Phosphorus

[nomolos]

I read many OZ natives do not like phosporus, does this mean OZ soils are low in phosphorus?

Should I fertilise with a fertilize to that will increase phosphate levels?

Phosphate seems important to producing a strong system? Yes?

Do palms need extra phosphorus?

[AggiePalms]

Phosphorus is of course one of the major nutrients that control good solid growth and metabolism, so yes I always make sure my palms get a good organic dose. Different soils, derived from the underlying rocks, have very different amounts of phosphorus...like the phosphate mining zone of Florida. Other areas have very little, such as the sandy coastal soils where I live. So I doubt that you can make a general evaluation of all of Oz, surely it must have high and low areas. I would have soil tested, and amend if needed. I can't imagine that increasing the phosphorus in a depleted area would harm the indigenous species; it may not help those species that have learned to live on low amounts, but it shouldn't harm them.

[mangolorry]

Phosphorus is of course one of the major nutrients that control good solid growth and metabolism, so yes I always make sure my palms get a good organic dose. Different soils, derived from the underlying rocks, have very different amounts of phosphorus...like the phosphate mining zone of Florida. Other areas have very little, such as the sandy coastal soils where I live. So I doubt that you can make a general evaluation of all of Oz, surely it must have high and low areas. I would have soil tested, and amend if needed. I can't imagine that increasing the phosphorus in a depleted area would harm the indigenous species; it may not help those species that have learned to live on low amounts, but it shouldn't harm them.

On the contrary. Phosphorus toxicity is a well documented phenomenon that can and does cause death in a number of Australian native genera. The problem is especially prevalent where run-off from urban areas leaches into adjoining native bushland. Plants growing in sandy soils are more prone to the problem as clay type soils tend to chemically "lock" the phosphorus up reducing it's availability to plants. Fertilizers designed for Australian natives will typically have reduced levels of phosphorus.

[Bennz]

Hi SOl,

I always think of Australia as having low P soils, but you need to get a soil test done to be sure for your specific situation. My personal feeling is that pH is the single most important thing, followed by C and N levels, then Ca/Mg ratio, then any toxicities, and only then total levels of P, K, S, Ca, Mg and TEs. My bias of course.

I suggest not applying P unless you know you need it. I suspect soil mineral balances are more important than total mineral quantities, which is why a well balanced organic-based fertiliser such as fish, seaweed or blood and bone etc seem to produce more growth response than you'd expect from an NPK-equivalent manufactured fertiliser source alone.

[Jonathan]

Hi SOl,

I always think of Australia as having low P soils, but you need to get a soil test done to be sure for your specific situation. My personal feeling is that pH is the single most important thing, followed by C and N levels, then Ca/Mg ratio, then any toxicities, and only then total levels of P, K, S, Ca, Mg and TEs. My bias of course.

I suggest not applying P unless you know you need it. I suspect soil mineral balances are more important than total mineral quantities, which is why a well balanced organic-based fertiliser such as fish, seaweed or blood and bone etc seem to produce more growth response than you'd expect from an NPK-equivalent manufactured fertiliser source alone.

I sugest adding a bit of ABC, followed by some LMNOP, and a nice heavy dose of XYZ....that way you have it all covered!

Seriously though Sol - have a wander around in the bush on the hill above your place, if there are Banksia's growing there, then you almost certainly have a low P soil. Aus flora is adapted to low P conditions because our soils are very old and very leached due to the comparative stability of the geology here.

NZ soils are low P because all Kiwis are evil.

Having said that, I agree with Ben - use a well balanced organic system to feed the soil, not the plant - the plant can feed itself in a healthy soil.

Cheers,

Jonathan

[Bennz]

NZ soils are low P because all Kiwis are evil.

Having said that, I agree with Ben - use a well balanced organic system to feed the soil, not the plant - the plant can feed itself in a healthy soil.

Cheers,

Jonathan

Hi Sol,

Jonathan and I see eye to eye on many things (that comment will cause him some serious introspection). While I go down the organic track, there is obviously also a place for applied fertilisation to get increased growth rates. I've seen Eucalyptus trees in NZ plantations with applied N and P grow at spectacular rates (I'm thinking of a small E. regnans plot about 15kms form here in a wet cool sheltered site with complete weed control and applied fert. that had grown 15m tall and over 400mm diameter in 3 years from planting). So adaptation to low P soils is not necessarily the same as preference to low P soils.

The trouble comes if you use fertiliser to grow a tree that will not survive without it. Then you are committed to a lifetime of continuing the nutrient input. On a small scale maybe it's worth it...

[AggiePalms]

Phosphorus is of course one of the major nutrients that control good solid growth and metabolism, so yes I always make sure my palms get a good organic dose. Different soils, derived from the underlying rocks, have very different amounts of phosphorus...like the phosphate mining zone of Florida. Other areas have very little, such as the sandy coastal soils where I live. So I doubt that you can make a general evaluation of all of Oz, surely it must have high and low areas. I would have soil tested, and amend if needed. I can't imagine that increasing the phosphorus in a depleted area would harm the indigenous species; it may not help those species that have learned to live on low amounts, but it shouldn't harm them.

On the contrary. Phosphorus toxicity is a well documented phenomenon that can and does cause death in a number of Australian native genera. The problem is especially prevalent where run-off from urban areas leaches into adjoining native bushland. Plants growing in sandy soils are more prone to the problem as clay type soils tend to chemically "lock" the phosphorus up reducing it's availability to plants. Fertilizers designed for Australian natives will typically have reduced levels of phosphorus.

That is most interesting; I would love to learn what biochemical pathways those species use to overcome the necessity for phosphorus in bioenergetics and ATP formation during photosynthesis. Somehow they must compensate for those basic biochemical needs. Any info would be appreciated!

[Jonathan]

That is most interesting; I would love to learn what biochemical pathways those species use to overcome the necessity for phosphorus in bioenergetics and ATP formation during photosynthesis. Somehow they must compensate for those basic biochemical needs. Any info would be appreciated!

I found this abstract which might shed some light:

"Banksia species (Proteaceae) occur on some of the most phosphorus (P)-impoverished soils in the world. We hypothesized that Banksia spp. maximize P-use efficiency through high photosynthetic P-use efficiency, long leaf lifespan (P residence time), effective P re-mobilization from senescing leaves, and maximizing seed P concentration. Field and glasshouse experiments were conducted to quantify P-use efficiency in nine Banksia species. Leaf P concentrations for all species were extremely low (0.14-0.32 mg P g(-1) DM) compared with leaf P in other species reported and low relative to other plant nutrients in Banksia spp.; however, moderately high rates of photosynthesis (13.8-21.7 micromol CO2 m(-2) s(-1)), were measured. Some of the Banksia spp. had greater P proficiency (i.e. final P concentration in senesced leaves after re-mobilization; range: 27-196 microg P g(-1) DM) than values reported for any other species in the literature. Seeds exhibited significantly higher P concentrations (6.6-12.2 mg P g(-1 )DM) than leaves, and species that sprout after fire ('re-sprouters') had significantly greater seed mass and P content than species that are killed by fire and regenerate from seed ('seeders'). Seeds contained only small amounts of polyphosphate (between 1.3 and 6 microg g(-1) DM), and this was not correlated with P concentration or fire response. Based on the evidence in the present study, we conclude that Banksia species are highly efficient in their use of P, explaining, in part, their success on P-impoverished soils, with little variation between species."

I had always thought that it was a michorrizal association with Banksias which helped with nutrient uptake, but according to the Australian National Botanic Garden website:

"Though a great many Australian plants form mycorrhizas, especially VA mycorrhizas, there are some noteworthy exceptions. For example, many genera in the Proteaceae (which includes the widespread genera Banksia, Grevillea and Hakea) do not form mycorrhizas. Even in artificial conditions, when attempts are made to force mycorrhizas these genera seem to actively resist mycorrhizal formation."

Hope that helps - by the way we should mention at this juncture that palms are generally not adapted to low p soils, although I wouldn't be surprised if some or most Livistona species are....

Cheers,

Jonathan

[AggiePalms]

Great, thanks Jonathan. I'll have to ponder the lack of miccorhyzea (sp.) Odd plants over there. They must be really efficient at cycling that minute amount of P!

Since our soils are very porous and sandy, and therefore low in phosphorus, I may just have to avoid supplementing Phosphorus on one or two of my Livistona to see how they react.