We ought, I think, to put our vegetables into groups in order to get into a proper position for suiting their requirements.
Group No 1 might be that class of vegetables which develop by swelling rapidly underground, and the roots of which are exceedingly susceptible to external influences. This is a very important group, because it includes Potatoes, Carrots, Parsnips, and Beets. Coarse, rank manure, or gritty, inorganic particles, such as stones and cinders, are bad for these crops, leading to scab, forking, and canker.
Fig. 8. An Experimental Garden Plot
Here is a plot divided into six differently manured sections: I., II., III., IV., V.,VI. Plot I. is subdivided, A, B. Have the crops running in rows across each, section, so that it can be seen at a glance which manure suits best. I.A might be dung alone; I.B dung with artificials; II. might contain an artificial mixture with potash, omitted; III., with phosphates omitted; IV., with nitrates omitted; V. might contain a complete mixture; VI., no manure at all. See remarks on manuring.
I cannot imagine any one system of manuring suiting such diverse crops as these equally well, nor, to be brief, is there one. Group No. 1 is suited by very little dung, and that only well decayed, friable, and dry. Finely ground artificials are the best. Groups Nos. 2 and 4 will take dung, rich, and plenty of it. Group No. 3, contrary to general belief, will thrive splendidly without dung, and needs, as a matter of fact, very little of any sort. Group No. 5 wants abundance of potash - far more than dung yields - and, therefore, artificials may be turned to with advantage.
These, it will be understood, are generalisations. An intelligent cultivator who took them as a guide, and worked out the details for himself, would doubtless get satisfactory returns, but it may be interesting to particularise a little.