26 
Bulletin 1356, U. S. Department of Agriculture 
of error in the data make conclusions unsafe. Under field conditions 
the use of broad levees would greatly reduce seepage. 
ROTATION EXPERIMENTS 
Crop rotation has not been a factor in rice culture in southwestern 
Louisiana because of the outstanding value of rice and the unwill- 
ingness of farmers to grow other crops which are not equally remu- 
nerative. Other crops grown are of secondary importance and are 
not a part of any established or intended rotation. The only recog- 
nition of the principle of crop succession in this section is the pastur- 
ing of rice fields after several years of cropping. Good tilla'ge and 
drainage have maintained production at a fair average yield, but 
that this yield can be increased and the higher yield maintained by 
proper rotation is shown by experimental data obtained at the Rice 
Experiment Station. In Table 19 are given annual and average 
yield data for rice grown in rotation with soybeans and on land con- 
tinuously cropped to rice during the 11-year period from 1913 to 
1923, inclusive. 
Table 19. — Annual and average yields of rice 1 grown in rotation with soybeans 
and on land cropped continuously to rice at the Rice Experiment Station, Crowley, 
La., during the 11-year period from 1913 to 1923, inclusive 
Yields per acre (pounds) 
Manner of cropping 
Annual 
Average for years 
stated (date 
inclusive) 
1913 
1914 
1915 
1916 
1917 
1918 
1919 
1920 
1921 
1922 
1923 
6 
years, 
1913- 
1918 
5 
years, 
1919- 
1923 
11 
years, 
1913- 
1923 
In rotation with soybeans^ 
Continuously to rice since 
1909 
2,940 
2,298 
2,020 
2,223 
2,166 
1,250 
2,230 
818 
2,457 
957 
2,000 
1,226 
3,080 
1,113 
3,240 
1,225 
1,830 
1,263 
2,400 
690 
1,860 
610 
2,302 
1,462 
2,482 
980 
2,384 
1,243 
i From 1913 to 1918, inclusive, the Honduras variety, and from 1919 to 1923, inclusive, the Wataribune 
variety, were grown in the experiments. 
2 The rotation began in 1912. The Barchet variety of soybeans was grown in 1913 and 1914 and the 
Biloxi variety from 1915 to 1923, inclusive. 
For the 6-year period from 1913 to 1918, inclusive, the Honduras 
variety grown in rotation with soybeans produced an average an- 
nual acre yield of 840 pounds larger than that produced where it 
was grown continuously. The higher yielding Wataribune variety 
produced during the 5-year period from 1919 to 1923, inclusive, an 
average annual acre yield 1,502 pounds larger than that produced 
where it was grown continuously. Allowing for differences in 
annual yields due to seasonal variations, larger yields were obtained 
and also maintained by the soybean rotation. Efficient drainage and 
good tillage, supplemented by the organic matter added to the soil 
by plowing under mature soybean plants after harvest, gave returns 
which were not obtained from commercial fertilizers. 
Increased yields were not the only advantage of the soybean 
rotation. When combined with good drainage the decomposed 
organic matter which was supplied by the soybean plants when 
plowed under put the soil in a loose and friable condition (fig. 7). 
The upturned soil readily responded to tillage in preparing a suit- 
able seed bed for rice. Such a seed bed is not easily obtained, even 
with extra tillage, when the soil is deficient in organic matter (fig. 8). 
