EFFECT OF AZOTOBACTER AND DIFFERENT SOURCES OF ORGANIC MATTER ON GROWTH AND NUTRITION OF VALENCIA SEEDLINGS IN NEW SOIL

The effects of usual or recommended rates of application of five organic amendments (FYM, compost, town refuse, Biogas and non-composted Mango tree leaves residues (NTLR)) on the response and improvement of Valencia seedlings growth and nutrition in salt affected sandy soil were studied.  In a field experiment conducted and carried out during two consecutive seasons 2004 & 2005 on one year old Valencia orange seedlings (Citrus sinensis, Osbeck) in citrus grove of Horticulture Research Station of El-Kassasin, Ismailia Governorate. Azotobacter chroococcum inoculation in combined with different rates of N-fertilizer (ammonium sulphate) was applied. The results showed that there is an increase in total bacterial (TC) and Azotobacter count in treated soil over the control (zero N without inoculation) especially in the first month with town refuse zero N and inoculation. TC showed even more activity than Azotobacter reaching 36.5 cfu million at the same period. Obtained results gave clear information concerning the suitability of adding non-composted residues to soils, to supplement their organic matter at least under new reclaimed soil. The carbon content of the control as well as of treated soil decreased during the first four months, gradually in the control but rapidly in the treated soil. TN showed the same trend in the treated soil and control, decreasing prior to the end of each season. But the decrease was much less and the increase was markedly greater than in the control. The improvement effect of organic manure with Azotobacter inoculation was very important due to the decomposition of organic matter and the release of nutrients in the available form. Addition of organic manure with inoculation to sandy soil greatly enhanced the potential productivity of the soil and improved the determined physical properties. Azotobacter inoculation increased dry weight of fibrous, skeletal and semi-skeletal roots of Valencia orange seedlings than in non-inoculated treatments. Biogas manure had highly effect with inoculation followed by compost and FYM, respectively. Azotobacter inoculation with mineral fertilizer had increased the dry matter percentages of fibrous roots in the 1^st foot of soil surface in comparison with other treatments. It is clear that there is a significant increase within singly added manure treatments, also, within Azotobacter inoculation with mineral or organic treatments.