"It is shown in the experiments conducted with nitrate of soda on different crops that in the case of grain and forage crops, which utilized the nitrate quite as completely as the market garden crops, the increased value of crops due to nitrate does not in any case exceed $14 per acre, or a money return at the rate of $8.50 per 100 pounds of nitrate used, while in the case of the market-garden crops the value of the increased yield reaches, in the case of one crop, the high figure of over $263 per acre, or at the rate of about $66 per 100 pounds of nitrate." (New Jersey Agricultural Experiment Stations, page 8, No. 172.)
Professor Voorhees, of the same station, experimented with tomatoes, with these results:
Manure and Fertilizer Used Cost Per Acre Value of Crop
No manure $271.88
30 tons barnyard manure $30.00 291.75
8 tons manure and 400 lb. fertilizer 15.00 317.63
160 pounds nitrate of soda alone 4.00 361.13
Such common crops as tomatoes, cabbage, turnips, beets, etc., in order to be highly profitable, must be grown and harvested early; any one can grow them in their regular season; their growth must be promoted or forced as much as possible, at the time when the natural agencies are not active in the change of soil nitrogen into available forms, and the plants must, therefore, be supplied artificially with the active forms of nitrogen, if a rapid and continuous growth is to be maintained.
It is quite possible to have a return of $50 per acre from the use of $5 worth of nitrate of soda on crops of high value, as, for example, early tomatoes, beets, cabbage, etc. This is an extraordinary return for the money and labor invested; still, if the increased value of the crop were but $10, or even $8, it would be a profitable investment, since no more land and but little additional capital was required in order to obtain the extra $5 or $8 per acre.
The results of all the experiments conducted in different parts of the country and in different seasons, show an average gain in yield of early tomatoes of about fifty per cent, with an average increased value of crop of about $100 per acre. The rest of the report shows similar results with other crops. (New Jersey Agricultural Experiment Station, Bulletin 172.)
Joseph Harris says, "Some years ego we used nitrate of soda cautiously as a top dressing on the celery plants. The effect was astonishing. The next year, having more confidence, we spread the nitrate at the time we sowed the seed, and again after the plant came up, and twice afterward during a rain.
"Instead of finding it difficult to get the plants early enough for the celery growers who set them out, they were ready three weeks before the usual time of transplanting.
"At the four applications, we probably used 1600 lb. of nitrate of soda per acre, and this would probably furnish more nitric acid to the plants than they could get from five hundred tons of manure per acre, provided it had been possible to have worked such a quantity into the soil. Never were finer plants grown. As compared with the increased value of the plants, the cost of the nitrate is not worth taking into consideration."
As a means of fertilization without the use of artificial fertilizer, soil inoculation has come. It has grown out of the discovery of the dependence of leguminous plants on bacteria which live on their roots. The discovery is one of the most important of those made in modern agriculture.