<p>OK I did a <a href="https://drive.google.com/file/d/1fkL-H4DzDITdvy6yygTZqsz8ROee1f10/view?usp=sharing" rel="nofollow noreferrer">paper</a> on mitigating climate change by enhanced weathering of rock on agricultural land for my masters (2014) it's not brilliant, but it does include some useful references if you want to research this further.</p>
<p>I would imagine the main limiting factor in the Sahel region would be that the process needs to be wet. So you're possibly only talking about being able to add material to irrigated areas. There are also the limitations you've already discussed of getting the material on site. In terms of crop yield, I would suggest that it will only increase plant growth in areas which do not already have alkaline geology (and I have no idea what the geology looks like in the Sahel, I'm afraid) and adding too much to soils may well actually <em>decrease</em> site fertility without the addition of something else (manure is the traditional amendment)</p>
<p>As far as I'm aware, enhanced weathering is perfectly technologically feasible, but it does have a limited application - due to the sheer quantity of it we'd need.</p>
<p>Hope this helps.</p>

CC BY-SA 4.0
2020-07-10T11:36:34.747Z
Though if it's small scale, and as simple as the farmer gets paid for half a tonne of carbon for every tonne of lime he adds to the farm - it shouldn't be *too* complicated.
Will
CC BY-SA 4.0
2020-07-10T13:39:58.483Z
Well lime is the standard amendment to increase soil pH, but the technique actually calls for ultramafic rocks (basalt is mafic) mainly olivine I believe (though I'm not a geologist)
Will
CC BY-SA 4.0
2020-07-10T10:39:53.887Z
2020-07-10T10:39:53.887Z
Will
<p>Note that the sahel is a lost cause for the rainfall/CO2 absorption side of the equation. Heat tends to mineralize soil and reduce its organic content, so the sahel may be too hot. For fertiliser, rock dust is economically significant.</p>
<p>The program should be quantified:</p>
<p>Available budget for the project.</p>
<p>KG mass of rock:</p>
<p>Quarry cost. Transport cost. Truck+Fuel cost. Crushing machine cost. Energy cost. Dissemination labour organization. Training schemes to instruct dust dissemination. Dissemination machines. Rain window period. Maximium rock load for a given precipitation rate, i.e. 10g/m2 per 1cm of rain.</p>
<p>Using planes to lift 100 tonnes of dust per day may be cheaper than using trucks (a 747 can lift 112 metric tonnes).</p>

CC BY-SA 4.0
2020-07-16T07:35:10.877Z
While planes might be economically viable I think that would defeat the entire purpose of the project. i.e. sequester CO2
Eric
CC BY-SA 4.0
2020-07-15T19:34:49.930Z
2020-07-15T19:34:49.930Z
bandybabboon
<p>More information on ERW here:</p>
<p><a href="https://www.nature.com/articles/s41477-018-0108-y.epdf?author_access_token=w1xYBFb3g3BwKnjkBD1cJtRgN0jAjWel9jnR3ZoTv0NSaZpth7Zz94N6_lHXNgths4xErTsML30mZS8Ql0FCuzY9k6ePi5nMsoEvmCXoU5g65l-c0C09tp3iWQMGMdfvbuwlRhm5_snv9tqy8Kc6ig%3D%3D" rel="nofollow noreferrer">https://www.nature.com/articles/s41477-018-0108-y.epdf?author_access_token=w1xYBFb3g3BwKnjkBD1cJtRgN0jAjWel9jnR3ZoTv0NSaZpth7Zz94N6_lHXNgths4xErTsML30mZS8Ql0FCuzY9k6ePi5nMsoEvmCXoU5g65l-c0C09tp3iWQMGMdfvbuwlRhm5_snv9tqy8Kc6ig%3D%3D</a></p>
<p><a href="https://www.nature.com/articles/s41477-018-0108-y.epdf?author_access_token=w1xYBFb3g3BwKnjkBD1cJtRgN0jAjWel9jnR3ZoTv0NSaZpth7Zz94N6_lHXNgths4xErTsML30mZS8Ql0FCuzY9k6ePi5nMsoEvmCXoU5g65l-c0C09tp3iWQMGMdfvbuwlRhm5_snv9tqy8Kc6ig%3D%3D" rel="nofollow noreferrer">Farming with crops and rocks to address global climate, food and soil security</a></p>
<p>Hot climates are good for ERW -- the kinetics of weathering are temperature dependent. But as noted above you need water too.</p>

CC BY-SA 4.0
2020-07-21T09:06:38.460Z
Link does not work by me. Could you please cite the most important part of the remote content?
peterh
CC BY-SA 4.0
2020-07-21T09:08:23.397Z
http://rdcu.be/HlCp
David Beerling
CC BY-SA 4.0
2020-07-21T08:26:37.120Z
2020-07-21T09:30:42.327Z
2020-07-21T09:30:42.327Z
David Beerling
<p>A recent <a href="https://www.theguardian.com/environment/2020/jul/08/spreading-rock-dust-on-fields-could-remove-vast-amounts-of-co2-from-air?CMP=Share_iOSApp_Other" rel="nofollow noreferrer">Guardian article</a> &quot;Spreading rock dust on fields could remove vast amounts of CO<sub>2</sub> from air&quot; has gotten some attention in the nongovernmental and UN organizations working in the Sahel who are desperate to combat the adverse effects of climate change in the region. This article is based on a <a href="https://www.nature.com/articles/s41586-020-2448-9" rel="nofollow noreferrer">Nature</a> publication on enhanced rock weathering (ERW).</p>
<p>Let's pretend a large international organization has tasked a newly employed software developer to look into the feasibility of performing ERW in the Sahel. Now this let's say this software developer, who has no geological background whatsoever, is trying to figure out what it would take to run a ERW pilot in the Sahel and decided to investigate <a href="https://www.google.com/maps/place/Bol,+Chad/@13.4694221,14.7031953,4529m/data=!3m2!1e3!4b1!4m8!1m2!2m1!1sKablewa+IDP!3m4!1s0x1110bf7f2511383b:0x9489d58a5875503c!8m2!3d13.4590796!4d14.71138" rel="nofollow noreferrer">Bol, Chad</a> to have a specific place to focus on.</p>
<p>Ideally, this pilot would seek to test two things (i) is ERW feasible to perform in the region of conflict, (ii) does the crushed basalt or silicate, which is added to the soil, increase crop yield?</p>
<p>In order to determine if this pilot is feasible to even consider I think the following should be investigated:</p>
<ol>
<li>Current farming methods in the region</li>
<li>Feasibility of acquiring and transporting crushed basalt or silicate</li>
<li>Method for applying the basalt or silicate to the soil</li>
</ol>
<p>What else should I look at?</p>
<p>If you were given this (completely hypothetical) task where would you start?</p>
<p>Is there any giant red flag I am missing which would be enough of a reason not to move forward with a pilot?</p>

CC BY-SA 4.0
2020-07-09T14:04:09.980Z
Coming from StackOverflow I realize this is a HORRIBLE question since it's very broad and not specific. If it gets flagged for removal I completely understand, just wondering if anyone has ideas. Stack Exchange is typically a nice place to turn to :)
Eric
CC BY-SA 4.0
2020-07-09T14:27:38.207Z
@a_donda that's for the reply! From my understanding, you're suggesting that the amount of CO2 created in transporting the basalt to the fields could likely be greater than the CO2 the basalt would capture (in 30 years per the Nature paper) after it is spread across the field? I guess a back of the envelope calculation could be made to see if this is true, assuming I can figure out where the Basalt would be sourced from (ideally not by destroying a mountain)
Eric
CC BY-SA 4.0
2020-07-09T14:34:57.627Z
@a_donda it's understood that applying ERW will not lower the temperatures in the Sahel. It would be used to capture carbon, which could ideally be sold as a form of carbon credit. Thus providing a bit of income for the region (paying people to spread rock dust on their fields) and ideally increasing the fertility of the soil and therefore increasing crop yields.
Eric
CC BY-SA 4.0
2020-07-21T09:59:56.727Z
There is already a huge project to preserve the Sahel from desertification: the Great Green Wall. A 15 km wide, 7800 km long strip of land, stretching from Senegal to Djibouti, meant to be reforested. For various reasons things are going slower than planned, but efforts are ongoing and this solution seems more realistic than the weathering thing. http://www.fao.org/in-action/action-against-desertification/overview/great-green-wall/en/
Jean-Marie Prival
<geology><climate-change><rocks>
Using Enhanced Rock Weathering in the Sahel Region of Africa
Eric
# Using Enhanced Rock Weathering in the Sahel Region of Africa

(Asked by: username_0 on 2020-07-09)

A recent [Guardian article](https://www.theguardian.com/environment/2020/jul/08/spreading-rock-dust-on-fields-could-remove-vast-amounts-of-co2-from-air?CMP=Share_iOSApp_Other) "Spreading rock dust on fields could remove vast amounts of CO2 from air" has gotten some attention in the nongovernmental and UN organizations working in the Sahel who are desperate to combat the adverse effects of climate change in the region. This article is based on a [Nature](https://www.nature.com/articles/s41586-020-2448-9) publication on enhanced rock weathering (ERW).

Let's pretend a large international organization has tasked a newly employed software developer to look into the feasibility of performing ERW in the Sahel. Now this let's say this software developer, who has no geological background whatsoever, is trying to figure out what it would take to run a ERW pilot in the Sahel and decided to investigate [Bol, Chad](https://www.google.com/maps/place/Bol,+Chad/@13.4694221,14.7031953,4529m/data=!3m2!1e3!4b1!4m8!1m2!2m1!1sKablewa+IDP!3m4!1s0x1110bf7f2511383b:0x9489d58a5875503c!8m2!3d13.4590796!4d14.71138) to have a specific place to focus on.

Ideally, this pilot would seek to test two things (i) is ERW feasible to perform in the region of conflict, (ii) does the crushed basalt or silicate, which is added to the soil, increase crop yield?

In order to determine if this pilot is feasible to even consider I think the following should be investigated:

1. Current farming methods in the region
2. Feasibility of acquiring and transporting crushed basalt or silicate
3. Method for applying the basalt or silicate to the soil

What else should I look at?

If you were given this (completely hypothetical) task where would you start?

Is there any giant red flag I am missing which would be enough of a reason not to move forward with a pilot?

**Tags:** geology, climate-change, rocks

> **Comments:**
> **username_0**: Coming from StackOverflow I realize this is a HORRIBLE question since it's very broad and not specific. If it gets flagged for removal I completely understand, just wondering if anyone has ideas. Stack Exchange is typically a nice place to turn to :)  
> **username_0**: @a_donda that's for the reply! From my understanding, you're suggesting that the amount of CO2 created in transporting the basalt to the fields could likely be greater than the CO2 the basalt would capture (in 30 years per the Nature paper) after it is spread across the field? I guess a back of the envelope calculation could be made to see if this is true, assuming I can figure out where the Basalt would be sourced from (ideally not by destroying a mountain)  
> **username_0**: @a_donda it's understood that applying ERW username_2 not lower the temperatures in the Sahel. It would be used to capture carbon, which could ideally be sold as a form of carbon credit. Thus providing a bit of income for the region (paying people to spread rock dust on their fields) and ideally increasing the fertility of the soil and therefore increasing crop yields.  
> **username_1**: There is already a huge project to preserve the Sahel from desertification: the Great Green Wall. A 15 km wide, 7800 km long strip of land, stretching from Senegal to Djibouti, meant to be reforested. For various reasons things are going slower than planned, but efforts are ongoing and this solution seems more realistic than the weathering thing. http://www.fao.org/in-action/action-against-desertification/overview/great-green-wall/en/  

---

## 3 answers

### Answer by username_2 on 2020-07-10. Score: 3

OK I did a [paper](https://drive.google.com/file/d/1fkL-H4DzDITdvy6yygTZqsz8ROee1f10/view?usp=sharing) on mitigating climate change by enhanced weathering of rock on agricultural land for my masters (2014) it's not brilliant, but it does include some useful references if you want to research this further.

I would imagine the main limiting factor in the Sahel region would be that the process needs to be wet. So you're possibly only talking about being able to add material to irrigated areas. There are also the limitations you've already discussed of getting the material on site. In terms of crop yield, I would suggest that it username_2 only increase plant growth in areas which do not already have alkaline geology (and I have no idea what the geology looks like in the Sahel, I'm afraid) and adding too much to soils may well actually *decrease* site fertility without the addition of something else (manure is the traditional amendment)

As far as I'm aware, enhanced weathering is perfectly technologically feasible, but it does have a limited application - due to the sheer quantity of it we'd need.

Hope this helps.

> **Comments:**
> **username_2**: Though if it's small scale, and as simple as the farmer gets paid for half a tonne of carbon for every tonne of lime he adds to the farm - it shouldn't be *too* complicated.  
> **username_2**: Well lime is the standard amendment to increase soil pH, but the technique actually calls for ultramafic rocks (basalt is mafic) mainly olivine I believe (though I'm not a geologist)  

---

### Answer by username_3 on 2020-07-15. Score: 1

Note that the sahel is a lost cause for the rainfall/CO2 absorption side of the equation. Heat tends to mineralize soil and reduce its organic content, so the sahel may be too hot. For fertiliser, rock dust is economically significant.

The program should be quantified:

Available budget for the project.

KG mass of rock:

Quarry cost. Transport cost. Truck+Fuel cost. Crushing machine cost. Energy cost. Dissemination labour organization. Training schemes to instruct dust dissemination. Dissemination machines. Rain window period. Maximium rock load for a given precipitation rate, i.e. 10g/m2 per 1cm of rain.

Using planes to lift 100 tonnes of dust per day may be cheaper than using trucks (a 747 can lift 112 metric tonnes).

> **Comments:**
> **username_0**: While planes might be economically viable I think that would defeat the entire purpose of the project. i.e. sequester CO2  

---

### Answer by username_4 on 2020-07-21. Score: -1

More information on ERW here:

<https://www.nature.com/articles/s41477-018-0108-y.epdf?author_access_token=w1xYBFb3g3BwKnjkBD1cJtRgN0jAjWel9jnR3ZoTv0NSaZpth7Zz94N6_lHXNgths4xErTsML30mZS8Ql0FCuzY9k6ePi5nMsoEvmCXoU5g65l-c0C09tp3iWQMGMdfvbuwlRhm5_snv9tqy8Kc6ig%3D%3D>

[Farming with crops and rocks to address global climate, food and soil security](https://www.nature.com/articles/s41477-018-0108-y.epdf?author_access_token=w1xYBFb3g3BwKnjkBD1cJtRgN0jAjWel9jnR3ZoTv0NSaZpth7Zz94N6_lHXNgths4xErTsML30mZS8Ql0FCuzY9k6ePi5nMsoEvmCXoU5g65l-c0C09tp3iWQMGMdfvbuwlRhm5_snv9tqy8Kc6ig%3D%3D)

Hot climates are good for ERW -- the kinetics of weathering are temperature dependent. But as noted above you need water too.

> **Comments:**
> **username_5**: Link does not work by me. Could you please cite the most important part of the remote content?  
> **username_4**: http://rdcu.be/HlCp  

---

