FOOD REQUIREMENTS OF CROPS 227 



Plant Food Removed by Crops 37 



Pounds per acre. 

 Phos- 

 Gross Nitro- phoric Pot- Sil- Total 



Crops. weight. gen. acid. ash. Lime. ica. ash. 



Wheat, 20 bus 1200 25 12.5 7 1 1 25 



Straw 2000 10 7.5 28 7 115 185 



Total 35 20 35 8 116 210 



Barley, 40 bus 1920 28 15 81 12 40 



Straw 3000 12 5 30 8 60 1 76 



Total 40 20 38 9 72 216 



Oats, 50 bus 1600 35 12 10 1.5 15 55 



Straw 3000 15 6 3^ 9.5 * 60 150 



Total 50 18 45 11.0 75 205 



Corn, 65 bus 2200 40 18 15 1 1 40 



Stalks 3000 35 2 45 ii' 89 160 



Total 75 20 60 12 90 200 



Peas, 30 bus 1800 .. 18 22 4 1 64 



Straw 3500 .. 7 38 71 9 176 



Total . . 25 60 75 10 240 



Mangels, 10 tons.. 20000 75 35 150 30 10 350 



Meadow hay, 1 ton 2000 30 20 45 12 50 175 



Red Clover Hay, 



2 tons 4000 . . 28 66 75 15 250 



Potatoes, 150 bus.. 9000 40 20 75 25 4 125 



Flax, 15 bus 900 39 15 83 0.5 34 



Straw 1800 15 3 19 13 3 53 



Total 54 18 27 16 3.5 87 



291. Plants Render Their Own Food Soluble. — It 



was supposed at one time that plants obtained all of 

 their mineral food from the mineral matter dissolved 

 in the soil water. Experiments by Liebig demonstra- 

 ted that plants have the power of rendering their own 

 food soluble, provided it does not exist in forms 



