‘Crop Rotation 289 
TABLE 4—Continued 
Plot 3 Beans Plot 4 Corn 
Nitrates—Parts per million Nitrates—Parts per million 
Month Moisture % |—- Moisture % |—- 
Fresh Incubated Fresh Incubated 
Samples Samples Samples Samples 
Wi 8 es SS Re es eee PALA 12.14 32.38 20.8 4.15 20.20 
DN. 5.945) Spe ae 18.6 1.96 19.64 19.75 1.99 23.90 
INFERS 5 SS Or eo RE 14.98 ster) 20.67 15.95 3.80 19.01 
TLS), dc oO a Ree 14.58 14.90 114.73 14.93 18.80 48 87 
ARIK. oe bo Oe OCS 13.36 40.62 40.59 17.5 42.66 54.26 
J NIE: . Jae gee 13.41 5.54 5.54 17.18 14.24 27.02 
Sa Od Eoig th tee ae eee 9.78 3.54 10.68 15.95 5.70 17.12 
OH OCR eae eee 21.33 2.04 4.06 21.39 4.09 10.24 
Total per period.......... 84.49 248.29 95.43 220.62 
Ave. per month.. ....... 10.56 31.03 11.92 27.57 
corn plot, 9.31 parts for the oats, 10.12 parts for the wheat, and 10.56 
parts for the soybean plot. 
The highest content of the fresh samples was found in July for 
the corn plot, in March with April and July also high for the oat 
plot, in March with April and July also high for the wheat plot, and 
in July with March and June high in the case of the soybean plot. 
During the latter part of the period, when conditions were less favor- 
able for the formation of nitrates, and during the months of heaviest 
crop growth, the content of the fresh samples ran low for all plots. 
Table 4 shows an average nitrate content for the incubated samples 
of 27.57 parts per million parts of moisture-free soil for the corn plot, 
23.37 parts for the oat plot, 25.71 parts for the wheat plot and 31.03 
parts for the soybean plot. 
The highest content of the incubated samples was found in July for 
the corn plot, in March for the oat and wheat plots, and in June for the 
soybean plot. 
The results for the corn and soybean plots check very closely with 
each other in regard to high and low periods and also the averages of 
the fresh and incubated samples. Both are cultivated crops. Also, as 
would be expected, the results on the oat and wheat plots check closely. 
DISCUSSION OF TABLE 5. 
Series If West—Rotation Corn, Wheat and Soybeans. 
Table 5 shows the average nitrate content of the fresh samples for 
the eight months to be 32.60 parts of nitrate per million parts moisture- 
free soil for the corn plot, 7.64 parts for wheat and 7.48 parts for the 
soybean plot. 
The corn plot contained the highest amount of nitrates in August, 
with June and July also high; the wheat plot showed highest in March, 
with April, May and July also high; the soybean plot contained most 
nitrates in June and July. 
The corn plot showed an average of 59.58 parts in the incubated 
samples, the wheat plot an average of 20.80 parts, and the soybean plot 
an average content of 28.12 parts nitrates per million parts moisture- 
free soil. The highest results for these samples were found in August, 
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