الفهرس 
IntroductionOnly 14 pages are availabe for public view
Abstract
Currently, the Egyptian government is working hard to encourage and motivate citizens to reclamation the desert soils. So, a pot experiment was carried out aiming at evaluating the effect of some organic fertilizers as main factor i.e., compost, chicken manure and town refuse at different rates (0.0, 10.0 and 15.0 Mg fed-1) as sub main factor as well as bentonite amendment at different rates (0.0, 10.0 and 15.0 Mg fed-1) as sub-sub main factor on the performance of lettuce plants grown on sandy soil. Lettuce growth criteria and concentrations of nutrients in plant tissues as well as some soil properties were measured at harvest stage. The results obtained could be summarized as follows :- 1. Growth criteria of lettuce plants. Except No. of leaves plant-1 which were non-significantly affected due to the type of organic manure, the lettuce plants treated with compost had the highest values of all studied growth criteria i.e., plant height (cm), plant fresh and dry weights (g plant-1), head diameter (cm) and root length (cm) under sandy soil conditions followed by that treated with chicken plant fresh and dry weights (g plant-1), head diameter (cm) and root length (cm) under sandy soil conditions followed by that treated with chicken manure, while lettuce plants treated with town refuse possessed the lowest values at harvest stage of lettuce plants. Concerning the studied levels of organic amendments, it can be noticed that the values of all aforementioned growth criteria increased as the added rate of the studied organic amendment increased. Regarding the bentonite amendment, the soil addition of bentonite had a positive effect on lettuce plant performance compared to the corresponding plants grown without soil addition of bentonite (control treatment), where the values of all growth criteria increased as the added rate of the bentonite amendment increased. 2. Chemical constituents in leaves of lettuce plants (quality parameters). The lettuce plants grown on sandy soil amended by compost had the highest values of N, P, K (%), Fe, Mn (mg kg-1) and DM (%), while the lettuce plants grown on sandy soil amended by chicken manure came in the second order for all aforementioned traits, whilst the lettuce plants grown on sandy soil amended by town refuse possessed the lowest values. As for the studied levels of organic amendments, the sequence order of studied levels from the most effective to the less was as follows ; 15.0 Mg fed-1 > 10.0 Mg fed-1> control (without soil addition). Data again indicated positive responses for bentonite conditioner particularly with high-added level (15.0Mg fed-1) compared to control treatment (without soil addition. In other words, the sequence order of studied levels of bentonite amendment from the most effective to the less was as follows ; 15.0 Mg fed-1 > 10.0 Mg fed-1> control (without soil addition of bentonite). 3. Soil post-harvest analyses. 3. 1. Nutrients content. The values of available nutrients (N, P, K, Fe and Mn, mg kg-1) in the studied sandy soil after harvest of lettuce plants generally increase due to all soil additions of organic amendments at all studied different rates. The sandy soil amended by compost possessed the highest values of available N, P, K, Fe, Mn (mg kg-1) followed by that amended by chicken manure, whilst the sandy soil amended by town refuse possessed the lowest values all studied soil available nutrients. On the other hand, regarding the studied levels, the sandy soil amended by any organic amendments at rate of 15.0 Mg fed-1 possessed the highest values of available N, P, K, Fe, Mn (mg kg- 1) followed by the rate of 10.0 Mg fed-1 and lately the rate of rate of 0.0 Mg fed-1 (control treatment).The soil addition of bentonite conditioner particularly with high-added level (15.0Mg fed-1) led to increase the values of soil available nutrients i.e., N, P, K, Fe and Mn, mg kg-1 after harvest of lettuce plants compared to the corresponding sandy soil without bentonite. where the values of all aforementioned soil available nutrients increased as the added rate of the bentonite amendment increased. 3.2. Other soil properties (EC, pH and OM). - Soil electric conductivity (EC, dSm-1) values. The values of soil electric conductivity (EC, dSm-1) after harvest of lettuce plants generally increase due to all soil additions of organic amendments at all studied different rates compared to the corresponding soil untreated with organic manure. The soil EC values were significantly increased as the added rates of bentonite increased as compared to control treatment (without soil addition of bentonite). Soil pH value. A clear response of soil pH values to all studied types of organic manures at studied different rates were found. Generally, it can be noticed that the effect of studied organic treatments on soil reaction (pH) was significant, where all organic amendments slightly reduced soil pH values compared to the corresponding sandy soil untreated as well as the positive effect of organic manures in reducing pH values increases as the added rate increased. Results revealed a non-significant response of soil pH values to bentonite rates of 15, 10 Mg fed-1 compared to control treatment. Soil organic matter (O.M, %). The concentration of organic matter in the studied sandy soil after harvest of lettuce plants generally increase due to all soil additions of organic amendments at all studied different rates. The sandy soil amended by ChM possessed the highest values of OM (%) followed by that amended by compost, whilst the sandy soil amended by town refuse possessed the lowest values of OM (%). On the other hand, regarding the studied levels, the sandy soil amended by any organic amendments at rate of 15.0 Mg fed-1 possessed the highest values of OM (%) followed by the rate of 10.0 Mg fed-1 and lately the rate of rate of 0.0 Mg fed-1 (control treatment). With regard to soil organic matter results due to bentonite amendment, data show that OM content slightly increased as bentonite rates increased as compared to control treatment (without soil addition).