| 【Objective】Soil microbial community structure and soil microbial activity has changed after irrigation and organic fertilizer application. Nutrient in fertilizer was dissolved, diffused and transported by water with time went by and affected by water distribution in soil profiles, thus water and nutrient in soil profile changed. This study used district simulation experiment to study the influence of different kinds of organic fertilizer(chicken manure, bio-organic fertilizer), different dripper positions on soil microbial activity in the distribution of soil profile, and provided a theoretical basis for the fertilization and irrigation techniques in field.【Method】The study conducted a district simulation experiment to research the special distribution characteristics of soil enzyme, quantity of soil microbes and microbial community structure.And it was under the combination of different dripper locations and different kinds of organic fertilizer with different modes. Soil microbes quantity determined by plate counting, soil enzyme measured by colorimetry, microbial community structure analyzed by PLFA.【Result】1. Analysis the influence of spot chicken manure and different dripper positions on enzyme activity in soil profile under the drip irrigation. The results showed that soil enzyme activities were higher in B0 treatment than in other treatments. Soil enzyme activities decreased with increased soil depth. In horizontal direction, enzyme activities was highest at horizontal distances of 10 cm from the fertilizer application point(CK from the dripper position)and distributions of soil enzyme activities which decreased radially from the dripper in soil profiles in control treatment and CM0 treatment during the whole process. In CM30 treatment, during 5-15 days distributions of Urease Activities in 0-60 cm layer which driven largely by water, decreased from the dripper position in soil profiles, decreased in the order30cm>20cm>10cm, however during 25-55 days which driven largely by chicken manure,decreased from the fertilizer application point in soil profiles, decreased in the order 10cm>20cm>30cm; Alkaline Phosphatase activities was highest in dripper position(at horizontal30cm) during 5-25 days, and then it was highest in the nearest horizontal location from fertilizer application point(at horizontal 10cm) and 30 cm during40-55 days, with increased soil depth the dripper position(at horizontal 30cm) has the highest activities in 20-40 cm soil layer; Invertase activities have no obvious trend during the process in 0-60 cm layer.2. Using district stimulation irrigation experiment to study the influence of bio-organic fertilizer and different dripper positions on enzyme activity and microbial quantity in soil profile. The results showed uniformed bio-organic fertilizer supplication was more conductive to improve the activity of soil Urease, Invertase and Alkaline Phosphatase Activities and the quantity of Bacteria, Fungi and Actinomycetes in early stage, with the incubation time prolonging, the enzyme activity and microbial quantity in localized bio-organic fertilizer were gradually higher than the same position in uniformed bio-organic fertilizer, in localized bio-organic fertilizer B0 treatment was beteer than B30 treatment, however Alkaline Phosphatase Activities was highest in BU treatment. Soil enzyme activities and microbial quantity decreased with increased soil depth, in horizontal direction, Soil enzyme activities and microbial quantity decreased with farther away from dripper position in CK and BU treatment, and decreased with increased horizon from fertilizer application point in B0 treatment. In CM30 treatment, during 3-15 days distributions of Bacteria quantity,Actinomycetes quantity and Invertase Activities in 0-20 cm layer which driven largely by water, decreased with farther away from the dripper position in soil profiles, however during30-60 days which driven largely by bio-organic fertilizer, decreased with increased horizon from the fertilizer application point in soil profiles; Urease Activities driven largely by bio-organic fertilizer during 7-60 days. The fungi quantity were influenced little by water and decreased with increased horizon from fertilizer point in horizontal direction during the process in 0-60 cm layer.3. Community structure were analyzed by phosphdipid fatty acid(PLFA) method after irrigation and bio-organic fertilizer application in 0-40 cm soil layer. The results showed that except Gram(+) bacteria and fungi PLFAs, other soil main microbial PLFAs decreased with increased depth. PLFA biomarkers revealed shifts in community structure with depth and horizon, driven largely by an increase in gram positive: gram negative biomarkers, a decline in bacterial: fungal ratios. Principal components analysis showed the 30 th days after irrigation and bio-organic fertilizer application, different treatments and different soil layers accounted for 76.1% and 14.3% of total variance, different horizontal locations and different treatments accounted for 81.6% and 8.4% of total variance in 0-20 cm soil layer and 78.1% and 10.3% in20-40 cm soil layer, especially dripper and fertilizer in the same location has the highest correlation with PC1.4. Different treatments and different treatment days accounted for 64.4% and 19.2% of total variance, and dripper and fertilizer in the same location has the highest correlation with PC1. Bacterial and Anaerobes PLFAs have the highest correlation with PC1 in soil main microbial biomass. Urease Activities have the highest correlation with PC1 in soil enzyme activity. With the incubation time prolonging, bacterial: fungal ratios increased and gram positive: gram negative ratios declined, spot bio-organic treatment decreased gram positive:gram negative ratios and increased bacterial: fungal ratios.Therefore, spot organic fertilizer and irrigation in the same location was contribute to improve microbial activity, and its activities decreased with farther away from fertilizer application point, which provided a scientific guidance for the rational use of water and fertilizer management in arid area. |
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