MANUS A HAND. 113 



be used, and" they will stand in this order : calcium, 

 nitrogen, phosphorus, and potassium; the last being 

 most important. 



Another and a more simple way to repeat this ex- 

 periment is to select in the spring a level space of 

 grass-land, and to set up ten stakes in the grass in two 

 rows two rods apart, and two rods apart in the row. 

 Number and mark the stakes as in the squares. Then 

 scatter on the grass, for ten feet about each stake, the 

 fertilizers containing these elements, in the same order 

 as in the squares ; leaving the space about stakes Nos. 

 2 and 9 untouched. As the grass grows, carefully 

 observe from week to week the grass about each stake, 

 and see if it grows any faster or taller and thicker, or 

 shows a darker color, about one more than another. 

 These surface indications will tell a good deal in regard 

 to the wants of the land, though the results will not be 

 so accurate as in the first experiment. In the Eastern 

 States nearly every experiment will show that any fer- 

 tilizer containing potassium will produce the best 

 results with all crops. 



Where shall we find these four elements? Calcium 

 is found in the form of lime, land-plaster, and gypsum. 

 We require less of this than of the other three ; and, 

 if our experiments prove that it does not help greatly, 

 we can omit it. If it does appear to help, one good 

 dressing of forty or fifty bushels per acre will be good 

 for fifteen years. 



The nitrogen we shall find in manure, in sulphate of 

 ammonia, nitrate of soda, guano, fish-guano or scraps, 



