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Nutrient Neutrality
Nutrient Neutrality
New government grants to reduce phosphate pollution! "50 extra Environment Agency inspectors to be recruited and aim to conduct 4,000 farm inspections this year. This has significantly increased the EA’s capacity to work with farmers to meet their obligations" They use the Guidance 'Applying the farming rules for Water' Updated 2022
This was put forward (with £280m funding) as a way to remove requirements on new housing estates for 'nutrient neutrality. NN requires new estates in sensitive areas to 'offset' their phosphate production (from sewage and detergents) by reducing phosphate (=nutrient) pollution in nearby rivers. It was estimated that this could release planning for 100,000 new homes. The Lords overturned this government's amendment - to 'Levelling Up' Bill - so it will now require new legislation.
NPK classic fertilser and the Phosphates a key part. P needed for ATP and many plants substances. High percentage in bird droppings - witness all problems in Wye Valley. But lead to the 'Guano Wars' where countries - US in partucalry taking over small islands for thie bird shit. Countries fought wiht each for these islands
Coprolite is fossil poo. During the mid-18th century , a curious parson at Cambridge University discovered that certain coprolites, when treated with sulfuric acid, yielded valuable phosphates then in demand by the growing chemical industry. For decades, the east coast of England was a hotbed of coprolite mining and refining, to the extent that even today, in the town of Ipswich, you can take a leisurely stroll down "Coprolite Street." In 1855, 650 tons of coprolite were brought into Fison's Thetford works from pits in Ipswich,
Sleeping walking into Phosphorus crisis. UK is dependent on phosphorus imports, increasingly unstable and expensive, yet has few plans for dealing with the loss of phosphates - eg no 'phopsphate exchange' scheme.
"UK theoretically has enough phosphorus already circulating in the food system: 90,000 tonnes per year of “legacy phosphorus” accumulate in agricultural soils, 26,000 tonnes per year leak into water bodies and 22,000 tonnes are sent to landfill and construction. These hotspots of phosphorus inefficiency and loss represent a critical resource, which could instead be used productively. "
UK PhosphorusTransformation Strategy :Toward a circular UK food system part of a larger, 3-year, UKRI-funded research effort, the RePhoKUs project.
Blood money
Europe’s secretive trade in Syrian phosphates;.
"Russian and Syrian private security contractors guard the phosphates mines and convoys to the coast." #phosphorus @RePhoKUs @H2020Recap @etnREFLOW
Scientists warn of Phosphagoddon "we have become profligate in the use of phosphates we put on our fields. Fertiliser washed from them – and discharges of phosphorus-rich effluent – have triggered large-scale contamination of water and created harmful algal blooms. Some of the world’s biggest bodies of freshwater are now afflicted, including Russia’s Lake Baikal, Lake Victoria in Africa and North America’s Lake Erie."
Phosphate Paradox 1hr + video of Dr Christine Jones. Key parts:
What is a holobiome Effectively functioning
Soil Disturbance Phosphate levels
The phosphorus sorption capacity of a soil refers to the ability of the soil to bind phosphorus applied to it (e.g. as fertiliser).
Soils with a high binding capacity will hold on to any phosphorus applied more tightly than soils with a low binding capacity
Phosphates
Phosphates
'P' for phosphate and is one of the three major crop nutrients found in 'NPK' fertilisers'. Phosphate is crucial in plant development as it supplies the source element for holding energy. ATP (Adenosine Triphosphate) is found in the powerhouse of all cells - the mitochondria - and drives all the plant processes.
Phosphates are particularly prevalent on bird guano manures, as well as dinosaur dung, as used by Fisons, This is what is causing major pollution in River Wye. River Pollution
There are now major worldwide concerns about the application of phosphate fertilisers. They have come to prominence in last year as phosphate prices have doubled. due to Russia-Ukraine war and Chinse controls on exports. They are a finite resource.
When applied, they are rapidly adsorbed in soil, so not available to plants. In the chemical adsorption, the phosphate ions (negative - anions) react mostly with Fe++/+, Al +++ and Ca (++positive - cations) on the clay surface (itself negatively charged, esp. with organic matter). There they form F, Al and Ca hydroxy phosphates. About one sixth of applied phosphates stay as soluble in soils, the rest either adsorbed or present in organic moieties, which are also hard to access.
Excess is washed away into the rivers causing algal blooms. Across the world, phosphates are polluting rivers and seas and wasting a lot of phosphates.
Phosphates are 'anions' - ie negatively charged. Around ¾ of the applied phosphate gets caught by ‘cations’ (positively charged particles) in the soil – by calcareous ones (Ca) in chalk and metal ones (Fe & Al) in more acid soils, like round here.
Science
Science
Utilisation of soil residual P and reuse in crops. "In general, compared with monocultures, crop rotation and intercropping significantly promote the release and utilization of residual P in soils. "
Phosphate, from dung (eg poultry) is held in organic molecules, which need to be 'mineralised' to release as soluble and available for plants. Because so much P is held, farmers add more to reach plants, causing more P to leach and runoff. Bacteria that 'solubise' phosphates work better in aerobic conditions, than anaerobic - with compaction & flooding. Check out RePhoKUs
Bacteria
Bacteria
Bacteria secrete organic acids like citric, oxalic, succinic, tartaric, and malic acids in the soil rhizosphere, and then ‘chelate' the cations - ie create complex (but soluble) compounds consisting of a central metal atom attached to a large molecule. Free-living bacteria which can ‘solubise’ phosphates, include Bacillus, Pseudomonas, Rhizobium, Micrococcus, Aspergillus, &Fusarium[2]. Other organism can too, like fungal genera Penicillium and Aspergillus, actinomycetes, and arbuscular mycorrhizal (AMF), which work aerobically.
PSBs
PSBs
Recently, it has been found that ‘consortia’ of Phosphate Solubising Bacteria (PSBs) –e.g.four bacterial taxa Enterobacter, Citrobacter, Pseudomonas and Comamonas – work much better than individual PSB and improve yields and blooming, and produce growth to levels equivalent to artificial fertilisers. This more holistic approach to improving soil health could be explored, rather than piling more into the reductionist approach of putting more, finite, phosphate on.
Most work on PSBs as biofertilisers is undertaken in developing countries. They have seen them as an alternatives to expensive fertilisers. Now we in UK want the same, but do not have the research.
The problem is that even with PSBs, they release the P into the soil. As Simon @ Wye said, all their farmers believe in soil health, but once soil became more alive, got even more P in water - to river.
Mobilising
Mobilising
Opportunites for mobilizing recalcitrant phosphorus from agricultural soils: a review. "Phosphorus (P) fertilizer is usually applied in excess of plant requirement and accumulates in soils due to its strong adsorption, rapid precipitation and immobilisation into unavailable forms including organic moieties.
Adsorbtion: Soluble P from freshly applied fertilizer interacts with soil surfaces, displacing other anions with less affinity.
Solubising
Solubising
'Solubising' bacteria release organic acids, through which their hydroxyl and carboxyl groups chelate the cations [an ion that have positive charge on it.] bound to phosphate and thus make 'soluble'. Main inorganic phosphates in soil are calcium, aluminum, and iron phosphates
Chelating agents include water ''softening' compounds as they bind Ca to make soluble - this stopping 'liming' in kettles. Phosphonates are also well-known chelating agents. Many commercially important compounds are phosphonates, including glyphosate ( herbicide Roundup). Glyphosate does not seem to affect phosphate solubuisation
Synthetic chelating "The EDTA, HEEDTA, and CA significantly (P<0.05) reduced P sorption in the Loam and Sand when measured by WSP. "
The organic acids, produced by PSBs in the periplasmic space by the direct oxidation pathway The excretion of these organic acids is accompanied by a drop in pH that results in the acidification of the microbial cells and the surroundings, hence, P ions are released by substitution of H+ for Ca2+
Gram-negative bacteria solubilize mineral of glucose to gluconic acid. Pyrroloquinoline quinone (PQQ) acts as a redox cofactor in glucose dehydrogenases (GDH) resulting in phosphate solubilisation
Mineralising
Mineralising
'Mineralising' bacteria 'digest' organic moieties containing P into inorganic available P. A major source of organic phosphorus in soil is the organic matter. The values of organic phosphorus in soil can be as high as 30–50% of the total P and soil organic P is largely in the form of inositol phosphate (soil phytate).
Phosphorus mineralisation refers to the solubilisation of organic phosphorus AND the degradation of the remaining portion of the molecule - to release inorganic P for the plant..
Measuring
Measuring
Azotobacter
Azotobacter
Can we ‘solubise’ phosphate better? This makes existing phosphate more available naturally reducing the need to add more.
In less developed countries farmers use Azotobacter, instead of chemical fetilisers. Azotobacter is a free-living bacter and has been around for four hundred million years. This is to distinguish them from 'legumunous' nodule forming N-fixing bacteria, we find in pea and bean plants, which have only been around about 100million years.
They struggle to be as N-nutritious as chemical applications. But there is an added property, which may make it worth considering here.
They also 'solubise' phosphates.
Aerobic & Anaerobic
Aerobic & Anaerobic
Phosphorus accumulating bacteria can be divided into two groups in respect of process; one group capable of utilising only oxygen as oxidant and another group capable of utilising both oxygen and nitrate (NO3)as oxidant.
The organic acids produced by bacteria in order to 'chelate' the phosphate require 'oxidation pathways. The phosphorus uptake was more rapid under aerobic conditions than under anoxic conditions. All phosphorus accumulating bacteria take up phosphate under aerobic conditions, whereas only part of the phosphorus accumulating bacteria take up phosphate under anoxic (=anaerobic) conditions. And please note: anaerobic bacteria use nitrate as their oxidant - so may well be consuming expensive nitrate fertilisers.
Anaerobic conditions are caused by compaction and flooding. Does slurry spreading make that worse? Slurry is an anaerobic solution, compared with muck spreading which is predominantly aerobic.
I believe (ie yet to proove) that anaerobic conditions are not conducive to solubising and holding phosphate, But aerobic conditions are better - and the mycorrhiza need aerobic conditions and they seem increasinly important on phosphate control..see below
Earthworms
Earthworms
The amount of readily available phosphorus (P) has been shown to be affected by earthworms, levels of available P being higher in casts (Jiménez et al., 2003; Kuczak et al., 2006; Vos et al., 2014; Ros et al., 2017) or in biopores formed by L. terrestris (Athmann et al., 2017) than in the bulk soil. Concentrations of water-extractable P in casts of the anecic (vertical burrower) earthworm L. terrestris have been reported to be 30–1000 times larger than those found in bulk soil (Ros et al., 2017). These earthworm-induced “P hotspots” depend upon the earthworm species and have been shown to be larger for the epigeic (surface feeder) L. rubellus than for the anecic L. terrestris or the endogeic (deep burrower) A. caliginosa (Vos et al., 2014).
The influence of earthworms on available P is particularly relevant in the rhizosphere, where earthworms can interact with arbuscular mycorrhizal fungi to enhance P solubility and transfer to the plant (Milleret et al., 2009; Cao et al., 2015a) (Box 1). Soil available P has been reported to increase in the presence of the endogeic (horizontal burrowers making permanent burrows) earthworm P. corethrurus (Lopez-Hernandez et al., 1993; Chapuis-Lardy et al., 1998; Patron et al., 1999), or of epigeic (surface dwelling worms loose burrows) E. fetida (Cao et al., 2015a), which has been linked to the enhanced microbial activity during soil ingestion or in earthworm casts, although the magnitude of the increase in available P may differ depending on earthworm functional groups (Wan and Wong, 2004; Bernard et al., 2012; Vos et al., 2014).
Mycorrhiza
Mycorrhiza
If bacteria help solubise P, that makes it more likely to get leached out. Need to have something to capture the solubised P before that, and most obvious is 'the roots'. Yet most roots perform much better when associated with fungi called mycorrhiza - the arbuscular fungi (AMF) in roots of 3/4 plants on planet.
The clear reason is that the mycorrhiza will pass the phosphates to the plant. But it is not just about amount passed, but it appears the fungi change the nature of the phosphate making it more suitable for plants. Most fertiliser advice concentrates on pH in order to determine P availability - higher pH (7+) involves Calcium - more available that less than 5.5 where Aluminium ions more involved. But perhaps it is not just chemical ions, probably fungal pathways that play great part.
Unfortunately there are not many AMF on annual agricultural crops. They are on grasses, flax and legumes, where soybeans and beans interact positively with mycorrhiza and strains of rhizobia. The soy, beans, corn and sorghum crops are highly dependent on associations with arbuscular fungi. (CC: the legume -rhizobia relationship arose late on in evolution - less than 100mya and is genetically similar to mycorrhiza which evolved 3 hundred million years before that)
Rice does not depend directly on this association. nor canoloa, mustard, spuds and the like. Trees are where AM fungi first related. So perennial longer rooted grasses (eg prairie) will work best. Cereals crops are known to have poor or intermediate responsiveness to AM (p2). A number of companies are now testing whether seed coating is a suitable method to inoculate AM fungi.
Pathway
Pathway
"Phosphate acquisition via the mycorrhizal pathway begins with the uptake of free phosphate from soil by fungal extra-radical hyphae (Bucher, 2007). These fungal hyphae extend beyond the host root system, allowing a greater soil volume to be exploited for phosphate uptake. Uptake at the soil-hypha interface is mediated by fungal high-affinity phosphate transporters
of the Pht1 family (Harrison and Buuren, 1995). Following fungal uptake, phosphate is transferred to the fungal vacuole where it is polymerized to form polyphosphate chains and translocated through the vacuolar compartment to the intraradical hyphae. The polyphosphate is then hydrolysed (CC: to orthophosphate ions (H2PO4–, HPO42- - the main form plants absorb) and phosphate released to the interfacial apoplast. From the interfacial apoplast, plant mycorrhizal Pht1 transporters guide the phosphate across the peri-arbuscular membrane. Once in the plant cytosol, phosphate is translocated
into the vasculature for delivery to all parts of the plant."
Mycorrhizae: Sustainable Agriculture & Forestry Chap 1.
This Chapter also spells out how certain genes like medic gene Medtu:Pht1;4 are only 'expressed' near arbusculated cells.
Approximately 150 species of arbuscular mycorrhizal fungi are present in agricultural soils and the symbiosis of these fungi with plants depends on a complex sequence of interactions, whose symbiotic relationship results in perfect morphological, physiological and functional integration. Not any convincing research work - Some says it isnt worth it - carry on spraying. other than usual Regen/CA,. saying those techniques improve AM. Do we just stick a tree in every so often?
It seems that major problem is that the mycorrhiza dies out if there are not appropriate roots to grow on the way they evolved. Hence the importance of cover crops, no tillage and crops working together.
Working together - but not sure of phosphate connection, check out the North American Indians '3 sisters'.
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