Polytunnel - Soil Analysis

24th Jan 2002

Soil Analysis

I am supposed to be the one telling you all how to carry out  everything in the correct manner and at the right time, yet this year I am well behind and still have some digging to do. This however must be completed soon as I need to send some of the soil away for analysis in order to make sure that I start off on a scientific footing rather than an haphazard one. For those of you who may have just started growing exhibition vegetables and may have had you very first polytunnel, testing your soil is important so that you know exactly what is deficient in it as well as knowing what is in too much abundance in it.

Potato Winston
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Both of the above scenarios can be harmful to you plants so do send a sample away to any good soil analyist.. I have personally used Lancrop laboratories for many seasons now and to be honest they have saved me money over the years. Without a soil analysis I would more than likely have spread some base fertiliser by hand on top of the soil without having a clue how much the soil needed and indeed possibly using far too much of it.

Bone Meal

A classic example of this is the regular annual use of Bone meal in the soil to act as a source of phosphate which all plants need in varying proportions.

The problem with Bone Meal, even though it is an excellent source of organic material it doesn't all get used in one season, particles of it still remain in the ground and be activated once more the following season. It therefore follows that repeated treatments of the same ground over many years would see the phosphate level in your soil rise dangerously high. The levels of phosphate can rise so much that it can effectively lock up some of the minor or micro elements in the soil which are so vital in producing the very best from your plants.

Flooding the Beds

Once the beds under cover have been dug over they must be flooded out prior to adding any fertiliser that the result of your soil analysis may dictate. By flooding out I really do mean soaking the beds thoroughly; obviously at this time of year try and pick a day when it"s not promising any frost as the last thing you want is freezing water all over the paths etc. The way I do it is to connect up my lawn sprinkler and position it on the central bed so that the water will cover everywhere, my tunnel is 25ft by 10ft and the one position centrally will suffice to cover all the beds in one go. The water needs to be left on for a few hours until you are happy that it has permeated right through the soil.

The reason I do this is to try as much as possible to emulate what is happening to the garden soil outside which is not covered over and exposed to the elements. Last year was my best ever year with onions and believe it or not, it was the year that I did the least amount of grafting with the soil. I had done no work at all on the beds until about early February when I decided that I would just roughly dig over the beds with a spade and leave the water sprinkler running all over it. A couple of weeks after, when the soil had dried out sufficiently, I used my small rotovator to break it all down.

Organic Matter and Fertiliser

The soil had no organic matter whatsoever added to it as I felt that it really had enough humus already in the beds after many years of continuously adding farmyard manure, peat or leaf mould. The only other main difference was the use of a totally new base fertiliser called Hydrocomplex which is a product that I believe was developed in Norway. It contains Magnesium which is a vital element for top growth and through applying the pellets to the soil it provides a steady supply of Magnesium throughout crop development. It also contains Sulphur, an important nutrient input in areas of low sulphur, light soils and high rainfall. Finally it also supplies important trace elements to meet crop removals as the plants takes up nutrients.

Parsnips

The work of re constructing my parsnip cover will be going ahead soon, indeed it has to be completed hopefully before the middle of next month so that I can get on with sowing the seed. This year I do intend to empty out the parsnip beds prior to having the re construction work to the overhead covers carried out. The first bed was completed a week before Christmas and the second one was finished the week after so it has time to settle down prior to boring out all the holes.

Onions

I have been re planting my best onions for seed for many years now and have always been able to get very good heads of seed from them. However it is only possible to do this if the onions being planted for seed production have developed a strong root system. This root system needs to be developed early and quickly and In order to make sure that this happens it's imperative that the onions are placed on some bottom heat so that the roots get pulled downwards in search of the warm temperature. Mine get placed inside my growing cover and after a month, when they have grown a good root system they are then removed but still kept on the bench in the same warm greenhouse for a few more weeks. Later on they will be gradually acclimatised to their final growing environment by placing them inside my polytunnel covering them over initially with fleece to give them some protection from falling night temperatures.

It is not too late to plant some or even just one of your best onions from last years crop. It is really very simple but do make sure first that the onions are solid and healthy and showing no sign of disease. Fill a 9 inch pot or and old florist bucket with drainage holes drilled in the bottom, with a good quality peat based compost, I use Levington M3. Form a small well on top of the pot and simply sit the onion up to half way on top of it, this is better than simply pushing the onion into the compost thereby creating a hard surface for the emerging roots to pierce through. Water the compost well and place it on some bottom heat and by next August you should have you very own seed.


For those of you who may have just started growing exhibition vegetables and may have had you very first polytunnel, testing your soil is important so that you know exactly what is deficient in it as well as knowing what is in too much abundance in it. Both of the above scenarios can be harmful to you plants so do send a sample away to any good soil analyist.
Other 2002 articles of interest

· Polytunnels & Heated Greenhouses
· Prize Winning Onions
· The Top Growers in the Country
· Peas and First Planting of...
· Growing Cabinets and Artificial...
· National Vegetable Society...
· Carrots - Stump Rooted or...
· Shifting Sand Around
· Preparing the Celery Beds
· Growing Vegetables in Raised...
· The Impact of the new hybrid...
· After the Vegetable Shows,...
· Growing Your Own Vegetables -...
· Growing Your Own Vegetables -...
· Sowing Dates Used by Exhibitors

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Prize-winning exhibition vegetable seeds give you the advantage whether growing for show or just for the family. You can see our range of top quality selected seeds and horticultural sundries in our online shop