Wednesday, 30 October 2013

Soil Preparation and Cultivation

Soil Preparation and Cultivation

Having come to the conclusion that modern life is all about money and that most advice on seed packets and books is based upon you buying seeds each year and all pest control in popular books is about buying chemicals and how you need to buy good seed compost and that many seeds are now F1 hybrids often coated in something blue or green, I decided to go about learning from a bygone era.

An era before commercial gene manipulation, before the main emphasis was purely about money and more about quality and before science of growing really took over. An era when observation and generations of knowledge were still past down. This era seems to be before the first world war.

Luckily many books from that time are now available for free in the form of ebooks and the language used in them is less complicated. These books can teach you simple techniques about growing and storing your food because back then it was more common for people to grow their own and make pickles and preserves but also they used to use so many more plants.

Two such books which I have been reading are:

The Vegetable Garden, What, When and Where to Plant which forms part of a farmers manual from 1912
Root Development of Vegetable Crops by John E. Weaver and William E. Bruner 1927

I was surprised to read in the first book that a vegetable garden can produce 10 to 15 times the value of vegetables compared to the same space taken up by a large farm. 

This seemed strange until I realised that even back then things were done with crops purely based upon financial return. They had a lot of knowledge about what would grow best and how to grow more and better but were restricted by market value, shipping costs, labour costs and fertilizer costs. Everything was a compromise between making a profit and getting the most vegetables. It shouldn't have been a surprise and it does highlight why we now use so many pesticides and chemicals and fertilizers. It also goes some way as to explain why all modern books tell you to add fertilizer, to spray pesticides to obtain best crops. Most modern knowledge about vegetables is based around the commercial reasons and takes no account that you, the home gardener, has the free labour and free compost and a small enough plot to make it worth while doing a different way.

Even the modern day seed producers, seed catalogue companies, are restricted in the same way. When they test how best seeds will grow in what environments they are limited to systems which are profitable on a larger scale. Knowledge is being past down and written about based upon systems that simply aren't applicable or of much interest to a home gardener. Instructions on seed packets such as sow in spring at this or that spacing and re-buy the seeds the following year don't take into account that the home gardener can setup a far better environment on a small scale which means seeds can be grown closer together, sown when nature intended and seeds can also be collected and re-used.

Looking a bit deeper it becomes obvious why the farmer ploughs and prepares soil to a depth around 6 inches and spaces rows as they do. They have to have a machine capable of going a certain depth, which need to compact the soil in between with a wheel or horse. To plough and prepare soil deeper requires bigger and heavier machines which meant more horses or more expensive more powerful machines.   

Looking at root systems and how much moisture and nutrients a plant takes up also restricts how close they can be planted. It's a compromise between crop yield and expense. Plant them further away and you have less plants, plant them closer and they need more water and more nutrients to be added, often more often.

You often hear and read that you can't sow seeds too close together because they compete for the same scarce water and nutrients, which is true, but this is surely based upon a commercial view since you can mitigate competition between plants by applying more nutrients and more water. The home gardener can also make use of deeper prepared soil because he or she doesn't have to worry about the cost or machine power needed to plough and till deeper he can simply double dig. Yes it takes longer and is more work but if you have the time this isn't an issue as it is with commercial farmers.

A home gardener can feed the plants as required and prepare the soil as per the root requirements of the individual plant thereby changing the the advice given by the seed companies. This also changes the answer to how much do I need to manure my vegetable patch and how often do I water and how much produce can I grow within a given space. The official commercial answer is not necessarily applicable.

What the home gardener needs to do is learn about root systems and feed the plants with what they need. 

To prepare the soil the farmer doesn't have much choice. He has the soil he has and he has a certain amount of money that it is worth spending on that soil for the specified crop. This also limits what the crop is.

We are told this or that crop won't grow in our climate and that may be true, in a commercial world, because the crop may need better protection from wind, it may need protecting from the sun or it may need shade which often the farmer can't give it simply because it isn't financially viable to drive a machine along each row for a second or third time during the growing season but the home gardener can take a plant and protect it, which may mean growing another plant next to it for shelter. It may mean earthing up on the south side to provide shade in the hottest time of the year or earthing up on the north side to shelter it from wind during the winter.

So many people are growing so many different crops and having success by breaking all the rules that suggests the commonly given rules are not correct or not applicable. 

By throwing away the rules and experimenting many people have found better ways of growing food. They can grow plants much closer together and have fewer problems.

To dig or not to dig, what method is best?

There always seems to be a debate about which method is better but after reading about soil and root systems I've decided that there isn't a better method. They are just different methods. To get a good crop, and there is even a question as to what a good crop is because surely a good crop depends on what you want out of the crop, perhaps just enough is good enough or perhaps as much as possible is a good crop, but with a no dig method you need to know if the soil is of good enough quality to hold moisture while at the same time as draining well enough to not bother about about digging and just apply compost or manure on the top. With this method you hope that nature can take nutrients from the top and provide them as deep as the roots need, and if the soil is too dense so that it can't breath or can't be broken up by worms and micro organisms then it can still work provided you put enough depth on top. That often involves using more compost and manure because you may not have as much usable depth, but less hard work which suits some people but will obviously be just as good as digging provided there is enough room for the roots and enough nutrients and moisture. With digging you can give the plants more room by preparing soil deeper and thereby giving the plant access to more nutrients deeper down. Manure or compost is still needed but perhaps less of it is needed. Neither way if done correctly would appear to be better than the other. 

The answer for myself is that I like the physical exercise part of digging but I also think that I will become lazy in time so I will dig first to break up my clay soil, add enough compost, manure and sand as required to provide as good a soil as I can, then probably only lightly dig over the following year or years and no doubt become lazy and won't bother to dig at all in the future.

If I am digging the question becomes how deep, and the answer to that appears to be in understanding the root system of the crops I will be growing and it appears that many crops have roots that go down 6 or 7 feet but most of the useful roots seem to be within 2 feet, so that will be my aimed for depth. I have plenty of time, manure and compost to be able to prepare soil to that depth and hopefully digging that deep will keep the soil in good condition for years. 

Another reason for me to dig is that the clay soil needs to be turned into a more loamy soil and at present it is very compacted and therefore contains very little oxygen. Watering a compacted heavy clay soil means the water just sits on top without draining away very deep. In fact the water only drains to a depth of a few inches. Clay soil is also a cold soil so digging it and adding humus will allow it to warm up which will also be very beneficial, but once it is loamy, draining and warmer the need to dig will diminish.

With either system the soil will become better quality if you keep applying organic material and nature should be able to help you to a large extent simply by having worms and roots growing. As long as water can drain through the soil without water logging around the roots while at the same time holding moisture and as long as you can replenish the lost minerals and nutrients there should be no difference between digging and not digging.

To Mulch or Not

The old farmers have answered this many years ago. Mulching in general with most crops does help because it helps to retain moisture but some conditions means that mulching can also cause problems. A better answer can only be found by reading what their experiments showed. Some plants benefit from it while others don't. Farmers often don't mulch because it is another cost they incur with time and material which the crop price can't justify but other crops benefit so much that it is a no brainer apart from the fact that modern methods, and different strains of plants are developed to give better crops without it, or at least good crops without doing it. 


I was surprised to learn that cultivation of the soil, breaking up the top surface of the soil, is actually a mulch. A dry soil mulch is almost as effective at retaining moisture as applying a straw or hay mulch. In some tests doing either would keep 17 or 18% moisture at a depth of 6 inches. A mulch of either type stops or slows down evaporation of moisture from the soil by providing a barrier between the air and the moist soil. This is beneficial providing there isn't too much moisture for the particular crop. If there is too much then you would want some to evaporated. Some plants do not want or need a top mulch of straw either because it makes no difference in some cases or because a top mulch may keep the moisture too high and effect the leaves or stems. A top mulch may also harbour insects and slugs or bacteria / disease which obviously wouldn't be good but in general a mulch keeps moisture in so is a good thing but in wet seasons may have a negative effect. 

The problem with cultivating the top few inches for a mulch is that it can damage roots. Traditionally the benefit of mulching in this way with some crops out weighs the damage of roots but only from a commercial point of view since any root damage is normally a bad thing and better crops can be obtained by cultivating at the correct depth as to cause no damage. If cultivation isn't deep enough to be an effective mulch it can still be beneficial but breaking the compacted top surface to allow drainage and also kill weeds.

Whether cultivating the top soil to form a mulch or laying straw as a mulch there are many benefits, stopping a top crust from forming, preventing weeds, and keeping in moisture as well as allowing the soil to breath. 

The home gardener should be mulching with either method or both but should also read up as to what crops benefit the most so as to work out whether the effort and expense is worth while. In some circumstances not mulching or removing a mulch may also be beneficial. As with anything there isn't a hard and fast rule that always applies.

A lot can be learnt by going back in time and seeing how things used to be done and why but also learning why something isn't done. Just because something isn't done by commercial organisations doesn't mean that it isn't worth the home gardener doing it, just that it doesn't always make commercial sense which is a totally different aspect.   

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