Asparagus is a gross feeder. There is hardly another plant in cultivation upon the vitality of which so great a demand is made. The cutting of all its sprouts, or shoots, as soon as they appear above the ground, for several weeks, is an abnormal and enormous tax upon the plant, which is thus forced to extra exertion in order to reproduce itself and perpetuate its kind. Therefore, it should have the most tender care, and an abundance of nourishing and readily available food. The earliness, tenderness, size, and commercial value of the product depends principally on the rapidity of its growth, and, as this is materially promoted by the richness of the soil, it is evident that the plants should receive all the food they can assimilate during the growing season.
There is a wide difference of opinion among growers as to which is the best kind of manure to use. Whatever the individual preferences may be, there is this satisfaction to know that no kind of plant food can come amiss on the asparagus bed, although the use of some kinds and combinations may be more economical than others. Formerly animal manures only were thought to be of any use for asparagus, and there are still some growers who cling to this opinion. In recent years, however, there has been a decided reaction in this regard in some of the principal asparagus sections. The objections made against stable manure are that it is more expensive to handle, that it is apt to get the land full of weeds, and that it does not contain sufficient phosphoric acid and potash. At present many growers use commercial fertilizers exclusively, convinced that asparagus needs liberal feeding of potash and more nitrogen than is generally supposed to be required.
The composition of 1,000 parts of fresh asparagus sprouts is, according to Wolff:
Water 933 parts Nitrogen 3.2 " Ash 5.0 " Potash 1.2 " Soda 0.9 " Lime 0.6 " Magnesia 0.2 " Phosphoric acid 0.9 " Sulphuric acid 0.3 " Silica 0.5 " Chlorine 0.3 "
This analysis shows very accurately what a given weight of asparagus abstracts from the soil, but it does not, and can not, show or even indicate certain indispensable demands. In this, as in other cases, the analysis of a crop is a very uncertain guide to its proper fertilization. It should be clearly understood by every cultivator of the soil that no rigidly fixed formulas can be given for any one crop on all soils. The question of quantity of application and of proportion must always, in the very nature of the case, remain more or less a matter of individual experiment. The following formula, given by Prof. P. H. Rolfs, makes a good asparagus fertilizer: