Nitrogen Immobilisation and Microbial Biomass Build-Up Induced by Miscanthus x giganteus L. Based Fertilisers

Abstract

Cultivation of Miscanthus x giganteus L. (Mis) with annual harvest of biomass could provide an additional C source for farmers. To test the potential of Mis-C for immobilizing inorganic N from slurry or manure and as a C source for soil organic matter build-up in comparison to wheat (Triticum aestivum L.) straw (WS), a greenhouse experiment was performed. Pot experiments with ryegrass (Lolium perenne L.) were set up to investigate the N dynamics of two organic fertilisers based on Mis at Campus Klein-Altendorf, Germany. The two fertilisers, a mixture of cattle slurry and Mis as well as cattle manure from Mis-bedding material resulted in a slightly higher N immobilisation. Especially at the 1st and 2nd harvest, they were partly significantly different compared with the WS treatments. The fertilisers based on Mis resulted in a slightly higher microbial biomass C and microbial biomass N and thus can be identified as an additional C source to prevent nitrogen losses and for the build-up of soil organic matter (SOM) in the long-term.

Utilisation of Miscanthus x giganteus L. Based C-Rich Fertilisers for N Immobilisation and Microbial Biomass Build-Up in a Crop Rotation

“…There, a tendency of a greater N immobilisation after application of fertilisers with Mis biomass (CS-Mis, CM-Mis) compared to WS amended fertilisers were explained by the microbial processes due to the biochemical differences in the carbon/nitrogen (C/N) ratio of the added substrates [33,[59][60][61]. In our field experiment, the differences of N immobilisation between Mis amended and WS amended fertilisers were less obvious compared to those of Stotter et al [34]. The Mis based fertilisers were characterised by a greater C/N ratio of between 25 to 35 for CS-Mis and CM-Mis, compared to a C/N ratio of 11 to 19 for CS-WS and CM-WS (Table 2).…”

“…This field trial showed a tendency of greater N immobilisation and lower inorganic N contents after application of Mis based fertilisers, whereas differences were not significant. In pot experiments, the effectiveness of Mis and WS biomass amended fertilisers for N immobilisation was already detected [34]. There, a tendency of a greater N immobilisation after application of fertilisers with Mis biomass (CS-Mis, CM-Mis) compared to WS amended fertilisers were explained by the microbial processes due to the biochemical differences in the carbon/nitrogen (C/N) ratio of the added substrates [33,[59][60][61].…”

“…It is well known that incorporation of C-rich components such as cereal straw stimulates anabolic processes in soil microorganisms and consequently reduces N losses, as well as contributing to SOC maintenance [28][29][30][31][32][33]. In greenhouse experiments we already showed that Mis biomass provides a suitable C source to induce N immobilisation in soil; part of this N immobilisation is caused by microbial growth which also contributes to C sequestration [34]. The cultivation of C-rich crops such as annual cereals can be supplemented with perennials such as Mis, whereas Mis provides important ecosystem services and can create new sales and utilisation opportunities [35].…”

Effect of Clover Sward Management on Nitrogen Fixation and Performance of Following Spring- and Winter Wheat Crops; Results of a 3-Year Pilot Study

“…The finding that greenwaste compost applications slightly increased leaf chlorophyll levels and grain protein content in winter-wheat and did not affect leaf chlorophyll and protein levels in spring-wheat suggests that the high C:N ratio compost did not result in immobilisation/locking-up of N as has been previously reported for organic fertilisers, composts and plant residue inputs with a C:N-ratio of >20 [31][32][33][34].…”