N min/n core sampling
- Thread starter ajd132
- Start date
CORK
Member
- Location
- East Cork, Ireland
N testing of the soil doesn’t really happen over here (across the Irish Sea)
I can’t remember the exact reason but it was deemed to be a poor measurement of actual N availability.
Previous cropping history is used to determine optimum rates.
I can’t remember the exact reason but it was deemed to be a poor measurement of actual N availability.
Previous cropping history is used to determine optimum rates.
- Location
- Lincolnshire
No. Rain, shine, cropping, gallons of digestate, much. Makes no difference. Always comes back at 20kg! I do it simply to show willing every now and again.
Hindsight
Member
- Location
- Lincolnshire
It’s pretty obvious to me what N is available after what crops.
i keep seeing it being advertised and people spouting about it so was wondering if we were missing a trick.
- Location
- Berkshire
Used to do some, the results never made any difference to the rec’s so haven’t done any for a while
RB209 works well enough
RB209 works well enough
I'll probably get shot down for saying this, but over the years i have had several conversations with various companies about this & no-one has had a counter-argument. N Min testing means removing a core, smashing it to pieces having been in a plastic bag for a few days while in transit to the test lab....They then do their magic, and come up with a figure of mineralisable N. Ace. But as what point do i actually do this to my soil in the field?! Adam, you zero til, how much soil disturbance and therefore mineralisation do you think you get? I guess it might have a place in a plough based system, but while we are not disturbing the soil, how can a test that relies on smashing the soil to pieces reflect what N might be available to us?
You talk sense, I hadn’t even thought of it like that. Thankyou.
yellow belly
Member
- Location
- south west lincolnshire
with the amount of rain we have had this winter the n in the soil will have been washed away
a dry month with warm temperatures will see it rise
imho measuring it needs to be on a regular basis and the test done on the day of sampling
alternatively look at the field and you can see if there is much n by the colour of the crop or cover
this year so far the cover crops planted last autumn have been desperatly short of nitrogen
in 2018 they were knee high by christmas
in 2019 they put a lot of growth on in januarry 2020
2020 wet autumn following 2019 20 and now cold january so not alot of n in the soil
all above notill
the exceptions will be field that have plenty of muck ploughed in
a dry month with warm temperatures will see it rise
imho measuring it needs to be on a regular basis and the test done on the day of sampling
alternatively look at the field and you can see if there is much n by the colour of the crop or cover
this year so far the cover crops planted last autumn have been desperatly short of nitrogen
in 2018 they were knee high by christmas
in 2019 they put a lot of growth on in januarry 2020
2020 wet autumn following 2019 20 and now cold january so not alot of n in the soil
all above notill
the exceptions will be field that have plenty of muck ploughed in
In extremes, yes. Mostly, no IMO.
RB209 is good enough. Look at your NIAB TAG data - they say that below 100 kg/ha soil N don't bother reducing doses and have the trials data to back that up. I host trial plots for them & they will soil N test, so I'll post up the results. They have already soil sampled & shown very low sulphur levels. Not very surprising given the rainfall since June 2020.
- Location
- Suffolk
lets me guess... the good reports are from those selling the service?
There is just too much variation for me... even within a few ft.
Hindsight
Member
- Location
- Lincolnshire
Can I be pedantic Brisel.
The point about the 100kg/ha is as you say 'don't bother reducing doses' but that is a glib statement - sorry. The truer English is that for trial sites where SMN was less than 100kg/ha there was no clear correlation between SMN and optimum nitrogen dose. Hence the advice to ignore SMN less than 100 kg/ha and thus 'don't bother reducing dose'. Sorry a pedants point, but more technically correct - though I stand as ever to be corrected by those more closely associated with the data and advice.
The NIABTAG data corroborated its own data sets with those used to produce RB209 and non UK data sets and was reviewed extensively by Jim Orson of NIABTAG.
Best wishes,
PS - this was in response to an earlier mid 2000s version of RB209 that included adjustments to applied N rates based on SMN and the marketing of SMN testing with advice to adjust N applications based on small differences in SMN (far less than 100kg/ha) and in addition knowing the vagaries of the SMN sampling and lab procedure in addition.
Sorry, I was pedant. Have collected my coat and off out to build a snowman.
Hindsight
Member
- Location
- Lincolnshire
I sit corrected.
Yes, the data was about SMN and the optimum N dose.
Sorry - I was bein terribly pedantic. I will collect my coat.
To add further. When Orson reviewed the data that is behind RB209 many, many trials going back decades and from different sources and analysed the data an application of 200kg/ha (as I recall) irrespective of any other knowledge accounted for the most accurate prediction, with hindsight, of the optimum N rate. The exceptions were sites where 'abnormal' amounts of SMN - so following routine applications of manure. The rate may have been a little higher than 200kg/ha - but I haven't time to go back to find out.
How are the thermals?
Best to get it right
Last time I did a soil N test it was comparing 2 neighbouring fields in stubble where 1 had a legume rich cover crop and 1 did not. 3 kg/ha difference in late Feb (78 vs 75 kg/ha) but I would expect that to give up its N slowly. The following crop yield was the same & the protein was hardly any difference too.
Hindsight
Member
- Location
- Lincolnshire
Best to get it right
Last time I did a soil N test it was comparing 2 neighbouring fields in stubble where 1 had a legume rich cover crop and 1 did not. 3 kg/ha difference in late Feb (78 vs 75 kg/ha) but I would expect that to give up its N slowly. The following crop yield was the same & the protein was hardly any difference too.
So the cover crop in that instance possibly lost money. But you felt good!? And you want it to be good, hence the comment about giving up N slowly. I shouldn't be so cynical as the evidence from Morley is the benefit (if there is one) of a cover crop may not show in the immediate following crop.
- Location
- Northumberland
Probably true - my consistent experience is that the 2nd wheat after grass is the one that gets the nutrient boost, though the first does enjoy the improved drainage.