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| Titel |
Aggregation and nitrogen mineralisation in two soils with different texture treated with live-stock derived organic materials. |
| VerfasserIn |
Giovanni Gigliotti, Luisa Massaccesi, Daniela Pezzolla, Alberto Agnelli |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250055974
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| Zusammenfassung |
| The use of the live-stock organic materials (LOM) in agriculture, is one of the measure to gain the soil C input. However, the possibility to increase the soil C stocks depends on the quality of the organic matter added to the soil in terms of stability and maturity. To this aim, fresh organic materials undergo treatments, such as anaerobic digestion, to reduce their degradability through the formation of molecules with low bioavailability, and so, less affected by mineralisation processes. The distribution of LOM in cultivated soils, other than the soil C cycle, favours a general improvement of the soil characteristics, such as structure, biological activity and content of micro and macro elements. To evaluate the effect of the addition of LOM i) on soil structure, ii) on distribution of C and N in the aggregates of different size and iii) on the N mineralisation processes, two soils with different texture were incubated for 45 days (25°C and 60% WHC) with a pig slurry (PS) and with a digestate produced by the anaerobic treatment of the same PS (DPS). The organic materials were added in an amount equivalent to 340 kg N ha-1, the maximum allowed by the European “Nitrate Directive”. At the end of the incubation period, samples were dry sieved to obtain four aggregates classes (2-0.5 mm, 0.5-0.25 mm, 0.25-0.05 mm, <0.05 mm) on which C and N contents were determined. Further, during the experiment, sample aliquots were collected at 3 hours, 5, 12, 20, 30 and 45 days and analysed for their content of total N, N-NH4+, N-NO3-, and microbial N. After the incubation, although the aggregates distribution showed a scarce variation, the C content slightly increased in the smaller aggregates (<0.25 mm), by confirming the high physical protection exerted by the microaggregates with respect to organic C. The highest incorporation of C occurred in the samples treated with DPS, the more stabile organic material used in the experiment. About the N content in the aggregates after the adding of the LOM, the two soils had different behaviour that was attribute to predominant nitrification processes in the soil with a low clay content, and to denitrification/volatilisation processes in the clay rich soil. These latter processes were higher in the case of treatment with DPS. The different N mineralisation pathways occurring in the two soils were confirmed by the amount of N-NH4+ and N-NO3- determined throughout the incubation period. The microbial N in the both soils treated with DPS was present in higher amount than in the soils treated with PS, in particular in the clay rich soil. This could be due to the presence of a microflora partly inherited from DPS (produced following an anaerobic process) and better adapted to a scarcely oxidative environment. The lower amount of oxygen in the clay rich soil should be indicated by the larger presence of N-NH4+. The results obtained indicated the ability of soil to control the processes driving transformation of exogenous organic matter differently stabilised. |
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