Plowdown for Nitrogen?

[bowhuntr311]

Tried doing a little searching before making a new thread about this but couldnt find the answers Im looking for.

I see alot of talk about plowing clover/alfalfa under for nitrogen in the fall for brassica plots. So here are my questions.

Does a person want to RUP the clover/alfalfa? If not, is mowing it short better, or leaving it to be fully mature before turning under?

What actually produces the nitroge? Rotting plant material?

What about plowing under just living grass/weeds? Is there any nitrogen benefit to them? We'll say an old abandon field or CRP; should a person RUP it and then till or no RUP?

Thanks.

 

[JNRBRONC]

The roots of alfalfa have nodules where nitrogen fixing bacteria live. When the plant dies, this nitrogen is freed for other plants to use. So if you RUP the field this fall, the roots would start to decompose over the winter so the nitrogen would be available next year.

Plowing down a field will incorporate the plant material into the soil, adding organic matter, whether it was mowed or standing tall. If I was going to plow, I wouldn't bother to mow, JMPO. When you plow, you increase the loss of soil due to erosion. You also stir up all kinds of weed seeds that have been laying dormant in the soil.

If it were me, I'd kill with herbicide in the fall and no-till into the killed sod next year. If there was a lot of matter on top next spring, maybe do a burn so the no-till drill has an easier time.

 

[dbltree]

Bronc pretty much covered your questions but I will just add that there are advantages to plowing down anything and that includes weeds, grasses etc.

Even with alfalfa and clover, a certain amount of nitrogen is in the foilage of the plants and when it is plowed under green, we capture ALL of it rather then just what is in the roots.

Plowing under any plant material increases organic matter so it does have distinct advantages.

The disadvantages are as bronc mentiones with stirring up weed seeds, erosion etc... but those things may not be a problem on all soils.

I prefer to no-till when I can for those very reasons but to improve poor soils plowing under plants whole and green will improve soil faster.

Old timers used to plow under sweetclover and ragweeds (before they went to seed) or almost any kinds of grasses and weeds. One option is to do this and then allow grasses to regrow and then kill them with glyphosate rather then before.

It is very different dealing with sod or untilled soils and plots or fields that have been worked and these type of things are not "one size fits all".

Great questions nonetheless! :way: