Basic HTML Version
Molecular Soil Biology (online), 2011, Vol. 2 No.1, 1
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8
ISSN1925-2005
http://msb.sophiapublisher.com
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type SSS based on cucumber farming, that would be
the reason why it is lack of some guidelines for the
application of nitrogen fertilizers in long-term
successive cropping areas in China.
So far, some guidelines of SSS management in
agricultural ecosystem have been proposed, which can
be summarized as follows. The SSS level can be
decreased by (1) taking some agricultural measures
such as irrigation and precise fertilization (Mustafa et
al., 2006; Rouphael et al., 2006; Yuan et al., 2004); (2)
soil replacement and amendments (Sui et al., 2009;
Liang et al., 2005; Conde et al., 2005); (3) establishing
flexible cropping system (Darwish et al., 2005;
Graeme and Ellen, 2009). Although the above
mentioned approached would be effective for
alleviating SSS, it might be difficult to be employed in
different greenhouses with different types of SSS.
Therefore, it is necessary to build “standard or
uniform” criteria to classify the types of SSS and to
manage soil and fertilizers in the system of facility
agriculture.
Jiangsu Province, neighboring Shanghai of East China,
is a typical representative region of facility agriculture
in China, where the nitrate (NO
3
-
) is a common salt
widely used in greenhouse soil (Ge et al., 2010). NO
3
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based soil salinization become dominant limiting
factor for the sustainable development in facility
agriculture. In this study, the major objective is to
develop a guideline for classification of SSS in
greenhouse and to provide insights to improve the
yield and quality of cucumber in greenhouse.
1 Results and Analysis
1.1 Soil NO
3
-
contents
Soil NO
3
-
contents of 0~8 cm soil layer at different
times are shown in Table 1. The NO
3
-
concentrations
in the control (ck) soil were lower than those in the
treatments. The initial NO
3
-
contents in the treatment
groups increased with the increase of salinity
concentrations from T1 to T4. The trend of the soil
NO
3
-
contents at the surface soils from 0 to 8 cm in
the control and treatments were to lower values with
experimental time.
Table 1 NO
3
-
contents of the surface soil layer (0~8cm) at different periods (Means, n=4)
NO
3
-
(mg/kg)
Treatments
T7ds
P40ds
FBA
H7ds
ck
T1
T2
T3
T4
92.45
325.43
680.15
998.15
1488.50
85.43
264.24
519.40
848.30
1406.80
40.15
159.85
294.60
568.50
932.60
23.22
111.40
258.26
445.60
843.50
Note: T7ds: Soil NO
3
-
contents after one week of salt treatment; P40ds: 40 days after planting; FBA: Full bearing age; H7ds: 7 days
after full harvest
1.2 SSS expressed by electrical conductivity (EC)
Soil electrical conductivity (EC) was determined at
four times, that is, 7 days after salt treatment, 40 days
after planting, 70 days after planting, and 7 days after
full harvest (Figure 1). The levels of SSS expressed by
electric conductivity (EC) were 2.78
ds/m
for T1,
3.65
ds/m
for T2, 4.66
ds/m
for T3 and 6.15 d
ds/m
for
T4, but 0.91
ds/m
for the ck. It is clear that the EC
values of the ck were always lower than those in the
treatments during the experimental period. The rates
of decrease in soil salinization (EC/sampling time) for
the different treatment groups (T1, T2, T3 and T4)
were almost the same although the difference in initial
levels of salinity existed. On the 7
th
day after full
harvest (day 77), the soil EC had decreased to 0.31
ds/m
for ck, 1.62
ds/m
for T1, 2.45
ds/m
for T2, 3.28
ds/m
for
T3, and 4.76
ds/m
for T4. Compared with the initial
value
，
EC values were dramatically reduced by
61.8% for ck, 41.7% for T1, 32.9% for T2, 29.6% for
T3 and 22.6% for T4, respectively.
1.3 Plant heights and fruit yields of Cucumber
In the T4 (EC = 6.15
ds/m
) the seeding was dead
totally after 7 days of planting due to its high
salinity. So the data of T4 were not shown. As
Figure 2 showed, the cucumber plant heights