الفهرس 
1.INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
To achieve this study, two experiments were conducted namely, leaching and pots experiments at laboratory and green house of Soil Sci. Dept., Fac. of Agric., Menoufia Univ., Shebin Elkom, Egypt to study application impact of biochar “RSB” and compost “RSC” derived from rice straw on sandy soil and its leachates content of pH, EC and soluble nutrients (N, P, K, Zn and Cu). Also, the effect of RSB and RSC applications on sunflower plants growth and their content of N, P, K, Zn and Cu were studied under sandy soil conditions. In addition to effect of the same applications on sandy soil properties after harvest and its content of available N, P, K, Zn and Cu.
Surface (0-30 cm) sandy soil samples were collected from Gabal Quisna, Minoufia Governorate (30° 31ꞌ 37.63ꞌꞌ N, 31° 10ꞌ 7.52ꞌꞌ E).
i-leaching experiment
This experiment was carried out using soil columns under laboratory condition at Soil Sci. Dept., Fac. Of Agric., Menoufia Univ., Shebin Elkom. Polyethylene columns with dimensions of 8.25 cm inner diameter and 25 cm depth were used. Prior to packing the columns, the prepared soil samples mixed and thoroughly homogenized with 0.00, 0.75, 1.50 and 3.00% RSC or/ and 0.00, 0.75, 1.50 and 3.00% RSB.
All soil columns were supplied by nutrient solution of (Hewitt and Smith, 1975) and incubated at room temperature for 25 days at moisture level of field capacity. At the end of incubation period, all soil columns leached by 180% WHC of the soil without treatments (C0B0) for 3 times with a ten-day interval. The collected leachate of each column was analyzed
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for EC, pH, and soluble NO3-, NH4+, P, K+, Cu++ and Zn++. The obtained results could be summarized in the following:
a- leachate
1- Biochar addition led to an increase in pH and EC (dS/m) values, while the addition of compost led to little change in pH and increase in EC (dS/m) values of leachate.
2- Soluble HN4+ (meq/L) in the studied soil leachate was increased with increasing the rates of compost application. On the contrary the leachate content of soluble HN4+ (meq/L) was decreased with increasing biochar rates.
3- Increasing rates of added biochar individually associated by a little decrease of sandy soil leachates content (meq/L) of NO3-N compared with control treatment but these leachates content (meq/L) of NO3-N increased with increasing rate of added compost alone.
4- The individual applications of biochar were resulted in a decrease of leachates content of soluble P compared with the control treatment. While the individual applications of compost were associated with an increase of the soluble P content (mg/L) in the soil leachates.
5- Application rates of individual biochar or compost were associated by an increase the leachate content (mg/L) of soluble K in the soil leachates compared with the control treatment.
6- The leachate content of soluble Zn (mg/L) decreased at the application rate of 0.75% compost and increased at high application rates up to 3% compost. On the other hand soluble Zn content decreased with increasing addition rates of biochar. Concerning to the leachate content of soluble copper (mg/L), increasing the application rates of compost or biochar led to
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decrease in soluble Cu concentration in sandy soil leachate through the three studied incubation periods.
b-Soil
Application rates of biochar were associated by an increse in the following soil properties: pH, EC, CEC and the content of available NH4+, p and k and a decrease in available Zn and Cu. While, the application rates of compost resulted in an increse in EC, CEC and the content of available NH4+, NO3-, P , K, Zn and Cu and a decrease in soil pH.
ii-Pot experiment
This experiment was carried out in the greenhouse, Soil Sci. Dept., Fac. of Agric., Menoufia Univ., Shebin Elkom, Egypt to study the effect of individual and combined applications of biochar and compost on sunflower plants growth under sandy soil condition and its content of N, P, K, Zn and Cu. Also, studied soil content of available NH4+, NO3-, P, K, Zn and Cu and their chemical properties pH, EC and CEC. Biochar was applied at rates of 0.0, 0.05, 0.10, 0.20 and 0.40%. The compost was applied at rates of 0.00 and 0.75%. The obtained results could be summarized in the following:
a- Soil properties
1-Concerning to mean effect of biochar level on soil pH after harvest, soil pH increased with increasing of biochar levels compared with the control treatment (B0). On contrary, the mean effect of compost level, where soil pH decreased at rate of C0.75 compared with the control treatment (C0).
2- Mean effect of biochar level on soil EC (dS/m) after harvest, soil EC (dS/m) increased with increasing of biochar levels compared with the control treatment (B0). Concerning to mean effect of compost level on soil
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EC (dS/m), it was found that, increasing of compost levels resulted in increasing of EC (dS/m) compared with the control treatment (C0).
3- Soil content of available NH4, P and K increased with increasing biochar rates compared with the control treatment (B0), on contrary the soil content of available Zn and Cu. Compost application resulted in an increase in the soil content of available NH4, P, K, Zn and Cu compared with the control treatment (C0).
b- Dry matter yield and nutrients uptake
1-The increase of added compost up to 0.75% and biochar up to 0.05% increased the dry matter of the sunflower plant then decreased at the high application rates of biochar. The additions of compost generally produced a sun flower dry matter higher than those of that resulted from the addition of biochar .
2- Concerning to mean effect of biochar level , macronutrients (N, P and k) uptake (mg/plant) increased with increasing of biochar levels up to 0.05% biochar compared with the control treatment (B0) and decreased at high levels of biochar. Zn and Cu uptake was significantly decreased with increasing biochar rates.
3-Regarding with mean effect of compost level, N, P, K, Zn and Cu uptake (mg/plant) increased at level of C0.75 compared with the control treatment (C0)