Legume Plowdown - (or Soil Health 101)

[ALLFARMER]

We "plowed down" a half section of sweet clover once but that was about 13 years back. I was only a young lad but if I remember correctly it didn't plug up the plow. Alfalfa & Peas are the most common ways today of adding ryzomes.

[wedino]

I'll take a stab at some of your questions, Vader. A lb. of N is a lb. of N regardless of how it is created.

Re: Soil organic matter, No till farmers realized long ago the value of organic matter in their soils. In the last 20 years I've doubled the organic matter in my soil, from 2% to 4%. I shudder at the thought of utilizing techniques that involve tillage.

I am interested in a green manure crop if it could be sprayed out in July(of the year it was planted) & I'm able to seed directly into it next spring. Clover, I think, requires 2 years before it fixes any N. Correct me if I'm wrong.

[lakenheath]

I think chemical companies have done a fine job of making us fear tillage. Yes, half and half 5 passes of summerfallow with a cultivator until the land is black seriously hurt our soil over the years. We had our land blow away and created hard pans that roots struggled to break through. And the result was a decrease in organic matter.

Responsible tillage, however, would not have had those damaging effects. What about disease pressure built up in no-till fields? Solution, spray fungicides.

Burning off a green manure crop (the research has been done) is not as effective as the nutrient cycle don't take place very quickley as plants remain on the soil surface.

I think some of our biggest enemies against yield are one we are not even aware off, like compaction. We grow crops with mega amounts of chemical fertilizer that grow at shallow depths, and once they run out of rainfall (even though the yield potential is there through nutrient planning), fail to yield. The roots cannot break the hardpan, and if they do the plant has spent it's enery breaking the pan rather than making yield.

Crops like alfalpha and clover have deep tap roots the break these compaction zones. Once again like Parsley would say, rotation, rotation, rotation.

Any dummy can conventionally farm. Just look to your neighbour or phone your local agrologist. Takes one hell of a farmer to pull of organics, and it can be done. Organcis can yield with conventional crops. It has been proven. The trick is getting our land back into the the proper state.

Too much emphasis has been put on the negative effects of tillage. But it is only one small piece of the puzzle.

[Vader]

wedino, is a pound of nitrate equal to a pound of nitrite and are those equal to a pound of ammonia or a pound of ammonium? How many pounds of nitrogen are represented by soil bacteria?

I listened to a speaker with a PhD in soil microbiology say that bacteria contain a substantial portion of nitrogen perhaps 5%. The nitrogen contained in soil bacteria is not subject to leaching or gassing off as might be the case with NH3, NH4 and ammonia and ammonium. So is a pound of nitrogen a pound of nitrogen. I think not.

The speaker went on to say that a healthy soil might have 2000 pounds of soil bacteria. If those bacteria are 5% nitrogen that would be equal to 100 pounds of nitrogen per acre. If other aspects of the soil biology were in a similar healthy abundance then normal bacterial activity would make this nitrogen plant available in the root zone when the plant most needed it. In fact the plant exudes through the roots as much as 50% of the sugars produced by the leaves providing food for the soil bacteria and adding to the health of the soil microbes. I find that simply amazing.

A green manure plow down provides a lot of sugar for soil bacteria. I am sure we have all heard numerous times that the reason sugar is bad for your teeth is because it promotes bacterial growth. So yes you can do a green cover crop and spray it down but you will deprive the soil bacteria of a copious amount of sugars as the plant tops dry down. Plowing the top growth into the soil may not add a huge amount of nitrogen directly but it does have a significant effect on total bacterial nitrogen storage. The plow down of the top growth also assists long term humus development. The humus and other soil organic matter ties directly into the nitrogen cycling due to the activity of the soil bacteria.

[lakenheath]

Vader. What do you use for a plow-down?

If I was to do it, here is what I would do. I would plant Trapper field peas at 1 bushel per acre along with 1/2 a bushel of oats per acres. I would single shoot these together and then broadcast through me double-shoot hose (spraying in-front of my sweep) a half rate of sweet yellow clover. I would seed as early as i could get on the land and plow it down at first flower.

Get bio-mass with the oats plus allopathy, hopefully N from the clover but also allopathy and N fixation from the peas. What do you think?

[craig]

Idea I have looked at. Intercrop sweetclover with spring cereal in year 1 and then in year 2 mow down sweetclover before seed set. Jill Clapperton has said that the residue breaks down very quickly due to the large amounts of N. My plan would be to mow high enough to leave stalks for snow catching. I would preseed burn early August for any regrowth and then plant winter wheat. A select variety would hopefully be able to use the slower release nitrogen for added protein( which you get paid for)Not sure if the sweet clover residue would have effect on winter wheat.

[lakenheath]

Interesting. Be careful with inter-cropping clover. During harvest it can put a strong smell on your wheat. Also, it can (if it catches strong) compete very aggressively with the wheat crop. In year 2 watch for excess moisture uptake. The clover will have a developed root system with a stong tap root. May want to burn off and mow down early.

[Vader]

I have alfalfa and clover in right now but am planning on green peas with cereal intercrop for this year. I had not thought to cut back so far on the peas. I thought maybe 2 bushels per acre and a bushel of oats.

Certainly the biggest hazard is the moisture used by alfalfa and clover. Could backfire on certain soil types with marginal moisture.

To properly understand the whole process I really think you need to listen to the soil foodweb CD.

[Vader]

wedino, I spoke to Martin Entz at the University of Manitoba about green manure cover crops. He tells me that producers are having success with rolling down their cover crops to "terminate" them. You have to wait until they have bloomed otherwise they will just shoot up new growth.

Go to google and type in "rolling rye".