26 
EXPERIMENTS WITH PLANTS GROWN IN SMALL FIELD PLATS. 
In addition to the pot cultures an experiment was made under natural 
conditions in the following manner: Four holes, 20 by 10 feet and feet 
deep, were dug and filled with prepared soil. The plats were sur- 
rounded by a ditch and separated from each other by 3 feet of clay 
soil. One plat was made up of a loamy soil containing no carbonate 
of lime. The other three plats contained respectively 10 per cent, 
25 per cent, and 50 per cent of calcium carbonate. The limestone 
used was No. 216 and was very thoroughly mixed with the soil. In 
each plat 16 Red Spanish slips were planted. The plants were here 
growing under perfectly natural conditions of moisture, temperature, 
and root space. 
All the plants in the check plat, with no carbonate of lime, made a 
good green growth throughout the experiment. The plants in the 
plat with 10 per cent of calcium carbonate at the end of five months 
were distinctly inferior in color, being a very light green. At the 
end of seven months 11 plants, which had made a fair growth, were 
strongly chlorotic; the remaining 5 plants, which fart grown but 
little, were only ete chlorotic. At the tenth month Bites were 
all slightly chlorotic. The plants in the third plat, with 25 per cent, 
of calcium carbonate, were slightly chlorotic at the fifth month. At 
the seventh month the 12 plants which had made a fair growth were 
very strongly chlorotic, being creamy white in color, while the 
remaining 4 plants, which had made little growth, were slightly 
chlorotic. At the tenth month all plants were strongly chlorotic. 
The plants in the fourth plat, with 50 per cent of calcium carbonate, 
were slightly chlorotic at the fifth month, and at the seventh month 
the 7 largest plants were creamy white, the remaining 9 plants of 
little growth were plainly though not intensely chlorotic. At the 
tenth month all were intensely chlorotic. At the end of 10 months 
the plants were cut and the average green weight of the plants was 
as follows: : | 
Average weight of plants. 
Grams. 
Check. plat, no calcnimcarbonates725 2 2552 seer = = ceee a eee 568 
Plat with 10 per cent caletum carbonate... ......-.-..2.22.2+.201.56 423 
Plat with 25 per cent calcium carbonate....22522.-5) 22s .4-555 Pe 
Plat with 50 per cent calenimt carbonate. 552. -- 2: s-2 0c 22.5. aes 374 
The results of the experiments with plants grown in pots and in 
small field plats were as follows: 
Plants grown on sandy and loamy soils to which natural carbonate 
of lime was added became chlorotic. Plants grown in a soil which 
was practically pure organic matter showed no chlorosis until the 
percentage of carbonate of ime reached 50 per cent. 
[Bull. 11] 
