Effect of microbial inoculants and nitrogen fertilization on soil mites and collembola in cowpea crop, at Kafr el - Sheikh, Egypt.

Abou-Tayesh, M.A.M

Abstract

Two field trials were conducted at Sakha Agric. Res. Station during the two successive summer growing seasons of 2010 and 2011. Cowpea plants (vigna unquiculata (L.) walp.) variety Dokki 331, were inoculated with micro symbiont . Bradyrhizobium sp along with urea fertilizer at 40 and 80 kg N/fed . applied in two equal doses : at 30and 45 days after sowing . The investigation lasted for three months in the two seasons of study aiming to survey the occurring soil predacious mites, miscellaneous mites and Collembola in four Nodulation and N – fertilization treatments : Nodulated + 50%N,Nodulated+100%N, Non – Nodulated+50%N, and Non - Nodulated +100%N under field conditions and the diversity between species under Nodulation and N- fertilization. Results revealed occurring of 8 species of predacious mite, belonging to 7 families in all Nodulators and N- fertilizers during the two seasons . while miscellaneous mite had 14 species belonging to 13 families in all Nodulators and N- fertilizers during the two seasons , except for Non - Nodulation +100%N during seasons 2010, which had 13species belonging to 12 families. Also, 5 species of Collembola belonging to 5 families in both two seasons. Results indicated that the population density of the soil mite and Collembola increased with application of both microbial inoculants and N-fertilization , recording the highest figure at 80kg N/fed . Amblyseius sp and Cheyletus malaccensis (Oudmans) were the most dominant species under different applications of microbial inoculants and N- fertilization .While , Cheyletus eruditus (Oudmans )was the least species to be recorded .Pygmephorus sp. was the dominant species under cowpea field in the two seasons under different types of Nodulators and N- fertilizers. While , Galumna sp was the least one Proistoma sp. was the dominant species in the two seasons under different types of Nodulators and N- fertilizers , while , Onychiurus sp. Hypogastura sp . Tulbergi sp. and Entombyra sp. were least recorded species . Diversity index values of predacious mite species were (0.8456, 0.8638, 0.9330, 0.8525) and( 0.8753, 0.8874,0.8659, 0.8866). While miscellaneous mite, were (2.1411, 1.0919, 2.7336, 1.0888) and (1.1047,1.1169, 1.1047 , 1.1096 ) on the other hand Collembola were(0.6974, 0.6966 , 0.6978, 0.6985) and (0.6977, 0.6976, 0.6981, 0.6984) for Nodulated + 50%N, Nodulated+100%N, Non – Nodulated+50%N, and Non - Nodulated +100%N during seasons (2010 and 2011) , respectively.

Key words

microbial incoulants , nitrogen fertilization , mites , collembola , cowpea