[GSBN] Sharing thoughts on pros and cons of using straw as a building material.

Sun Jul 29 16:09:41 UTC 2018

Hello Lars and all

I agree that returning straw to farmland is very important - ideally after it has been used as feed or bedding for animals so that it has added nitrogen. The quality of agricultural soils has diminished at an alarming rate over the last 50 years. Very little organic matter left in a modern arable field. Yields are dwindling and the scientists use this as an excuse for GM but improving the soil would be a much better starting point.

A healthy soil is full of earthworms and these will take the straw based manure down without the need to plough.

In Europe burning straw in the field is banned. However, burning straw in an inefficient power station is supported in the UK with Government subsidy. Attached is an essay I wrote a few years back spurred on by this madness. I do argue that using straw for building one year in three would provide sufficient building material for all new houses to be super insulated, low energy demanding, carbon storing straw ones!

The climate/energy/soil health/food security/CO2 issues are all very closely intertwined. Some would argue that we shouldn't grow cereal crops at all. Locally grown vegetables or perennials and grass raised animals would use far less energy and be healthier for people and planet. Too much vested interest in agri-business for that to happen though.

all the best
Carol

-----Original Message-----
From: Lars Keller <larskeller at gmail.com>
To: Global Straw Building Network (private, with public archives) <GSBN at sustainablesources.com>
Sent: Sat, 28 Jul 2018 15:19
Subject: [GSBN] Sharing thoughts on pros and cons of using straw as a building material.

Hi GSBNers
As I am soon expecting to be questioned about the reasoning behind using straw for buildings, I am eager to hear arguments pro and con.
Last year in Denmark we had an unusually low yield of straw due to rain.
This year in Denmark we are having an unusually low yield of straw due to drought. This is intensified by poor hay yields causing farmers to use straw also for fodder. 

My thoughts:

First, ecologically speaking, after the cereal has been harvested, the straw belongs in the earth. If straw is not returned, nutrients such as Phosphorous and Potassium are removed, and the soil structure is negatively influenced due to the removal of Carbon.
In reality we are probably far from this situation being acted seriously upon almost anywhere. The main reason as always being money: the cost of replenishing the nutrients and the negative impacts of less carbon is estimated to be balanced out by the savings from not having to chop and plough in the chopped straw.

Second, you could argue that we are after all only delaying the return of the straw to the earth.

Third, you could argue that there are even bigger pressing problems at the moment for which straw is a very big step forward, such as substituting CO2 producing building materials with a CO2 sequestering material.

Fourth, straw is not a waste product from a commercial point of view. At least not in Denmark. It sells for app €90/ton straw ab farmer at 15% water content.

Best, Lars

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