Permaculture - The most important properties of soil, which affect its fertility (lesson 16)

In this lesson, we will describe a few of the most important soil properties which we should be aware of while having a farm or garden. Of course, making the professional soil tests will give us the answer about all the parameters but in the article, I will suggest some natural ways to deduce what pH or soil heating level is just based on the observation of surroundings.

pH

What we can cultivate will depend on the pH of the soil in our garden. Some plants can not stand alkaline soils, others acidic. The ideal pH that allows the cultivation of the greatest variety of plant species is 6.8, good for the vast majority ranges between 6.0 and 7.0, but flora is generally present in soils with pH from 4.5 to 10.

If the soil is too alkaline, which is very rare, you can change it with acidic compost and slurry (see: a lesson about compost). You can also mix needle litter with acid peat or apply sulfates.

Too acidic soil is much more common due to the acid rain phenomenon. It can be slowly changed by liming the substrate, e.g. with algae lime or metallurgical lime (more details in the lessons about mineral fertilizers and lessons with soil components description).

We can check the pH of the soil by sending a probe to the laboratory, but if we want to do it more naturally, we could just observe the nature and deduce the soil pH based on the plant indicators' presence.

Acidic soil	Alcaline soil
heath speedwell	cabbage
holly	cauliflower
field woundwort	tricolor violet
rhubarb	asparagus
hempnettle	celery
chicory	peas
black currant	onion
chestnut	spinach
endive	broccoli
potato	common sainfoin
fennel	meadow sage
watermelon	spurge
shallots	mustard
tricolor violet	alfalfa
clover	leek
sphagnum moss	parsnips
Morison's spurry	nettle
sorrel	white dead-nettle
common heather	field pennycress
swamp cranberry	common fumitory
stiff clubmoss	broadleaf plantain

---

Soil depth

The required depth may vary depending on the plants we have in our garden. Most vegetables and flowers require the soil to be at least 45-65 cm deep.
In the case of trees and shrubs, in most cases, it is 65-100 cm.
There are exceptions, such as pear trees, oaks, and chestnut trees, which take root even 2 meters deep into the soil.

Indicators of the soil depth can be acacias, Prosopis, and the honey locust. They grow in both: deep and shallow soils, but in shallow soils, they will only become stunted in size.

---

Soil heating and the occurrence of frosts

How quickly the soil heats depends on its composition and color.
The wetter the soil, the more heat it uses to drain, so it heats more slowly. The rate of soil heating can be increased by sprinkling the soil with humus or fine coal. Heat loss can be avoided by using mulching too, which should also be necessary for other reasons (protection against nitrogen loss from the soil, protection against overgrowth of weeds, etc.). Under natural conditions, uncovered soil is very rare. The soil without mulch easily crusts, dries up, requires more watering and fertilizing

Plants that do not tolerate frosts, such as bananas, tomatoes, or potatoes, can be our indicator. When they occur in the wild, you can be sure that the temperatures in this location do not fall below zero throughout the year.

---

Protection from the wind

It is important, for example, because of the potential mechanical damage or the lower temperature that accompanies unprotected places. However, if we are going to plant wind-pollinated plants, a place sheltered from the wind will be unfavorable for them.
Details on wind screening methods will be described in a separate lesson.

---

Potential soil contamination and other threats

It is very important to find out what was previously cultivated on the land on which you want to set up a garden and pay attention to the crops in the surrounding plots. Plants and animals can store pollutants from the air and soil, and the process of removing pesticides from the ground, especially DDT, BHC, Aldrin, and Dieldrin, takes at least 15 years.

The worst are the soils after the cultivation of sugar cane, cotton, pineapple, tobacco, banana, and orchards plantations because the most harmful substances are used in their cultivation. The only way to get them off the ground is to wait patiently. In the meantime, the forest can be planted to use the land for purposes other than food production.

Soil and water are also often contaminated due to the unreasonable use of fertilizers in the past (especially nitrogen-rich fertilizers and natural fertilizers), the presence of oil deposits or mines in the vicinity, etc.
Remember - never use untested well water and test the soil before starting any food crops.

It is also worth checking the frequency of fires in the region where you want to buy a plot. This can be done by cutting down the tree and observing the rings. In the years when there were fires in the area, they will be darker on one side from which the wind was blowing, bringing smoke from nearby fires.

Indicators of high concentrations of greenhouse gases in soil:
capeweed, sodom apple, oxalis

---

---

---

All my lessons are shared totally for free with a CC-0 license (which means you can copy my text and share it wherever you want to, without the need to mark me as an author). I hope it will bring you joy.

Previous lessons can be read here:

Fertilizers

---

Soil and minerals

---

---

---

Thank you for reading,
@papi.mati