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| Home > Publications database > Effect of organic soil amendments on increasing soil N retention and reducing N losses from agricultural soils |
| Book/Dissertation / PhD Thesis | FZJ-2023-04188 |
2023
Forschungszentrum Jülich GmbH
Jülich
ISBN: 978-3-95806-721-9
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Please use a persistent id in citations: urn:nbn:de:0001-20240124105929449-9127001-7 doi:10.34734/FZJ-2023-04188
Abstract: Loss of soil N through nitrous oxide (N2O), ammonia (NH3) emissions, and nitrate (NO3–) leaching is considered to be the main pathways leading to environmental pollution. Applying high carbon amendments (HCA) may mitigate N2O emission and NO3 – leaching. After HCAaddition, soil microbes are stimulated to immobilize excess mineral nitrogen (N) from the soil, which is running at risk of getting lost in gaseous or dissolved form, to maintain the microbial C:N ratio of about 7. Moreover, the effect of carbon (C) availability on soil N content is moderated by phosphorus (P) availability, but so far, this aspect has not been adequately studied. Therefore, this thesis aimed to investigate the potential response patterns of soil N retention to changes in soil C, N, and P availability. Chapter 2 used a meta-analysis to explore the effect of HCA on soil N retention at different locations, and for different climatic and soil conditions, and agricultural management strategies. On average, HCA incorporation stimulated N2O emissions significantly by 29.7% but decreased NO3 – leaching by 14.4%. Chapter 3 investigated the impact of HCA on soil N dynamics at different P levels and soil types ((nutrient-rich silty soil (RUS), nutrient-rich sandy soil (RSS), and nutrient-poor silty soil (PUS)). The results revealed that the effect of HCA on PUS was not significant. Compared with leonardite, wheat straw and sawdust significantly increased CO2 emission and microbial biomass C in RUS, implying that the initial soil nutrient status is the determining factor for HCA degradation, and N dynamics in soil are strongly controlled by C and P availability. Chapter 4 was an incubation experiment with a factorial design of one N level × two P levels × six C amendments. The added C amount in the form of 13C-glucose was 20% of the total C content of HCA. Compared with the control, HCA addition increased the microbial biomass C and N but decreased the NO3 – content in the soil. The δ13C of the microbial biomass (δ13C-MB) and 13C recovery in MBC showed an increasing trend. HCA decreased the δ13C-MB, while P addition had the opposite effect. Hence, the labile glucose C was more readily available to microbes and probably formed stable substances that remain in the microbial community for along time rather than being lost rapidly. Chapter 5 presents data of a two-year lysimeter experiment. Compost was applied to assess the effect of nutrient-rich HCA on soil N retention and crop yield at different P levels. Compost application significantly increased plant aboveground biomass and grain yield, particularly in the double compost treatment, which increased winter wheat and winter barley yield by 62.4% and 34.8%, respectively. Double compost addition increased dissolved organic carbon and soil nutrient content, especially total N and P-CAL, while it caused no significant increase in greenhouse gas (GHG) emissions. This work contributes to understanding how changes in soil C and P availability control soil N retention and crop yield, and can make a science-based recommendation that the combination of compost and mineral N fertilizer can increase crop yield without increasing GHG emissions and leaching of NO3 – and P.
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