262 IIOIITUS GRAMINEUS WO J5 U RN ENSI5. 



Nutiitive 

 Green Food. Matter, 

 lbs. lbs. 



average, 15 tons per acre, affording of 

 nutritive matter per pound 1,000 grs... 33,600 4,800 

 The common field or white turnip {hras- 

 sica rapa, var.), affords from a sandy- 

 loam, upon an average, per acre, 16 

 tons of green food, a pound of which 

 contains 320 grains of nutritive matter 35,840 1,638 

 The Swedish turnip, or ruta baga {Bras- 

 ska rapa, var.), produces on a favourable 

 soil, or a strong loam, on an average, 



13 tons per acre, a pound weight of 

 which affords of nutritive matter 440 



grains 29,120 1,830 



Cabbages {hi-assica oleracea, var.), which 



deliorht in a rich strono- loam, afford of 



green food, on an average per acre, 25 



tons, every pound of which contains 



430 grains of nutritive matter 56,000 3,440 



Kohl rabi {brassica oleracea, var.), the 



produce from a soil similar to that for 



cabbages or Swedish turnips, is on an 



average 14 tons per acre, and affords 



of nutritive matter per pound 420 



grains 31,360 1,881 



If a plant, therefore, impoverishes the soil in proportion to 

 the weight of vegetable substance it produces on a given 

 space of ground, the following will be the order in which 

 the plants just mentioned exhaust the land. 



Mangel-wurzel..... 25 1 



Cabbages 25 



White Turnip 16 



The proportions which tliey 



Potatoes 15 / bear to each otlier with rc- 



Kohl-rabi 14 



Swedish Turnip 13 



Carrots 11 



spect to weight of produce. 



