Second week in May

I can't believe it is the middle  of May.  The cold east winds have kept me from sowing seed and planting out.  I am quite grateful for this because there have been some significant frosts.  The only things that has been cut back are the grapes.  I am not too sure whether I will have any fruit this year because everything was flowering.  The apples particularly.

The winter and early spring have been particularly dry  and this has lead to me loosing four of my apple grafts and they are the ones that I didn't really want to loose.  Two May Queens, a Queen Cox and a Orleans Reinette.  There is always next year and more anticipation to look forward to.

Got most of my seed sown.  The only seed that has not germinated are the carrots.  I think that they need a good dose of water to get them started.  So we have parsnips, beetroot, chard, spinach, dill, chamomile, tarragon,  Florence fennel and Good King Henry.  I am going to put some more carrots in just in case the others don't germinate.  The sweetcorn has begun to grow in the greenhouse but with  poorer germination than I wanted.  I have used last year's seeds so I should not expect too much.

Lots of squashes have germinated and have been transplanted into three inch pots.  Leeks are coming on well and will need to be transplanted soon.  I already have some planted in the onion bed.  Garlic and Elephant garlic are growing and not being eaten by the Phytomyza gymnostoma.  The onions are fairly securely protected by the scaffold nettling stretched over the blue water pipes.  I have buried the edges of the netting in the soil.  Thankfully, I had just hoed up the potatoes before the worst of the frosts and they have survived unscathed until now.

I have planted all the early sweet peas and am starting to plant the later ones.  They are being watered in with comfrey liquid but I am not giving them any other nutrients except what was in the soil from the green manure.  I planted them as late as I could to avoid the flea beetle and I seemed to have missed most of it.

The tall peas and the ordinary ones have germinated and I have put up the mesh for the Alderman and Onward to grow up.  I will wait until the others have got a little bigger before I put up the mesh for them.  I dug down at least three feet to get out some old curbing  that was concreted into the soil in the pea bed.  Who buried it here is anybodies guess and I could have ignored it, however it was annoying me and I could use it for edging the path.  So I dug down and hit it with the bull hammer.  Remarkably, it came away without a fuss and now lives on the edge of the main allotment path.  The bits of old scaffold boards that I had there originally had rotted away and were just good for slug homes.

Sowed some swedes in the brassica bed.  I don't really think that I will sow any kohl rabi this year.  It is good to put into stews, vegetable curries and soups but I had far too much last year.  I don't have any seed left so I will have to buy some more if I do decide to sow some.  The other things I have not sown this year are American land cress, Hamburg parsley, salsify and Scorzonera.  Got a few herbs sown in the greenhouse to replace the ones that are getting a little moth eaten in the allotment.  The thyme and sage are already germinated.

Being so late with everything this year, I have decided to buy tomato plants.  I always did in the past and it is much more convenient unless you want to grow specific varieties.  I have Alicante and a couple of others making twelve plants in all.  They will easily fit into the two greenhouses.  I am only going to have two tomato plants in the peach house.  Mainly because I don't really need that many tomatoes but also because it shades the peach tree and that is the main plant in this greenhouse.  The peach has quite a few fruitlets.  This never usually converts into ripe peaches but you can always hope and that is what I do.

I need to transplant out all my brassicas into three inch pots - I told you that the I was behind - and plant out the beans.  After I plant out all of these, the allotment will be full.

Finishing off the hugelkultur in the potato bed.

Starting off a new Hugelkultur in the potato bed.

Bloke came down with a lorry load of shredded woody material and had some logs on the back as well.  He gave me the logs so I decided to make another trench Hugelkultur in the potato bed.  I wanted to raise the soil at the north end of the bed in order to create a surface water calming bank alongside the espaliered fruit trees.  The Hugelkultur trench will be a subsurface water calming structure until it decomposes. 
I dug down one spit today and left the soil on the side of the trench.

I always use garden lines because I can't keep a straight line without them.  There are lots of reasons for not digging but there is no other way of introducing large quantities of organic matter and deepening the top soil.  I will take another spit out of the bottom of the trench and then fork over the bottom which will give me three spits of turned over soil.  Loads of waste material from around the allotment will be used to put into the trench. 

The old vegetables from last season.  A few celery and celeriac together with carrots and beetroot. 

Old bits of wood that I have collected from under the hedge and in the woody chippings piles.  I will probably get some more before I fill in the trench.  I will certainly clean the bottom of the hedge a little more. 

The logs off the lorry.  These will go at the bottom of the trench.  I think they are mostly cherry laurel. 

I will move the frames off the hot bed, which has not been that hot during the winter.  The woody chippings have rotted down now and will go at the bottom of the trench.  I will put the frames on top soil now and just rely on the glass to heat the soil.

If that is not enough shreddings, I will resort to the woody chippings pile to add more woody material.

Mostly X Cupressocyparis laylandii and holly but it is all grist to the mill.  I will also be putting the cuttings from my daughter's garden in the trench too.  It will all be two spits down and can moulder there for a year under the potatoes and whichever green manure I plant after them. 

The top soil is deepening and now is more than a spit deep.  The subsoil is darkening with organic matter too.  Deeper topsoil means more organic matter, more nutrients, more microbes, more water and more air for vegetable roots to delve into. 

Now I am going to try and explain why I think that it is a good idea to introduce organic matter into the subsoil as deep as I can.  In normal conditions plants can get water and dissolved nutrients easily from the top soil.  There is usually decomposition going on and nutrients being released.  As drought conditions start to appear the roots start to forage for water lower and lower in the soil profile.  The dry top soil means that they cannot obtain nutrients from here because there is no water to dissolve them in.  Nutrients can only enter the root as dissolved ions.   As the roots pass out of the dry topsoil they pass into the moist but infertile subsoil where nutrients are much more scarce.  Little is dissolved in this water and although the plants have adequate water they begin to get nutrient shortages.  Bottom old leaves start to yellow as nitrogen is transported away to the growing tips, although the plant is not wilting.  If we can deepen the soil, adding lots of organic matter, it will make plants more able to withstand drought conditions and the shortage of nutrients that it might bring.

So that's what I have been doing today - that and turning one of the compost bins.  I will use the compost to mix in with the top soil as I rake it back into the trench. 

The possibilities of using slope to benefit the allotment.

My allotment slopes to the south east.  What advantages does that give to the allotment crops?  The aspect of the allotment can give quite an advantage.  Being south facing means that the sun's heat and light is a little more concentrated and will warm up the soil earlier in the year and allow crops to be grown later in the autumn. 

Path alongside the allotments looking down the south facing slope.

Although I grow crops in north south rows,  I have put in paths from east to west at right angles to the slope.  The paths have been made as mini ditches and soil has been taken out and put onto the growing areas to raise them.  The mini ditches are aligned more or less with the contours across the allotment.  Water will flow at right angles to the contours soaking in as it does.  Some surface water will flow into the ditches and spread out.   I have filled the  ditches  with woody shreddings which will soak up some of the water and prevent it from evaporating creating a reservoir of stored water. 

Espaliers planted on the top of the raised bank.

This allows surface rain water to be spread out evenly along the path, slowed down and soaked into the soil.  Although irrigation is not a particular priority in the UK climate, we still have to consider the effects of leaching and soil erosion. 

Raising the level of the soil, creating banks on the downside of the slope and planting espaliered fruit trees or soft fruit along the east west raised soil aids in the slowing down of water (mass flow) through the soil.  As the water is slowed, it allows dissolved nutrients to be taken up by plants before it is lost though leaching. 

As plant nutrients are soluble minerals they will be leached slowly as the water flows to the bottom of the slope.  I have planted comfrey at the bottom of the slope to catch as much leached nutrient as I can.  Their deep roots will absorb much of the available nitrogen and any potassium and phosphorus that is available.  The leaves and stems of the comfrey can then be composted, made into comfrey liquid or put into the worm bin to recycle the nutrients. 
It is all about slowing the mass flow of water through the soil.  This will slow leaching, allow more time for uptake of soluble minerals; capture eroded soil particles, enhance water filtration  and provide more opportunity for upward water capillary action for plant growth.


My compost heaps are at the top of the slope so that any leachate that they produce will flow down the slope and into the allotment soil.  In a similar way, I have planted perennial nitrogen fixing legumes along the top of the slope so that any nitrogen they fix will flow naturally into the allotment top soil.  I will be planting perennial legumes alongside the fruit trees and bushes on the banks alongside the paths so that nitrogen will flow with the water into the growing areas. 

Compost bins at the top of the slope so that leachate will flow into the allotment.

Laburnum and lupins planted at the top of the slope so that nitrogen they fix will

flow into the allotment growing areas.

In the UK there is often too much water flowing through the allotment.  It is necessary to put in some kind of drainage to prevent waterlogging.  I have dug out a trench at the bottom of the allotment and filled it with stone sieved from the top soil.  The stone was covered with paving slabs to make a path alongside the hedge. 

Drainage ditch under the slabs.  Path is at the bottom of the slope.   

During the driest months in summer, the soil is covered by mulches to reduce evaporation and the trench Hugelkultur further slows the soil water and retains it as a reservoir that is accessible to plant crop roots. 

So slopes can be very useful. 

Is mulch made from conifer wood chip or bark acidic?

I have seen it often suggested that organic mulches such as wood chip and bark from conifers are acidic.  The pH is a measure of the amount (the negative log of the concentration)of hydrogen ions and this measurement must be done in a liquid.  You cannot measure the pH of a solid unless you dissolve it in water.  As most of the solid from wood chip and bark  is insoluble in water, it is virtually impossible to measure the pH of these materials.

The woody chippings or bark could be giving off substances that acidify the soil solution as they decompose.  However, neither pine bark nor pine chippings have been found to have any effect on soil pH.  (Tahboub, Lendemann and Murray 2008) There is no significant change in soil pH for wood chip incorporated into soil measured over a three year period.   Bare soil is more likely to have a low pH (be acidic) than organic mulches.  Shredded bark and woodchip have been found to be the least acidifying of the organic mulches.

Regardless, wood chip could be shaken up in water and the resultant solution tested.  This should be done with distilled water or deionised water to make sure that you are testing the pH of the dissolved substance not the pH of the water.  Tap water contains a lot of substances although it usually has a neutral pH of around 7. 

Now, I haven't tested the pH of  woodchip solution, however I would conjecture that it would be fairly neutral or possibly slightly alkaline.  There are some that suggest that the phenolic substances secreted by the above ground structures of a plant may be acidic. I don't know. 

What I am going to do is test the soil beneath an estimated 2000 year old yew tree.  The tree is in my local nature reserve.  There is nothing growing under the tree within about a 50 food diameter. 

I would suggest that the pH of the soil is no different from the rest of the wood so I will take samples from outside the yew trees influence as well as under its canopy.  After 2000 years of falling litter surely it would have affected the soil underneath it. 

My suggestion is that there will be no difference between the soil pH from beneath the canopy of the yew tree and the soil from outside the canopy.   

The fact that there is no build up of litter under the tree would suggest to me that some invertebrates, such as worms, are feeding on the organic matter from the tree.  Worm's preferred habitat is one with a neutral or alkaline pH.

Usually scientific consensus is pretty solid, however sometimes explanations that purport to be scientific are merely based on hearsay and anecdote and need to be challenged by experiment.