Hi guys, ive seen a few people expressing interest in trying to incorporate native clay from their area into a ROLS mix.
Probably the simplest way to add clay to your soil mix would be to add some good quality loam topsoil which will generally have a proportion of clay already in it. In the Uk the 'holy grail' of topsoils is called "kettering loam" which has about 20% clay content. i add this to my soil mix at 20%, giving me a fairly ideal 4% clay content in the mix overall. (afaik 4-5% clay is ideal)
My (regular) garden is on clay which has been worked over the years into some nice soil and there are a few tricks that folk use to break up clay and make a nice tilth. these methods could also be utilized to process clay for your soil mix.
The main method used is to dig the soil over in the autumn and leave the big clods of clay on the surface - over the course of the winter the freezing/thawimg action of the frosts will fracture the big lumps of clay and in the spring they can be easily forked over and broken down into a nice crumb structure and then can be easily mixed up with additions of compost etc.
I recently tried to mimic this natural process with a freezer
i got a big clod of my native clay - this was from a hole dug for a fence post. (in my area the top layers of clay are yellow and underneath that is grey)
i then sprayed it with a little water and put it in the freezer. over a few days i froze it and thawed it 3 or 4 times and after that it looked like this
by this time the clay was damp but not wet, and sure enough i could gently crumble it into a reasonably fine tilth that would be easy to add to a soil mix, perhaps after screening any larger bits out. the volume of it increased dramatically too and my advice would be to use the volume of the tilth to add to your mix at 4-5%
it is also worth noting that the clay is very water retentive so you may need to add extra drainage/aeration amendments to compensate. my mix uses 30% perlite/calcined clay.
another technique for breaking down native clay is to use gypsum - although this process can take 2-3 years to make a big difference it really does work. the soil can be topdressed with powdered gypsum at the rate of 8oz per square yard annually (athough it is best to do 2oz every 3 months) the gypsum causes the clay particles to flocculate (stick together) and this gives a nice tilth/crumb structure that will drain much better and be workable.
Those that use gypsum in their ROLs mix will probably find that it further helps to break down the clay crumbs.
VG
Probably the simplest way to add clay to your soil mix would be to add some good quality loam topsoil which will generally have a proportion of clay already in it. In the Uk the 'holy grail' of topsoils is called "kettering loam" which has about 20% clay content. i add this to my soil mix at 20%, giving me a fairly ideal 4% clay content in the mix overall. (afaik 4-5% clay is ideal)
My (regular) garden is on clay which has been worked over the years into some nice soil and there are a few tricks that folk use to break up clay and make a nice tilth. these methods could also be utilized to process clay for your soil mix.
The main method used is to dig the soil over in the autumn and leave the big clods of clay on the surface - over the course of the winter the freezing/thawimg action of the frosts will fracture the big lumps of clay and in the spring they can be easily forked over and broken down into a nice crumb structure and then can be easily mixed up with additions of compost etc.
I recently tried to mimic this natural process with a freezer
i got a big clod of my native clay - this was from a hole dug for a fence post. (in my area the top layers of clay are yellow and underneath that is grey)
i then sprayed it with a little water and put it in the freezer. over a few days i froze it and thawed it 3 or 4 times and after that it looked like this
by this time the clay was damp but not wet, and sure enough i could gently crumble it into a reasonably fine tilth that would be easy to add to a soil mix, perhaps after screening any larger bits out. the volume of it increased dramatically too and my advice would be to use the volume of the tilth to add to your mix at 4-5%
it is also worth noting that the clay is very water retentive so you may need to add extra drainage/aeration amendments to compensate. my mix uses 30% perlite/calcined clay.
another technique for breaking down native clay is to use gypsum - although this process can take 2-3 years to make a big difference it really does work. the soil can be topdressed with powdered gypsum at the rate of 8oz per square yard annually (athough it is best to do 2oz every 3 months) the gypsum causes the clay particles to flocculate (stick together) and this gives a nice tilth/crumb structure that will drain much better and be workable.
Those that use gypsum in their ROLs mix will probably find that it further helps to break down the clay crumbs.
VG
