TY - GEN A1 - Boldt-Burisch, Katja A1 - Schillem, Steffi A1 - Schneider, Bernd Uwe A1 - Hüttl, Reinhard F. T1 - The effect of nitrogen-modified lignite granules on mycorrhization and root and shoot growth of Secale cereale (winter rye) in a nutrient-deficient, sandy soil T2 - Archives of Agronomy and Soil Science N2 - Organic soil amendments such as modified lignite and biostimulants like arbuscular mycorrhizal fungi (AMF) may have the potential to improve soil biological conditions of agricultural soils. The aim of the study was to test if nitrogen-modified lignite granules (NH) are beneficial for mycorrhization, root and shoot development compared to common mineral nitrogen (Nmin) in a nitrogen and phosphorus limited soil. A greenhouse experiment with Secale cereale L. was carried out using non-sterilized and sterilized sand substrate treated with NH, AMF or Nmin and AMF+NH and AMF+Nmin and was compared to an untreated substrate (control). 7.5 t ha-1 NH and 120 kg Nmin ha−1 led to a similar increase of AMF colonization compared to the control; however, Nmin had a more positive influence on biomass development. Significantly highest mycorrhizal colonization intensity was found for AMF+NH. The co-application of AMF+NH revealed that shoot and root development and shoot nutrient concentrations were significantly higher or were among the significantly highest values, when compared to the other treatments. AMF+NH may be a suitable soil amendment for nutrient-limited soils and may be more sustainable than Nmin due to a combined increase of nitrogen, AMF and carbon/humic acids in the soil that comes with the NH. Y1 - 2020 U6 - https://doi.org/10.1080/03650340.2020.1869724 SN - 1476-3567 ER - TY - GEN A1 - Dimitrova, Tsvetelina A1 - Repmann, Frank A1 - Freese, Dirk T1 - Degradation of ferrocyanide by natural isolated bacteria T2 - International Journal of Phytoremediation N2 - This study aims at investigating the iron cyanide (CN) degradation potential of two natural bacterial isolates with the purpose of their application in iron CN phytoremediation. The strains were isolated from contaminated soil and incubated over 4 months with 50 mg L-1 CN (as ferrocyanide) as the sole iron and nitrogen source. Unlike previous reports, the study provides control for bacterial growth, biotic and abiotic CN losses. Bacterial growth, CN, ammonium, and nitrate concentrations were monitored regularly. Both strains grew less rapid with iron CN compared with the positive control. However, the growth was diauxic. The CN concentration in the media decreased with 20% and 25% respectively, while that in the sterile controls remained stable. Ammonium was detected in the media of both strains implying that a fraction of the initially applied ferrocyanide has been converted. The nitrogen lost from the system evened out with that in the cells at the end of the experiments. These results showed that the investigated strains were undoubtedly able to grow on iron CN as an alternative nitrogen source, but contrary to some previous findings, the iron CN utilization is much slower and takes place only after complete exhaustion of the cellular nitrogen reserves. KW - iron cyanide KW - detoxification KW - microorganisms Y1 - 2020 U6 - https://doi.org/doi:10.1080/15226514.2019.1633996 SN - 1522-6514 VL - Vol. 22 IS - 1 SP - 20 EP - 28 ER - TY - GEN A1 - Gypser, Stella A1 - Freese, Dirk T1 - Phosphorus release from vivianite and hydroxyapatite by organic and inorganic compounds T2 - Pedosphere N2 - Based on recent mining rates and the exhaustion of global phosphorus (P) reserves, there is a need to mobilize P already stored in soils, and its recovery from secondary resources such as Ca- and Fe-phosphates is important. The Ca-phosphate hydroxyapatite forms a good fertilizer source, while vivianite is formed in waterlogged soils and sediments. During sludge treatment, the formation of vivianite has been identified, being mainly Fe-phosphate. Long-term P release from both hydroxyapatite and vivianite was studied using different inorganic (CaCl2 and CaSO4) and organic (citric and humic acid) reagents during batch experiments. Reagents CaCl2 and CaSO4 represent the soil solution, while citric and humic acids as organic constituents affect P availability in the rhizosphere and during the process of humification. Additionally, the flow-through reactor (FTR) technique with an infinite sink was used to study the long-term P release kinetics. The cumulative P release was higher by organic acids than by inorganic compounds. The cumulative P release rates were higher in the FTR with CaCl2 as compared to the batch technique. The infinite sink application caused a continuously high concentration gradient between the solid and liquid phases, leading to higher desorption rates as compared to the batch technique. The predominant amount of the total P released over time was available for a short term. While inorganic anion exchange occurred at easily available binding sites, organic acids affected the more heavily available binding sites, which could be embedded within the mineral structure. The results showed that organic compounds, especially citric acid, play a superior role as compared to the inorganic constituents of the soil solution during the recovery of already stored P from the tertiary phosphates vivianite and hydroxyapatite. Y1 - 2020 U6 - https://doi.org/10.1016/S1002-0160(20)60004-2 SN - 1002-0160 VL - 30 IS - 2 SP - 190 EP - 200 ER - TY - GEN A1 - Schütze, Elisabeth A1 - Gypser, Stella A1 - Freese, Dirk T1 - Kinetics of phosphorus release from vivianite, hydroxyapatite, and bone char influenced by organic and inorganic compounds T2 - Soil Systems N2 - The availability of P is often insuffcient and limited by accumulation in soils. This led to the necessity of solutions for the recovery as well as recycling of secondary P resources. Batch experiments were conducted with CaCl2 and citric acid to characterize P release kinetics from vivianite, hydroxyapatite, and bone char. While the P release during the CaCl2 treatment was so low that only vivianite and hydroxyapatite showed a slightly higher release with increasing CaCl2 concentration, the increase of dissolved P was more pronounced for citric acid. The application of citric acid resulted in a 32,190-fold higher P release for bone char. Fourier-transform infrared spectroscopic data suggested higher instability of hydroxyapatite than for bone char. The kinetic data showed that bone char, especially at a lower particle size, had a higher long-term P release than hydroxyapatite or vivianite. The suitability of hydroxyapatite and bone char as a poorly soluble, but sustainable P source is better than that of vivianite. However, the efficiency as a P fertilizer is also dependent on present soil P mobilization processes. The results underline the importance of the accessibility of fertilized or naturally bound P for plant roots to benefit from the excretion of organic acids. KW - bone char KW - hydroxyapatite KW - vivianite KW - phosphorus release KW - citric acid Y1 - 2020 U6 - https://doi.org/10.3390/soilsystems4010015 SN - 2571-8789 VL - 4 IS - 1 SP - 1 EP - 20 ER -