become available later on, hence we may take 234 pounds nitrogen in the form of nitrate of soda, and 3634 pounds in the form of sulphate of ammonia. Cottonseed-meal, dried blood, tankage, etc., might also be used if desired.

Nitrate of soda containing 151⁄2 per cent. nitrogen; to furnish 234 pounds nitrogen it requires 150 pounds Sulphate of ammonia containing 20 per cent. nitrogen; to furnish 363⁄44 pounds nitrogen, it requires 184 pounds

Acid phosphate containing 16 per cent. available phosphoric acid; to furnish 120 pounds phosphoric acid it requires 750 pounds

Muriate of Potash containing 50 per cent. potash; to furnish 200 pounds potash it requires 400 pounds Filling, sand, etc., used to make weight if desired

Pounds

150

184

750

400

516

2,000

Unless care be taken in mixing fertilizers loss of valuable ingredients may result.

1. Nitrate of soda and soluble phosphate of lime-as, acid phosphate-must not be mixed and allowed to stand for any length of time, or chemical action will take place, resulting in a loss of nitrogen and phosphoric acid.

2. Do not mix an ammonium salt-as, sulphate of am

monia-with any other fertilizer containing free lime, as the lime will set free the ammonia, which will be lost.

3. Do not mix soluble and insoluble phosphates together.

4. Nitrate of soda is very deliquescent, and if left mixed with other fertilizers is liable to render the whole mass wet and pasty, and so difficult to apply. Cottonseed-meal is a very useful source for part of the nitrogen of mixtures. If it is necessary to hold a quantity of nitrate of soda for a time, it is advisable to empty it out of the bags, as they are liable to ignite spontaneously. When emptied do not leave the bags lying in a heap in the corner of the barn. Store nitrate of soda in a dry place.

5. Kainit is also very deliquescent, and it is the worst potassic fertilizer to use in a mixture on this account. Sulphate or muriate of potash are better for mixtures.

Applying Fertilizers.-When a horse planter is used the fertilizer is usually distributed in the row at the time of planting. The fertilizer may be sown broadcast or in the rows as desired, but it should be incorporated with the soil and not left on top.

Water Requirement.-It has been shown clearly that the available water content of the soil exerts a great influence upon the life of the potato plant, upon its assimilation of plant-food, and upon the yield. At the Wisconsin Experiment Station' it was found that when two acre inches of water were added in two irrigations in one case the yield was increased 100 bushels of salable potatoes per acre, thus showing that the right amount of water at the right time is a very important factor in determining the yield. Whitson,' of

1 Wis. Report, 1899, p. 213.

2 Wis. Report, 1902, p. 190.

Wisconsin, shows that if it is assumed that under the existing climatic conditions of that State 18 inches of rainfall during the growing season is sufficient for potatoes, then, on this basis, there was a shortage of 4 inches or more in ten of the past twenty-one years. In Utah' it was noted that the largest yield was obtained from a plat irrigated every eighth day and receiving 14 inches of water, and another year2 16.62 inches of water with practically no rain produced a yield of 423 bushels per acre. The importance of water was also shown at the same station, when amounts of water varying between 4.3 inches and 9.45 inches were applied between July 18 and August 6, and the yield increased with the increase in amount of water. At the New Jersey Station irrigation increased the yield 36.4 per cent., while at Wisconsin the increase has been 159.58 * bushels per acre over the unirrigated plat, and the average gain per year during the six years-1896-1901-was 83.9 bushels per acre. That some risk must be taken in irrigating heavy soils in a humid climate was demonstrated at Wisconsin." Thus, in one year, while there was an increase of 81.4 bushels per acre from irrigating sandy land, on heavier land the yield was reduced 56 bushels per acre because heavy rain followed the second irrigation.

5

Corn and potatoes require somewhat similar amounts of water to make one pound of dry matter. The figures of Wilfarth and Wimmer' and Whitson are as follows:

1 Utah Report, 1893, p. 180. 3 Utah Bul. 5.

Wis. Report, 1901, p. 198. 'E. S. R., XIV., p. 561.

2 Utah Bul. 26, p. 14.

N. J. Report, 1900, p. 184. • Wis. Report, 1900, p. 188. 8 Wis. Report, 1902, p. 191.

King' has shown that the amount of water required to make one pound of dry matter in the tuber and vine of potatoes varied between 272 pounds and 497 pounds during the years 1892-7, while that for oats ranged between 446 and 595 pounds; barley, 375 to 404 pounds; peas, 477; corn, 223 to 398 pounds; clover (first crop), 370 to 582 pounds; clover (second crop), 730 to 983 pounds.

"Irrigation and Drainage." F. H. King.

CHAPTER VI

CONSIDERATIONS OF SEED

Source of Seed.-It is often advised that potatoes be obtained from another soil and from a more northern latitude if vigor and delayed maturity are desired, and from a southern latitude if earliness is sought; but, generally speaking, potatoes bred for a district do better there than elsewhere. Few European varieties of potatoes are worth growing in America, and any introduction requires acclimatization and selection. In England we noted that northern grown Scotch seed did not yield so heavily the first year as the second, and the same was true of Maine grown seed in the Hudson River valley. Brooks,' of Massachusetts, and Bishop, of Maryland, report exactly to the contrary, although in a subsequent year Brinkley,' at the same station, obtained higher yields from home grown seed. The Rhode Island Station3 found that varieties which produced large yields gave increasing yields the longer the seed tubers had been home grown, and that those which produced smaller yields gave diminishing yields the longer the seed had been home grown. Louisiana Station' home grown seed was equal to, if not better, than western, or eastern grown or Boston seed. At Georgia Station' southern grown seed did

1 Mass. (Hatch) Report, 1896, pp. 25, 26. 3R. I. Report, 1897, p. 380.

Ga. Bul. 17, p. 166.

2 Md. Bul. 17, p. 257.

At

La. Second Series Bul. 4, p. 77.