FERTILITY AND APPEARANCE 



573 



stalk, and retards maturity, and that small growth and a pale color 

 show lack of nitrogen; that phosphorus produces the seed and has- 

 tens maturity, and that poorly filled ears and heads show lack of 

 phosphorus; that weakness of straw shows lack of potassium. 

 However, these and other " rules" have commonly been evolved 

 from experience on soils of one class, and they may have little or 

 no value on other soil types. 



Any kind of malnutrition produces imperfect growth. On sand 

 land and other soils deficient in nitrogen, the addition of nitrogen 

 does not retard, but positively hastens, maturity, sometimes by one 

 or two weeks, and markedly increases the development of the seed 

 or grain. On peaty swamp lands, which are well supplied with 

 nitrogen, the plants are small and pale or yellowish in color, and 

 under the rule appear to suffer "nitrogen hunger," but rank 

 growth, dark color, and well-filled heads or ears result from the 

 addition of potassium. On soils rich in nitrogen and potassium and 

 deficient in phosphorus, the growth and strength of straw or stalk, 

 as well as yield of grain, are markedly increased by addition of 

 phosphorus; and 100 bushels of good sound corn will often mature 

 where the soil is properly balanced two weeks in advance of a 20- 

 bushel crop grown from the same kind of seed planted at the same 

 time on the same type of soil, where not properly balanced. 



Nitrogen is an important constituent of the organic matter of 

 the soil; consequently, soils rich in organic matter are also rich in 

 nitrogen; and, conversely, soils markedly deficient in organic 

 matter, such, especially, as worn hill lands and sand soils, are also 

 deficient in nitrogen. Potassium is not a fixed constituent of or- 

 ganic matter, is easily leached from plant residues, and is usually 

 deficient in peat soils, as well as in soils derived largely from quartz, 

 as from some residual sandstones. Carbonates and phosphates 

 derived from shells and skeletons may have some relation, 1 and 



1 Whitson has suggested (Wisconsin Agricultural Experiment Station Bulletins 

 1 39 and 174) a vice versa relationship; namely, that there is correlation between soil 

 acidity and lack of phosphorus. He says: "So far no case has been found in 

 which acid soils have not shown a need of phosphate." While it is true that many 

 acid soils are deficient in phosphorus, there is no necessary correlation between 

 these two facts. The highly phosphatic soils of Tennessee and Kentucky are some- 

 times acid, and some of the peat soils of Illinois, which are as rich in phosphorus as 

 any soil in the state, are distinctly acid. This is the case, for example, with the deep 



