Thursday, 30 August 2012

New strawberry bed

The new strawberry bed is finished now.  I have four rows of new plants and two rows of one year old plants.  That will be more than enough for me.

I was all ready to plant some rocket, American winter cress, lambs lettuce, spinach and winter lettuce until I discovered that I had left my seeds at home.  Not to worry.  The seed bed is raked and level ready for when I do remember to take the seeds to the allotment whenever that might be.

I dug over the old strawberry bed and dug in the old plants mixing in a little pigeon manure.  I was practising (NB I am writing in English) my digging techniques because I will be lecturing on how to dig effectively on the 30th of September.  I was just single digging throwing up the sods onto the top of the dug soil and slicing off the top 2 inches and letting it fall into the trench.  I kept the surface of the turned soil level by breaking up the sods with the back of the spade.

There is some thought that you should leave the soil rough and the clods unbroken so that the winter frosts can break them up.  This might work with some soils but it certainly doesn't with mine.  If I were to leave the soil rough dug then I would have to spend time in the spring breaking down great clods of soil that have set like concrete.  I will continue to break down the soil into a good friable texture and carefully level it as I dig  during the autumn and winter.  If the winter frosts then want to break it down even further then it is welcome to.

I wanted to continue to cover this bed with grazing rye and winter tares for the winter and this necessitates making a seed bed.

I raked over the ground but did not have time to plant green manure because I spent about an hour weeding between the rows I planted earlier.  The rye grass and tares mix will prevent weeds from growing but not until they have grown quite large and formed a good canopy of leaves to cover the ground.  Until then, I will  keep the weeds down.

I usually go along the rows with a hoe and cultivator and this seems to be adequate to remove most of the weeds.  However, I am experimenting with using the hand fork because I have seen Don use it very effectively to take off weeds from his allotment.  Not only does it enable you to hand weed more effectively, it also makes the soil very friable.  The soil looks very good when you have forked it over and broken all the lumps.

It does not necessarily make plants grow any better but it is pleasing to see neat rows with smooth, clean soil between.

There are several reasons for covering the soil with a green manure.

Using a fibrous rooted grass like grazing rye produces a really good soil  tilth when it is dug in.  The roots are incredibly adventitious and the soil in between them is fine and sandy.  These roots seem to be ideal for gleaning nutrients from the soil and fixing them within the structure of  the plant preventing  loss from leaching by heavy winter rain.

Although the leaves of grazing rye are soft and not very robust they are very effective in forming a barrier that is fairly impenetrable to light.  This will  prevent germination of weed seeds keeping the soil clean during the autumn and winter months.

Rye grass is used as green manure because it rots down quickly adding carbon and  nutrients to the soil speedily.

The tares forms a symbiotic relationship with soil bacteria such as Rhizobium leguminosarum biovar viciae  which can fix nitrogen from the air.  Rhizobium leguminosarum biovar viciae  can infect several leguminous plants including peas. Nitrogen is reduced through the action of several enzymes; the most important for this process being nitrogenase.   Nitrogen is an important plant nutrient.

So the Rhizobium captures the nitrogen from the atmosphere and passes it onto the plant that uses it for growth.  This process occurs within the plant root nodules and only benefits the infected plant.  Some say that nitrogen can be passed to other plants when growing close to an infected leguminous plant. I cannot see how this happens because of the intimate nature of the symbiosis.  However, there is a large turnover of roots in most plants and as the roots die they must give up their constituent nutrients to the soil which then could be used by other plants.

The only way that other plants can benefit from this symbiosis is when the infected plant dies and rots down releasing nutrients; including the nitrogen that was fixed by rhizobium.    The fixed nitrogen is transported and used throughout the plant and this means that all the plant should be dug into the soil to get the full benefit.

Some might say that rhizobium bacteria may well continue to fix nitrogen in plant roots even when the tops of peas, beans and tares have been cut off.  I would question this because nitrogen fixation is a very energy intensive process.  The energy to promote nitrogen fixation in the root nodule of legumes comes from the plant.  While there may be a small amount of stored food in the roots this will quickly be used up by the nitrogen fixing process. Once the energy from the food is used up, nitrogen fixation will cease because there are no photosynthesizing structures to replenish the food.  Any nitrogen that is fixed will pass straight into the root and will only be released when the roots decompose.

The benefit only comes when the dug in tares breaks down in the soil releasing nitrogen that was initially captured from the air.

Wednesday, 29 August 2012

Moving the strawberry bed and planting green manure

Spent the day digging over the old brassica bed.  I have taken out the swedes and kolhrabi and put them in the store shed.  There are not that many left and the ones that are will be eaten over the autumn.

Comfrey leaves have been dug into the trenches because strawberry plants seem to grow better when this is done.  I also dug in some pigeon manure.  After digging over the ground was consolidated by shuffling over it and raked as flat as that part of the allotment would allow.  I went around looking for some well rooted stolon plantlets in the strawberry bed and transplanted them into the new area.

 I planted four lines with about 15 plants in each line.  The plants were spaced about 30cm each way.  I could have offset the planting but didn't mainly because I didn't think of it but also because it is easier to hoe when the plants are in lines both ways. A little mychorrhizal fungi was added to each of the planting holes and    each plant was watered in with a little comfrey liquid.

I am going to plant another two lines of the year old strawberry plants because they will still be fruiting well next year.

There will still be room left on this bed so I will plant some rocket, lambs lettuce and American land cress for winter salads.

This will still leave a considerable number of old strawberry plants unused.  I will dig these into the ground they are occupying now adding some pigeon manure as well.  Then the grazing rye and winter tares green manure will be planted in rows to cover this area.

This will mean that two whole allotment beds will be covered in green manure.  I am hoping that I will be able to cover much more of the allotment in green manure before I run out of seed.  

I have put most of the onions into the store shed as well.  They have got to a reasonable size despite the onion fly and the cold wet weather.

Sunday, 19 August 2012

Planting the green manure

Rather than creating my own green manure seed mixture, I have bought some grazing rye and winter tares seed already mixed.

The grazing rye forms an incredible fibrous root system that holds moisture and nutrients within the top soil.  It forms a dense mass of leaves that cover the surface of the soil an protect it from winter rain.  Both the roots and the leaves are a reservoir of  nutrients that will break down quickly when dug into the topsoil during the spring.

Tares and rye green manure 
The winter tares are in the leguminosae family which form symbiotic relationships with nitrogen fixing bacteria.  Nodules of bacteria form on the roots and provide the plant with nitrogen which is incorporated into proteins within the tares's cells.  (NB the apostrophe is in the correct place)

Green manure planted in rows goes further
and forms a weed suppressing canopy

All the green manure has been planted in rows.  It gives
the opportunity to hoe out weeds when the green manure is
small like this.

It grows best if sown in the late summer
- late August or September in the UK

This green manure has grown well but
later sowings have been attacked by
slugs and snails.

Planting in sucession
 As crops have been harvested the ground has been dug over, manure added and carefully raked to make a seed bed.  So, this ground had the early peas in the background with the later maincrop in the foreground.
The green manure canopy is closing over - not many
weeds evident

If you look carefully you can see seedlings of Sinapsis alba 
and Veronica agrestis.  So not all the weeds have been
hoed out

But you can't see 'em when the green manure forms a canopy
October 2012.  It looks a little more untidy in December 2012
because of winter rains and frost but it is doing its job. 
 This green manure will only be dug in at the last minute before next years crop plants are planted or sown.  There is some suggestion that there may be an allelopathic effect so digging in about two or three weeks before planting may be the best strategy.  My idea is to get the maximum effect possible and that means leaving the green manure until late spring before digging in.
Green manure on the old onion bed.  
Green manure on the old Lathyrus odoratus bed
I am trying to catch the nutrients from the dug in sweet pea plants because they fix nitrogen from the air.  This is an addition of nitrogen and is probably significant for a small allotment like this.  If the nutrients and the carbon can be captured in the green manure plants then there is a chance that it could be used by crop plants when they are dug in.  (The carbon will only be used to produce a really good root run here, although it can be utilized by mychorrhizal fungi in other parts of the allotment.)  This is the new brassica area so no mychorrhizal fungi will be used here in the new season.
Late sowing like this means that the plants have not grown
very much and no canopy has been formed yet

When winter tares are dug in the nitrogen that has been fixed by the bacteria and passed to the plant returns to the top soil when the tares rots down. Tares will rot down relatively quickly.

After digging over the potato bed to remove any little potatoes that I missed and added pigeon manure, I have sown green manure in rows.  There is some thought that green manure should be sown broadcast.  I see no good reason for doing this and several reasons for not doing it.

I want to keep the green manure as free from weeds as possible.  This is difficult when sowing broadcast.  When planted in lines I can get to weedy areas and remove the unwanted plants.  I can keep the green manure watered with comfrey liquid and hoe between the lines to keep the soil open and free of weeds.

I have also put this mixture of green manure on the old pea bed after adding pigeon manure.  I still have one line of Hurst Green Shaft that is producing peas so I will not be able to cover the whole area yet.  I also want to put green manure on the old leaf and root bed.  The carrots, parsnips and beetroot will stay in the ground but a lot of the leaves have gone over now so I will be removing them to put the green manure in.

Most of the vegetables have cropped much better than I thought they would.  The potatoes are washed, dried and bagged and waiting to go into the store shed.  Onions and leeks are starting to swell up and make decent plants.  The sweetcorn has produced some good cobs and the pumpkin and courgettes are producing  fruit now.  No squashes yet and no cucumbers either.

I have taken out all the stems that fruited from the raspberries and tied in all the new canes.  I await the autumn raspberries.  They will be fruiting soon.

I am leaving the sweet peas to go to seed which I will collect and plant in the autumn.

I need to take more of the swedes and kohlrabi or they will go woody.   I am finding it difficult to keep up with them. I need this area to plant the new strawberry bed so they will have to be harvested soon.  I will put straw around the strawberries again next year.  It was a great success this year.

A few more of the cabbages are ready for harvest now.

The runner and climbing French beans are cropping now.  I am getting quite a few runners even though it is a really late year.

Most of the Florence fennel and celery that is left has gone to seed.  No matter they will make good green manure.

 Carrots and beetroot are being slowly cropped.  The carrots are a little forked this year and I am not too sure why.  I did not add any manure to this bed this year.  They did get a lot of green manure and pea plants dug in last autumn though.

So overall not as bad as I thought it was going to be.  Probably the most disappointing were the sweet peas.