3. Results
3.1. Effect of RS-based hydrogel on some chemical properties of
treated soil
Comparing the initial soil chemical analysis before starting the
experiment (Table 1) to the analysis at the end of the 3rd growing
season (Table 3) and with only one exception, i.e., soil pH
it is clear that, studied soil chemical properties were improved
due to plantation during this period. As can be seen, soil plantation
raises its CEC by 6%, OM and OC by 300%, total N
by 41%, available N, P and K by 30.6, 600 and 350%,
respectively. Therefore, C/N ratio was decreased from 10.6
before plantation to be 9.7:1 at the end of the 3rd growing
season.
More improvement in the studied soil properties by varying
degrees was noticed due to soil conditioning (Table 3).
Regarding soil pH, all examined conditioning treatments
provided a slight decrease in the pH values of the soil. The
decrease in soil pH was calculated to be 0.1 and 0.13 units
by applying 2 and 4 g of G1 kg1 soil; while using 2 and 4 g
of G2 kg1 soil pH lowered by 0.09 and 0.11 units, respectively.
Moreover, data refer that, treating the soil with hydrogels
raises its CEC, and consequently overcomes the
limitations of soil fertility, as a result of low cation exchange
capacity (CEC) of the soil, since many soil properties such as
adsorption of water, nutrients and the attraction forces
between particles are all surface phenomenon. Values of
CEC were increased with increasing the application rate of
hydrogels. Where, using 2 g and 4 g of G1 kg1 soil as soil conditioner
raised its CEC by 16.1% and 22.4%, respectively,
compared to the non-conditioned soil; while, CEC values of
conditioned soil with the hydrogel G2 were 1.14 and 1.20 times
that of the untreated soil, using 2 and 4 g G2 kg1 soil,
respectively.
With respect to soil organic matter treating the soil with the
hydrogel leads to an increase in its carbon content, where, G1
at the rates of 2 g and 4 g kg1 soil increased organic carbon
content of the soil to be 2.0 and 2.55 times that of untreated
soil, respectively. While, the organic carbon content of treated
soil with 2 g or 4 g kg1 soil of the hydrogel G2 was 1.8 or 2.25
times that of the non-conditioned soil, in sequence.
Similarly, total nitrogen and organic nitrogen content
took the same trend of organic carbon (OC) content.
Comparing these contents of the hydrogels treated soil with