504 SOILS. 



Valley states ; and the same is true of other trees, and of her- 

 baceous plants as well. The fruit on the lime soils is often 

 smaller, unless much humus is present ; but the statement made 

 in Europe that cultivated fruits, and especially grapes, are 

 sweeter on calcareou= lands, is abundantly verified in the native 

 fruits of the Mississippi Valley states as well ; where the various 

 wild berries, haws, plums, etc., are well known to the younger 

 part of the population to be much sweeter and higher-flavored 

 in certain (calcareous) localities than in others, besides being 

 usually more abundant. 



This is entirely in accord with the well-known fact that the 

 application of lime checks the excessive wood and leaf growth 

 resulting from excess of nitrogen as well as moisture ; while on 

 the other hand, the injurious effects of overdressing with lime 

 or marl are known to be repressed by the use of stable manure, 

 or by green-manuring. The repression of excessive wood 

 growth by lime would seem to offer a simple explanation of the 

 compact habit of growth on calcareous lands ; and the extraor- 

 dinary sweetness of fruits grown in the arid region as com- 

 pared with the same in the humid, is fully in accord with the 

 high lime-content of the arid lands. 



Stunted Groi^tJi. In practice it will be found in most cases 

 that a stunted native growth is clue not so much to lack of 

 plant-food in the soil, as to unfavorable physical conditions. 

 Among these, shalhrnnicss, and extreme heaviness of the soil 

 are the most common causes. The " scab lands," underlaid by 

 impervious rock at a depth too slight for culture plants, as in 

 many plateaus of the Pacific Northwest, and in rocky or mount- 

 ainous regions generally, are cases in point. Strata of imper- 

 vious clay often produce the same result ; but in this case, 

 should such clay be intrinsically capable of supporting plant 

 growth, the land can often be made available for orchard pur- 

 poses by blasting with dynamite (see chapter 10, p. 181). 



The post oak ( and black-jack) flats of the Mississippi Valley 

 states are familiar examples of land whose dwarfed tree growth 

 causes it to be avoided by settlers ; similarly, a dwarfed growth 

 of red elm (Ulinus nibra], hack-berry and ash indicates in the 

 flood plain of the Red river of Louisiana a heavy " waxy " red 

 clay, or " gumbo " land, scarcely available for agricultural pur- 



