Questions related to Biogeochemical Cycling
It is well known that the elements like C, N. P, O undergo bio-geochemical cycling in nature. I am interested to know what are the basic reasons of this natural process.
I am trying to estimate phytate-P from soil by enzyme addition method. I consulted several papers and most of them had use malachite green for P determination. I followed the method described in Jarosch et al., 2015 and tried several time for estimating MRP from NaOH-EDTA extract of different soils, after and before enzyme incubation. But I failed to develop color in every cases. Rather I ended up with greenish precipitate inside glassware. I am unable to understand the problem, can anybody please help me?
Studies always illustrated C/N ratio stay constant, because C and N are usually coupled closely in natural ecosystems, even under a changed environmental conditions. While recently i collected data from two-period soil surveys in croplands, the results indicated that soil C/N ratio increased significantly during this period (30 years). I was wondering how did this happened? what are the possible reasons for this? thank you so much for your help.
Many studies claim one of the benefits of arboriculture is the increased uplift, retention, and recycling of mineral nutrients. However, quantification of this topic tends to be limited to very rudimentary techniques, such as simply quantifying the total nutrients redelivered to the soil surface through litter. I am interested to attempt to quantify the uplift and recycling of nutrients in arboricultural systems. The only way I can think to do it is to define a ratio of isotope fractionation for the tree crop (which will likely change with the ratio on isotopes in the soil), and to assess the isotope ratios in the soil and tree over time. Any thoughts, suggestions, citations, etc. along this topic?
I am developing a phosphorus (P) budget for an agricultural watershed. Chemical fertilizers and organic matters (compost and manure) are the main sources of P in my study site. In addition, the soil of the watershed is characterized as sandy loam. P sorption capacity of manured sandy loam soils is lower than chemical fertilized soils. So, can I conclude like that P coming from organic matters are mainly exported through waterways. Or is there any way to identify which part of P mainly exported from the watershed hydrologically?
The main methods of net ecosystem CO2 exchange are static chamber and eddy covariance. I have done some experiments about static chamber and got some data about eddy covariance in the same place during the same period. So I want to combine the data of static chamber with the data of eddy covariance, and scale the static chamber to the eddy covariance by using some models. However, I have no idea how to scale or use the model.
Would you like give me some advise?
Any help appreciated.
Thank you much indeed!
We know the internal P loading is a big contributor to algal bloom for many eutrophic lakes. But there is a lack of studies that can identify and quantify the amount of P from sediment resuspension in a eutrophic lake. Any idea or suggestion?
Im working in La Matanza River and study the interaction between humic substances and metals and their mobilization influenced by dissolved organic mater in water column. I want to modelize it
Traditionally people use 15N fertilizers to trace the N in soil. For lab incubation without plants, priming means extra or less mineralization of soil native N (organic matter) within N treated soils compared to N mineralization in no-N soils. However, when plants present, the priming is the difference of the amount of N taken up by plants and the control (no-N) plants. This priming with plants, however, is not a real priming effect but a estimate of priming, as plants cannot take up all N mineralized in soil, so the remains of mineralized N may get lost via leaching, denitrification, etc. We know they are different but classical papers ( such asJenkinson, et al, 1985 SBB) always use plant N uptake as a proxy for priming or mineralization of soil native N (or organic matter). Can we compare the N priming results derived from plant N uptake and soil net N mineralization?
I have been reading many papers about adding glucose, sugar or other complex substates (cellulose, litter, crop residues) to soil to analyze soil organic matter decomposition and soil respiration. The confusing issue I ran into was: how to express the amount of C from substates added to soil? For example, some report the ug or mg C per g soil, and some simply use the percentage of C based on the soils used. For the respiration, some use the ug CO2-C per g per h, some ug CO2-C per g per day or week, and some even use mg CO2-C per g per h/day/week.
Other than the inconsistent report of the amount of substrate, different papers have different experiments periods or lengths. I am wondering if it is better to express the amount of C from substrates using a time scale? For instance, two papers report the same amount of 1000 ug C per g soil, but they have different duration, let's say 10 days and 100 days. By using the time scale, we see the C addition is completely different: 10 ug C/g soil/day vs 100 ug C/g soil/day. But I don't know which way is best for respiration.
Does anyone agree or disagree that we should propose a common way to specify the expression of substrate input and respiration? Feel free to leave your comments and suggestions below. Thank you.
Actually I am working on the biogeochemical cycling of the carbon, right now I am targeting plant assisted as well as some soil practices for enhancing the carbon pool. But I want to target the microbial mediated processes of carbon capture. I don't have much expertise in this field. So I am asking questions to know the some basic facts behind this idea from the concerned experts so that I can proceed further.
Thanks a lot for the cooperation.
Tree crops can uplift soil nutrients from deeper in the soil profile, redistribute them to the surface via leaf litter, and therefore reduce nutrient losses from leeching in agricultural systems. Does anyone know of any studies that quantify this effect? It will obviously depend on the soil type, nutrient availability, tree species, etc., but Iʻm curious if people have tried to look at the effect in a highly quantified way (i.e. what density of tree plantings is ideal in a cropping system to promote adequate uplift to then be cropping annuals around the trees). I understand that the variability of the effect will be huge and complex, but there is an ancient cropping system that I am trying to wrap my head around how to examine and discuss the long term effects. Is there a stable isotope signature or ratio that might be useful in understanding long term cumulative effects?
Symbiotic N fixation has been shown to respond to N availability and is limited by high energy requirements. Plants appear to use symbiotic N fixation as a facultative strategy to overcome N limitation. However, in many ecosystems, N fixing plants are not present, and even in ecosystem where they are present, N fixation by free-living organisms appears to be an important additional source of N to the ecosystem. But, what controls this input on an ecosystem scale? Is there any observed variation across certain gradients? And how close is the interaction between plants and free-living fixers? Is there plant exudation of labile C as energy provision to free-living heterotrophs? - Thanks for any answers and references!
I am studying the functional significance of tree species diversity on soil C, N and pH in mature semi-natural forests. We have plots selected with a rigorous selection procedures based on basal area threshold, soil types, previous land-use history, management, aspect, climatic factors. We established a gradient of 1-5 tree species richness. Apart from basal area threshold,we have also evenness restriction to each species in the plot (how much percentage of the basal area per plot a particular species should account for).
I am here to learn from your experiences if any of the researchers in the field have addressed the issue before.
Since the study focuses on the effect(s) of diversity, the main goal is to demonstrate whether diversity is positively, negatively or none related to the soil properties in question.
Using diversity indices and calculating net diversity effects (relative yield) can be two of the options.
1. How to address the diversity effect ? Many measure Diversity (richness, evenness, or both) using different indices. Which one of the known indices is more appropriate in this situation?
2. If you were calculating net diversity effects (observed yield in mixtures minus the expected yield in the corresponding mono-cultures) how did you take into account the variation of individual trees and their influence? i.e did you apply some weighting? if yes, which parameters of the trees (basal area, biomass, volume, height etc) you had weighted and how?
I am doing a lot of modeling in biogeochemical cycles in forest soils. I would need to include in my model a function to predict soil temperature at different depths from the temperature of the atmosphere. I have a complete data set of soil temperature measurements but I don't have any measurements of the soil thermal properties (conductivity...). I am looking for a simple way of modeling this. Does anyone have some suggestions?
I do a lot of modelling and system analysis. The best mean for that is paper, however, it would be handy to have a piece of software to build these diagrams on a computer for publication, presentations, or for teaching. Up until now I have used vector image software such as Inkscape or Adobe Illustrator.