Microbial biomass and N mineralization in relation to N supply of sugar beet under reduced tillage

Abstract

Reduced tillage may affect N supply of plants by influencing soil microbial biomass and thereby N release. The aim of this study was to evaluate changes in microbial biomass due to tillage in relation to N mineralization and to assess the contribution to the N supply of sugar beet. For this purpose, in a field trial near Göttingen in 1995 microbial biomass and net N mineralization were determined in an in situ incubation of ploughed and reduced tilled soil in plots which were not given application of mineral N fertilizer. In reduced tilled soil the increase in mineral N concentration in the upper 10 cm of soil was mainly attributed to an increase in microbial biomass. The organic matter was more easily decomposable, indicated by the increase in Cmic/Corg and Nmic/Nt ratios; this was further supported by the enhanced turnover of microbial biomass in reduced tillage plots. A regression function was used to relate seasonal fluctuations of microbial biomass, soil moisture and soil temperature to N mineralization rate. There was a good agreement between measured and calculated N mineralization rate. Reduced tillage affected N mineralization by affecting the quantity and quality of microbial biomass. In 0–30 cm soil depth 169 kg N/ha were mineralized, 30 kg more N than in ploughed soil. However, despite improved N availability, the N uptake of sugar beet was decreased in reduced tilled soil. Because the N concentration in plants did not differ, it was concluded that sugar beet growth in reduced tilled soil was impaired due to other factors than N supply.

Probing the Mechanical Properties of Hybrid Inorganic–Organic Frameworks: A Computational and Experimental Study

“…The quality development at individual sites may differ from the average owing not only to weather conditions, but also to nitrogen availability. Despite the strong dependence of N mineralization on water availability and temperature 41. nitrogen availability may be a potential cause of the lack of correlation between the summer and autumn values of α‐amino nitrogen and total soluble nitrogen, although on average the concentrations were nearly constant after July.…”

Probing the Mechanical Properties of Hybrid Inorganic–Organic Frameworks: A Computational and Experimental Study

“…The quality development at individual sites may differ from the average owing not only to weather conditions, but also to nitrogen availability. Despite the strong dependence of N mineralization on water availability and temperature 41. nitrogen availability may be a potential cause of the lack of correlation between the summer and autumn values of α‐amino nitrogen and total soluble nitrogen, although on average the concentrations were nearly constant after July.…”

Effects of biochar and sewage sludge on spinach (Spinacia oleracea L.) yield and soil NO3- content in texturally different soils in Glen Valley, Botswana

“…Although N immobilization can result in reduced yields (Deenik et al, 2010), in a wet season such as the March -June period in this study, it probably mitigated NO 3 leaching potential, which possibly resulted in higher N efficiency. However, from a long-term field trial in Gottingen, Hoffmann et al (1997) concluded that minimal tillage systems increased Nnet mineralisation compared with conventional tillage systems, mainly due to the greater microbial biomass under reduced tillage. More research is therefore required to determine the factor(s) with overriding effects on sewage sludge N mineralization under Botswana conditions for development of sewage sludge management guidelines on agricultural soils.…”

Model-based assessment of biomass incorporation to mitigate nitrogen losses from arable fields in Central Europe

“…In addition to lowering the overall mineralization intensity by reducing tillage operations after harvest (Goss et al, 1993;Di and Cameron, 2002;Beaudoin et al, 2005) or introducing catch crops, microbial N immobilization can reduce leaching losses (Nicholson et al, 1997;Trinsoutrot et al, 2000). The idea is that microbes degrading carbon-rich organic matter, so-called high carbon amendments (HCA), consume SMN to build enzymes and microbial biomass (Hoffmann et al, 1997;Yansheng et al, 2020). Nitrogen would be conserved in organic compounds and at best re-mineralized, when the crop N uptake increases, leading to fertilizer savings, increased nutrient use efficiency, and lower greenhouse gas emissions.…”

Probing the Mechanical Properties of Hybrid Inorganic–Organic Frameworks: A Computational and Experimental Study

“…The quality development at individual sites may differ from the average owing not only to weather conditions, but also to nitrogen availability. Despite the strong dependence of N mineralization on water availability and temperature 41. nitrogen availability may be a potential cause of the lack of correlation between the summer and autumn values of α‐amino nitrogen and total soluble nitrogen, although on average the concentrations were nearly constant after July.…”

Effects of biochar and sewage sludge on spinach (Spinacia oleracea L.) yield and soil NO3- content in texturally different soils in Glen Valley, Botswana

“…Although N immobilization can result in reduced yields (Deenik et al, 2010), in a wet season such as the March -June period in this study, it probably mitigated NO 3 leaching potential, which possibly resulted in higher N efficiency. However, from a long-term field trial in Gottingen, Hoffmann et al (1997) concluded that minimal tillage systems increased Nnet mineralisation compared with conventional tillage systems, mainly due to the greater microbial biomass under reduced tillage. More research is therefore required to determine the factor(s) with overriding effects on sewage sludge N mineralization under Botswana conditions for development of sewage sludge management guidelines on agricultural soils.…”

Model-based assessment of biomass incorporation to mitigate nitrogen losses from arable fields in Central Europe

“…In addition to lowering the overall mineralization intensity by reducing tillage operations after harvest (Goss et al, 1993;Di and Cameron, 2002;Beaudoin et al, 2005) or introducing catch crops, microbial N immobilization can reduce leaching losses (Nicholson et al, 1997;Trinsoutrot et al, 2000). The idea is that microbes degrading carbon-rich organic matter, so-called high carbon amendments (HCA), consume SMN to build enzymes and microbial biomass (Hoffmann et al, 1997;Yansheng et al, 2020). Nitrogen would be conserved in organic compounds and at best re-mineralized, when the crop N uptake increases, leading to fertilizer savings, increased nutrient use efficiency, and lower greenhouse gas emissions.…”

Probing the Mechanical Properties of Hybrid Inorganic–Organic Frameworks: A Computational and Experimental Study

“…The quality development at individual sites may differ from the average owing not only to weather conditions, but also to nitrogen availability. Despite the strong dependence of N mineralization on water availability and temperature 41. nitrogen availability may be a potential cause of the lack of correlation between the summer and autumn values of α‐amino nitrogen and total soluble nitrogen, although on average the concentrations were nearly constant after July.…”

Effects of biochar and sewage sludge on spinach (Spinacia oleracea L.) yield and soil NO3- content in texturally different soils in Glen Valley, Botswana

“…Although N immobilization can result in reduced yields (Deenik et al, 2010), in a wet season such as the March -June period in this study, it probably mitigated NO 3 leaching potential, which possibly resulted in higher N efficiency. However, from a long-term field trial in Gottingen, Hoffmann et al (1997) concluded that minimal tillage systems increased Nnet mineralisation compared with conventional tillage systems, mainly due to the greater microbial biomass under reduced tillage. More research is therefore required to determine the factor(s) with overriding effects on sewage sludge N mineralization under Botswana conditions for development of sewage sludge management guidelines on agricultural soils.…”

Model-based assessment of biomass incorporation to mitigate nitrogen losses from arable fields in Central Europe

“…In addition to lowering the overall mineralization intensity by reducing tillage operations after harvest (Goss et al, 1993;Di and Cameron, 2002;Beaudoin et al, 2005) or introducing catch crops, microbial N immobilization can reduce leaching losses (Nicholson et al, 1997;Trinsoutrot et al, 2000). The idea is that microbes degrading carbon-rich organic matter, so-called high carbon amendments (HCA), consume SMN to build enzymes and microbial biomass (Hoffmann et al, 1997;Yansheng et al, 2020). Nitrogen would be conserved in organic compounds and at best re-mineralized, when the crop N uptake increases, leading to fertilizer savings, increased nutrient use efficiency, and lower greenhouse gas emissions.…”