الفهرس 
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Abstract
Field experiment was conducted during the two successive season of (2009-2010)and (2010-2011) at the organic farm of the Environmental Studies and Research Institute (ESRI), Minufiya University at Sadat city; Minufiya governorate; Egypt. This investigation studied the influence of humic acid, fulvic acid, Serratia and potassium on growth of Valencia orange seed lings .
Fifty seedlings (3 years old) of Valencia orange budded on sour orange and planted 5x5 in sandy soil; were selected as uniform in size and vigorous in growth they are planted in sandy soil. Ten different treatments with 5 replicate (using 5 seedlings for each treatment). Combinations of Humic and Fulvic acids as organic fertilizers; Serratia as a biofertilizers; and NPK) as mineral fertilizer were applied as follow:
1- Control (T1)
2- 50% NPK (T2)
3- Humic acid (HA) + 50% NPK (T3)
4- Fulvic acid (FA) + 50% NPK (T4)
5- Algae + 50% NPK (T5)
6- Humic acid (HA) + Serratia- Bio (T6)
7- Fulvic acid (FA) + Serratia- Bio (T7)
8- Algae + Serratia -Bio (T8)
9- Fulvic acid (FA) + Humic acid (HA)+ Algae + -Bio (T9)
10- Serratia -Bio (T10)
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The obtained results could be summarized as follows:
1- Effect on Growth attributes:
1. Applications of Humic acid; Fulvic acid and Algae increased average leaves number per shoot, shoots number and leaf area as compared with the control application.
2. Organic fertilizers (Humic –Algae - Fulvic) and Bio fertilizer (Serratia) treatments to9 ether increased average leaves number per shoot, shoots number and leaf area as the highest values compared with other applications at main study seasons.
2- Effect on chlorophyll, macro and micro nutrient leaf content:
1. Applications of organic and bio fertilizers treatments increased leaf chlorophylls A&B content compared with the control Treatment
2. Organic fertilizers (Humic –Algae - Fulvic) and Bio fertilizer (Serratia) together increased leaf chlorophylls A&B content to the highest values compared with other applications for both study seasons.
3. Applications of organic acids(Humic –Algae - Fulvic) and bio fertilizers treatments increased leaf N, P and K percentages; also Fe , Zn and Mn content compared with the control application.
3- Effect on Soil Microbial activity and roots respiration:
1. The applications of organic (Humic –Algae – Fulvic) and bio fertilizers treatments to 9ether increased soil microbial activity and roots respiration
2. Organic fertilizers (Humic – Fulvic- Algae) and Bio fertilizer (Serrate) treatments together increased soil nutrients (macro and micro)
3. Addition of brown algae powder to the soil redeced the soil pH(to 6.4reaching the normal pH).which improves the physico –cheruical reactions in the risozephyr zone
4. Applied as of both Humic and Fulvic acid were effective in increasing the humus capacity of the avidly ail,which makes it more abie to pervert
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irrigates water leashing ; and these by in crease the water canter in the vicinity layer.
5. All the organic or bio fertilizers used eland with the algae were of low price comparing to chemical fertilizers cost ; and that reffect on raise the economic value and reducing the pollution and thereby protecting the environment .
6. Reduction in chemical fertilizer not only save the environment (soil – air )from chemicals polluting but also save both the plants and the human as the end –user for the produces .
Conclusion 1-The results proved that no significant difference in the rate of growth of seedlings and mineral content of leaves when you use the full dose of NPK or half the dose in the presence of humic acid and bacteria Seerataa and algae extract 2. The study proved that when you reduce the use of chemical fertilizer led to the preservation of the agricultural environment (soil - ambient air plants) of damage, chemical fertilizers, and water protection groundwater pollution and the protection of naturalresources from depletion 3. The study also proved that reducing the use of chemical fertilizers, reduce the cost of material and thereby increasing the economic value of the crop cultivated and supports the national income. 4. That by using nature again can get a food product is clean and healthy human security ... and a little pollution to the environment, whether above or below the soil.