2.1 Effects of different water and fertilizer optimal management
on soil microbial biomass carbon and nitrogen change characteristics
Under the same optimal management of water and fertilizer, the
difference in soil microbial biomass C and N content was significant
with different growth periods (p<0.05), and the changing trend
was increased first and then decreased with time, and the order was
flowering, fruiting, seedling and rooting period from big to small. As
shown in Fig. 1, the carbon content of soil microbial biomass ranged
from 0.49~1.05 g.kg-1, increased by 14.37% and
39.59% respectively from rooting period to flowering period, and the
difference between the flowering period and rooting period of W3F4 was
the largest, 0.26 g.kg-1; the difference between the
flowering period and rooting period of W1F3 was the smallest, 0.11
g.kg-1; the difference between the flowering period
and rooting period of CK was 0.25 g.kg-1, which was
second only to that of W3F4 and ranked the second among all treatments.
The soil microbial biomass nitrogen content ranged from 14.98 to 66.21
mg.kg-1, increasing by 26.55% and 43.86%
respectively from rooting period to flowering period. The difference
between the flowering period of W3F4 and the rooting period was the
largest, 20.67 mg.kg-1, while the difference between
the flowering period of W2F1 and the rooting period was 9.23
mg.kg-1, the smallest difference for all treatments.
The CK flowering period increased by 10.88 mg.kg-1compared with the rooting period, ranking 12th among all treatments.
Therefore, the soil microbial biomass C and N content of W3F4 changed
most in the four growth periods.
Soil microbial biomass C and N content in the same growth period had
significant differences with different water and fertilizer optimal
management (p<0.05), and the soil microbial biomass C and N
content increased with the increase of irrigation amount and fertilizer
application amount. It could be seen from Fig. 1 that the soil microbial
biomass C and N content of W3F4 in all growth periods was greater than
that of other treatments. The soil microbial biomass C W3F4 at the
flowering period increased by 0.41 g.kg-1, compared
with the minimum value W1F1, and increased by 39.38% compared with CK
at the same period. During the seedling period, W3F4 increased by 0.29
g.kg-1,compared with the minimum value of W1F1, and
W3F4 at the seedling period was 1.9 times that of CK. The soil microbial
biomass nitrogen at the flowering period was the maximum, and W3F4
increased by 39.52 mg.kg-1 compared with the minimum
value of W1F1, and increased by 55.08% compared with CK at the same
time. However, during the rooting period W3F4 increased by 29.63
mg.kg-1 compared with the minimum value of W1F1, and
W3F4 during the rooting period was 2.36 times as much as CK. In the same
growth period, CK was greater than that of W1F1, and the difference in
the rooting period was the largest, 3.86 mg. kg-1, and
the ratio of CK to that of W1F1 was the largest, 20.51% in the rooting
period.