Soil Fertility 61 



nevertheless they add some nitrogen to the soil. In all sec- 

 tions of the country legumes suited to the particular soil and 

 climatic conditions can be found and many progressive farmers 

 are now helping to maintain the fertility of their soils by plant- 

 ing legumes for green-manure, for hay, for pasturage, or for 

 seeds. 



Feeding live-stock in relation to soil fertility. A business- 

 like method of returning to the soil the fertility taken up by 

 crops is to feed these crops to live-stock, save the manure care- 

 fully to prevent excessive loss of plant-food, and place the 

 manure on the soil. Only part of the plant-food and organic 

 matter of the feed remains in the animal body ; the remainder 

 is excreted in the manure. On many live-stock farms much 

 feed for the animals is purchased and the fertilizer elements 

 thus brought to the farm are recovered in part in the manure. 

 If legumes are in the rotation on live-stock farms and the feed 

 grown together with that purchased are fed and the manure 

 saved, it is possible to maintain the nitrogen and organic 

 supply of the soil. In some cases the mineral elements 

 phosphorus and potassium may need to be purchased, but, 

 as these are not usually expensive in normal times, the cost of 

 maintaining the fertility of the soil on such farms is not ex- 

 cessive. 



GREEN-MANURE 



27. Use of green-manure crops. A green-manure crop 

 may be defined as one planted for the purpose of plowing under. 

 Crops plowed under help to maintain fertility and humus 

 and also act as cover-crops, thus preventing excessive soil 

 washing and plant-food leaching. Often the most economical 

 way of building up a piece of poor land is to devote it entirely 

 to green-manure for a year or more. In carrying out such a 

 practice legumes should be used, and it will probably be well 

 to use some fertilizer containing phosphorus and potassium 

 in order that the foods in the soil will be balanced after nitro- 

 gen has been added by the legumes. 



