FORMERLY it was thought that plants took up their nitrogen in the form of ammonia. Now it is known that they take it up in the form of nitric acid, the acid being combined with some base, such as lime, soda, potash, etc.

Ammonia applied as manure will do as much good as it did before the above fact was discovered. The only difference is, that we know that the ammonia is converted into nitric acid in the soil before it can be taken up by plants. Experiments are sometimes quoted to show that some plants can take up nitrogen in the form of ammonia, but the rule, at any rate, is as above stated.

Prof. Goodale, in Garden and Forest, says : "The beet and tobacco thrive best when combined nitrogen is afforded them in the form of ammoniacal salts".

So far as the beet is concerned the fact that such large quantities of nitrate of soda are used as a manure for beets grown for sugar in Germany and France, even in the absence of actual experiments, would seem to indicate that nitrates were better than ammonia.

Lawes & Gilbert's experiments on sugar beets were commenced in 1871. The same amount of nitrogen was used in the form of nitrate of soda as in ammoniacal salts. The following are the results:

It is not necessary to give the results of later years. It should be understood that the unmanured plot has received no manure of any kind since 1846, and the plots, one of which had nitrate of soda and the other the same quantity of nitrogen in the form of ammonia, had no other manure. When this is understood, we think the above table will interest some of your readers. It should also be remarked that Vilmorin's White Silesian sugar beets were grown in the years 1871, '72 and '73. The manures were omitted in 1874 and '75. In 1876, and since, Yellow Globe mangel wurzel has been grown.

The year 1879 was the wettest season of the century, and this will account for the small yield. It is a surprising fact that with nitrates alone, with no potash or phosphates or ash constituents of any kind, 748 bushels per acre should be grown in 1883, after the removal of so many crops.

The experiment is still continued, the same manures being used year after year on the same land. The crop for 1888, the last yet reported, was as follows:

There are cases where a given amount of nitrogen in the form of ammonia produces as large a crop as when nitrate is used. The ammonia is converted into nitrate by the growth of bacteria or a minute live plant in the soil. If this growth takes place early enough to convert the ammonia into nitrate as soon as the plants need it, an application of ammonia is just as good as an application of nitrate. But for many early, crops, or for crops like beets, which seem to especially need a little ready formed nitrate to give the young plants a good start, the bacteria will not grow early enough in the cold soil in spring to furnish the nitrate.

This fact is one of the most important agricultural and horticultural discoveries of the age. It explains many of the old practices of experienced farmers and gardeners.

Many modern writers advocate applying manure to the soil in the fresh state. And sometimes this is the quickest and cheapest and best way to get rid of it. But experienced gardeners, to my own knowledge for 50 years, and probably for 500 years or 5,000, have found well rotted manure particularly valuable for certain crops. And he is an unwise man who ignores the well established facts of experience.

Forty years ago, Mr. P. Barry in his then just published book, "The Fruit Garden," speaking of the pear-leaf blight, said : " To avoid its evil effects as far as possible, the great point is to get a rapid, vigorous growth before midsummer, when it usually appears." In reviewing the book in the Horticulturist for July 1851, the lamented A. J. Downing singled out the above few lines for criticism. He admitted that it was important to get the growth before midsummer, but claimed that " It was a pretty well settled point among American fruit growers who have studied this subject, that the great desideratum to prevent blight is to place the tree in a condition where all ' rapid and vigorous growth' - a growth always most liable to disease, and especially to the blight - should be guarded against, and a moderate growth of well-formed, short-jointed wood secured. It is because of the luxuriant growth of the pear on the rich soils of the west, that the blight is ten times more frequent and destructive there than in eastern gardens".

Here we have the opinions of two of the most distinguished pomologists of the age. Mr. Barry was, in our judgment, unquestionably right in endeavoring to secure an early, rapid, vigorous growth before midsummer. Mr. Downing was right when he said "a late growth is frequently caught immature at the approach of winter, and suffers thereby, either in frost, blight or in some other way".

The remarkable thing about it is that Mr. Barry, nearly 30 years before the discovery of the " nitrate fungus " should have come to precisely the same conclusion, in regard to the desirability of vigorous early, growth, as those of us have reached who have studied the question in the light of the recent facts.

When Mr. Barry wrote it was not an easy matter to manure the land so as to produce the desired early vigorous growth without running considerable danger of forcing a late succulent growth of wood and buds that would not mature in time to stand our severe winters. The best he could do was to carefully pile manure and let it slowly ferment for months till more or less of the organic nitrogen and ammonia were converted into nitrates, and avoid the risk of their leaching away by covering the piles with soil or sods.

We now know how to produce a rapid, vigorous, healthy growth in the spring, such as Mr. Barry desired, without the excessive growth in the fall deprecated by Mr. Downing. This is done by the direct application of nitrates early in the spring.