192 GREEN MANURE. 



is an additional reason for sowing a great deal of 

 seed. Eighth : the land which is to be manured 

 must itself be rich enough on its surface to sustain 

 the green manure on its first development. All 

 endeavors, by ploughing in green plants, to fertilize 

 a soil Avhich is deficient in all vegetable nourish- 

 ment, will be vain. If land is very poor, such plants 

 must be selected as need very little nourishment, 

 like spurry. They should be ploughed in, and re- 

 sown repeatedly, till the land is capable of bearing 

 something better. This, of course, takes several 

 seasons. In most cases, nature is the best nurse, 

 and a field wdiich is too poor to repay the outlay 

 for cultivation, if left fallow, or used for pasturage, 

 will by degrees produce a scanty vegetation. Grasses 

 or clover may be sown, and then, if the field has 

 been fed from three to five years, and is again 

 ploughed, the soil will have received some nourish- 

 ment from the roots of the grass, and will produce 

 a tolerable crop. Ninth : all plants used for green 

 manure should be ploughed in at the very moment 

 when they are in blossom ; if it is done before this 

 time, the herbage will not have attained its greatest 

 growth ; if later, the humus from the decaying leaves 

 will needlessly evaporate, and nitrogen be exhaled 

 from the flowers." 



Thus it is evident that green manure gives to the 

 soil those organic substances which it has absorbed 

 from the atmosphere, and the inorganic, derived 



