الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 136 |  |  |
| | | from | 136 | | |
Abstract
93
5. S U H H A R Y
This work was conducted to evaluate the effects due
to organic manuring on the availablility of soil P. To
substantiate these effects, the following trials and
analyses were carried out.
1- Compost preparation experiment:
Organic residues of soybean and rice straw as well
as cotton stalks (3 sources) were compos ted to distinct
C/N ratios namely, 49, 33, 17 and .10 to ·1 beside the raw
materials (5 C/N ratios).
2- Huatc acid preparation:
The tested 15 organic materials, composted to different
degrees, were subj ected to humic acid extraction in order
c
to be used as a tool for explaining the results.
In this respect, humus extraction was run through
0.5 N NaOH and was purified using water electrodialysis
until complete free of Cl •
Isola ted pur i f i ed humic aci ds were ident if ied through
elementary analysis for C, H, N, Sand 0 as well as infrared
analysis.
94
3- Soil aanuring experiment:
Soil samples obtained from three different locations
namely, Moshtohor (clay), El-Dair (sandy) and El-Nobaria
(calcareous) were treated with the different organic sources
(15 samples).
The soils were treated with these residues at a rate
of 5 s residues/lOO g soil. This
the laboratory conditions for 6
experiment lasted under
months where subsamples
were removed after 7, 30, 60 and 180 days from experiment
starting. These subsamples were subjected to organic,
inorganic, total and available P determinations.
The obtained data of P forms were also subjected to
statistical analysis.
The obtained results could be briefly summarized as follows:
A) Properties of isolated humic acids:
1- Total carbon content of humic acids amounted to about
44.32, 47.31 and 41.29% for humic acids derived from soybean
straw, rice straw and cotton stalks, respectively.
2- The ~orresponding average values of total nitrogen were
4.79, 2.84 and 2.21%. respectively.
3- The C/N rat t os of humic acid samples are fluctuating
between 6.30: 1 and 40: 1.
95
4- The highest C/N ratios were observed in humic acid samples
derived from both rice straw and cotton stalkst whereas
the lowest ones were obtained from humic acid prepared
from soybean straw~
5- The infrared absorption by humic acids showed the
following trends:
i) Absorption
-1·
at 3409-3300 em (due to frequency H bending
of OH) reached its maximum with humic acid derived from
soybean straw whereas the lowest one was
obtained from
humic acid prepared from rice straw
ii) At 1620-1600
-1
em (due to frequency of aromatic
C;C and H-bonded C==O)t maximum absorption was observed
with soybean
and the lowest value was due to cotton
stalks H.A.
iii) At 1590~1517 cm-1 (due to frequency of C;C), maximum
absorption was observed with
soybean H.A. and the
lowest values was due to cotton stalks H.A.
iv) At 1400-1390 cm-1 (due to frequency of O-H bending)t
maximum absorption was observed wi th
rice straw H.A.
and the lowest value was due to cotton stalks H.A.
------------- ----------------- -~-_._-.-----
96
v) At 1280-1200
-1 em (due to frequency of C-O stretching
and OH bend Lng ) I maximum a bsor pt ion was observe d wi t h
cotton stalks H. A. and the lowest. value was due to
rice straw H.A.
However, it was observed that infrared absorption
by H.A. derived from soybean straw residues at 3409-
3300 and 1620-1600
-1 cm tended to be inc r eased as the
C/N of the residues ~as closer.
B) Effects due to organic source:
1- Organic P fraction:
Treating the soils with different organic residues
led to:
1- In general the organic P content was approximately doubled
in Mosh tohor clay and El-Dair sandy soils, meanwhi Le it was
increased to more than 5 times in El-Nobaria calcareous
soil as a results
c
of treating so i 1s wi,th or ganic manures.
2- It was proved that the highest inducing effect due to
or ganic res id ues application resulted from so ybean st raw,
rice straw and rice straw or cot ton stalks residues for
calcareous, sandy and clay soils, respectively.
11- Inorganic P fraction:
The hi ghest figures obtained f or this P frac t ion wer e
yielded wi th application of soybean or rice straw residues
----_.~---_. ------------------------------ --
97
in case of EI-Nobaria calcareous soil and EI-Dair sandy
soil or soybean straw in case of Moshtohor clay soil.
111- Soil available P fraction:
The compost derived from soybean straw significantly
affected the level of soil P availability in a I I the tested
soils if compared with the other two sources.
c) Effect of elM ratio:
1- Organic P fraction:
The level of organic P was significantly induced with
the use of residues having C/N ratio of 17: 1 in El-Nobaria
and EI-Dair soils and residues of wider ratios (raw. and
49:1) in case of Moshtohor soil.
11- Inorganic P fraction:
The raw applied residues were more
calcareous soils. The organic residues
efficient with
of C/N ratio
amounting to (17-33:1) or·· (10-33:1) were more efficient
for the sandy soil(El-Dair)and clay soil(Moshtohor),respec~-
ively.
~--- -~----~~-~ ------~~---- ---_._- ----
98
111- Soil available P fraction:
The soil content of available P (in all the tested
soils) increased progressively as the C/N ratio of the
added residues became closer and closer and thus the C/N
ratio of 10:1 yielded the highest inducing effect on soil
content of available P.
D) Effect of contact period:
1- Organic P fraction:
The organic P fraction occurrence in the soils was
significantly increased with increasing the period of soil
con tac t wi t h the different organic residues from 7 to 30 days.
11- Inorganic P fraction:
The soil content of inorganic P was initially decreased
with increasing the interaction or contact period from
7 to 30 days. thereafter this fraction was gradually
increased as the contact period was prolonged upto 60 and
180 days. respectively.
111- Soil available P fraction:
The soi 1 con ten t of available P was inc reased wi th
inc reasi ng the can tac t period from 7 to 30 days. dec reased
after 60 days and increased again with time to reach its
maximum values after 180 days of interaction.
_._-_ .. _------------
99
E- Combined effect of organic source and C/K ratio:
1- Soybean residues:
1- The highest level of organic P was observed with residues
of C/N ratio amounting to 49: it 57: 1 (Raw) in EI-Nobaria,
El~Dair and Moshtohor soils, respectively, while the minimum
values were observed with residues having C/N ratios of
(raw), 33:1 and 57:1 (raw) for calcareous., sandy and clay
soils, respectively.
2- The inorganic P fraction, occurred at
maximum levels
with application of soybean residues having C/N . r at Lo s
of 57:1 (raw) and 10:1 for El-Nobaria, Ei-Dair and MoshtoRor
soil, respectively, while the minimum values were· observed
wit h soy be an res idue s havi n gel N rat i0 s 0 f: -10:1, 57: 1 (r a-w)
and 33:1 for the aforementioned _soils, respectively.
11- Rice str~w residues:
1- The maximum values of soil organic P fraction were
achieved with application of rice straw residues having
C/N ratios of 17:1 and 97.5:1 (raw) for EI-Nobaria and Moshtohor
soils, respectively, but no significant differences could
be detected in El-Dair sandy soil, while the minimum
occurrence of organic P fraction in soils was observed
with rice straw residues having c/N ratios of 49: 1, 97.5t1
(raw) and 17:1 for El-Nobaria, El-Dair and Moshtohor soils,
respectively.
.~--------------------_._--_._.-----
100
2- The maximum values of soil inorganic P fraction were
achieved with rice straw residues having elN ratiosof 33:1,
17:1 and 17:1 for El-Nobaria. EI-Dair and Moshtohor soils,
respectively, while the minimum values were recorded with
ric est raw res i due s ha v in gel N rat i OS 0 f 97. 5 : 1 ( raw), 49: 1
and 97.5:1 (raw) for the aforementioned soils, respectively.
c
111- Cotton stalks residues:
1- The maximum values of organic P due to addition of cotton
stalks residues were achieved when their elN ratios were
49:1-17:1, 17:1-10:1 and 49:1 for EI-Nobaria, EI-Dair and
Moshtohor soils, respectively, but the minimum occurrence
was observed with cotton stalks residues having elN ratios
of 96:1 (raw), 33:1
and 33: 1 for the aforementioned soils,
respectively.
2- The inorganic P fraction, occurred at maximum leve 15
with application of cotton stalks residues having elN ratios
of 96:1 (raw), 33:1 and 33:1 for El-Nobaria, El-Dair and
Moshtohor soils, respectively. but the minimum values were
ac cur e d wit h res i 4 ue 5 ha vin gel N rat i as o f 17 : 1. 17 : 1 and
10:1. respectively.
lY- Soil aYailable P:
Gradual and consistent increase in the soil available
P was obtained as the elN ratio of added residues became
102
10:1 in
when their C/N ratio amounted to
EI-Nobaria and E1-Dair soils.
17: 1 and
residues
respectively,
while the corresponding value in case of Moshtohor soil
was achieved with the raw residues.
2- The highest values of inorganic P were recorded after
180 days from treating the soils with the different organic
residues when their C/N ratio was 17:1 in case of El-Dair soil
and 33:1 in case of both El-Nobaria and Moshtohor soils.
3- Available P content of all the investigated soils reached
its highest value at C/N ratio of 10:1 and after 180 days
of interaction.