Nashwa A.H. Fetyan, Massoud, O.N., Ebtsam, M. Morsy and Khalil. H.M. ( 2015). Biological Evaluation of Soil Cultivated with Egyptian Clover (Trifolium alexndrinum L.) though Long Term Trial at Bahtim Region, Egypt. Middle East Journal of Applied Sciences. Volume : 05 | Issue : 02 |, Pages: 515-525
Abstract: Long-term experiments are leading indicators of sustainability and serve as an early warning system to detect problems that threaten the future productivity. Soil quality assessment is considered as a tool for evaluating the sustainability of soil management practices. In a long-term crop rotation experiment set up in (1912) at Bahtim Agricultural Research Station, Agricultural Research Center (ARC), Egypt. A study was conducted to determine the effects of long-term addition of organic and inorganic fertilizer amendments at low rates on soil chemical and biological properties. Soil biological qualities including microbial diversity population, microbial enzymes (dehydrogenase, phosphatase, urease and nitrogenase) activities, macroelements in soil including N, P and K as well as the dry weight of Egyptian clover (Trifolium alexandrinum L.), N, P and K in plant, root nodules number, native mycorrhizal colonization percentage. Isolation, characterization and identification of native Rhizobium sp. were also determined as the cultivated crop didn’t receive fertilizer which it depended on the residual effect of the fertilizer from the previous crop (Zea mays).The obtained results revealed that the higher soil microbial population was assessed with the application of 90 kg N/fed, 19.5 kg P2O5/fed and 48 kg K2O/fed. The total yeast and actinomycetes counts were not affected by the residual manure or NPK fertilization. Phosphate solubilizing bacteria (PSB) were significantly affected by mineral NP input. Silicate bacteria are considered the unique ones as it obtained the highest populations at all as recorded with T7 (45 UN/fed. + 19.5 kg P2O5/fed + 48 kg K2O/fed) and T10 (90 UN/fed. + 19.5 kg P2O5/fed + 48 kg K2O/fed) during the two cuts, respectively. The highest number of Azospirillum spp. recorded with FYM treatment. Azotobacter population increased with the lowest dose of N (22.5 kg/fed) on the contrary dehydrogenase, phosphatase and urease activities were higher in N 90 PK. Nitrogenase activity increased with the decreased of mineral nitrogen input as T3 (22.5 UN/fed. + 19.5 kg P2O5/fed) recorded the highest activity in both nodules and soil, respectively. The percentage of native mycorrhizal increased with T10 (90 UN/fed. + 19.5 kg P2O5/fed + 48 kg K2O/fed). Control treatment recorded higher pathogenic fungi followed by FYM treatment. T10 (90 UN/fed. + 19.5 kg P2O5/fed + 48 kg K2O/fed) exhibited the optimum macronutrients in both soil and plant. However, T8 (90 UN/fed.) recorded the highest shoot dry weight. The native Rhizobium isolated from the nodules was identified as Rhizobium trifolii.
Keywords: (long term trial, microbial activities, dehydrogenases, Phosphatase, urease, Nitrogenase.)
