CLOVER AS A PREPARATORY CROP FOR WHEAT. 477 



iron. The precipitate is collected, washed with ammonia water, 

 dried, burned in a platinum crucible or capsule, weighed, and the 

 phosphoric acid calculated from the weight of the tri-basic phos- 

 phate of magnesia left on burning. 



Following this plan and the precautions here indicated, the 

 smallest amount of lohosphoric acid in a soil can be determined 

 with great precision. If the magnesia precipitate be not redis- 

 solved and freed from silica, as pointed out, a higher percentage 

 of phosphoric acid necessarily is obtained than the actual quantity 

 which the soil contains. 



Glover Roots. The roots from one square foot of soil were 

 cleaned as much as possible, dried completely at 212°, and in that 

 state weighed 240 grains. An acre consequently contained 14931 

 lbs. of dried clover roots. 



The clover roots contained : Dried at 212- Fahr. 



*Orgatiic' matter 81.33 



fMineral matter (ash) 18.67 



100.00 



*Yielding nitrogen 1.C35 



Equal to ammonia 1.985 



flncluding insoluble siliceous matter (clay and sand) 11.67 



Accordingly the clover roots, in an acre of land, furnished 24^ 

 lbs. of nitrogen. We have thus : 



Lbs. of Nitrogen. 



In the 6 inches of surface soil 3350 



In large clover roots 24^ 



In second inches of soil 1875 



Total amount of nitrogen in 1 acre of soil 12 inches deep 5249 



Equal to ammonia 6374 



Or in round numbers, 2 tons 6 cwts. of nitrogen per acre, an 

 enormous quantity, which must have a powerful influence in en- 

 couraging the luxuriant development of the succeeding wheat 

 crop, although only a fraction of the total amount of nitrogen in 

 the clover-remains may become sufficiently decomposed in time 

 to be available to the 3'oung wheat plants. 



Glover Soil from part of l\-acre Field of Burcott Lodge Farm, 

 Leighfon Buzzard, once mown for Hay, and left afierioards for 

 Seed. 



Produce 2\ tons of clover hay and 3 cwts. of seed per acre. 

 This soil was obtained within a distance of five yards from the 

 part of the field where the soil was dug up after the two cuttings 



