Nutrient Availability in Soil Amended with Wheat Straw and Legume Residue

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Study: Residue addition frequency influences respiration, microbial biomass and nutrient availability in soil amended with high and low C/N residue

In the image above I’ve basically highlighted the mature dried wheat straw in yellow with a C:N of 80:1 that was first applied to soil. After two weeks the same amount of the green young dry faba bean with a C:N of 20:1 was applied at differing amounts and frequency for two more weeks.

After application of the wheat straw you can see a decline in plant available nitrogen by 75% & phosphorus by 50% in the first two weeks.

After that two week period, adding the equivalent amount of faba bean residue then doubled the original available nitrogen and phosphorus availability, and it seems to me like it may have sustained much higher levels for longer had the study continued. Soil carbon priming in action.

The H1-L4 (High C:N wheat followed by 4 applications of Low C:N faba over two weeks) part of the study however is the most interesting for me. Instead of applying all the faba bean reside in one go, applying it in stages gradually increased (red line) the available N and P. This approach would probably be the most efficient nutrient wise as plant nutrient removal increases as the plant grows, so it makes sense to add the nutrients as it needs them. Plants typically remove nutrients in a sigmoid curve.

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Soil Carbon, Grazing & Cropping Grasslands of Alberta, Canada

114 site study.

Grazing:

  • Grazing increased plant diversity
  • Grazing increased introduced species in higher rainfall (>350mm May – Sept) areas
  • Grazing increased aboveground biomass productivity in high rainfall areas, decreased it in lower rainfall areas.
  • Grazing saw no change in SOC in the 6 study regions.
  • Grazing increased root growth in the top 30cm of soil in high rainfall areas.
  • Grazing increased decomposition of plant litter in high rainfall areas.
  • Grazing lowers CO2/N20 flux.
  • Rotational grazing (High intensity, low frequency) significantly lowered CH4 production.
  • Native grasslands store most carbon.

Conclusion: Rotational grazing native grasslands in high rainfall areas FTW.

Cropping:

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  • Perennial grasslands produce higher below ground biomass than above
  • Cultivation leads to a rapid loss 30-60% of soil C
  • Continuous wheat cropping led to 19% loss of C
  • Cropping saw 30-40% C loss after 5 years.
  • Silvopasture (perennial pasture system) produced least CO2
  • Naturally re-vegetated areas failed to recover even after 50 years.

Conclusion: Silvopasture intercropping FTW.

Basically what Colin Seis does with Pasture Cropping native grasses.

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Microbes measure ecological restoration success

The researchers used next generation sequencing of the DNA in soil from samples taken across the site that had a range of plantings between six and 10 years old.

The technique – high-throughput amplicon sequencing of environmental DNA (eDNA), otherwise known as eDNA metabarcoding – identifies and quantifies the different species of bacteria in a sample.

The researchers – students Nick Gellie and Jacob Mills, Dr Martin Breed and Professor Lowe – analysed soil samples at the restoration site at Mt Bold Reservoir in the Adelaide Hills, South Australia, and compared them with neighbouring wilderness areas as ‘reference sites’.

“We showed that the bacterial community of an old field which had been grazed for over 100 years had recovered to a state similar to the natural habitat following native plant revegetation – an amazing success story,” says Dr Breed, Research Fellow in the Environment Institute.

“A dramatic change in the bacterial community were observed after just eight years of revegetation. The bacterial communities in younger restoration sites were more similar to cleared sites, and older sites were more similar to the remnant patches of woodland.”

Revegetation rewilds the soil bacterial microbiome of an old field – Gellie – 2017 – Molecular Ecology – Wiley Online Library

Small Molecule Could Have Big Future in Food Security

Crops all over the world are susceptible to infection by fungi of various Aspergillus species, a fungus that produces secondary metabolites known as aflatoxins. These compounds have been implicated in stunting children’s growth, increasing the risk for liver cancer, and making people more susceptible to diseases such as HIV and malaria.

“Aflatoxin is one of the most potent toxins on the planet,” Schmidt said. “Usually it won’t kill a person outright, but it can make you very sick.”

Schmidt and her team set out to study whether a naturally occurring biological mechanism called RNA interference could be used as a weapon against the Aspergillus toxin.

The modified corn plants carry a genetic blueprint for small RNA molecules, each only about 20 base pairs long, only in the edible kernels, not the whole plant.

“The corn is constantly producing that RNA during the entire development of the kernel,” Schmidt explained. “When the kernels come in contact with the fungus, the RNA moves over into the fungus.”

Once inside the fungal cells, the hairpin-shaped RNA molecules pair up with corresponding target sequences of the fungus’ own RNA that code for an enzyme needed for toxin production, in a process called RNA interference. This causes the toxin production to shut down, but does not in any other way impact the fungus, which continues to grow and live on the corn, albeit harmlessly.

Small Molecule Could Have Big Future in Food Security

Continuous Monocropping.

A new study using a LARGE dataset has found for corn and soybean:

  • Analysis of 748,374 yield records showed a 4.3% yield penalty for continuous corn.
  • Corn yield penalties were more severe in areas with low moisture and low yields.
  • Continuous soybean showed a 10.3% yield penalty, worse in low-yielding years.
  • Corn yield penalties grew with up to 3 yr of continuous cropping, but not more.
  • Soybean penalties increased monotonically with number of years continuously cropped.

Continuous Corn and Soybean Yield Penalties across Hundreds of Thousands of Fields

 

The Anthropocene Minerals

Roughly 2.4 billion years ago a great deal of oxygen arose in our atmosphere, causing the number of minerals to skyrocket from around 2,000 to 5,000 with the addition of so many oxide versions. Hazen’s work now shows human events trump that so-called Great Oxidation Event, which was previously the largest known increase in minerals (taking the broad sense of the term). “There are so many things that we produce that are mineral-like that we have really changed the sedimentary horizon in which we are now living,” Hazen says.

Found: Thousands of Man-Made Minerals–Another Argument for the Anthropocene – Scientific American

Room Temperature Ceramics

The scientists used a calcium carbonate nanopowder as the starting material and instead of firing it, they added a small amount of water and then compacted it.

“The manufacturing process is based on the geological process of rock formation,” explains Florian Bouville, a postdoc in the group of André Studart, Professor of Complex Materials. Sedimentary rock is formed from sediment that is compressed over millions of years through the pressure exerted by overlying deposits. This process turns calcium carbonate sediment into limestone with the help of the surrounding water. As the ETH researchers used calcium carbonate with an extremely fine particle size (nanoparticles) as the starting material, their compacting process took only an hour. “Our work is the first evidence that a piece of ceramic material can be manufactured at room temperature in such a short amount of time and with relatively low pressures,” says ETH professor Studart.

Sustainable ceramics without a kiln | ETH Zurich

Microbial communities affected by type of carbon “food” sources

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A new study has found that:

The type of carbon source affects not only the composition and activity of natural microbial communities, but also in turn the types of mineral products that form in their environment.

“We’ve illustrated that as microorganisms alter their environment, their environment then affects the type of microorganisms that are there and their activity.”

Researchers took anaerobic respiration microbial communities and presented them with one of three carbon sources: glucose, a six-carbon sugar; lactate, a four-carbon compound; or acetate, a simple two-carbon compound.

Their analysis showed that a distinct series of changes occurred consistently when microbes were exposed to lactate or acetate-rich environments. However, in glucose-rich environments, they observed varying patterns of changes.

“We think that, because glucose is a larger, more complex compound that can be broken down into many simpler compounds, this opens up more chemical pathways in the community through which it can be used, and that this diverse metabolic potential accounts for the different patterns we’re seeing,” said O’Loughlin.

Impact of Organic Carbon Electron Donors on Microbial Community Development under Iron- and Sulfate-Reducing Conditions