The Effect of Bio, Organic and Mineral Fertilizations on the Activity of the Urease, L-Glutaminase and L-Aspartase Enzymes in the Soil

Abstract

The study aimed to investigate the effect of the application of various sources of fertilizers on the activity of urease, L-glutaminase, and L-aspartase enzymes in the rhizosphere and bulk soils. Pots experiment was carried out in the wire canopy in one of the fields affiliated to the Faculty of Agriculture - the University of Qadisiyah for the summer season 2018 in soil with a silty loam texture. Seeds of mung bean crops were cultivated of a local variety (Khedrawi). The treatments of the study were two levels of nitrogenous mineral fertilizer (urea) (M1 and M2) (20 and 40) kg.N.h-1, respectively, a single level of organic fertilizer (poultry waste) (10 tons h-1), a single level of bio-fertilizer with Pseudomonas fluorescens bacteria, the control, and their interactions. The experiment was carried out according to Completely Randomized Design (C.R.D) with six replications. Means were compared according to the (L.S.D) test at the probability level (α=0.05(. The efficiency of urase, L-clotamene, and L-aspartase in the soil of the root zoon and bulk soil were estimated for all study parameters 30 days after planting. These measurements were done once again for some characteristics of vegetative and root growth after 60 days of planting.
 The bio-fertilizer treatment (B) resulted in the highest increase in the efficiency of the urease enzyme and L-aspartase for 30 days of cultivation compared to the control treatment that recorded the least value of the enzyme activity average (45.22 and 42.54) µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere and bulk soils. These values were increased after 60 days of cultivation (45.34 and 43.16) µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere and bulk soils. This treatment achieves the highest increase in the activity of L-enzymes (25.89 and 24.72) µg N-NH4+.g-1 soil.2h-1, respectively, for the region of the rhizosphere and beyond. It increased after 60 days of cultivation (26.23 and 25.06) µg N-NH4+.g-1 soil.2h-1, respectively, for the region of the rhizosphere and bulk soils. The treatment of poultry wastes (O) resulted in the highest increase in the value of the activity of the L-clotamines enzyme in the rhizosphere and bulk soils for a period of 30 days from planting (43.47 and 57.39) µg N-NH4+.g-1 soil.2h-1, respectively. Its activity values then increased after 60 days of cultivation, reaching (44.33 and 40.43) µg N-NH4+.g-1 soil.2h-1, respectively.
 The overlap treatment between poultry residues and biofertilizers (OB) achieved the highest increase in the activity value for the urase enzyme, L-clotamines and L-aspartase in root zoon soil and distant soil for 30 days of cultivation (54.47, 46.84 and 28.28 µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere and (49.14, 37.81 and 23.94) µg N-NH4+.g-1 soil.2h-1, respectively. The activity of enzymes then increased after 60 days of cultivation (54.56, 47.69 and 28.62) µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere (49.23, 38.67 and 24.18) µg N-NH4+.g-1 soil.2h-1, respectively, for the bulk soil. The combination treatments between poultry residues, bio-fertilizer, and urea at level II (OBM2) achieved the highest increase in the activity values for urease enzyme, L-clotamines and L-aspartase in root zoon soil and bulk soil for 30 days of cultivation (58.46, 48.58 and 30.40) µg N-NH4+.g-1 soil.2h-1, respectively for the rhizosphere, and (54.13, 46.30 and 27.62) µg N-NH4+.g-1 soil.2h-1, respectively, for the bulk soil. The activity of enzymes then increased 60 days after planting (58.55, 49.44 and 30.74) µg N-NH4+.g-1 soil.2h-1, respectively, for the rhizosphere (54.22, 47.15 and 27.96) µg N-NH4+.g-1 soil.2h-1, respectively, outside the rhizosphere.