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FIG CULTURE 



ly upon this small addition of nitrogen, from forty 

 to fifty pounds to the ton. Whether it is economy 

 to buy fertility in this form is a matter of compu- 

 tation to be easily determined by each farmer. Fig- 

 uring its original cost, the haul, spreading and mix- 

 ing with soil, as compared with the expense of ac- 

 cumulating nitrogen from the air by growing in- 

 noculated legumes, and that saved from percolat- 

 ing rain water, it can be estimated which source 

 is most economical. An acre of cow peas will ordi- 

 narily accumulate as much nitrogen as is contained 

 in a ton of fertilizer, and deposits it in a state read- 

 ily assimilated. The cow peas hold nitrogen in 

 their roots longer than when it is spread in fertil- 

 izers, a fact greatly favoring the use of green ma- 

 nure. Consider their beautiful root systems, which 

 offer such web-like protection against leeching, and 

 their nodules break so slowly, the store is available 

 over a longer period than when a definite amount 

 is spread on the surface by manual applications. 

 The pea roots themselves are of value, gradually 

 resolving into humus, and if tops are plowed under 

 the benefit is increased. So, if the cost of green 

 manure is not greater than that of an equivalent 

 quantity of nitrogen in commercial forms, the form- 

 er should be preferred. 



Chemists tell us that an inch of rainfall contains 

 about one and one-third pounds of nitrogen per 

 acre. If rain came regularly each week this supply 

 would meet all demands of growing trees. But, 



