The plan of top-dressing beds during the fall or early winter is gradually giving way to the more rational mode of top-dressing in the spring or summer. It was believed that autumn dressing strengthened the roots and enabled them to throw up stronger shoots during the following spring. This is a mistake, however. In the Oyster Bay region formerly all manuring was done in the spring, but the practice of applying all fertilizers immediately after the cutting is finished is rapidly increasing. The reason for this is found in the fact that, during the growth of the stalks, after the cutting season is over, the crowns form the buds from which the spears of next season spring, and it is probable that it is principally during this period that the roots assimilate and store up the materials which produce these spears. This being true, the plant food added to the soil and becoming available after the cessation of vegetation in the autumn can have little, if any, effect upon the spears which are cut for market the following spring; it first becomes of use to the plant after the crop has been cut and the stalks allowed to grow. Thus the manuring of the autumn of 1901 will not benefit the grower materially until the spring of 1903.
Nevertheless, some highly successful asparagus raisers continue to apply fertilizers in the spring, as evidenced by the following directions given by one of the most prominent growers in the Oyster Bay district. "After the roots have been set in the drill, put enough soil on them to cover about two inches. Then sow about 500 pounds of high grade potato fertilizer per acre in the drill. As the weeds commence to grow, cultivate and hoe, letting the soil cave down in the drill. About the middle of the season sow about 500 pounds more of fertilizer in the drill. Continue to cultivate and hoe the remainder of the season. At the end of the season the drill should be entirely filled up. The second year sow about 2,000 pounds of fertilizer per acre broadcast, plow the ground and harrow it down level, and keep the ground clean. The third year open the drill over the asparagus with a one-horse plow, broadcast 2,000 pounds of fertilizer per acre about the time the shoots begin to show, and back-furrow it up with a plow over the drill to form a ridge. Then smooth the ridge down with a home-made implement resembling a snow-plow reversed. Cut every morning all the shoots that show through the ground. Do not cut more than four weeks in the first cutting season. Continue to broadcast 2,000 pounds of fertilizer per acre every year."
From what has been said in regard to the various methods of applying fertilizers to asparagus, it will be readily understood that it can make but little difference how it is distributed, whether on the rows, between the rows, or broadcast, so long as enough of it is put on the land. In an established asparagus bed the entire ground is a dense network of roots, and wherever the fertilizer is put some of the roots will find it, but not those of the plants over the crowns of which it has been planted; not more so than the feeding roots of an apple tree can reach a heap of manure piled around its trunk.
SALT AS A FERTILIZER
Salt is but little used now by commercial asparagus growers, though it has been recommended for this crop from time immemorial. About the principal advantage to be derived from its use is that of killing weeds without injuring asparagus, although it may be applied in sufficient quantities to injure the asparagus. The indirect fertilizing value of salt is mainly due to the fact that it has the power of changing unavailable forms of plant food into available forms; but this object may be secured cheaper and better by the use of kainit. In sandy soils it may encourage the supply of moisture, but on naturally moist and retentive soils heavy dressings of salt may do more harm than good.
Much of the benefits to asparagus for which salt gets credit is its use in a small way in the home garden, due to the fact that not dry salt, but the brine and residue of the pork and corned beef barrels is applied to the asparagus beds. This brine is rich in animal matter extracted from the meat, and usually also in saltpeter, which has been used in pickling. The latter substance alone, without the addition of salt, exerts a strong fertilizing effect upon the plants.
After a series of carefully conducted experiments by Mr. Charles V. Mapes, he writes:
"Salt was only effectual as a fertilizer in proportion as the soil contained accumulated supplies of plant food, either from previous manurings or from natural strength. Asparagus, unlike nearly all other crops, will stand almost unlimited quantities of salt without injury. It also thrives near the seashore, and it was therefore generally believed that liberal quantities of salt were a necessity to its successful growth. Experience has shown, however, that its presence is not at all necessary for its growth, and that the reason that a bed to which salt has been applied shows quickened and improved growth is that the salt dissolves out of the soil plant food which, without the presence of the salt, would have become too slowly reduced to available condition for producing good crops. The salt acted practically as a stimulant and added nothing except chlorine and soda, neither of which in any considerable quantity is essential for growing this crop. It is this dissolving action that takes place in the soil whenever any soluble salt or fertilizer, like kainit, potash salts, acid phosphates, etc., be applied to the soil, that is often mistaken for a manuring one. The result is an exhaustion, not a strengthening, of the soil. The crop is grown at the expense of the limited supply of food that the soluble salt can act upon. The fertilizer has acted practically as a stimulant."