PJiosphatic Manures for Root-Crops. 
63 
Sotimary. 
1. A crop of turnips, weighing per acre 20 tons of roots 
and 6 tons of tops, removes from the soil 177^ lbs. of potash, 
104i lbs. of lime, and 40 lbs. of phosphoric acid. 
2. Phosphatic manures appear to hasten on early maturity ; 
ammoniacal salts to retard it. 
3. Phosphatic manures, especially in cold or wet seasons, pro- 
duce more nutritious roots than ammoniacal manures, and a 
liner sample of wheat or barley than the latter. 
4. Late-sown barley, or barley grown on land out of condition, 
is much improved by superphosphate, or, better still, by a mix- 
ture of equal parts of superphosphate and guano, applied at the 
rate of 3 to 4 cwts. per acre. 
5. In a warm climate or a good season, ammoniacal salts mav 
be used with greater advantage than in a colder country or in an 
ungenial season. 
6. The ash-analyses of plants, do not afford a sufficiently trust- 
worthy guide to the practical farmer in selecting the kind of 
manure which is best applied to each crop. 
7. The ash-analyses of plants, however, teach the important 
practical lesson that certain mineral matters in certain pro- 
portions are essential to the luxuriant growth of all cultivated 
plants ; and that our crops must remain scanty or become diseased 
if the soil on which they are grown is deficient in one or more of 
the essential ash-constituents of plants. 
8. Superphosphate of lime, applied to root-crops, has a different 
practical effect on different soils. 
9. Few soils contain an amount of phosphoric acid which 
renders the direct application of phosphatic manures superfluous. 
10. On good calcareous clay soils and land that is moderately 
stiff and in good heart, heavy crops of swedes and turnips mav be 
grown with no other manure than superphosphate rich in soluble 
phosphate. 
11. 3 to 4 cwts. of mineral superphosphate is a sufficient 
dressing per acre on such land. 
12. The addition of ammoniacal salts to phosphates in many 
instances produces no beneficial effect on turnips grown on calca- 
reous clay soils. 
13. Phosphatic manures are inefficacious on some soils which, 
like those in the greensand formation, contain a much larger 
proportion of phosphoric acid than is common. 
14. Soluble phosphate of lime is the most valuable constituent 
of commercial superphosphates. 
15. All arable soils have the power of absorbing or rendering 
soluble phosphate insoluble. 
