Soil

CHARCOAL: WHEN THE SOIL YEARNS

Charcoal is produced from wood while biochar is produced from waste material. Different sources but finished products with the same characteristics.

A sack full of charcoal may occupy much space but weighs less than we could imagine.

But that’s just the reason why charcoal sells…

A mound of dirt containing a high carbon content produced by high temperature processes under limited oxygen.

Heat volatilizes material leaving pores in it’s structure creating an internal surface area that is simply unmatched.

Infact a gram of some forms of charcoal such as activated carbon contain as much surface area as 2 combined soccer pitches!

The blackness of charcoal symbolises the presence of carbon…

a substance easily burnt to produce energy.

And that’s why we use it as fuel.

But besides providing our lives with the carbon we so much need as fuel, charcoal holds a secret confined in it’s pores…

A secret that may seem too good to be true but one which is bound to revolutionise agriculture in poor soils.

These pores act as centres of activity too minute for the eye to see yet so impactful in agriculture.

HOUSEHOLD OF NUTRIENTS

Ever tried tasting charcoal?

Well I wouldn’t recommend it but it’s tasteless simply because it pulls stuff such as ions and dissolved salts and sugars from our saliva towards itself.

This is noticeable when using a charcoal filter to clarify water.

So what happens when you throw a mound of charcoal into a pile of manure or compost?

It sucks in some of the nutrients.

Of great concern are nitrates that are easily lost to the atmosphere as nitrous oxides categorised as greenhouse gases.

Charcoal is able to ‘hold onto’ such nutrients preventing atmospheric loss reducing their global warming potential.

REDUCING POLLUTION

It’s ability to ‘hold onto’ nutrients (which is technically called adsorption) enables charcoal to not only reduce stinky smells from manure but also mitigate against pollution of our water ways.

Picture a livestock farmer shovelling manure out of his cattle pen which ends up sitting there for a while before he uses it on his farm or gets a buyer.

During the rainy season, the more soluble nutrients such as nitrates are easily carried off to the nearby lakes or streams leading to nutrient pollution and destruction of aquatic systems.

But what if the farmer throws in some charcoal into the mound of manure?

These nutrients are adsorbed onto it’s surface resulting into a lower nutrient loss and less pollution.

But besides the ability to hold onto nutrients, charcoal provides another advantage to sandy soils.

SOIL WATER HOLDING CAPACITY

Picture a column filled with large sand particles with water being poured from the top of the column.

As expected, the sand will allow fast draining of water which is good for some applications but not for agriculture.

Crops require just that right balance in water requirements.

They thrive by enjoying well drained soils which also don’t dry up too fast.

Charcoal has a large water holding capacity compared to many soils precisely because of it’s high porosity.

These pores act as holding cages.

So when we water the soil, the charcoal particles accumulate more water due to the many water holding centres on it’s surface.

Ultimately the soil remains moist but not water logged…a good thing in crop farming.

But these pores do more than just hold water and nutrients.

BOOSTING MICROBIAL LIFE

The soil is an ecosystem teeming with all sorts of microorganisms which are good for the soil.

However, over tillage, usage of mineral fertilizers and pesticides significantly reduces their numbers affecting soil fertility in the long run: The rise of unsustainable agriculture.

Since the overall health of soils is directly correlated to the number of microorganisms it holds, boosting their numbers improves on yields in more ways than we could imagine.

And charcoal provides us with opportunities to actualize this.

It’s pores function as sites for microbial colonies to develop.

So whether we’re talking about the nitrogen fixing nitrosomonas bacteria, the soil loving lactobacillus, fungal colonies or helpful nematodes, charcoal aged in soil provides compartments or pores which facilitate build up of useful microbial communities.

In many instances, some farmers accomplish this by ‘charging’ charcoal before putting it into the soil.

Charging of charcoal (or biochar) involves mixing it with compost and ageing it over time allowing build up of useful microbial communities.

Humus or soil carbon is a good nutrient source for soil microorganisms which is why compost plays a crucial role in this regard.

Other forms of humus might include dead leaves or plant matter which are essential in conservation agriculture.

These microbial communities boost soil fertility by continuously releasing nutrients into the soil.

But because production might outweigh crop needs at a certain point in time, these same pores function as storage centres allowing slow release of nutrients if necessary.

Charcoal loaded with nutrients such as nitrates are possibly a cheap and underexploited slow release type of fertilizer that could prove useful to farmers in the long run.

IN CONCLUSION

Charcoal is not the panacea to all our agricultural problems.

However, it could provide relief to those farmers struggling to produce enough food on poor soils.

But more research and development needs to be done in this regard.