Abstract
The aim of this study was to evaluate the potential of short rotation alley cropping systems (SRACS) to improve the soil fertility of marginal post-mining sites in Brandenburg, Germany. Therefore, we annually investigated the crop alleys (AC) and black locust hedgerows (ABL) of a SRACS field trail under initial soil conditions to identify the short-term effects of tree planting on the storage of soil organic carbon (SOC) and its degree of stabilization by density fractionation. We detected a significant increase in SOC and hot-water-extractable organic C (HWEOC) at ABL, which was mainly restricted to the uppermost soil layer (0–10 cm). After 6 years, the SOC and HWEOC accumulation rates at ABL were 0.6 Mg and 46 kg ha−1 year−1, which were higher than those in the AC. In addition, comparatively high stocks of approximately 4.6 Mg OC and 182 kg HWEOC ha−1 were stored in the ABL litter layer. Density fractionation of the 0–3 cm soil layer at ABL revealed that the majority of the total SOC (47%) was stored in the free particulate organic matter fraction, which was more than twice that of the AC. At the same time, a higher and steadily increasing amount of SOC was stored in the occluded particulate organic matter fraction at ABL, which indicated a high efficiency for SOC stabilization. Overall, our findings support the suitability of black locust trees for increasing the soil fertility of the reclaimed mining substrate and, consequently, the high potential for SRACS to serve as an effective recultivation measure at marginal sites.
Highlights
80% of terrestrial soil organic carbon (SOC) stocks are bound in soils (Blume et al 2016), and recent estimates indicate that roughly 2060 ± 215 Pg C can be found in the uppermost two metres (Batjes 2016).soil contains significantly more carbon than the atmosphere (~ 800 Pg C) and terrestrial vegetation (~ 500 Pg C) (FAO and ITPS 2015) taken together
In 2008 the initial soil pH-values indicate a wide range among the different sampling locations and soil depths, from extremely acid to slightly alkaline (Table 3)
SOC accumulation in the uppermost soil layer of the corresponding hedgerows turned out to be superior. This was largely accompanied by a higher increase in SOC in the labile free particulate organic matter (fPOM) and intermediate oPOM fraction, indicating a steady supply of organic matter (OM) derived from the trees and the formation of first organic-mineral associations, respectively
Summary
80% of terrestrial soil organic carbon (SOC) stocks are bound in soils (Blume et al 2016), and recent estimates indicate that roughly 2060 ± 215 Pg C can be found in the uppermost two metres (Batjes 2016).soil contains significantly more carbon than the atmosphere (~ 800 Pg C) and terrestrial vegetation (~ 500 Pg C) (FAO and ITPS 2015) taken together. The C sequestration potential of soils is adversely affected by the degradation caused by land use change and agricultural management, which are globally seen as the major drivers of SOC losses (FAO and ITPS 2015). Agroforestry is of particular interest in this connection, as it represents an agroecosystem in which trees are intercropped with crops or pasture to create ecological and economic benefits (Nair 1993). It combines the potential for increasing above- and below-ground carbon storage by increasing organic matter (OM) inputs (e.g., leaf litter, fine roots) with the maintenance of agricultural production (Cardinael et al 2015). Both consist of linear hedgerow structures, but the hedges in the ACS are planted closer to each other (10 to 100 m), and are more integrated into the agricultural system (Kurz et al 2011)
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