Letter to the Editor: David Tayler of Millthorpe (near Orange)

I read through Dr Mary Cole’s FAQ’s and found them most interesting.

I also noted where your [Dr Cole’s] property is and looked up the annual rainfall in the district. Quite a beautiful area with so much rain.  About the same a I get (860mm). Until recently I had 330 head of cattle, and 200 fat lambs on my 700 ac.  No rain for 3 months meant I had to reduce cattle numbers to about 150 head. (and the 100+ kangaroos remain).

I’ve been in agribusiness most of my life as an orchardist (15,000 lemon trees), as a consultant and as a R&D commercialiser.  One 8 yr venture was developing biodegradable insecticides efficacious against small soft bodied insects – myriads, aphids, two spotted mites – without killing the beneficials –  bees, jasids, spiders.

Since my orcharding days, I’ve had a leaning towards the ecological way, or to put it another way farming with less external inputs of spray and fertiliser, but unfortunately I find it difficult in even in my current grazing operation. Plant available phosphorus is my limiting factor (other than rain) and I need to address it in the near future.  Chemical fertilisers are not my choice, poultry manure may have to suffice, applying some on an annual basis until I reach a satisfactory P level.  Perhaps its a manure/microbial tea solution.  Applying poultry manure (600 cubic meters or 12 semi-trailer loads) is hardly the ecological way.

Fortunately, I believe I have the equipment to make the microbial teas here with the vats (400 liter with stirring capacity) I used to produce the insecticides. I can decant liquid from the base.  What do I use to make the teas and how long should they ferment.  Can I use household (no meat) scraps, lawn clippings, pasture hay, cow manure, stir it all up and let the microbes multiply.  Then, I dilute the decant and spray it on the pasture with or without applied chicken manure and see if there is a complementarity.  A trial.  What sort of time is involved – by spring I should be able to measure the impact of the chicken manure (phosphorus and all the other nutrients) and if the tea is working, I’ll see extra benefits.  What a demonstration.  I’m sure others have done similar measurements.  I do not like trawling the web for this sort of info as there’s too much “false” eccentric material to sort out or, as often happens, they skirt around the issue.  Again this is something the coop could do (and even in time warrant a more realistic membership fee).

I find out the “commercial” teas are no ordinary exudate of microbial decomposition and cell multiplication.  Not the right bacteria for the soil and the vital fungi forms absent.  Now getting back to the phosphorus need, will the teas help release bound phosphorus in the soil, ie will the fungal hyphae etc be able to access other forms of phosphorus in the soil and eventually make them available to plants.  Soils have an enormous reserves of phosphorus mostly chemically combined in insoluble forms with calcium, iron, aluminum and other cations in the soil.  Even when I apply Superphosphate with plant availability levels at 80 kgs/tonne, nearly half of this is insolubalised over a short period, and so really only about 50 kgs in that tonne is available to plants.  Not too good is it !  Just about every farmer is in this situation.  I looked up the solubility of rock phosphate on the web, but I got sick of all those sites purporting to tell me, but didn’t, and so I’m no wiser.

I need to find a way to ecologically use my inherent phosphorus, and still be economically viable.  Or even to apply phosphorus in a less costly manner.  I need to apply plant available phosphorus to balance what is being removed chemically in the soil, or in the food and fibre exported.  An ecological mess !

I guess my next step is to dust off my vats which I can even temperature control, and start.  Will the microbes in the teas give me greater access to the phosphorus in the soil at the levels required and in a timely manner. Do you have any comments.  They would be gratefully received.

Cheers
David

If you have a comment to make you can write to the newsletter editor since the question David asked about teas, use of rock phosphates and their alike, and their usefulness will have universal appeal, or you can write straight to David at dtayler@ozemail.com.au <mailto:dtayler@ozemail.com.au>

Two questions and answers taken from Dr Mary Cole’s FAQs are as follows:

What are the effects of herbicides on my soil?
Answer: Herbicides do affect the soil biota unnecessarily. Weeds should be looked at ‘mulch potential’ and mulched after mowing. Good soil does not allow weeds to grow as they need a bacterially dominated soil. Most cropping plants are perennial and benefit from a fungal dominated soil. Addition of compost and mulches to increase the organic matter in the soil will turn over the soil biota to fungal domination. It is better to farm the soil and build soil health than it is to apply chemicals. Growers using Glyphosate, a broad spectrum herbicide, are having great success in managing weedy species as they transition to biological systems, by adding humic acids to the herbicide in dilutions of 50% to 75% herbicide. The mix has less impact on the soil biota allowing it to recover much more quickly than straight herbicide alone.
What is the effects of phosphorus on soil microbes?
Answer: Any salts adding in large amounts will damage soil microbes to a greater or lesser extent. Metals such as copper will affect all fungi and phosphates have a negative effect on mycorrhizal fungi in particular. Mycorrhizal fungi have a role in the soil of scavenging for phosphates and supplying them directly in plant available form to plant roots in exchange for carbohydrates which fungi cannot manufacture because they are non- photosynthetic. Any disruption to this symbiotic relationship causes loss of mycorrhizal fungi leading to loss of soil structure and loss of water holding capacity. Look at literature in the journal ‘Acre’, J. of SoilMicrobiology, and others, for peer reviewed papers.

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