الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The objectives of this study were to evaluate the impact of organic
residues, time of incorporation of residue before sowing wheat vis-a-vis
residues burning and removal on soil chemical properties, soil fertility
status and crop production in rice–wheat system. This study aimed also to
investigate rice straw decomposition, then nutrients release as a function
length of incorporation period of rice straw. The study was also carried
out to evaluate the bioavailability status of the studied nutrients in soil in
a trial to control the environmental pollution. To achieve these objectives,
four sets of studies were performed.
The first study investigated the effect of incorporation period of rice
straw on organic matter decomposition and on soil chemical properties
under controlled conditions of the column experiment. The second
experiment investigated the role of starter dose of N combined with rice
residues together, or with either pig manure or the leguminous green
manure of Sesbania sesban to enhance the decomposition of rice straw
under field conditions (field experiment). In addition, the same study
investigated the effect of incorporation period of rice residues on soil
fertility parameters and on the yield of both wheat and rice. The third
experiment was designed to estimate rice straw residues decomposition
under field conditions using litterbag technique during the pre wheat
fallow period and during wheat and rice growth.
The obtained results of the three experiments could be summarized
as follows:
1. Column experiment:
1. The alluvial soil exhibited higher EC and pH values, and N and K
contents, as well, compared with the calcareous soil, in all
treatments.
2. On contrast, the calcareous soil showed a higher P content when
compared with the alluvial soil as a result of the applied all
treatments.3. The treatment pig manure + rice straw residues incorporated at
105 days incubation gave the lowest pH and EC values of the
calcareous and alluvial soils, while the control treatment gave the
highest pH and EC values
4. The treatment pig manure + rice straw residues incorporated gave
the highest values of N, P and K soil content, while the control
gave the lowest values.
5. Incensing NPK fertilizer dose decreased pH values of the
calcareous and alluvial soils but it increased EC, N, P and K
values.
6. The treatment pig manure + rice straw residues incorporated +
100% NPK gave the lowest PH values followed by rice straw
residues incorporated alone + 100% NPK.
7. The treatment pig manure + rice straw residues incorporated
increased values of soil N, P and K were noticed with followed by
rice straw residues incorporated alone
8. The treatment pig manure + rice straw residues incorporated
+100% NPK gave the highest soil N, P and K, while the lowest
values were obtained by control treatment.
2. The field experiment:
2.1. Soil N, P and K contents, Humic acid, fulvic acid, nutrients
contents of humic acid & fulvic acid and organic matter after
wheat harvesting:
1. Rice straw compost gave the highest soil N, P and K content,
while, rice straw burning and rice straw removal gave the lowest
values.
2. Increasing fertilizer dose increased soil N, P and K content
3. Rice straw compost + 100% NPK gave the highest values of soil
N, P and K content while, the lowest values were obtained by 50%
NPK with rice straw burning or rice straw removal
4. Rice straw incorporated at 45 days +pig manure+ 100% NPK andrice straw compost + 100% NPK enhanced humic acid, fulvic
acid and organic matter, followed by rice straw incorporated at 45
days +green manure+ 100% NPK.
5. Rice straw incorporated at 45 days +pig manure+ 100% NPK and
rice straw compost + 100% NPK enhanced the values of available
nutrients of humic acid and fulvic acid at 15 and 30 cm depth after
wheat harvesting comparing with rice straw burning + 100%
NPK.
2.2. Soil EC, pH and SAR after wheat harvesting:
1. Rice straw incorporated at 45 days +green manure gave the
lowest EC value (1.71ds/m) followed by rice straw compost and
rice straw incorporated at 45 days+ pig manure(1.72 and 1.73 d
S/m) respectively,
2. Rice straw incorporated at 45 days +green manure+ 50% NPK
gave the lowest EC value followed by rice straw compost + 50%
NPK and rice straw incorporated at 45 days+ pig manure+ 50%
NPK
3. Rice straw incorporated at 45 days+ pig manure showed the
lowest p H value followed by rice straw compost
4. Rice straw incorporated at 45 days+ pig manure+ 50% NPK
produced the lowest pH value followed by rice straw incorporated
at 45 days+ pig manure+ 100% NPK and rice straw compost +
50% NPK ( 7.72, 7.79 and 7.81)respectively.
5. Rice straw incorporated at 45 days +green manure+ 50% NPK
and rice straw compost + 50% NPK showed the lowest SAR
followed by rice straw incorporated at 45 days+ pig manure+
50% NPK (8.29, 8.29, and 8.42) respectively.
6. Increasing fertilizer rate decreased EC, p H value and SAR
7. Rice straw burning + 100% NPK, rice straw burning + 50% NPK
and rice straw removal + 100% NPK gave the highest EC, p H
and SAR values.2.3. Wheat leaf, grain and straw N, P and K contents:
1. Rice straw incorporated at 45 days +green manure gave the
highest values of leaf N, grain N and straw P contents followed by
rice straw incorporated at 45 days +pig manure and rice straw
compost. Leaf P, grain P and K and straw K contents were
enhanced by rice straw compost, rice straw incorporated at 45
days +green manure or rice straw incorporated at 45 days +pig
manure. Rice straw compost and rice straw incorporated at 45
days +pig manure increased Leaf K and straw N contents,
respectively. On contrast, rice straw burning gave the lowest
values.
2. Increasing NPK fertilizer dose increased wheat leaf, grain and
straw N, P and k contents. Rice straw incorporated at 45 days
+pig manure+ 100% NPK and rice straw compost + 100% NPK
enhanced leaf K, grain N, increased P and K and straw P contents.
3. Rice straw incorporated at 45 days +green manure+ 100% NPK
increased leaf N and P and straw K contents. While, the lowest
values were obtained by rice straw burning or rice straw removal
with 50% NPK.
2.4. Recovery efficiency, physiological efficiency and agronomic
efficiency of wheat:
1. Rice straw incorporated at 45 days +green manure gave the
highest values of N recovery efficiency (21.63%) and N
agronomic efficiency (4.92 kg grain/kg N uptake) of wheat
followed by rice straw compost and rice straw incorporated at 45
days +pig manure, respectively and the lowest values were
produced by rice straw burning.
2. Rice straw incorporated at 30 days showed the highest value of
physiological efficiency, while rice straw removal gave the lowest
value.
3. Increasing NPK dose decreased physiological efficiency and
agronomic efficiency of wheat but it increased recovery efficiency of N.
4. Rice straw incorporated at 45 days +green manure+ 100% NPK,
rice straw incorporated at 30 days+ 50% NPK and rice straw
incorporated at 45 days +green manure+ 50% NPK gave the
highest values of N recovery efficiency, physiological efficiency
and agronomic efficiency of wheat .
2.5. Wheat grain yield, straw yield, biological yield dry weights,
harvest index and crop index:
1. Rice straw incorporated at 45 days +green manure gave the
highest wheat grain yield, biological yield dry weights, harvest
index and crop index (3.090 t/fed, 6.758 t/fed, 45.71% and
84.24%, respectively) followed by rice straw compost. While, the
lowest values were obtained by rice straw burning.
2. Increasing fertilizer rate recorded the highest values of grain yield,
straw yield, biological yield dry weights, harvest index and crop
index
3. Rice straw incorporated at 45 days +green manure or rice straw
compost with 100% NPK gave the highest values of grain yield
dry weight (3.364 and 3.349 t/fed, respectively). in addition, rice
straw incorporated at 45 days +green manure+ 100% NPK gave
the highest biological yield dry weight (7.280 t/fed). on contrast,
the lowest values of grain yield, straw yield and biological yield
dry weights (2.531, 3.147 and 5.678 t/fed, respectively) were
produced by rice straw burning + 50% NPK.
4. Rice straw compost + 100% NPK gave the highest values of
harvest index and crop index (46.63 and 87.38%, respectively,
followed by rice straw incorporated at 45 days +green manure+
100% NPK. While, rice straw burning + 50% NPK gave the
lowest values.2.6. Soil N, P and K contents, humic acid, fulvic acid, nutrients
contents, humic acid & fulvic acid and organic matter after rice
harvesting:
1. Rice straw incorporated +pig manure+ 100% NPK and rice straw
compost + 100% NPK gave the highest values of soil humic acid,
fulvic acid, humic acid and fulvic acid of nutrients contents and
organic matter after rice harvesting.
2. Rice straw incorporated at 45 days +pig manure+ 100% NPK and
rice straw compost + 100% NPK gave the highest values of soil
N, P and K contents, humic acid, fulvic acid, humic acid and
fulvic acid of nutrients contents and organic matter after rice
harvesting followed by rice straw incorporated +green manure+
100% NPK.
2. 7. Soil EC, pH and SAR after rice harvesting:
1. Rice straw compost gave the lowest EC value followed by rice
straw incorporated at 45 days +green manure and rice straw
incorporated at 45 days+ pig manure
2. Rice straw compost + 50% NPK gave the lowest EC value
followed by rice straw incorporated at 45 days +green manure+
50% NPK and Rice straw incorporated at 45 days+ pig manure+
50% NPK.
3. Rice straw incorporated at 45 days+ pig manure gave the lowest
p H value followed by rice straw compost
4. Rice straw incorporated at 45 days+ pig manure+ 50% NPK gave
the lowest value of p H followed by rice straw compost + 50%
NPK and rice straw incorporated at 45 days+ pig manure+ 100%
NPK.
5. Rice straw compost + 50% NPK gave the lowest SAR followed
by rice straw incorporated at 45 days+ pig manure+ 50% NPK
and rice straw incorporated at 45 days +green manure+ 50%
NPK 6. Rice straw burning + 100% NPK, rice straw burning + 50% NPK
and rice straw removal + 100% NPK gave the highest EC ,p H
and SAR value.
7. Increasing fertilizer rate decreased EC, p H and SAR value.
2.8. Rice leaf, grain and straw N, P and K contents:
1. Rice straw incorporated at 45 days +pig manure gave the highest
rice leaf N, P and K, grain N, P and K and straw N and K contents
values followed by rice straw compost and rice straw
incorporated at 45 days +green manure. The highest K straw
content was obtained by rice straw compost. While, rice straw
burning gave the lowest values.
2. Increasing NPK dose enhanced rice leaf, grain and straw N, P and
K contents values.
3. Rice straw at 45days +pig manure or rice straw incorporated at 45
days +green manure with 100% NPK improved rice leaf N and P
and grain N. Also, Rice straw incorporated at 45 days +pig
manure+ 100% NPK enhanced leaf K, grain P and K and straw N
and P contents. While, rice straw burning + 50% NPK gave the
lowest values.
2.9. Recovery efficiency, physiological efficiency and agronomic
efficiency of rice:
1. Rice straw incorporated at 45 days +pig manure gave the highest
values of N recovery efficiency (56.93%), rice straw incorporated
at 45 days gave the highest values of N physiological efficiency
(28.59 kg grain/kg N uptake) and rice straw compost gave the
highest values of N agronomic efficiency (9.92 kg grain/kg N
uptake) of rice were obtained.
2. Rice straw burning and rice straw removal gave the Lowest
values in this respect
3. Increasing NPK dose decreased N physiological efficiency and
agronomic efficiency of rice but it increased recovery efficiency.
4. Rice straw incorporated at 45 days +pig manure+ 100% NPK gave The highest values of N recovery efficiency (58.63%), rice straw
incorporated at 45 days +green manure+ 50% NPK gave The
highest values N physiological efficiency (35.54 kg grain/kg N
uptake) and rice straw compost + 50% NPK gave The highest
values of N agronomic efficiency (15.44 kg grain/kg N uptake) of
rice.
2.10. Rice grain yield, straw yield, biological yield dry weights,
harvest index and crop index:
1. Rice straw compost, rice straw incorporated at 45 days +green
manure or rice straw incorporated at 45 days +pig manure gave
the highest grain yield dry weight (2.875, 2.863 and 2.818 t/fed,
respectively). Also, rice straw incorporated at 45 days +pig
manure produced the highest straw yield and biological yield dry
weights (4.247 and 7.065 t/fed, respectively). While, the lowest
values were obtained by rice straw burning.
2. Increasing NPK dose increased Rice grain yield, straw yield and
biological yield dry weights.
3. Rice straw incorporated at 45 days +green manure+ 100% NPK
produced the highest grain yield dry weight value and the highest
straw yield was noticed with rice straw incorporated at 45 days
+pig manure+ 100% NPK. Also, rice straw incorporated at 45
days +green manure+ 100% NPK or rice straw incorporated at 45
days +pig manure+ 100% NPK gave the highest biological yield
dry weight (7.740 t/fed). On contrary, rice straw burning + 50%
NPK gave the lowest values.
4. Rice straw burning + 50% NPK and rice straw incorporated at 15
days+ 100% NPK produced the highest harvest index values
produced by (46.69 and 46.63%, respectively). Also, rice straw
burning + 50% NPK gave highest crop index (87.96%). While,
rice straw incorporated at 45 days +pig manure+ 100% NPK gave
the lowest values.3. The third experiment:
1. Rice straw incorporated at 15 days gave the highest values of rice
straw residues remaining weight%, C% and C: N ratio were
noticed with litterbags buried in plots received followed by Rice
straw incorporated at 30 days, Rice straw incorporated at 45 days
and rice straw incorporated at 45 days +green manure. While, rice
straw incorporated at 45 days +pig manure gave the lowest values.
2. Litterbags buried in plots received rice straw incorporated at 45
days +pig manure produced the highest values of residues N, P
and K contents followed by straw incorporated at 45 days +green
manure. On contrast, rice straw incorporated at 15 days gave the
lowest values.
3. Increasing NPK does decreased remaining weight%, C% and C: N
ratio of rice straw residues, but it increased rice straw residues
N%.
4. Rice straw residues buried at 15 cm in plots had higher values of
N, P and K contents but it had lower values of remaining
weight%, C% and C: N ratio compared with burying at 30 cm.
5. Litterbags of rice straw residues buried at 15 cm in plots received
rice straw incorporated at 45 days +pig manure+ 100% NPK gave
the highest values of N%, P and K contents and the lowest values
of remaining weight%, C% and C:N ratio.
4. Evaluation of the bioavailability status of the studied nutrients in
soil and water:
4.1. Bioavailability of Nitrogen in soil as a new recent approach to N
management in soil or use of organic waste in agriculture in
order to control N environmental pollution:
A trial was made to apply an approach to N management in soil or
use of organic waste in agriculture. The approach aims to calculate the
amount of supplemental mineral N fertilizer needed by a desired crop
yield from a simple equation gained from N –balance studies.If the mineral N added is lower than the amount should be added, it
means that mineral N added is lower than crop N requirement of the
desired yield needing more supplemental mineral N by the amount
calculated. If the mineral N added is higher than the amount of N should
be added, it means that mineral N added is higher than the crop N
requirement of the desired yield. This excess of mineral N will be lost
from the rooting zone, and mainly by leaching to the ground water in the
form of NO3- .
This approach was checked up for all yields of wheat field
experiment for all the studied treatments. The values of excess mineral N
may be either positive or negative. Negative values indicate the lake of N
added, this appeared only with treatment of rice straw removal and
50%NPK(T1+F1), which means that mineral N added is deficient to
balance N outputs in order to verify the wheat yield of this treatment
(T1+F1). Positive values point to a tendency towards excess N from all
inputs that represent a potential for N losses.
The rest of the studied treatment exhibited positive excess of N
added. The organic wastes; compost , green manure and pig manure, as
well as incorporating rice straw proliferated an excess N as a result of the
application of such wastes especially when receiving 100%of NPK of the
recommended dose by the Ministry of Agriculture. 50% NPK (F1)
treatments appeared an excess ranged from (-2.3 to +13.1 kg/fed.) while
treatments of 100%NPK (F2) exhibited an excess ranged from (23.8 to
30.1 kg/fed.). The highest values were obtained with pig manure or rice
straw compost.
4.2. Bioavailability of phosphorus in soil:
Total fertilizer P inputs should balance the output to avoid hazards
due to both excess and deficient P. Organic wastes addition proliferated
an excess P as a result of the application of such wastes especially when
receiving 100% NPK of the recommended dose by the Ministry of
Agriculture. The excess of P for F1 (50% NPK) ranged from +6.8 to 11.8
kg P/fed., and F2 (100%NPK) ranged from 16.9 to 22.6 kg P/fed.However, the same trend of N was observed for phosphorus.
Finally: it could be concluded that the proposed approach, although it
needs more investigation, it seems to be valid either for N & P
management in soil or for use of organic wastes in agriculture, without
sacrificing crop yields but significantly reducing environmental pollution.
4.3. The status of nitrate and some micronutrients in the water
sources:
1. NO3- concentration in the irrigation water of EL- Nasser canal is
good for irrigation and can be used without any restrictions for
different soils and various plants.
2. NO3- concentration in water of EL- Salam canal as well as the
drainage water of both canals can be used for irrigation with slight
to moderate restrictions.
3. NO3- concentration in the drainage water was higher than the
irrigation water.
4. The chance of nitrate pollution is higher in EL- Salam canal area
as compared with EL- Nasser one.
5. The concentration of micronutrients (Fe, Mn, Cu, and Zn) in all
sources of water are lower than the maximum permissible limits in
irrigation water.
Conclusion:
Farmers practicing rice-wheat system under similar conditions are
recommended to incorporate rice straw with either green manure or
organic manure instead of burning or wasting otherwise. Also, rice straw
compost can reduce the environmental pollution. Hence, higher yield with
more income is expected for the farming community in this system of
farming. The overall fertility and productivity of the land can be
improved on sustainable basis.
If the mineral N added is higher than the amount of N should be
added, it means that mineral N added is higher than the crop N
requirement of the desired yield. This excess of mineral N will be lost from the rooting zone, and mainly by leaching to the ground water in the
form of NO3- , where over application of N in cereal crops led to low N
recovery efficiency and risk of NO3 pollution to ground water.
Finally: it could be concluded that the proposed approach, although
it needs more investigation, it seems to be valid either for N & P
management in soil or for use of organic wastes in agriculture. It is
possible by this approach to calculate that amount of mineral fertilizers
should be added to soil to verify the optimum realistic yield. This will
lead to reduce the amounts of mineral fertilizers added to soils, and
consequently control environment pollution.