24 
Experiment II is the same as experiment I throughout, except 
that the loamy clay soil No. 18 was used instead of the sandy soil. 
The results are given in the table below. 
The object of this experiment was to see whether the chlorosis 
would be as intense in a calcareous clay as in a sandy soil. The 
results show that check plants had a good color throughout the 
experiment and made a fair growth, though not equal to that of the 
check plants in experiment I; that 10 per cent of calcium carbonate 
did not produce as intense a chlorosis as the same amount of lime in 
a sandy soil; that 20 to 50 per cent of calcium carbonate caused as 
intense a chlorosis in the clay soil as in the sand, though the plants 
made a greater growth. 
Results of experiment in which calcium carbonate was added to loamy soil. 




Average 
reen 
aco. maw Appearance of plants during growth. Weieat 
end of 10 
months. 
Grams. 
Checkia ose. : All plants dark green throughout the experiment........ ............------ 781 
10 per cent. ....| Color of 2 plants lighter than check at fourth month; at sixth month 2 plants 622 
slightly chlorotic; at ninth month 1 plant chlorotic, 4 plants inferior to 
check in color. 
20 per cent. ....| Three plants showed symptons of chlorosis at fourth month; at sixth month 685 
3 plants chlorotic, 1 slightly affected; at ninth month 3 plants chlorotic, 
2 slightly affected. 
30 per cent. ....| Color of 5plants lighter than check at fourth month; at sixth month 3 chlorotic 650 
at center, 1 slightly chlorotic; at ninth month all 5 plants chlorotic. 
40 per cent. ....| At fourth month 1 plant strongly chlorotic, 2 plants color equal to check, 2 471 
plants color lighter than check; at sixth month all 5 plants chlorotic; at 
ninth month all plants strongly chlorotic. 
50 per cent. ....| At fourth month 1 plant slightly chlorotic, 4 plants color lighter than check; 534 
ab eern month all 5 plants chlorotic; at ninth month all plants strongly 
chlorotic. 



Experiment III is the same as experiment I throughout, except 
that the soil rich in humus (No. 222) was used. The results are 
given in the table following. 
The object of this experiment was to see whether the addition of 
calcium carbonate to a soil exceptionally rich in organic matter would 
cause it to produce chlorotic plants. Briefly the results were: The 
check plants maintained a good color and made an exceptional growth; 
the plants in the pots with 10 to 30 per cent of calcium carbonate were 
practically equal to the checks in color and growth; three plants in the 
pots with 40 per cent calcium carbonate showed chlorosis at the sixth 
month but recovered later, the growth being about equal to the checks; 
the five plants in the pots with 50 per cent calcium carbonate were 
slightly chlorotic at six months but all except one recovered their 
green color later. The results of this experiment are in harmony with 
the conditions obtaining in the Florida-Keys. They show that the 
tendency of calcium carbonate to cause chlorosis is counteracted by 
[Bull. 11] 
