Sunday 27 January 2019

My garden each month, January

Out of my pond
I have made a new year resolution!  

It is to report what is happening in my garden each month. Every year is different with new triumphs and disasters - some tiny shimmers when some gardening gem reappears or deep gloom when a shrub bites its head off. Major events such as flood, drought or cows crossing the garden. It won't all be pretty but if I snap any nice pictures I will surely show you. I will sometimes cheat when previous year's pictures are better than this time round.

All gardens are different and mine is more different than most (this is not intended to be complimentary) and not all I do will be relevant to you and sometimes you will look on with amusement or even distain.

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Clearing my two ponds

Danger of oxygen depletion as debris decays
My twin ponds have become overgrown. For eighteen years now I have merely scooped out unwanted vegetation, leaves and litter with my upturned scarifier. All of sudden what was welcome cover for the fishes has become somewhat excessive. I have been indulgent with the hippurus horsetail, wilful with the water bean and cavalier with my oxygenators.

I think part of the trouble was last years's drought and Brenda regularly refilling with tap water. (Regular readers will know I always blame my beloved). There is more nitrate in tap water than you might imagine and did the plants grow! (permitted levels are below 10 ppm are completely safe)

Getting started
I have given it a much more thorough clear out this January. I have used my normal methods but much more intensively. I dragged out everything that I could find. (Not the water lilies which have spread out of their containers). In all I have removed twenty piled barrowloads.
I like to divide such heavy jobs into repeated short efforts. It took several more sessions than my hour on New Year’s day. Under the thick mat of surface vegetation it was surprisingly clear and the amount of well decayed organic matter accumulated at the bottom was not as much as I feared and is so well decayed it is unlikely to deplete oxygen and I am very happy to leave it.

 Cyano-bacteria exposed
The pollution in the above picture looks pretty bad. I have encountered it before and it has quickly disappeared after clearing. It is toxic to fishes and can be very serious in overgrown waterways

Narcissus romieuxii

Five years ago Peter gave me a pot of seedlings and I have been building up my stock by annual division in alpine pots in the greenhouse. I just love them and now I have enough stock to try them outside
I was heartbroken in October when a snail went on a rampage and grazed to the ground emerged centimetre long shoots. The snail was soon dealt with and the shoots regenerated. I have been reading how plants rapidly internally transmit warnings of a predator and seem to know whether the best survival strategy is to keep on growing or die back. The ones radulated by snails are now flowering as well as the others.
I was puzzled why another pot failed to emerge until two months after the others. I think that when I divided them they went to the bottom of the pot and perhaps upside down. They have caught up and are now looking fine

Lonicera purpusii fragrantissima

Not very photogenic but its gorgeous scent is very well worth having shortly after Christmas 
No flowers on Garrya elliptica

Last year the beast from the east ravaged a magnificent display of my best ever long dangling catkins which at that time we had enjoyed for ten weeks or so. It eventually regenerated with strong growing shoots and this Summer it escaped my over enthusiastic pruner (guess who). My reward has been zero flower production!
I conclude that in our long lasting drought new growth came too late and inhibited flower bud development. 

Before the 2018 beast
Heaven scent

Hiding behind the dead miscanthus top (which is now cut down)
Daphne Jacqueline Postill loves my sandy soil and has spread to make a very fine clump. We nearly lost it in the double Winter of 2010 and it took a couple of years to return to its earlier glory.
You would imagine from the prolific shoots it sends up from the ground that you could easily divide it. Not so, dug out rooted shoots usually look promising but eventually go yellow and die. I have succeeded only twice with two rather large pieces and now have three very fine  plants, one in a large tub, and all give gorgeous penetrating pink perfume January to March

Readers fail to identify daffodil but David steps in

Narcissus 'Rijnvelds Early Sensation'
Some of last years daffodils stood in flooded garden for three months in last years exceptionally wet Winter. They have not turned a hair and this year they are now emerging strongly. I had forgotten the name of my earliest variety and turned to daffodil expert David Willis and he gave me its name. You don’t see it in all the bulb catalogues but it is very well worth buying. 

Cutting back dieback on cut leaf maple
Every year my dormant cut leaf maples (and some of the dogwoods) show frizzy white dieback on young shoots. After last year's drought one plant  was particularly bad and I have ruthlessly pruned out some large pieces

Pruned out pieces
One shoot was showing severe dieback and coral spot had taken over
Should I take out the large piece on the left?
Quick flicks

Happy accident

Little things please little minds
Unfortunately this hamamelis retains its dead leaves


No reward for pressing this link to be the 10,000th reader about Garrya elliptica

Cut leaf maple can be difficult but is well worth growing

I wrote about my twin ponds last year

Although a large strong daffodil flowering in January might look out of place I love mine

Apologies for the glych I had publishing this post

Wednesday 16 January 2019

The long and the short of it; why some soil organic matter lasts a very long time.

And does humus exist?

My soil is high in organic matter as a result of twenty years of minimum cultivation and recycling organic matter. Unfortunately my soil lacks clay and with different management much of the organic matter will oxidise away
Most bulky organic matter of the kind that we add to our compost heaps decays and is gone within five years. For soft nitrogen-rich debris it’s gone very much sooner. I experienced this myself when I accepted a good will gesture from the local organic disposal plant and used the lovely brown stuff to fill up a couple of no longer wanted small ponds. After two years the ponds have almost returned. As well as decay no doubt the worms have done some shifting.
You might also notice how your 'green' potting compost soon sinks in its pot

Photographed in Madeira this compost from decayed woody  debris might last a little longer
Alongside such phenomenon other organic matter remains in the soil for decades or even centuries. Radio carbon dating has shown so called humus more than a thousand years old. What is going on?

 Humus is just mineral stabilised organic matter

Blogger Robert Pablis has written a clear explanatory post about why we should question the word ‘humus’. In his dry way he notes it might not exist but a lot of people sell it. 
The word has always been misused and carries different meanings.

It is wrong to equate the word 'humus' with bulky organic matter such as peat and garden compost. On the other hand the word has legitimacy in describing organic deposits such as natural mulches; ecologists talk about ‘humic layers’

The real meaning of the word humus to a soil scientist refers to the long lasting organic material intimately mixed into the soil. I like the term ‘mineral stabilised organic matter’  better, having spotted it in a technical report I will refer to.
The term ‘humus’ has always been difficult in that you can’t properly define it. It can only be extracted from soil by intensively corrosive laboratory methods that according to Robert raise the pH to thirteen. The organic materials it is reduced to are often described as fulvic and humic acids (And you can buy them too but don’t waste your money). The point is that such organic residue bears zero resemblance to what exists in the soil

What is mineral stabilised organic matter?  
Over the years I have heard various attempts at explaining this amorphous material. I have always favoured the idea that organic breakdown is such a chaotic process that some of the organic remains are such erratic irregular molecules that bacterial enzymes that operate by lock and key mechanisms just have nothing to latch on to.
There are millions of clay particles here already to form intimate relations with organic matter
Perhaps more mainstream is that some organic molecules are so small they can effectively hide away from bacteria  in close and intimate associations with soil particles. Between the internal latices of clay spaces are tiny. Perhaps some kind of bonding locks soil particles and organic molecules together.

Let us step back and consider the overall contributions of long and short term organic matter to fertility. A fairly high level of organic matter is hugely important to all living processes that work in and improve the soil. Organic matter is fundamental to soil structure and plant nutrient requirements.
It has always been a paradox that long lasting organic matter is basic to soil health and yet organic breakdown - ultimately to water and carbon dioxide - releases essential nutrients that plant and soil biology needs.
It always galls me that some gardeners seem to think that it is mandatory to buy and bring in extra organic matter to add every year to their soil. I wish more people would recognise that nature itself will produce enough organic matter if only we would let her. Just like in the wild.
No matter however organic matter gets into the soil it is a very good thing. (Except where the ignorant use inappropriate material and apply it in silly ways such as layers of peat or sheep’s wool residue on the surface - ugh. Or where they add herbicide contaminated manure - or in manure and sometimes compost, spread weed seed and slugs around or….)

Farmyard manure is the most excellent soil improver, unfortunately it often contains copious weed seed and is sometimes contaminated with herbicide

I am fascinated by the paradox that cultivating the soil oxidises away organic matter to release nutrients whereas the non digger builds up his soil organic store (clearly both can happen in parallel).

More recent understandings
Mycorrhiza make a huge contribution to plant nutrition and soil structure
Apart from the fact that the ‘humus’ extracted in soil analysis does not really exist in the soil, another source of long term organic matter dubbed glomalin was only discovered in 1996. It is tough glycoprotein which strengthens the hyphal walls of mycorrhizal fungi and can remain stable in the soil for up to a century. Until 1996 this tough un-reactive material had not been picked up in laboratory soil analyses and had been thrown away. Worldwide research now shows that glomalin makes up about 30% of soil long term organic matter. 
Sometimes called nature’s glue it intimately binds soil particles together and creates the ‘stable soil aggregates ‘ much beloved by gardeners.
Mycorrhizal fungi are much encouraged by minimum cultivation. Grist to my mill.

When I was at school little mention was made of soil rhizosphere and it would have been vehemently denied that roots ‘leak’ sugars into the soil. 
I have recently discovered the website Botany One and am finding all kinds of fascinating facts. It reports recent research into this sweet phenomenon by which the plant creates an absorptive nutrient wonderland in close vicinity to the roots. Organic matter entering this system, according to the researchers, is more likely to become stable than that added by bulky deposition.
The research shows this makes a large contribution to ‘mineral stabilised organic matter’ (their phrase) only dwarfed by that from the shear bulk of organic matter entering the system in the conventional natural or gardening  way. (Yes, a little of your compost heap does eventually make long term organic matter).

Earthworms intimately mix organic matter and soil particles in their gut and the resultant casts much improve soil fertility. I have no idea how much this mixing contributes to long term organic matter!

Another factor that is receiving more attention than previously is inorganic carbon in the soil. Described as recalcitrant it remains for a very long time. Through most of my life I have been unaware of this substance which is the remains of historical fires. I now wonder if my old allotment in Bolton Percy was so fertile partly because  cottagers in this domesday - book  village had over the centuries emptied their hearths there.

Homemade charcoal mixed into my soil
Readers will know of my interest in adding my homemade biochar to the soil. Not my subject for today but will be next month.

More questions no answers
I wonder how much of this leaf-fall will become long term organic matter
Although I could make a list of relative advantages of composting versus leaving fresh organic matter on the surface - (such as scattering lawn mowings or leaving hoed or glyphosate-sprayed weed to desiccate and die) - I have no idea which leads to the most efficient formation of long term organic matter. I suspect where soil and fresh vegetation are in intimate contact over the many and varied phases of decay this leads to more stability and intimate mixing than the crash bang wallop of a highly oxygenated pile of vegetation.

Following this line of thought are their any benefits of including soil in our compost heaps - or even adding biochar?
And what about the intimate mixtures of mineral particles and organic matter formed in the guts of worms?
I am a huge fan of earthworms

Robert Pavlis's explanation of why humus does not exist

Google this reference on the link from Botany One -  'Microbial formation of stable soil carbon is more efficient from below ground than above ground input'

My own previous post on this subject

Monday 7 January 2019

Crash course on roundup

Twenty important things to know about glyphosate

Although glyphosate is the basis of my weed control I also use other methods
I use the name 'roundup' generically to catch more attention. Of course I mean glyphosate. You don’t want to pay premium prices for trade names when all glyphosate is the same, products differing only in the ‘soap’ used as a wetter and spreader. 

The patented name is used for both amateur and professional products. In dilution they are VERY different
1. Glyphosate comes in a range of prices and concentrations. It is very expensive to those who insist they are amateurs but very cheap to those who buy professional products. Whichever product you use when diluted to the necessary concentration it is equally effective

2. In my opinion glyphosate is the safest pesticide ever invented. If you believe propaganda put out by campaigners and listen to easily swayed politicians and silver tongued lawyers, then you and I do not agree

I sprayed this intact couch grass for an allotment holder with glyphosate. None of it will regrow and although as yet rather inconvenient the plot can be planted straight away!
3. For practical purposes glyphosate completely degrades on contact with the soil. One consequence is that within reason you can plant or sow new plants very soon after application. Also, if you apply it to weeds close to your plants (again with a minor qualification) the roots of your plants will not absorb residue.

4. Glyphosate is NOT of itself selective. Potentially it can kill all plants (There are exceptions such as liverwort and moss). It is used selectively by such means as directed application and timing

5. There are some products such as those used for weed control on roads and pathways that are cocktails with other chemicals. You are generally advised not to make up your own mixtures - but I often quote exceptions

6. Glyphosate is not very rain fast and it is often stated it needs six hours in rain free conditions. This might be true for optimal uptake but for most garden conditions the advice is inappropriate. A short shower of very light rain in this uncommon circumstance can even enhance its effectiveness. In most cases a rain free hour is sufficient for most common ‘weedlings’ Both Peter Williams and myself will set out with our knapsack unless rain immediately threatens or we know a depression is coming over!
If you do have a project against severe established perennial weed you will need the full six hours or better a couple of days.

Just a silly illustration of how accurate you can be with a knapsack sprayer at almost zero pressure. Such accuracy is almost never needed!
7. Uptake of glyphosate is most efficient when applied as a fine spray short of ‘run off’. A coarser spray will be more wasteful but in respect of drifting more accurate. To apply with a watering can is very wasteful indeed and I do not recommend it.

8. It is best to spray on a completely still morning and for delicate spraying this is essential. I personally find in most cases this is over prescriptive and with my own often ‘coarser’ application I am prepared to spray in a light breeze.

The most accurate and speedy spraying is done with a professional knapsack sprayer (which is much cheaper than your mower)
9. Probably the most important thing about spraying with glyphosate is that it needs to be applied to a large and proportional leaf area. Sprayed onto an intact young weed however small it will have efficient ‘take up’ but sprayed onto an emerging large perennial as it peeps out of the ground  is completely useless.

10. To emphasise the above point, if you have already chopped up a perennial’s roots by cultivation you are  wasting your time

Sprayed  three weeks earlier, nicely dying in November
11. It actually takes quite along time for glyphosate to kill weeds. Perhaps two to three weeks in Summer but as long as eight in Winter. Don’t worry once sprayed the weeds are as good as gone. Weeds in flower might continue to set seed for a short while.

12. Strong long-established perennial weeds with a large root system will inevitably regrow after a single spray. Leave such weeds intact with zero cultivation and later spray regrowth. (It’s ok to just cut them back for tidiness a week or so after spraying).
It might need two or three resprays to completely eliminate such weeds - a season or so -  and for really vigorous or part-resistant weeds such as horseradish, equisetum or ground elder it needs repeated respraying over a couple of years - as much as a total of (say) five applications.

At this stage or sooner these herbaceous perennials are vulnerable to damage. Be very careful and direct  your spray head down and at low pressure close to the ground as you spray round the clumps
13. I find herbaceous weeds are killed most efficiently when growth is soft, extensive and vigorous rather than old and tough. Conversely old growth on garden plants is less likely to be damaged by misdirected spray

90% of this bindweed was completely killed by a single spray in early July
* It's not in my garden!
14. Large plants are less likely to be damaged by a little herbicide drift than small ones - they have more resources to out grow misdirected weedkiller and normally you will never know.

Couch sprayed in November, dead in December. Note the iris in this boggy area was already brown when I sprayed
15. Glyphosate is effective all year round provided the weeds are intact, green and preferably growing. Weeds such as convolvulus (bindweed) that have died down or gone brown brown are completely unaffected. Similarly dormant garden plants will be undamaged and early winter is an excellent time to spray such as still green couch grass within plant clumps that have died down in your herbaceous border!

You will need a strong mix for this one - and best to apply a first spray before it flowers
16. The optimum dilution rate for glyphosate varies with the weeds and conditions. My routine strength is 1 in 50 commercial 360gm concentrate to water. Against ‘difficult’ weeds my spray might exceptionally be as strong as 1 in 30. Contrary to general advice, within reason the stronger the mixture the more effective glyphosate will be. 
On the other hand it horrifies and amazes me how much glyphosate some so called gardeners get through.

I demonstrate selective spraying
17. You will need to read some of my other posts to learn all the tricks and wheezes to achieve selectivity by means of direction

When annual limnanthes dies down in July you can spray weeds before self seeded seed germinates in August
18. As to selectivity by timing don’t forget spraying weeds in otherwise bare soil in winter, spraying bulbs when they have died down and clearing weeds between one crop and another.

19. Glyphosate is particularly useful when the soil is too wet to dig or hoe as it might be in winter.

20. If horror of horror you carelessly spray a precious plant you might save it by immediately drenching the spray away, even lifting and washing a very small plant! In desperation if far from a tap I sometimes dust with dry soil to absorb the spray. For plants with a strong root system that readily regrows just cut off the leaves. 
In defence of glyphosate you will damage or kill far more plants with routine digging and hoeing.

In this case too much of the plant becomes the weed
No links today. You can just browse my previous articles by going to glyphosate in the links column or insert topics or named weeds in the search box

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