MINERAL COMPOSITION OF CROPS 



31 



at a rapid rate in the leaves, in contrast with potassium, which 

 decreases appreciably, while magnesium increases more slowly 

 throughout the growing season. 



Table 12. — Variations in the potassium, calcium, and magnesium content of alfalfa 

 leaves 1 grown in different soil types 



[Fonder (188, 189)] 



Stage of growth and soil type on which grown 



K 



Ca 



Mg 



May 8: 



Plainfield loamy sand- _ _ _ _ . 



Percent 

 4.63 

 2.98 

 2.70 

 2.22 

 2.40 

 3.02 

 1.62 



Percent 

 1.103 

 1.211 

 1.182 

 1.571 

 1.353 

 1.161 

 1.468 



Percent 

 0.256 





.224 



Hillsdale sandy loam . . .... 



.226 



Fox sandy loam . 



.268 





.313 





.241 



Miami silt loam . _ _ 



.265 









2.80 



1.293 



.256 







May 22: 



1.69 

 1.82 

 2.18 

 1.90 

 1.64 

 2.05 

 1.50 



0. 826 

 1.683 

 2.120 

 1.737 

 1.710 

 1.748 

 1.917 



.285 





.309 



Hillsdale sandy loam . _ 



.244 





.297 





.250 





.203 





.284 







Average _ _ - _____________ 



1.83 



1.677 



.267 







June 7: 



3.02 

 2.02 

 1.56 

 1.22 



.67 

 1.14 



.88 



2.140 

 1.695 

 2.339 

 3.108 

 3.830 

 2.568 

 2.148 



.258 



Coloma loamy sand._ 



.199 



Hillsdale sandy loam __ ______ 



.241 





.397 



Conover loam 



.444 



Brookston loam _ _ 



.263 



Miami silt loam ___ _ __ _ _ 



.262 









1.50 



2.547 



.295 







July 2: 



Plainfield loamy sand. _ _ _ _ ___ 



2.26 

 2.13 

 1.34 

 .95 

 1.39 

 2.20 



2.522 

 2.930 

 4.060 

 4.020 

 2.250 

 2.610 



.337 



Coloma loamy sand - _ __________ 



.321 



Hillsdale sandy loam _ _ _ _ ___ ___ 



.330 



Fox sandy loam 



.587 



Brookston loam__ _____ 



.263 



Miami silt loam _ ._ _ _ _ 



.298 









1.71 



3.065 



.356 







Averages for each soil: 



Plainfield loamy sand _ _ 



2.90 

 2.24 

 1.94 

 1.57 

 1.57 

 1.90 

 1.55 



1.648 



1.880 

 2.425 

 2.609 

 2.298 

 1.932 

 2.036 



.284 



Coloma loamy sand. _____ _ _ _________ 



.263 



Hillsdale sandy loam ___ _ 



.260 



Fox sandy loam 



.387 



Conover loam _____ ___ ________ 



.336 



Brookston loam _ _ ___ 



.242 



Miami silt loam 



.277 







Average.. _ _ _ 



1.95 



2.118 



.293 







Moisture-free basis. 



In his investigation of the soil solution, Fonder reported that al- 

 though the amounts of calcium and magnesium present in the several 

 soil solutions varied greatly at the beginnning of growth, by the time 

 the plant had reached the mature stage the amounts had been reduced 

 until there was but little difference among the soil types. The 

 reduction in the concentration of the two elements in the solution 

 was not rapid and was very uniform, the soil types maintaining the 

 same order with respect to each other during most of the growth 

 period. He concludes: "In general, the calcium contents of the 



