34 BULLETIN 1180, U. S. DEPARTMENT OF AGRICULTURE. 
Results with corn. — Table 17 shows that the increases in yields 
produced by ammonium chlorid and double salt were of about the 
same order as with ammonium sulphate. The soil of this section 
lacked uniformity, the yields from the check plats varying from 9.3 
to 32.5 bushels for the second year. Hence, no accurate quantita- 
tive comparisons can be made between treatments. Ammonium 
chlorid seemed to be slightly toxic the first year at the largest rate 
of application but gave strictly normal results the second year, the 
yields increasing as the nitrogen supply increased. Plate X, Figure 
2, shows the marked contrast in the growth of corn with and without 
double salt. 
The fertilizer tests comparing ammonium phosphate, ammonium 
sulphate, and ammoniated superphosphate were unsatisfactory 
because the natural fertility of the soil was considerably above the 
average. No conclusions can be drawn. Cyanamid produced unusually 
food increases in yields considering that the soil was very fertile, 
t was not injurious even when applied in the row at the rate of 40 
pounds of ammonia. The results compared very favorably with 
those obtained in Section I With ammonium sulphate. Again, it has 
been shown that corn can utilize cyanamid nitrogen under conditions 
where it is largely unavailable for cotton. 
Field No. 4. 
This field, a diagram of which appears as Figure 4, was used for experi- 
mental work during the seasons of 1920 and 1921. Cotton and corn 
were grown both years, but a combination of late planting and an 
unusually bad attack of boll weevils resulted in practically no cotton 
for the first year. These results are omitted from this report. The 
sources of nitrogen used were ammonium sulphate, urea, ammonium 
chlorid, ammonium nitrate, ammoniated superphosphate, ammo- 
nium phosphate, cyanamid, and double salt. 
Results with cotton. — The extremely dry weather during the first 
part of the growing season undoubtedly played an important part 
in the yields. There was not sufficient rainfall during the period of 10 
weeks subsequent to planting to moisten all of the dry surface soil. 
The result was a dwarfing of the plants and little effect from the ferti- 
lizer treatments. The moisture was adequate during the latter half 
of the season, and an exceedingly rapid growth resulted. At the 
time of maturity the plants were normal in size and the fruiting 
good, but the bolls were small. 
The cotton yields are given in Table 18. These figures show no 
appreciable difference in the availability of the nitrogen in urea, 
ammonium chlorid, and ammonium nitrate. At the largest rate of 
application the results with all of these newer materials were better 
than with ammonium sulphate. The soil irregularities probably were 
responsible for this, as shown by differences in } T ields on the unferti- 
lized plats of Section I, ranging from 368 to 1,040 pounds of seed 
cotton per acre. The responses to growth produced by all of these 
materials indicated that they were equally good. The growth with 
urea is shown in Plate XIII, Figure 1. 
The yields from the plats of Section II show that this soil was 
nearly as variable as on series A, the check plats showing yields of 
351 to 840 pounds of seed cotton per acre. In the comparisons be- 
