TY - JOUR

T1 - Rate of soil-aggregate formation under different organic matter amendments-a short-term incubation experiment

AU - Andruschkewitsch, Rouven

AU - Geisseler, Daniel

AU - Dultz, Stefan

AU - Joergensen, Rainer Georg

AU - Ludwig, Bernard

N1 - Copyright: Copyright 2014 Elsevier B.V., All rights reserved.

PY - 2014/4

Y1 - 2014/4

N2 - To improve soil structure and take advantage of several accompanying ecological benefits, it is necessary to understand the underlying processes of aggregate dynamics in soils. Our objective was to quantify macroaggregate (> 250 μm) rebuilding in soils from loess (Haplic Luvisol) with different initial soil organic C (SOC) contents and different amendments of organic matter (OM) in a short term incubation experiment. Two soils differing in C content and sampled at 0-5 and 5-25cm soil depths were incubated after macroaggregate destruction. The following treatments were applied: (1) control (without any addition), (2) OM1 (addition of OM: preincubated wheat straw [< 10mm, C : N 40.6] at a rate of 4.1 g C [kg soil]-1), and (3) OM2 (same as (2) at a rate of 8.2 g C [kg soil]-1). Evolution of CO2 released from the treatments was measured continuously, and contents of different water-stable aggregate-size classes (> 250 μm, 250-53 μm, < 53 μm), microbial biomass, and ergosterol were determined after 7 and 28 d of incubation. Highest microbial activity was observed in the first 3 d after the OM application. With one exception, > 50% of the rebuilt macroaggregates were formed within the first 7 d after rewetting and addition of OM. However, the amount of organic C within the new macroaggregates was ≈ 2- to 3-fold higher than in the original soil. The process of aggregate formation was still proceeding after 7 d of incubation, however at a lower rate. Contents of organic C within macroaggregates were decreased markedly after 28 d of incubation in the OM1 and OM2 treatments, suggesting that the microbial biomass (bacteria and fungi) used organic C within the newly built macroaggregates. Overall, the results confirmed for all treatments that macroaggregate formation is a rapid process and highly connected with the amount of OM added and microbial activity. However, the time of maximum aggregation after C addition depends on the soil and substrate investigated. Moreover, the results suggest that the primary macroaggregates, formed within the first 7 d, are still unstable and oversaturated with OM and therefore act as C source for microbial decomposition processes.

AB - To improve soil structure and take advantage of several accompanying ecological benefits, it is necessary to understand the underlying processes of aggregate dynamics in soils. Our objective was to quantify macroaggregate (> 250 μm) rebuilding in soils from loess (Haplic Luvisol) with different initial soil organic C (SOC) contents and different amendments of organic matter (OM) in a short term incubation experiment. Two soils differing in C content and sampled at 0-5 and 5-25cm soil depths were incubated after macroaggregate destruction. The following treatments were applied: (1) control (without any addition), (2) OM1 (addition of OM: preincubated wheat straw [< 10mm, C : N 40.6] at a rate of 4.1 g C [kg soil]-1), and (3) OM2 (same as (2) at a rate of 8.2 g C [kg soil]-1). Evolution of CO2 released from the treatments was measured continuously, and contents of different water-stable aggregate-size classes (> 250 μm, 250-53 μm, < 53 μm), microbial biomass, and ergosterol were determined after 7 and 28 d of incubation. Highest microbial activity was observed in the first 3 d after the OM application. With one exception, > 50% of the rebuilt macroaggregates were formed within the first 7 d after rewetting and addition of OM. However, the amount of organic C within the new macroaggregates was ≈ 2- to 3-fold higher than in the original soil. The process of aggregate formation was still proceeding after 7 d of incubation, however at a lower rate. Contents of organic C within macroaggregates were decreased markedly after 28 d of incubation in the OM1 and OM2 treatments, suggesting that the microbial biomass (bacteria and fungi) used organic C within the newly built macroaggregates. Overall, the results confirmed for all treatments that macroaggregate formation is a rapid process and highly connected with the amount of OM added and microbial activity. However, the time of maximum aggregation after C addition depends on the soil and substrate investigated. Moreover, the results suggest that the primary macroaggregates, formed within the first 7 d, are still unstable and oversaturated with OM and therefore act as C source for microbial decomposition processes.

KW - Ergosterol

KW - Microbial biomass

KW - Soil respiration

KW - Water-stable aggregates

UR - http://www.scopus.com/inward/record.url?scp=84898058960&partnerID=8YFLogxK

U2 - 10.1002/jpln.201200628

DO - 10.1002/jpln.201200628

M3 - Article

AN - SCOPUS:84898058960

VL - 177

SP - 297

EP - 306

JO - Journal of Plant Nutrition and Soil Science

JF - Journal of Plant Nutrition and Soil Science

SN - 1436-8730

IS - 2

ER -