Soil N and no till- is this normal?!

[Wigeon]

Just had some test results back for the spring barley ground. All conventionally max tilled fields (shakerate and cultipress in the autumn, top tilth and horsch drill in the spring) have available N results in the region of 35-55kgs /ha. My zero till experiment field however reads 161kgs, and it's not a mistake because I've had it checked.

Had oat and vetch cover crop, and was grazed off in Jan with sheep. Not drilled it yet.

Is this normal?! Will the plants really be able to get it?

Should I not put any fert on?!

Can I do this every year and never buy fert for spring crops again.... (bit optimistic!)

Anyone else seen similar?

Cheers

 

[Badshot]

That's a lot of n kept available in the soil.
No doubt having sheep on it will have helped with muck n urine.
I'd have to put some n on this time round, but maybe it'd be worth a test strip left untreated to see what happens.

I've some oats, vetch and oil radish being grazed off at the moment ahead of zero till linseed at the end of April.

160kg of n would be more than enough for it.

How long does it take? The sheep will be there till the end of the month

 

[Wigeon]

It had 22 ewes per ha for 3 weeks, off at end of Jan. Been sprayed off 3 weeks now.

Want to try and make malting on it, so a bit tricky. It was actually the only cover crop that I have ever managed to get to grow successfully!

 

[JAB]

Monitor N levels in soil and plant tissue during the growing season to make sure the plants are continuing to get what they need. When you harvest the barley you’ll be pulling N off, so you will have to replace it in the future one way or another.

 

[Wigeon]

Thanks, yes will do.

As a general point I suppose my question should have been:

is a very high level of residual n a common byproduct of zero till when combined with a leguminous cover and short term grazing?

 

[JAB]

The answer to your question is: it depends. It depends a lot on rotation. But it makes sense that your cover crop is not allowing N to leach, and the lack of disturbance is not allowing it to volatize. Plus the livestock doing their thing to recycle nutrients.

 

[Wigeon]

Thanks- that all makes sense, though the result is higher than I had expected. Will be worthy of a test post harvest too I think.

 

[JAB]

Definitely keep us updated! This is pretty exciting stuff.

 

[britt]

There are soil bacteria which take N from the air and release it to plants. But they need they need well aerated soil to have access to N and the correct soil conditions to thrive. These are other than the bacteria associated with legumes.
But your results do seem very high.
I worked out the N deposited by sheep on my turnips last winter using the Standard values in the NVZ pack. It was only 10Kgs N/Ha on one field and 15 on the other.

 

[yellow belly]

How long have the 2 fields been treated the same

Long term pasture put into arable takes 50 plus years before the soil is deprecated of residual nutrients
I have fields that were ploughed up in the 1940s and others in the 1970s and fields that were arable from the victorian era you can see the differences especially in osr crops they have been farmed the same since the 1980s
Incorporating straw also has long term effects

 

[Clive]

I think last year a lot of crops won’t have used all the N applied to them as it was so dry - this is why we had such fantastic cover crop growth this autumn

So the cover will have captured it and that’s why you are seeing such high levels

I’m not sure it’s something you can bank on every year but a cover crop will always help retain nutrition that would otherwise be lost