Soil Organic Carbon, Microbial Biomass, and Mineralizable Carbon and Nitrogen in Sorghum

1995 ◽  
Vol 59 (2) ◽  
pp. 460-466 ◽  
Author(s):  
A. J. Franzluebbers ◽  
F. M. Hons ◽  
D. A. Zuberer
2020 ◽  
Author(s):  
Deborah Linsler ◽  
Jacqueline Gerigk ◽  
Ilka Schmoock ◽  
Rainer Georg Jörgensen ◽  
Martin Potthoff

<p>Reduced tillage is assumed to be a suitable practice to maintain and promote microbial biomass and microbial activity in the soil. The microbial biomass in particular is considered as a sensitive indicator for detecting soil disturbances. The objective of this study was to quantify the influence of different tillage practices on microbial parameters in the soil. Furthermore, we analyzed the relation of those microbial parameters with site-specific conditions.</p><p>To get a deeper insight in that topic, soils from different fields of agricultural farms with different tillage practices in France (12 fields), Romania (15 fields) and Sweden (17 fields) were examined within the “SoilMan project”. The tillage practices were no-tillage (absence of any tillage), minimum tillage (non-inversion tillage for instance by chisel plough or cultivator) and conventional tillage (inversion tillage by ploughing), all of which were carried out for at least five years prior to sampling. Soil samples were taken in spring 2018 from all fields under winter wheat (Triticum aestivum) at three soil depths (0-10 cm, 10-20 cm, 20-30 cm). As microbial parameters we measured microbial biomass carbon and nitrogen contents, ergosterol contents (as proxy for fungi) and basal respiration rates. For site-specific conditions we measured soil organic carbon, total nitrogen and total phosphorus contents, texture, pH and the soil water content.</p><p>Results show that microbial biomass carbon and nitrogen were more affected by soil type and soil texture as well as climatic conditions (mean precipitation and temperature) than by tillage practices. For instance, an increased clay content had a positive effect on the microbial biomass and, in addition to the higher average annual temperature, explained the generally low values ​​in France. The lack of inversion tillage primarily led to stratified levels of soil organic carbon, microbial biomass carbon and ergosterol contents, which can be explained by the lack of crop residue incorporation. There were hardly any differences in microbial indicators between the tillage intensities when looking at the whole of the sampled soil profile (0-30 cm). In France, the microbial biomass carbon / soil organic carbon ratio was lower for no-tillage than for conventional tillage, which may indicate, among other things, that the mechanically ground organic matter incorporated into the soil under conventional tillage was better colonized by microorganisms. However, this effect could not be confirmed in the other countries. The metabolic quotient was generally increased at the lowest sampled depth (20-30 cm), irrespective of the cultivation.</p><p>We can conclude that the soil tillage intensity influenced the distribution of microbial biomass carbon and soil organic carbon contents more strongly than the total amounts in the sampled soil profile and that the soil texture had a greater impact on microbial soil properties than the agricultural management practice.</p>


2016 ◽  
Author(s):  
Ruzhen Wang ◽  
Linyou Lü ◽  
Courtney A. Creamer ◽  
Heyong Liu ◽  
Xue Feng ◽  
...  

Abstract. Soil coarseness decreases ecosystem productivity, ecosystem carbon and nitrogen stocks, and soil nutrient contents in sandy grasslands. To gain insight into changes in soil carbon and nitrogen pools, microbial biomass, and enzyme activities in response to soil coarseness, a field experiment of sand addition was conducted to coarsen soil with different intensities: 0 % sand addition, 10 %, 30 %, 50 %, and 70 %. Soil organic carbon and total nitrogen decreased with the intensification of soil coarseness across three depths (0–10 cm, 10–20 cm, and 20–40 cm) by up to 43.9 % and 53.7 %, respectively. At 0–10 cm, soil microbial biomass carbon (MBC) and nitrogen (MBN) declined with soil coarseness by up to 44.1 % and 51.9 %, respectively, while microbial biomass phosphorus (MBP) increased by as much as 73.9 %. Soil coarseness significantly decreased the activities of β-glucosidase, N-acetyl-glucosaminidase, and acid phosphomonoesterase by 20.2 %–57.5 %, 24.5 %–53.0 %, and 22.2 %–88.7 %, respectively. Soil coarseness enhanced microbial C and N limitation relative to P, indicated by the ratios of β-glucosidase and N-acetyl-glucosaminidase to acid phosphomonoesterase (and MBC:MBP and MBN:MBP ratios). As compared to laboratory measurement, values of soil parameters from theoretical sand dilution was significantly lower for soil organic carbon, total nitrogen, dissolved organic carbon, total dissolved nitrogen, available phosphorus, MBC, MBN, and MBP. Phosphorus immobilization in microbial biomass might aggravate plant P limitation in nutrient-poor grassland ecosystems as affected by soil coarseness. We conclude that microbial C:N:P and enzyme activities might be good indicators for nutrient limitation of microorganisms and plants.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jishan Chen ◽  
Ruifen Zhu ◽  
Qiang Zhang ◽  
Xiaolei Kong ◽  
Dequan Sun

AbstractThe reduced-tillage (Rt) has been proposed as a strategy to improve soil organic carbon and soil total nitrogen pools. However, little is known of the role of the reduced-tillage compared with the organic (Org) and conventional (Con) management in the Songnen Plain of China. We studied the 4 yr effect of three management strategies (Con, Org and Rt management) on labile soil organic carbon (C) and nitrogen (N) pools, including variation in mineralizable carbon and nitrogen, microbial biomass carbon and nitrogen, dissolved organic carbon and nitrogen in the rotation of alfalfa-corn established in 2009. Soil characteristics including soil organic carbon (SOC), soil total nitrogen (STN), dissolved organic carbon (DOC), dissolved organic nitrogen (DON), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) were quantified in samples collected during the 9 yr rotation of 5yr-alfalfa (Medicago sativa L.) followed by 4 yr corn (Zea mays L.). The mineralizable C was increased in the four years, and although not statistically significant, 12% higher in the fourth year under reduced-tillage than conventional management (268 kg ha−1). Soil organic C was increased by 30% under reduced-tillage compared to conventional management (15.5 Mg ha−1). Three management strategies showed similar labile N pools in the Con and Org management, but differed in the Rt management. Org management showed significantly lesser mineralizable and inorganic N compared to other strategies, but soil microbial community and comparable crop yield across management strategy in year 4, indicating more efficient N use for organic than other management strategy. In our conditions, reduced-tillage for corn cropping after five years of alfalfa grassland can accumulate labile C and N and improve N utilization to for crop yields in the forage-based rotations. These findings suggest an optimal strategy for using Rt management to enhance soil properties and crop yield in plantation soils and provide a new perspective for understanding the potential role of Rt management in plantation soil.


Wetlands ◽  
2021 ◽  
Vol 41 (1) ◽  
Author(s):  
Yu An ◽  
Yang Gao ◽  
Xiaohui Liu ◽  
Shouzheng Tong ◽  
Bo Liu ◽  
...  

2021 ◽  
Author(s):  
Christoph Rosinger ◽  
Michael Bonkowski

AbstractFreeze–thaw (FT) events exert a great physiological stress on the soil microbial community and thus significantly impact soil biogeochemical processes. Studies often show ambiguous and contradicting results, because a multitude of environmental factors affect biogeochemical responses to FT. Thus, a better understanding of the factors driving and regulating microbial responses to FT events is required. Soil chronosequences allow more focused comparisons among soils with initially similar start conditions. We therefore exposed four soils with contrasting organic carbon contents and opposing soil age (i.e., years after restoration) from a postmining agricultural chronosequence to three consecutive FT events and evaluated soil biochgeoemical responses after thawing. The major microbial biomass carbon losses occurred after the first FT event, while microbial biomass N decreased more steadily with subsequent FT cycles. This led to an immediate and lasting decoupling of microbial biomass carbon:nitrogen stoichiometry. After the first FT event, basal respiration and the metabolic quotient (i.e., respiration per microbial biomass unit) were above pre-freezing values and thereafter decreased with subsequent FT cycles, demonstrating initially high dissimilatory carbon losses and less and less microbial metabolic activity with each iterative FT cycle. As a consequence, dissolved organic carbon and total dissolved nitrogen increased in soil solution after the first FT event, while a substantial part of the liberated nitrogen was likely lost through gaseous emissions. Overall, high-carbon soils were more vulnerable to microbial biomass losses than low-carbon soils. Surprisingly, soil age explained more variation in soil chemical and microbial responses than soil organic carbon content. Further studies are needed to dissect the factors associated with soil age and its influence on soil biochemical responses to FT events.


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