الفهرس 
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Abstract
This study was carried out in Soil Science Department, Faculty of Agriculture, Minia University, Minia Governorate, Egypt during 2003-2006 to explore the possibility of using date palm trees wastes particularly their stalk bases as organic fertilizer for sandy soil through composting and cultivation trials.
The soil used for the study was collected from west Minia city, Minia Governorate to represent the virgin sandy dunes soils.
The organic waste used as raw material in the compost preparation was the crashed stalk bases ( CSB) of date palm trees.
A composting experiment was conducted for seven months to evaluate the effect of five composting treatments (CT) used as microbial activators as following: CT1= CSB alone, CT2= Abo El-Fadl microbial activator, CT3= CSB + poultry manure (10%) + rock phosphate (5%) + clay material (5%), CT4= CSB + cattle manure (10%) + rock phosphate (5%) + clay material (5%) and CT5= CSB + sheep manure (10%)+ rock phosphate (5%) + clay material (5%) on the manorial value of the resultant composts in terms of compost characteristics.
The compost maturity lab tests data allowed to conduct the further pot culture experiments in composts of seven months composting age. Consequently, two pot culture experiments using four application rates (5, 10, 15 and 20 tons/fed ) of each compost were carried out during the late winter of 2003/2004 and winter of 2004/2005 with tomatoes and wheat as direct and residual crops, respectively. The aim of these two experiments is to evaluate the manorial value of composts prepared with different composting system ( microbial activators ) in terms of its initial and residual beneficial effects on soil properties and in turn on plant growth and chemical composition.
The obtained data of the present study could be summarized under the following main points:
5.1. Composting experiment:
1-Irrespective of the composting period, all the composting treatments led to decreasing OC% and increasing N% which reflected in decreasing C/N ratio as compared to the raw organic waste.
2-Similar positive effects of composting treatments on increasing P (%), K (%), MWHC (%) and CEC (cmol/kg-1) were recorded regardless of the composting period.
3- Enriching raw material had a further positive impact on the above mentioned characteristics regardless of the composting period.
4- Compost-2 was the superior and compost-1 was the inferior regardless of composting period and the studied characteristic of compost.
5.2. Effect of composted palm trees wastes application on dry
matter yield , water use efficiency and some nutrients uptake by two successive crops (tomatoes and wheat) grown in virgin sandy soil:
1-Treating sandy soil with different application rates significantly increased dry matter yield, water use efficiency and nutrients (NPK) uptake by first and second crop over the respected controls, regardless of composting treatment.
2-The increase in the above mentioned parameters of the two successive crops was proportional to the increase in the application rate apart from the composting treatments.
3-The composting treatments (enriched or not) had a significant positive impact on the studied parameters.
4-In a given composting treatment, the difference between application rates were also significant.
5-In a given application rate, compost-2 was the superior and compost-1 was the inferior.
6-The above mentioned trends were common in direct and residual effects.
5.3. Comparison between the direct and residual effects of composted palm trees wastes application on some soil properties before cultivation and after harvesting the two successive crops:
5.3.1.Moisture retention constants:
1-Field capacity, wilting point, available water and MWHC of the compost treated soils had significantly improved as compared to controls and the improvement was proportional to the application rate.
2-The improvement was more pronounced in the treated soils before cultivation as compared to after harvesting. Also, the first crop and in post harvest soil of the first crop as compared to the second crop.
3-Enriching the organic material before composting with the microbial
activator resulted in a significant increase in F.C over that of the unenriched one.
4-Among the enriched composts, Abo- El fadl compost (T2) was the
superior, whereas, T4 and T5 were the inferior and were on par with
each other.
5- Among rates, the differences were significant regardless of composting treatment or cultivation period.
6- Generally, the compost-2 (T2) was superior and the compost-1 (T1) was inferior, at all the application rate whether before cultivation or after harvesting the two successive crops.
5.3.2.Physico-chemical properties:
1-Treating sandy soils with date palm waste composts slightly decreased soil reaction and increased EC , OC and CEC values.
2-The decrease in soil reaction and the increase in EC, OC and CEC were proportional to the increase in the application rate and generally followed a decreasing trend with land use time passing, i.e. before cultivation and after first and second crop, however, the difference between treated and untreated soils still significant.
3-Compost-2 was superior and compost-1 was inferior on their effect on increasing OC and CEC, at all the application rates.
5.3.3.Nutients content in soils:
1-Addition of composted date palm waste to sandy soils significantly increased their total nitrogen and available P and K in the treated soils before cultivation and after harvesting of the two successive crops as compared to controls.
2-The increase in N,P and K content was proportional to the increase in the application rate of compost.
3-The nutrients content was followed a decreasing trend with land use time passing except in the case of available P which performed a reversed trend.
4- Compost-2 was superior and compost-1 was inferior at all the application rates.
Finally and according to the obtained results, the following conclusions and recommendations could be made:
1-Composting palm trees wastes for at least seven months and enriching this waste before composting is a must to get mature composts.
2-using the composted organic material had positive impact in improving soil physical and chemical properties, water use efficiency and crop performance in coarse textured soils.
3-The integrated use of organic and inorganic fertilizers is recommended in such poor soil.
4-Coarse textured soils still have a significant response to high rates of compost application and from the obtained results, 20 t/fed. at least is the recommended application rate particularly in the first few years of cultivating such virgin poor soil.
5- Further studies on field level including the economic aspects are required to get sure of the obtained results, field applicability and economics.