Influence of land use and tillage depth on dynamics of soil microbial properties, soil carbon fractions and crop yield after conversion of short‐rotation coppices

Abstract

The effect of conversion of short-rotation coppices (SRCs) to agricultural land on soil organic carbon (SOC), soil microbial properties and crop yield is largely unknown. The objective of this study was to assess the effects of subsequent land use and tillage depth after conversion of SRCs on (i) total SOC (ii) soil C fractions with differentiation of total harvest residues and woody harvest residues from SRC and maize by 13 C analysis and (iii) dry matter and N yield of grassland and maize. For this purpose, field trials were established after conversion of SRCs at three sites in Germany and cultivated with maize and grassland with shallow (5 cm), medium (15 cm) and deep tillage depth (30 cm). Crops were sampled for 5 yrs, and soil samples were collected at a depth of 0-5, 5-15 and 15-30 cm. Amount of total carbon and soil carbon fractions immediately and 4 yrs after conversion of SRC were compared. Tillage depth had no effect on dry matter yield of maize and grassland. The amount of woody harvest residues decreased over time following conversion at all sites irrespective of land use or tillage depth, but SOC decreased only at one site. Microbial biomass was particularly sensitive to land use, but microorganisms reacted differently to tillage depth depending on the soil conditions. Our results reveal that decomposition of woody harvest residues is rapid and that effects of tillage and land use on different soil C-pools are site specific.

Short-Term Mineralization of Belowground Biomass of Perennial Biomass Crops after Reversion to Arable Land

“…This is in agreement with previous findings that the C/N ratio of residues does not regulate the residue decomposition in the soil, but mineralization depends more on the biochemical quality of the residues [46]. Toenshoff et al [25] reported a value of C mineralization of PBO and FR of poplar residues of about 20% and 25% of added C after 30 and 42 days of incubation, while Wachendorf et al [47] showed that decomposition of woody harvest is rapid.…”

“…Miscanthus FR had the lowest C mineralization and lowest values of k DEOM (Figure 4). Amounts of FR C mineralization were comparable with values of about 10% of added C measured by Wachendorf et al [47] and values in the range of 7-13% found by other authors [52,53]. More likely, C mineralization of FR was lower than PBO, due to the different biochemical quality, resulting in different accessibility of degradable C compounds to microbes [39,54,55].…”

Belowground biomass C outweighs soil organic C of perennial energy crops: Insights from a long‐term multispecies trial

“…There are concerns that at the end of the PEC cultivation cycle, the conversion of these crops back to arable land could negatively affect the SOC stock. However, a positive effect of conversion on SOC is possible, due to the high amount of crop residues entering to the soil as new particulate organic matter (POM) with the disruption of BGB during the re‐conversion process (Toenshoff, Georg, et al, 2013; Toenshoff, Stuelpnagel, et al, 2013; Wachendorf et al, 2017).…”

Development of a Distributed Hydrologic Model for a Region with Fragipan Soils to Study Impacts of Climate on Soil Moisture: A Case Study on the Obion River Watershed in West Tennessee

“…The depth to the fragipan layer in ranges between 0.1 m and 2.0 m below the surface. In most locations, the fragipan layer is below historical tillage depths, typically 30 cm, and is therefore intact [34][35][36]. Furthermore, no-till practices are currently practiced throughout the watershed to prevent additional disturbances to the fragipan layer.…”