Thirty years ago, Dr. Gilbert threw out the suggestion, that while it was evident that turnips required a larger proportion of soluble phosphates in the soil than wheat; while wheat required a larger proportion of available nitrogen in the soil, than turnips, it was quite probable, if we were growing turnips for seed, that then, turnips would require the same kind of manures as wheat.
We want exceedingly rich land for cabbage, especially for an early crop. This is not merely because a large crop of cabbage takes a large amount of plant-food out of the soil, but because the cultivated cabbage is an artificial plant, that requires its food in a concentrated shape. In popular language, the plants have to be “forced.”
According to the analyses of Dr. Anderson, the outside leaves of cabbage, contain, in round numbers, 91 per cent of water; and the heart leaves, 94½ per cent. In other words, the green leaves contain 3½ per cent more dry matter than the heart leaves.
Dr. Vœlcker, who analyzed more recently some “cattle-cabbage,” found 89½ per cent of water in the green leaves, and 83¾ per cent in the heart and inner leaves—thus confirming previous analyses, and showing also that the composition of cabbages varies considerably.
Dr. Vœlcker found much less water in the cabbage than Dr. Anderson.
The specimen analyzed by Dr. V., was grown on the farm of the Royal Ag. College of England, and I infer from some incidental remarks, that the crop was grown on rather poor land. And it is probably true that a large crop of cabbage grown on rich land, contains a higher percentage of water than cabbage grown on poorer land. On the poor land, the cabbage would not be likely to head so well as on the rich land, and the green leaves of cabbage contain more than half as much again real dry substance as the heart leaves.
The dry matter of the heart leaves, however, contains more actual nutriment than the dry matter of the green leaves.
It would seem very desirable, therefore, whether we are raising cabbage for market or for home consumption, to make the land rich enough to grow good heads. Dr. Vœlcker says, “In ordinary seasons, the average produce of Swedes on our poorer fields is about 15 tons per acre. On weighing the produce of an acre of cabbage, grown under similar circumstances, I found that it amounted to 17½ tons per acre. On good, well-manured fields, however, we have had a much larger produce.”
In a report on the “Cultivation of Cabbage, and its comparative Value for Feeding purposes,” by J. M. M’Laren, of Scotland, the yield of Swede turnips, was 29¾ tons per acre, and the yield of cabbage, 47¾ tons per acre.