This section is from the book "Commercial Gardening Vol3", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The borders must next receive attention. These are scraped clean of every scrap of rubbish, such as bits of bark which have fallen on them during the cleaning of the rods, which work should have been done over a piece of canvas laid on the border to catch the fine rubbish. A dressing of complete manure, at the rate of 3 oz. per square yard - or a good guano may be used instead - also a dressing of ground chalk, enough to whiten the border all over, or basic slag at 3 oz. per square yard should be pricked into the back borders and dug lightly into the other borders. A good complete manure for the purpose is made by mixing 2 parts superphosphate with 1 part each of sulphate of potash and sulphate of ammonia. The dressing of ground chalk is added to correct any acidity of the borders and to assist in the proper working of the other artificials. If the grower likes, he can use instead basic slag, 1 1/2oz.; calcium cyanamide or nitrolim, 3/4 oz.; and sulphate of potash, 3/4 oz. per square yard. These manures can be sown separately or mixed up together in the following proportions: 5 cwt. basic slag, 1 1/2 cwt. sulphate of potash, 1 1/2 cwt. nitrolim. This at 3 oz. per square yard makes a good dressing, and has the advantage of being alkaline. Some growers give a lot of bone meal and other special Vine manures, which are sold ready mixed and generally at a price far beyond their value. The grower is well advised who has his soil analysed and takes expert opinion as to the manures required for it. Most nurserymen use enormous dressings of artificials without any consideration as to whether they are wasting money and material. If the soil is inclined to wash when watered, i.e. to run close together and refuse to take further waterings without being pricked up afresh, it is a good plan to give a mulch of spent mushroom manure; this will keep the border nicely open and moist. Most growers like to give a mulch of well-rotted manure at some time during the season, and a favourite time is after the stoning time, when the berries begin to swell again. One disadvantage of this practice is the number of little flies which immediately cover the glass and the grapes, marking the latter badly and detracting seriously from their appearance. If this mulch must be put on, it is better to do it when the Vines are started.