Managing forward crops and tips for N management were on the agenda at a meeting of the Penrith AHDB monitor farm.
Lodging risk in crops is likely to be higher this year as a result of forward crops after ideal early drilling conditions and a good back-end. Speaking at the Penrith AHDB arable monitor farm meeting, ADAS head of crop physiology, Dr Pete Berry, said managing that risk was essential and that good lodging management was key.
There are two key lodging risk timings - the first when the root is the cause, and the second, later in the season, when the stem is the issue.
Stem strength now has a massive impact on lodging. A small canopy will have double the strength, and plant population is also key; anchorage strength increases as plant population decreases. A thick stand has much more risk of root lodging as, like trees, the root plate will be narrower and is more likely to be blown over.
He warned that even where a variety with a good lodging score had been drilled, that scale was based on a typical sized canopy.
You may have a variety with a good rating, but every increase in Green Area Index (GAI) above 1 will push that score down by two points, and every additional tonne of yield will reduce lodging score by 0.5.
For a crop of Graham, for instance, a high GAI crop at GS30 with a yield potential of 10 tonnes/hectare would see its lodging resistance score (without PGRs) fall from 7 to 5.5, he warned.
He added that farmers need to be working towards a score of 8, which meant taking action now. A variety of practical options can be used to increase lodging resistance in crops.
Rolling the crop now can increase the score by one point. Delaying the first split of N until GS30 will add 0.5-1, and reducing N application by 50kg/ha will add another point. Using a PGR will increase it by 0.5-1.5 points.
He acknowledged that applying a PGR could give variable results.
Sometimes you will put them on and the crop does not respond. It is not your fault, but we would therefore recommend splitting PGR application at GS30/31/32 and making sure you use a range of actives.
Spring barley, in particular, would warrant additional attention this year, he said.
None of the varieties has a particularly strong standing score, so be very vigilant - I have seen the worst lodging with these crops, even when they have had a score of 7.
Dr Pete Berrys key tips for N management this year
- The economic optimum N rate is the N rate at which the cost of applying one extra kg of N gives the same value in terms of extra yield
- RB209 N recommendations are based on a fertiliser cost:grain price break even ratio (BER). As an example, if the ammonium nitrate price was 690/t (2 per kg N) and wheat price was 200/t, the BER would be 10, or for OSR at a price of 500/t, the BER would be 4. At 1,000/t, N is 3/kg
- Yield reduction from lower N is not as big as is often perceived. Reducing the rate by 50kgN/ha would typically result in a yield drop of 0.36t/ha for cereals and 0.16t/ha for OSR
- Ask yourself whether it will be more valuable to have some fertiliser left in the store for use next year as prices may remain high
- Expected yield of a crop does not affect how its N rate should be adjusted according to fertiliser price, nor the amount of yield lost at lower N rate
- Prioritise the first split for wheat with take-all risk and for barley (which needs high tiller numbers). However, if you are targeting the milling wheat market, it will still be economically justified in targeting milling quality, especially if premiums are 30/t or more
- The cost of getting N rate wrong is more when using lower N rates, so estimate SNS as carefully as possible. Use crop sensing tools and visual observations to fine tune N rates during the season
- If you are sending soil for SNS sampling, treat it carefully. Do not freeze or mix it, and keep it cool. Do not send it on a Friday when it may spend the weekend in a couriers van which will increase mineralisation and affect results - get it to the lab as soon as possible to prevent a false reading
- Maintain recommended S dose rates, as yield (and S demand) is only reduced by a modest amount by lower N rates. Maintain target indices of P and K
