الفهرس 
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Abstract
SUMMARY AND CONCLUSION
The current work aims to evaluate the changes of soil quality indices as a result of long term organic and conventional management systems, and to assess quantitatively the sustainability of such management systems. This study had focused on selecting the most appropriate procedure for evaluating sustainability. The study also aims to find out relationships between biomass yield and both of minimum data set (MDS) and cumulative rate (CR), and to select the best models of minimum data set (MDS) to predict biomass yield under different conditions.
The studied farms were selected from two areas i.e. El-Sharqia governorate in which the organic farming has been commenced in 37 years on a farm, nearby (Bilbeis) district north east of Cairo and El-Ismailia governorate where the organic farming started since 19 years, in El-Abtal village; East El-Ismailia governorate at the middle part of east Sinai. In such areas, twelve farms in El-Sharqia governorate were selected in Bilbeis district (five farms had been in conventional farming and seven farms had been in organic farming). Nine farms were selected in east and west El-Ismalia governorate (five farms have been in conventional farming and four farms have been in organic farming).
Soil samples were collected at triplicate at 0-20, 20-40 and 40-60 cm depths from selected fields for each of selected farms by soil auger. Then each field was represented by one sample of each depth. These disturbed soil samples were air dried, crushed and passed through 2 mm sieve and saved for soil analysis. In addition, undisturbed soil samples were collected from surface soil layer (0-20 cm) to determine soil bulk density (BD), total porosity (TP %) and effective porosity (Pe %). The disturbed soil samples were used for some soil physical, chemical and fertility status analyses. Also, irrigation water samples were taken and for their some basic chemical properties analyzed.
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SUMMARY AND CONCLUSION
Omnia M. Wassif, (2017), Ph.D., Fac. Agric., Ain Shams Univ.
The main steps to assess the sustainability status were as follows:
I. selecting the minimum data set (MDS) of indicators that best represent the best soil function.
II. Scoring (MDS) indicators based on performance of soil function.
III. Using two approaches of evaluation to classify sustainability status:
1) The first one was sustainability index (SI) approach that calculated as the arithmetic mean values of sustainability indices to classify the sustainability status to two categories sustainable >1 and unsustainable <1.
2) The second approach was the cumulative rate (CR) as a second approach to classify the sustainability status to five categories {highly sustainable, sustainable, sustainable with high input, sustainable with another land use and unsustainable}. It was calculated by assigning a relative weighting factor (RWF) to each of soil indicator values. Relative weighting factor (RWF) was obtained from critical limits approach for MDS of indicators. The CR of sustainability was obtained by adding the values of RWF based on critical limitation of each soil indicators within each soil depth separately for each farm.
The study also included biomass yield measurements to find out the relationship between biomass yield as representative by relative yield (Ry) and both of MDS and CR indicators. Moreover, the best models to predict the biomass yield under both conditions (organic and conventional farming) were elicited.
The results obtained can be summarized as follows:-
1. Particle size distribution:- For El- Sharqia farms, the soil texture representing organic and conventional farms are characterized by
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Omnia M. Wassif, (2017), Ph.D., Fac. Agric., Ain Shams Univ.
sandy loam in most of soil layers. on other hand, El-Ismailia farms, soil texture of conventional farms is sandy texture classes and organic farming have different texture classes varied from sandy loam to sandy clay loam and loamy sand.
2. Carbonate content: - The lime content of the El-Sharqia farms and El-Ismailia farms, either under organically and conventionally cultivation conditions were non calcareous nature.
3. Available soil moisture:- Soil moisture retention and availability in El-Sharqia farms showed that at 0.01 MPa i.e. soil field capacity (FC) for the tested soil depths are ranging between 15.08% and 27.58%; meanwhile the corresponding values of permanent wilting point (PWP) of such depth vary between 7.45% and 11.80%. Consequently, the amount of available water (AW) range between 7.64% and 16.76 %. Moreover, With respect to El-Ismailia farms, the data showed that the values of water content at field capacity range between 13.20% and 32.24%, while they varied between 5.58% and 11.92% at PWP. Therefore available soil water ranged between 4.26% and 22.23%.
4. Soil bulk density and porosity:- The values of the soil bulk density increased with soil depth in all cases. In addition, the values of El-Sharqia farms soils ranged between 1.37 to 1.79 Mg/m3 which, the values of El-Ismailia farms soils were 1.29 and 1.76 Mg/m3. The soil porosity took reverse trend to that manifested for soil bulk density in both study areas. Nevertheless, the difference in total and effective porosity of the organic and conventional farms at El-Sharqia and El-Ismailia farms was relatively small and could be related the natural variability of soil.
5. Soil erodibility (I) and coarse fragment fractions (CFF):- The soil erodibilty (I) and coarse fragment fraction (CFF) appeared inverse relationship in the surface layers due to soil texture.
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Omnia M. Wassif, (2017), Ph.D., Fac. Agric., Ain Shams Univ.
6. Electrical conductivity (ECe) and soluble ions and sodium adsorption ratio (SAR):- The values in both conventional and organic farming system in El-Sharqia and El-Ismailia farms showed that the soils have different salinity classes with pH < 8.5, they could be the soil samples considered non-saline, slightly saline, moderately saline and very saline. Concerning sodium adsorption ratio (SAR) the obtained values in soils of El-Sharqia and El-Ismailia farms can be grouped into two categories, the first having SAR values < 13, these soils are non-saline, slightly saline and saline soils. The second category has SAR values > 13 and considered as saline sodic regarding EC > 4 dS/m and pH < 8.5. As regard to general classification of salt-affected soils the obtained results can be grouped in four classes : (non-saline, slightly saline, saline and saline sodic).
7. Soil pH:- The results showed that the pH values for the different depths of the selected farms in El-Sharqia and El-Ismailia are fluctuating from 7.33 to 7.80 and from 7.50 to 8.03, respectively. These values indicate that the soils of such farms are considered slightly to moderately alkaline.
8. Cation exchange capacity (CEC):- The obtained values CEC was ranging between 6.70 and 14.58 mmolc/kg soil for El-Sharqia farms. However, the values fluctuate between 5.69 and 13.91 mmolc/kg soil in El-Ismailia farms.
9. Soil fertility status of the studied farms:- The soil organic carbon percent SOC of organic farming in both El-Sharqia and El-Ismailia farms were greater than that of conventional farming and it is considered a key component in the creation and maintenance of high soil quality. The values of total nitrogen remain in the high level category in all farms. The soil were suffered from phosphorus deficiency and phosphorus fertilizers should be added.
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The values of Av.K in all farms are remaining in the sufficient and high category levels.
10. Some basic chemical properties of irrigation water:- The analysis of irrigation water samples showed that such irrigation water in the El-Sharqia and EL-Ismailia farms lie in three categories of salinity levels for both governorates. The first category is non-saline water (< 0.7 dS/m). The second category is slightly saline (0.7 - 2 dS/m). The third category is moderately saline (2-10 dS/m).
11. Soil quality assessment:- Multivariate statistical techniques were used to select minimum data set (MDS) for each soil depth for evaluating soil quality and sustainability. Results indicated that (MDS) can be used in assessing soil quality and sustainability instead of considering total data set (TDS) with respect to saving time and cost. The results of principal component analysis PCA were used in both farming systems in 0-20 cm soil layer and those of eigenvalues ≥1 explained that the five components accounted 83.8% and 91% as cumulative proportion of the total variance in both of El-Sharqia and El-Ismailia farms respectively, however, the PCs in the 20-40 cm and 40-60 cm with eigenvalues ≥1 explained that the five components accounted 87% as cumulative proportion of the total variance for El-Sharqia farms and for El-Ismailia farms the PCs in the 20-40 cm and 40-60 cm with eigenvalues ≥1 explained that the four components accounted 87% as cumulative proportion of the total variance . It is clear that PC1, PC2, PC3, PC4 and PC5 for different soil depths had explained high positive or negative loadings of different soil attributes in both of El-Sharqia and El-Ismailia farms. Consequently, there were direct positive or negative correlations between some pairs of soil attributes. Within each PC, the variable with the highest factor
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loading was selected as the most important contributor to the PC for MDS.
12. Soil sustainability status:- Sustainability index (SI) scored 10% and 90% of the farms were sustainable and unsustainabile, respectively in both of governorates. In El-Sharqia farms, using CR approach, it scored in 0-20 cm soil layer depth 33.33%, 58.33% and 8.33% of farms were classified as sustainable, sustainable with high input and sustainable with another land use, respectively. In 20-40 cm soil depth, 36.36% and 63.63% of farms would be sustainable only and sustainable with high input, respectively. In 40-60 cm soil depth, 30%, 40 % and 30% of the farms represented sustainability only, sustainable with high input and sustainable with another land use, respectively. In El-Ismailia Governorate using CR approach, in the 0-20 cm soil depth, 33.33% and 66.66% of the farms were under sustainability group only and sustainability with high input respectively. Also, in the 20-40 cm soil layer recorded CR of 22.22%, 55.55% and 22.22% of the farms were under sustainability group only and sustainability with high input and sustainability with another land use, respectively. Finally in the 40-60 cm soil layer, results recorded 33.33% ,55.55% and 11.11 % of the farms were under sustainability group only, sustainability with high input and sustainability with another land use respectively. The overall results indicated that , in El-Sharqia farms, the cumulative rate (CR) was (26.48) for organic farms and (28.35) for conventional farms while in the EL-Ismailia farms, the cumulative rate (CR) was (27.16) for organic farms and (28.5) for conventional farms and it is clear from this, that, the cumulative rate (CR) of organic farms was less than that of conventional farms and this showed that the sustainability status of the organic farms better than the sustainability status of conventional farms.
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13. The higher SI indicated soil quality improvement and higher CR indicated poor soil quality. Also, a significant linear relationship and a highly significant correlation coefficient were obtained between SI and CR in 0-20, 20-40 and 40-60 cm soil depth. In addition, a Comparison between two approaches for assessing sustainability status was carried out. Both sustainability index (SI) and cumulative rating (CR) approaches indicated similar results in evaluating soil sustainability, however cumulative rating approach (CR) was more remarkable than sustainability index (SI) for evaluating soil sustainable status, because CR grouped the sustainability to five classes having more flexibility of use selecting the appropriate management practices to achieve sustainability and to evaluate the changes in soil quality. In addition, such approach helps policymakers, researchers and farmers to take decisions on selection of management strategies and to monitor the changes in soil quality.
14. The relationship between MDS and biomass yield:- The The results of one parameter models in farms of El-Sharqia governorate showed the variation in crop yield of all the farms and at all depths was (82%) due to pH, (59%) SAR, (0.53%) organic carbon, (0.79%) BD and (0.56%) EC. The results showed that there were six models of two parameters, as well as there were four models of three parameters. As in the case of farms El-Ismailia governorate results of one parameter model explained the variation of crop yield in all the farms and at all depths (60%) due to pH, (96%) SAR, (0.88%) SOC, (0.67%) BD and (0.73%) EC Moreover, F test values were significant. It is possible to use these linear models to predict biomass yield also, F test values were significant. There were eight models of two parameters, as well as there were two models of the three parameters. The results showed that it is possible to use these linear models to predict biomass yield and the best one is the three parameters model which
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Omnia M. Wassif, (2017), Ph.D., Fac. Agric., Ain Shams Univ.
associated with high R2 given from all of these models under both conditions. In addition, the correlations and regression coefficients between measured and predicted biomass yield were calculated.
15. The relationship between CR and biomass yield:- The CR also showed a significant inverse relationship with biomass yield as a dependent variable and CR as independent variables in both farming systems of El-Sharqia and EL-Ismailia farms (R2 = 78%; P<0.05) and (R2 = 79%; P<0.05) in El-Sharqia and El-Ismailia farms, respectively. It is meaning that, biomass yield decreases as CR increases. The results showed that there were six models linear equations as one and two parameters model between the biomass yield and the CR of the soil properties and can also be used in the prediction of biomass yield in the El-Sharqia farms. And also it has been reached eight models as one and two parameter models between the biomass yield and CR of soil properties in El-Ismailia farms. The value of F calculated > 5 in both of El-Sharqia and El-Ismailia farms.
16. from all the above mentioned results, it could be concluded that: i) the conventional farming system was least sustainable as compared with organic farming. ii) The CR approach is better than SI for evaluating soil quality and sustainability. iii) Three parameters models for El-Sharqia farms and El-Ismalia farms were {Y=-264.595+-1.916*EC+42.312*PH+10.473*SOC} R2=95% F-value = 55.9 and {Y=93.041-18.245*EC+40.507*SOC+1.6*SAR} R2=92% F-value = 15.82, respectively were the best model to be recommended to predict the biomass yield.
Finally, it can be recommended that CR approach and three parameters models can be used for evaluating sustainability and predicting biomass yield, respectively. Increasing agricultural inputs or changing the land use practices of conventional farming system