A few thoughts on soil
Posted: Tue Dec 16, 2014 9:39 pm
The thread in the classifieds looking for a ripper got me to thinking…. Folks have been complaining about this joint being dead so I will get on a soap box for a piece.
Now I will warn you that what I’m about to say goes against the grain for the most part, but its something I’ve been researching and experimenting with for a couple years now.
It started by looking at compaction on row crop land with a penetrometer. Come to find out in many soils, across many growers, a fall ripping did very little to reduce the compacted layer come spring planting time. Now this is not a blanket statement at all, but there are situations where ripping simply isn’t doing any good. Why is that? The conclusion I’m at now, which is subject to be altered as I learn more, is that soil problems begin with mineral/nutrient imbalance and the lack of soil biology (aka life). Take calcium and magnesium for example. Calcium is needed to provide structured, aerated soils with good water infiltration and storage. However, even if you have more than adequate calcium, but have high magnesium, then the soil can become tight and compacted reducing aeration, infiltration, etc. So mineral ratios play a big role in defining soil properties.
Organic matter also plays a huge role in all of this. Only problem is we’ve tilled most of our OM out, along with the soil biology. Most of the soil tests used around here measure total organic matter by burning the carbon out and weighing the difference. Only problem is it doesn’t tell how much of that OM is humus, the only part that really benefits us, which can lead one to think they are in better shape than they actually are. Something else to think about concerning OM. Everybody wants to grow high protein forage for deer, cattle or whatever. Well what makes protein? Amino acids. What are they made of? Mostly carbon, hydrogen, oxygen, and nitrogen. The latter of which is commonly considered the crucial nutrient as the others are normally are in adequate supply. Nitrate is the major plant available form of nitrogen and its an anion, has a negative charge, and it is not held by clay based soil particles. This is why nitrate leaching is such a problem. What soil particle can have a positive charge and hold nitrate? Humus. So I guess the humus fraction of OM may be pretty important if you’re goal is to maximize growth and health of plants and animals.
Moving on to the biological side. Soil is meant to be full of life, bacteria, fungi, worms and stuff. These critters take care of making nutrients available to the plant, fixing nitrogen from the air, creating pore space, building organic matter, etc. These guys are just like deer or ducks, they have to have habitat to live. Their habitat is degraded when organic matter is lost, soil structure destroyed, and by a few harsh fertilizers/chemicals. Unfortunately the system we have created and most operate in is not conducive to producing or maintaining healthy soils.
So back to the compaction issue, there is another way.
1 – Provide adequate and balanced nutrient and minerals
2 – Minimize tillage
3 – Keep living roots in the soil year around
4 – Grow a diversity of plants to achieve specific goals
To expand on the last point more, because that is where this all started, you can address compaction by including plants such as tillage radish and sweet clover. These put down a tap root that is very effective in breaking hard pans, they also help build OM. We dug a soil pit on a field in Yazoo County that has been no-till for five years and had tillage radishes and other cover crops for four years. We found soybean roots at 38 inches. That field is non-irrigated and averaged 76 bu/ac this year. Granted, it was a wet year. However, this field has also been producing 180 bu/ac corn, a 50 bu/ac increase from when it was conventionally tilled. The soil structure has started to develop, internal drainage has improved (gets in field quicker) and water holding capacity has increased.
There is another way of doing things, its just not supported by big marketing and industry funded research. If it weren’t for seeing these alternative approaches working very well on very successful and profitable farms, I would be a major skeptic. But now I’m on a mission to learn more and I would encourage everyone else who manages a piece of land to start doing the same. Rather than simply doing what appears to work for most folks, start thinking about what your doing and instead of addressing a symptom (i.e. ripping) look for the root of the problem and work to address that.
Now I will warn you that what I’m about to say goes against the grain for the most part, but its something I’ve been researching and experimenting with for a couple years now.
It started by looking at compaction on row crop land with a penetrometer. Come to find out in many soils, across many growers, a fall ripping did very little to reduce the compacted layer come spring planting time. Now this is not a blanket statement at all, but there are situations where ripping simply isn’t doing any good. Why is that? The conclusion I’m at now, which is subject to be altered as I learn more, is that soil problems begin with mineral/nutrient imbalance and the lack of soil biology (aka life). Take calcium and magnesium for example. Calcium is needed to provide structured, aerated soils with good water infiltration and storage. However, even if you have more than adequate calcium, but have high magnesium, then the soil can become tight and compacted reducing aeration, infiltration, etc. So mineral ratios play a big role in defining soil properties.
Organic matter also plays a huge role in all of this. Only problem is we’ve tilled most of our OM out, along with the soil biology. Most of the soil tests used around here measure total organic matter by burning the carbon out and weighing the difference. Only problem is it doesn’t tell how much of that OM is humus, the only part that really benefits us, which can lead one to think they are in better shape than they actually are. Something else to think about concerning OM. Everybody wants to grow high protein forage for deer, cattle or whatever. Well what makes protein? Amino acids. What are they made of? Mostly carbon, hydrogen, oxygen, and nitrogen. The latter of which is commonly considered the crucial nutrient as the others are normally are in adequate supply. Nitrate is the major plant available form of nitrogen and its an anion, has a negative charge, and it is not held by clay based soil particles. This is why nitrate leaching is such a problem. What soil particle can have a positive charge and hold nitrate? Humus. So I guess the humus fraction of OM may be pretty important if you’re goal is to maximize growth and health of plants and animals.
Moving on to the biological side. Soil is meant to be full of life, bacteria, fungi, worms and stuff. These critters take care of making nutrients available to the plant, fixing nitrogen from the air, creating pore space, building organic matter, etc. These guys are just like deer or ducks, they have to have habitat to live. Their habitat is degraded when organic matter is lost, soil structure destroyed, and by a few harsh fertilizers/chemicals. Unfortunately the system we have created and most operate in is not conducive to producing or maintaining healthy soils.
So back to the compaction issue, there is another way.
1 – Provide adequate and balanced nutrient and minerals
2 – Minimize tillage
3 – Keep living roots in the soil year around
4 – Grow a diversity of plants to achieve specific goals
To expand on the last point more, because that is where this all started, you can address compaction by including plants such as tillage radish and sweet clover. These put down a tap root that is very effective in breaking hard pans, they also help build OM. We dug a soil pit on a field in Yazoo County that has been no-till for five years and had tillage radishes and other cover crops for four years. We found soybean roots at 38 inches. That field is non-irrigated and averaged 76 bu/ac this year. Granted, it was a wet year. However, this field has also been producing 180 bu/ac corn, a 50 bu/ac increase from when it was conventionally tilled. The soil structure has started to develop, internal drainage has improved (gets in field quicker) and water holding capacity has increased.
There is another way of doing things, its just not supported by big marketing and industry funded research. If it weren’t for seeing these alternative approaches working very well on very successful and profitable farms, I would be a major skeptic. But now I’m on a mission to learn more and I would encourage everyone else who manages a piece of land to start doing the same. Rather than simply doing what appears to work for most folks, start thinking about what your doing and instead of addressing a symptom (i.e. ripping) look for the root of the problem and work to address that.