Land suitability analysis can help to achieve sustainable crop production with a proper use of the natural resources. The current study was carried out on the soils of north-western area of Libya to assess their morphological, physical and chemical properties and their suitability for growing irrigated crops. The studied area lies between latitudes 32° 30′ 00.9" and 32° 57′ 34.2'' N and between longitudes 11° 35′ 08.4" and 11° 45′ 09.2" E. Two suitability methods (Sys &Verhey and Storie methods) were used to assess the land suitability of this area. According to Sys and Verhye method, the soils of the studied area varied in the suitability for irrigation between highly suitable (S1) to marginally suitable (S3). However, according to modified Storie index method the soils productivity, ranged from excellent (grade 1) for agriculture to non-agricultural (grade 6). The modified Storie index method was more effective in assessing the land suitability of this area. The drip irrigation system was also more suitable than surface irrigation method for most of the soils of the studied area. The indeces of soil suitability rating and percentage for growing alfalfa, sorghum, barley, maize, millets, wheat and safflower were higher compared to those for growing soybean, sunflower and sesame. Onion and green pepper crops were moderately suitable to be grown in 42% of the soils of the studied area while the other vegetables were not suitable to be grown in most of the soils of the studied area. The evaluated fruit trees could be arranged according to the soil suitability rating and percentage in the order of date palm > olives > guava > citrus > banana. The results also revealed that the studied area has a good potential to produce the selected crops under irrigation provided that the water requirements for these crops are met. The main limiting factors for land suitability for growing crops are soil texture, soil depth, calcium carbonate, alkaline pH and soil salinity.

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This study was carried out to calculate response of two cultivars of wheat which represent the hexaploid and tetraploid species to different cropping sequences and nutrient rates of NPK. This study was carried out in the Experimental Farm of Faculty of Agriculture, Assiut University in the two growing seasons of 2004/2005 and 2005/2006 seasons. Two cropping systems were studied, i.e. corn – clover – wheat and corn – fallow – wheat. The cultivars studied were Sakha 93& Beni-suef 1 in 2004/2005 and Sids 1 & Beni-suef 1 in 2005/2006 season. The nutrient rates of NPK (kg/fed.) were 80, 15 and 50, i.e. the recommended rates, 40, 7.5 and 25 kg/fed. of NPK, 20, 3.75 and 12.5 kg/fed. NPK and without nutrients. The variables studied were distributed in a split-split plot design in which crop sequence was allotted in the main plots. The cultivars were in split plot whereas the nutrients were distributed in the sub-sub plots. The results obtained in this study could be summarized as follows: 1- The growth parameters such as plant height, leaf area index, number of tillers/plant and total dry matter/plant were improved by planting wheat after clover as compared with the cropping system of corn-fallow-wheat. Cultivars belong to the hexaploid cultivars were characterized by favorite growth parameters as compared with simolina cultivar. The recommended nutrients of NPK favored the growth attributes. 2- Average interval from planting to 50% heading tended to be increased significantly when planting wheat was after clover. No significant differences in earliness among the two cultivars studied were detected. The consistent increase in nutrient rates prolonged the interval to 50% heading. 3- Yield components such as number of tillers/plant at harvest spike length, number of spikelets/spike, and seed index tended to be increased when wheat planting was after clover as compared with the sequence of corn-fallow-wheat. Wheat yield components of hexaploid cultivars, i.e. bread wheat surpassed the semolina cultivar in all attributes except the seed index. The later took the contradict trend in this respect. Linear increases in all yield components were observed as nutrients rates were increased. 4- Average grain yield/fed of wheat was increased significantly when wheat was grown after clover compared with cultivating it after fallow. This is true in the two growing seasons. No significant difference among the cultivars studied was observed. Grain yield per unit area tended to be increased as nutrient rates were increased. Here too, the first order interaction of intensification x fertilization revealed that the cropping sequence of corn-clover-wheat increased the response of grain yield to the recommended rates of NPK compared with the sequence of corn-fallow-wheat. 5- Straw yield/fed was reacted significantly to the cropping sequence practiced in favor of planting wheat after clover. Hexaploid cultivars were superior in straw yield production per unit area compared with tetraploid cultivar. Average straw yield was increased significantly as nutrient rates were increased up to the recommended rates. 6- The biological yield/fed was influenced significantly by cropping systems studied in favor of the cropping sequence of corn-clover-wheat in the two growing seasons. The bread cultivars produced heavier weight of biological yield than semolina cultivar. This relation was significant in the two growing seasons. Consistent increase in biological yield/fed was achieved as nutrient rates increased. 7- Harvest index did not show any definite response to intensification system. Here, semolina cultivar improved harvest index as compared to bread cultivars. Negative trend was noted between harvest index and nutrient rates. This means that harvest index tended to be increased as nutrient rates was decreased. 8- Here it should be noted that the average yield of clover produced from the cropping sequence of corn - temporary clover - wheat was ranged from 8781.82 to 10650 kg/fed. in 2004/2005 season. In 2005/2006 it ranged from 12109.09 to 17318.18 kg/fed.

This study was carried out to calculate response of two cultivars of wheat which represent the hexaploid and tetraploid species to different cropping sequences and nutrient rates of NPK. This study was carried out in the Experimental Farm of Faculty of Agriculture, Assiut University in the two growing seasons of 2004/2005 and 2005/2006 seasons. Two cropping systems were studied, i.e. corn – clover – wheat and corn – fallow – wheat. The cultivars studied were Sakha 93& Beni-suef 1 in 2004/2005 and Sids 1 & Beni-suef 1 in 2005/2006 season. The nutrient rates of NPK (kg/fed.) were 80, 15 and 50, i.e. the recommended rates, 40, 7.5 and 25 kg/fed. of NPK, 20, 3.75 and 12.5 kg/fed. NPK and without nutrients. The variables studied were distributed in a split-split plot design in which crop sequence was allotted in the main plots. The cultivars were in split plot whereas the nutrients were distributed in the sub-sub plots. The results obtained in this study could be summarized as follows: 1- The growth parameters such as plant height, leaf area index, number of tillers/plant and total dry matter/plant were improved by planting wheat after clover as compared with the cropping system of corn-fallow-wheat. Cultivars belong to the hexaploid cultivars were characterized by favorite growth parameters as compared with simolina cultivar. The recommended nutrients of NPK favored the growth attributes. 2- Average interval from planting to 50% heading tended to be increased significantly when planting wheat was after clover. No significant differences in earliness among the two cultivars studied were detected. The consistent increase in nutrient rates prolonged the interval to 50% heading. 3- Yield components such as number of tillers/plant at harvest spike length, number of spikelets/spike, and seed index tended to be increased when wheat planting was after clover as compared with the sequence of corn-fallow-wheat. Wheat yield components of hexaploid cultivars, i.e. bread wheat surpassed the semolina cultivar in all attributes except the seed index. The later took the contradict trend in this respect. Linear increases in all yield components were observed as nutrients rates were increased. 4- Average grain yield/fed of wheat was increased significantly when wheat was grown after clover compared with cultivating it after fallow. This is true in the two growing seasons. No significant difference among the cultivars studied was observed. Grain yield per unit area tended to be increased as nutrient rates were increased. Here too, the first order interaction of intensification x fertilization revealed that the cropping sequence of corn-clover-wheat increased the response of grain yield to the recommended rates of NPK compared with the sequence of corn-fallow-wheat. 5- Straw yield/fed was reacted significantly to the cropping sequence practiced in favor of planting wheat after clover. Hexaploid cultivars were superior in straw yield production per unit area compared with tetraploid cultivar. Average straw yield was increased significantly as nutrient rates were increased up to the recommended rates. 6- The biological yield/fed was influenced significantly by cropping systems studied in favor of the cropping sequence of corn-clover-wheat in the two growing seasons. The bread cultivars produced heavier weight of biological yield than semolina cultivar. This relation was significant in the two growing seasons. Consistent increase in biological yield/fed was achieved as nutrient rates increased. 7- Harvest index did not show any definite response to intensification system. Here, semolina cultivar improved harvest index as compared to bread cultivars. Negative trend was noted between harvest index and nutrient rates. This means that harvest index tended to be increased as nutrient rates was decreased. 8- Here it should be noted that the average yield of clover produced from the cropping sequence of corn - temporary clover - wheat was ranged from 8781.82 to 10650 kg/fed. in 2004/2005 season. In 2005/2006 it ranged from 12109.09 to 17318.18 kg/fed.

This study was carried out to calculate response of two cultivars of wheat which represent the hexaploid and tetraploid species to different cropping sequences and nutrient rates of NPK. This study was carried out in the Experimental Farm of Faculty of Agriculture, Assiut University in the two growing seasons of 2004/2005 and 2005/2006 seasons. Two cropping systems were studied, i.e. corn – clover – wheat and corn – fallow – wheat. The cultivars studied were Sakha 93& Beni-suef 1 in 2004/2005 and Sids 1 & Beni-suef 1 in 2005/2006 season. The nutrient rates of NPK (kg/fed.) were 80, 15 and 50, i.e. the recommended rates, 40, 7.5 and 25 kg/fed. of NPK, 20, 3.75 and 12.5 kg/fed. NPK and without nutrients. The variables studied were distributed in a split-split plot design in which crop sequence was allotted in the main plots. The cultivars were in split plot whereas the nutrients were distributed in the sub-sub plots. The results obtained in this study could be summarized as follows: 1- The growth parameters such as plant height, leaf area index, number of tillers/plant and total dry matter/plant were improved by planting wheat after clover as compared with the cropping system of corn-fallow-wheat. Cultivars belong to the hexaploid cultivars were characterized by favorite growth parameters as compared with simolina cultivar. The recommended nutrients of NPK favored the growth attributes. 2- Average interval from planting to 50% heading tended to be increased significantly when planting wheat was after clover. No significant differences in earliness among the two cultivars studied were detected. The consistent increase in nutrient rates prolonged the interval to 50% heading. 3- Yield components such as number of tillers/plant at harvest spike length, number of spikelets/spike, and seed index tended to be increased when wheat planting was after clover as compared with the sequence of corn-fallow-wheat. Wheat yield components of hexaploid cultivars, i.e. bread wheat surpassed the semolina cultivar in all attributes except the seed index. The later took the contradict trend in this respect. Linear increases in all yield components were observed as nutrients rates were increased. 4- Average grain yield/fed of wheat was increased significantly when wheat was grown after clover compared with cultivating it after fallow. This is true in the two growing seasons. No significant difference among the cultivars studied was observed. Grain yield per unit area tended to be increased as nutrient rates were increased. Here too, the first order interaction of intensification x fertilization revealed that the cropping sequence of corn-clover-wheat increased the response of grain yield to the recommended rates of NPK compared with the sequence of corn-fallow-wheat. 5- Straw yield/fed was reacted significantly to the cropping sequence practiced in favor of planting wheat after clover. Hexaploid cultivars were superior in straw yield production per unit area compared with tetraploid cultivar. Average straw yield was increased significantly as nutrient rates were increased up to the recommended rates. 6- The biological yield/fed was influenced significantly by cropping systems studied in favor of the cropping sequence of corn-clover-wheat in the two growing seasons. The bread cultivars produced heavier weight of biological yield than semolina cultivar. This relation was significant in the two growing seasons. Consistent increase in biological yield/fed was achieved as nutrient rates increased. 7- Harvest index did not show any definite response to intensification system. Here, semolina cultivar improved harvest index as compared to bread cultivars. Negative trend was noted between harvest index and nutrient rates. This means that harvest index tended to be increased as nutrient rates was decreased. 8- Here it should be noted that the average yield of clover produced from the cropping sequence of corn - temporary clover - wheat was ranged from 8781.82 to 10650 kg/fed. in 2004/2005 season. In 2005/2006 it ranged from 12109.09 to 17318.18 kg/fed.

This study was carried out to calculate response of two cultivars of wheat which represent the hexaploid and tetraploid species to different cropping sequences and nutrient rates of NPK. This study was carried out in the Experimental Farm of Faculty of Agriculture, Assiut University in the two growing seasons of 2004/2005 and 2005/2006 seasons. Two cropping systems were studied, i.e. corn – clover – wheat and corn – fallow – wheat. The cultivars studied were Sakha 93& Beni-suef 1 in 2004/2005 and Sids 1 & Beni-suef 1 in 2005/2006 season. The nutrient rates of NPK (kg/fed.) were 80, 15 and 50, i.e. the recommended rates, 40, 7.5 and 25 kg/fed. of NPK, 20, 3.75 and 12.5 kg/fed. NPK and without nutrients. The variables studied were distributed in a split-split plot design in which crop sequence was allotted in the main plots. The cultivars were in split plot whereas the nutrients were distributed in the sub-sub plots. The results obtained in this study could be summarized as follows: 1- The growth parameters such as plant height, leaf area index, number of tillers/plant and total dry matter/plant were improved by planting wheat after clover as compared with the cropping system of corn-fallow-wheat. Cultivars belong to the hexaploid cultivars were characterized by favorite growth parameters as compared with simolina cultivar. The recommended nutrients of NPK favored the growth attributes. 2- Average interval from planting to 50% heading tended to be increased significantly when planting wheat was after clover. No significant differences in earliness among the two cultivars studied were detected. The consistent increase in nutrient rates prolonged the interval to 50% heading. 3- Yield components such as number of tillers/plant at harvest spike length, number of spikelets/spike, and seed index tended to be increased when wheat planting was after clover as compared with the sequence of corn-fallow-wheat. Wheat yield components of hexaploid cultivars, i.e. bread wheat surpassed the semolina cultivar in all attributes except the seed index. The later took the contradict trend in this respect. Linear increases in all yield components were observed as nutrients rates were increased. 4- Average grain yield/fed of wheat was increased significantly when wheat was grown after clover compared with cultivating it after fallow. This is true in the two growing seasons. No significant difference among the cultivars studied was observed. Grain yield per unit area tended to be increased as nutrient rates were increased. Here too, the first order interaction of intensification x fertilization revealed that the cropping sequence of corn-clover-wheat increased the response of grain yield to the recommended rates of NPK compared with the sequence of corn-fallow-wheat. 5- Straw yield/fed was reacted significantly to the cropping sequence practiced in favor of planting wheat after clover. Hexaploid cultivars were superior in straw yield production per unit area compared with tetraploid cultivar. Average straw yield was increased significantly as nutrient rates were increased up to the recommended rates. 6- The biological yield/fed was influenced significantly by cropping systems studied in favor of the cropping sequence of corn-clover-wheat in the two growing seasons. The bread cultivars produced heavier weight of biological yield than semolina cultivar. This relation was significant in the two growing seasons. Consistent increase in biological yield/fed was achieved as nutrient rates increased. 7- Harvest index did not show any definite response to intensification system. Here, semolina cultivar improved harvest index as compared to bread cultivars. Negative trend was noted between harvest index and nutrient rates. This means that harvest index tended to be increased as nutrient rates was decreased. 8- Here it should be noted that the average yield of clover produced from the cropping sequence of corn - temporary clover - wheat was ranged from 8781.82 to 10650 kg/fed. in 2004/2005 season. In 2005/2006 it ranged from 12109.09 to 17318.18 kg/fed.

The study evaluated wheat, faba bean and onion uptake of Fe, Mn, Zn, Cu, Cd and Pb and characterized the microbial biomass and distribution in a soil under irrigation with sewage wastewater for 40 years at ElMadabegh, Assiut, Egypt. With sewage wastewater irrigation concentrations of Fe, Mn, Zn and Cu in all crops are optimal for plant growth, but that of Cd and Pb were high. Compared to that irrigated with the Nile River fresh water, irrigation with sewage waste water resulted in lower dehydrogenase activity, soil respiration and microbial biomass carbon and higher quantities of bacteria, actinomycetes, fungi and denitryfing bacteria and decreased the quantities of nitrifying bacteria, Azotobacter bacteria and sulphere oxidizing bacteria. In the rhizosphere of onion, the biomass of actinomycetes and fungi was lower, but that of bacteria was higher with sewage wastewater irrigation than with the Nile River fresh water irrigation. Lowest log numbers of fungi, denitryfing bacteria, nitrifying bacteria and Azotobacter bacteria were found in the rhizosphere of onion, but the log numbers of certain other bacteria and actinomycetes were not significantly different between the three crops. These results showed high Pb and Cd concentrations in the crops irrigated with the sewage wastewater and that the sewage wastewater affected the quantity of common and functional microorganisms in the plant rhizosphere, but the magnitude of the microbial population is dependent on the crop type.

The study evaluated wheat, faba bean and onion uptake of Fe, Mn, Zn, Cu, Cd and Pb and characterized the microbial biomass and distribution in a soil under irrigation with sewage wastewater for 40 years at ElMadabegh, Assiut, Egypt. With sewage wastewater irrigation concentrations of Fe, Mn, Zn and Cu in all crops are optimal for plant growth, but that of Cd and Pb were high. Compared to that irrigated with the Nile River fresh water, irrigation with sewage waste water resulted in lower dehydrogenase activity, soil respiration and microbial biomass carbon and higher quantities of bacteria, actinomycetes, fungi and denitryfing bacteria and decreased the quantities of nitrifying bacteria, Azotobacter bacteria and sulphere oxidizing bacteria. In the rhizosphere of onion, the biomass of actinomycetes and fungi was lower, but that of bacteria was higher with sewage wastewater irrigation than with the Nile River fresh water irrigation. Lowest log numbers of fungi, denitryfing bacteria, nitrifying bacteria and Azotobacter bacteria were found in the rhizosphere of onion, but the log numbers of certain other bacteria and actinomycetes were not significantly different between the three crops. These results showed high Pb and Cd concentrations in the crops irrigated with the sewage wastewater and that the sewage wastewater affected the quantity of common and functional microorganisms in the plant rhizosphere, but the magnitude of the microbial population is dependent on the crop type.

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