous to being laid out for irrigation, while the rent was raised to £25, then the difference, £20 per acre, is the annual value of the irrigation. There being 250 acres, gives £5000 as the return, or upwards of 5 per cent. on the cost of the sewers.
"The produce of the various irrigated meadows round Edinburgh is sufficient to supply the present demand for grass; necessitating any further application of the sewage to some other kind of crop, unless a more extensive market is obtained for thee grass produced."
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