pH of the different types of compost and soil

Each plant has specific pH requirements in order to develop harmoniously. The table below shows the pH of compost and soil. The pH up to 6,8 is consider acidic, or sour, pH between 6,8 – 7,0 neutral and above 7,0 bitter or alkaline.

Type of soil/ substrate / compost	pH minimum	pH maximum
Compost (depending on the proportion of potassium)	6,3	8,0
Manure (fully composted stable manure)	6,3	7,4
Old forcing manure (fully composted)	7,0	7,6
Leaf compost (it depends on the type of deciduous foliage)	5,0	6,0
Compost from coniferous needles (depending on the type)	4,0	4,7
Turf ground (depending on the turf)	6,8	7,4
Clay	7,0	7,8
Moss ground	3,5	5,0
Heathland ground (in chunks)	4,0	5,2
Peat	4,0	4,6
Coarse sand	5,7	6,4
Ditch sand	7,4	8,0

Soil mixes for plant propagation and germinating seeds

For propagation of your plants and for seed germination indoors or in a greenhouse you will need different types of soil. Some seeds are sensitive to the type of soil and the diseases related to the ground and this means that they can best germinate in a soilless substrate. In addition, most of the cuttings prefer a soil-less substrate. Nevertheless, there are seeds that require immediately nutrients and then they are the best seeded in a rich soil mixture. On this blog we will make often references to these particularities.

Ingredients for your soil mixes will be shown below.

Leaf mold

It is obtained from rotting leaves and it has a high cationic exchange capacity, good mineral content but it is missing macronutrients (Nitrogen, Phosphorus and Potassium). It has a lower pH and may contain agents for diseases. It should always be sterilized. Coarse texture is best used in rooting media or potting mixes.

Well rotten compost

Compost

Compost results after the decaying organic material under the influence of fungi and bacteria. Because of the existence of microorganism it may protect your plants against diseases. It has a high cationic exchange capacity and a good balance between macronutrients and minerals.

Fine washed river sand

Fine sand

It is used for a better drainage of your soil because the sand grains have different sizes and the water is drained quicker leaving air spaces in between. It is inert and it does not contain any nutrients. Use always washed sand and never use sand from the beach because it contains killing amounts of salt.

Grit

Grit or coarse sand

Use always washed grit or coarse sand to improve drastically the aeration and drainage of your mixes. It mostly used for the rooting of cacti and other desert plants that require a more open medium.

A brick of dehydrated cocopeat

Coconut fibres / coco peat

Usually are sold in forms of dehydrated bricks that need to be rehydrated before use. It is derived from composted coconut shells and it is good replacement for less fine sphagnum moss in soilless substrates.

Perlite

Perlite

It is resulted from expanded volcanic rocks. It retains the water good and because it is inert it also drains water quickly. It is used in sterile mixes to improve drainage and aeration.

Potting soil

Potting soil

Use soil of the best quality for seed germination and plant propagation. The soil must free of any other seeds, insects eggs. This soil is used for rich soil mixes.


Coir

Coir is a fibre resulted from coconut husks used as peat substitute. It dries out less quickly that peat but
requires more feeding. It is a good base for soilless mixes.

Peat

Peat

Is stable, long lasting and well aerated and retains the water well, but low in nutrients. It is difficult to re-humidify once it has gone dry. It is used for lightweight mixes intended for short use.

Dried and groud moss

Sphagnum moss

Sphagnum moss

Do not use coarse sphagnum moss in propagation for this is intended mostly as an orchid medium. Use finely ground sphagnum moss for soil mixes intended for seed germination and semi-coarse for cuttings media.

Vermiculite (magnified photo)

Vermiculite

It is expanded and air-blown mica. It contains traces of Magnesium and has high cationic exchange capacity. Acts similarly as perlite but holds more water and less air. It supports drainage and aeration. It comes in various degress of grinding. Some of the finest are used on the top part of the substrate as a physical barrier against harmful bacteria and fungi.


 
Fine bark

Fine bark or chipped barked is used as peat substitute or for free draining acidic mixtures, especially for orchids, palms and other indoor plants.

Recipes for mixes

Making your own mix has the advantage of knowing what your mix contains. Accordingly, you can realize the ideal medium for a specific type of propagation technique or plant. You can find in the shops ready-made soil mixes generically Seeding and Cutting Soil Mix. When you mix your substrate, hygiene is very important. Use only clean tools and sterilized soil.

How to sterilize soil?

If you are planning to use garden soil in your mixes it is crucial that you sterilize it before incorporating it. Sterilization will kill possible harmful organisms that could affect seedling and cuttings. To do this the soil must sifted to remove clumps, stones and any other residue, but also to obtain a finer structure. Sterilizing garden soil for commercial use is done in special units. These are expensive and unnecessary for home use. An oven or a microwave would do just fine.

For soil sterilization in an oven you will need a deep baking tray, of about 8 to 10 cm. Bake the soil for about 30 minutes on 200 degrees C. You should know that unpleasant badly-smelling vapours may be released.

In order to sterilize soil in the microwave you need a roasted bag, resistant to high temperatures. After soil is inserted seal the top of the bag to avoid the contamination of the microwave. However, make a few holes and place in the oven for 10 minutes on maximum power.

Observation: some of the substrate mixes cited below, require some addition of non-biological nutrients. You may avoid using those mineral nutrients by excluding them from the mixes. Later on we will publish some ways in which you can obtain your own biological fertilizers.

Substrate recipes for potting mixes, rooting media and seeding mixes.

Rich potting mix	Soilless potting mix	Soil based seeding mix
2 parts compost 1 part potting soil 1 part sand 1 part vermiculite 1 part perlite	3 parts peat or substitute 1 part sand or perlite For each 36 liters add 14 g ammonium nitrate 28 g potassium nitrate 45 g superphosfate 85 g ground limestone 85 g dolomitic limestone	2 parts potting soil 1 part peat or substitute 1 part sand
7 parts potting soil 3 parts peat or substitute 2 parts sand For every 36 litres add 113g general purpose slow release fertilizer and 21 g limestone	3 parts peat or substitute 1 part sand or perlite For each 36 liters add 14 g ammonium nitrate 28 g potassium nitrate 45 g superphosfate By avoiding the use of limestone you will obtain an acidic composition	2 parts potting soil 1 part peat or substitute 1 part sand For each 36 litres you may also add 42g superphosfate 21 g ground limestone
7 parts acidic potting soil 3 parts peat or substitute 2 parts sand For every 36 litres add 113g general purpose slow release fertilizer This potting mix is used for acidophile plants.		2 parts potting soil 1 part peat or substitute 1 part sand For each 36 litres you may also add 42g superphosfate

Soilless seeding mix	Soilless rooting media	Sterile substrate
3 parts peat or substitute 1 part fine bark 1 part perlite For each 36 litres add 36 g trams of slow release fertilizer	1 part peat or substitute 1 part sand (or perlite or vermiculite)	1 part finely ground Sphagnum Moss 1 part perlite
1 part perlite 1 part vermiculite 2 parts finely ground sphagnum moss	1 part peat 1 part fine bark To each 36 litres add 36 g of slow release fertilizer	1 part cocopeat 1 part perlite
	1 part peat 1 part fine bark 1 part perlite To each 36 litres add 36 g of slow release fertilizer

 

Plants which indicate the type of the soil

The table below comprises some of the most popular indigenous weeds. They are also indicators of the type and quality of the soil when they are wildy growing.

Name of the plant	Photo	What do they show?	Observations
Field Bindweed (Convolvus arvensis)		Heavy clay soil, rich in Nitrogen	Avoid using the rotary tiller because it multiplies the fragments of the rhizomes which root very quickly.
Lawn Daisy (Bellis perennis)		Clay soil with an acidic tendency	This plant is not at all competing with the others.
Smooth Pigweed (Amaranthus hybridus)		Soil rich in Nitrogen	The plant produces many seeds and becomes quickly invasive.
Common Broom (Cytisus scoparius)		Acid soil, often sandy	Usually good soils for strawberries and asparagus.
Common Dandelion (taraxacum officinale)		Heavy clay soil, rather compact, rich in organic matter.	While it is not competing with other plants, it still needs to be removed completely from the ground.
Couch grass (Elytrigia spp)		Exhausted soil, too mechanically cultivated, too rich in potassium and nitrogen	Avoid using the rotary tiller because each fragment produces a new plant.
Common purslane (Portulaca oleracea)		Sandy soil which does not retain water, showing first signs of erosion	Rather a Southern type of plant which can be consumed fresh or prepared. Rich in vitamins.
Common Horsetail (Equisetum arvensis)		Wet soil, insufficinetly aerated	Horsetail indicates that a high flow of water.
Wild carrot (Daucus carota)		Lime dry soil	Do not remove all the plants because it is a host for various useful butterflies and insects.
Flanders poppy (Papaver rhoeas)		Humus rich soil	Indicates a good agricultural soil.

Know your soil

This is the time when you can best evaluate what type of soil you have in your garden or allotment. This is important because certain plants have a preference for a particular type of soil, while the others will recede. We will discuss about certain important features of the soil like: profile, texture, pH, fertility and living organisms. The quality of the soil determines the quality of your products.
The profile of the soil is the represented by several different layers:

1. The highest layer may be litter, this is clearly seen in the forests and it is the result of falling leaves and other parts of the plants living in the area.
2. Just under the litter it is the humus. It is usually darker, finer and well drained. It is composed mostly by mineral parts and organic parts. Most of the organic part of the soil is found in the upper layer, ideally somewhere between 60 – 90 cm.
3. The upper layer is a mixture of organic and inorganic matter, lighter in colour less fertile. The roots of the plants are digging through this layer looking for food, still.
4. Underground it is the lower part of the soil. It is more compact, it may contain stones or water, it lacks aeration and roots receive less oxygen. Most of the fruit trees expand their radicular system into this layer.
5. Underground may rest of different type of rocks which are impenetrable and they do not offer a source of food. Sometimes the roots of the tress may go around the blocks of stone to seek support. In other parts, near the rivers, this part may be always waterlogged and the survival of the roots of the plants is impossible.

In the left picture you are shown a soil profile or a grass land. This is not the ideal profile that you like to have in the garden, because the humus layer is not thick enough (the darker part). The deeper you go, the lighter the soil it gets. This is because deep soil lacks organic matter.


The texture of the soil may or not be identical in a garden. It all depends on the plants that were previously cultivated, the original features and the improvements given to the soil. The size of the particles forming the soil determines its texture. From this point of view we may classify the soil into three categories: clay soils, sandy soils, loamy soils.

• Clay soils
  
  Are composed of very fine particles of sand of the size of 2 microns. This is about 100000 times smaller than a normal grain of sand. These soils are heavy, they tend to be on the wet side and they keep water and nutrients very well. The drawback is that they are compact and difficult to work and many of the plants will have difficulties in developing their roots. Also during the dry spells, the soils tend to dry forming light grey rocky blocks, difficult to break apart. They have a tendency to waterlogging and extra-care should be given to the overwintering plants, because it facilitates rotting of the roots. In addition they warm up slowly during the spring and seed germination is delayed.
• Sandy soils
  

  

  They are just the opposite of the clay soils. They are composed mostly of sand, which has the capacity of being airy and oxygen reaches easier the roots of the plants. However they have a low water and nutrient retention. Certain root plants (like carrots, or potatoes) will flourish in these grounds provided that they receive regulate feeding and watering. They warm up quickly during the spring and they can be worked easy.
• Loamy soils.
  

  

  They are crumbly rich organic grounds, with good water retention and light structure. They are the best soil you can have in your garden, because they are composed of a good ratio of humus, clay and sand. 
  The ideal soil for the garden is composed of 65% sand, 10 % lime and 5 % humus. It is supple, crumbly, easy to work, had good water retention without the risk of becoming waterlogged.

How to determine your soil texture?
Look at your soil, take some samples. If you can make out of your soil a sphere, and while you shaping it you are reminded of Plasticine then you most probably have a clay soil. If it is sandy it loses shape immediately and if you have loam you will see that it is crumbly and the surface of your sphere is not regular.
pH. Is your soil alkaline or acidic?
pH measures whether your soil is bitter or sour, alkaline or acidic. pH is measured on a scale from 0 to 14. The lower the pH value, the more acidic the substance, the higher the value the more alkaline the substance is. For instance, lemon juice has a pH of 2, orange juice a pH of 3 and tomato juice a pH of 4, while sea water has a pH of 8, backing soda of 9, bleech of 13. The neutral value stands at 7. That is the pH of distilled water. 

Because of the composition of the soil, normally, the garden soils fall between 4.5 and 7.5. Certain plants, like Hortensias, Rhododendrons and Azaleas prefer rather acidic soils, others, like cabbages, more alkaline. Most of the garden plants flourish at pH of 6.5, so a very slightly acidic soil. While is relatively easy to increase the pH of the soil by adding lime, the things are not so simple when you desire to lower the pH.
The pH of the soil is important because the plants are able to absorb nutrients they need only under specific pH conditions. If the pH is too high or too low, certain nutrients, even if they exist in the soil, they practically unavailable to the plants. The attached diagram shows the availability of certain nutrients according to the pH of the soil.
Fertility of the soil is determined by five aspects: air, water, pH, organic matter and mineral nutrients. A fertile soil is rich in major nutrients (nitrogen, phosphorus and potassium), has sufficient quantities of mineral nutrients also called minor or oligo-nutrients (boron, chlorine, cobalt, copper, iron, manganese, magnesium, molybdenum, sulphur, and zinc), it has a good pH (usually 6.5). It is rich also in organic matter which has the capacity of making the soil lighter, easier to cultivate and contributes to drainage and water retention. A fertile soil is not only able to retain water but also has the capacity to avoid waterlogging. Air is important for the developing of the roots. Without air, the roots simply suffocate and then rot and the entire plant is compromised.

The soil is a true ecosystem by being the siege of intricate alimentary chains. The organisms in the soil participate actively in furnishing a good quality soil by their way of feeding themselves. The woodlouse, myriapoda, larvae of the flies and termites are fragmenting the organic matter. Certain mites, springtails and termites continue the fragmentation of organic matter in even smaller compounds. Beetles and their larvae, fungi, nematodes, worms and bacteria continue the fragmentation to even simpler compounds, making them available for the roots of the plants. At the same time ants, moles, slowworms, voles, termites are digging and making small tunnels in the ground, making it more airy. However some of these organisms may prove to be dangerous itself. Snails are feeding themselves on the crops but they are enriching the humus with organic matter once they are dead. Earthworms, although they are not directing menacing the crops, while they are digging tunnels underground can bring diseases and viruses to the roots of the plants. On the market exist a large assortment of chemicals destined to destroy all the insects in the ground, however this not ecological, and on long term these chemicals unbalance the healthy ecosystem of the soil.