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Fertilisation of Winter Crops and Green Area Index

As we move into the middle of February it is a very important time to assess your winter crops and in conjunction with results from recent soil tests, make a planned approach to fertiliser spreading. To achieve the best results try to take a field by field approach which involves assessing plant counts, most recent soil tests and as discussed in our January update, consider yields taken from the field from the previous crop. Once you have this information compiled, fertiliser programmes on a field by field basis can be formulated.

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Evaluation of winter crops 

Crops in general look very good coming out of this winter due to very mild conditions and low rainfall levels, but some crops are now starting to come under pressure with ‘yellowing’ appearing. This is directly due to the weather we experienced which facilitated good growth during December and January, and some fields of winter barley are now starting to run out of steam.
Prioritising the application of fertiliser to crops like winter barley (especially early sown crops) and particularly hybrid barley crops will be paramount. The first crops of winter barley to be fertilised should be early sown hybrid winter barley crops which should receive up to 30% of their total N in the first split, starting from the middle of February on the earliest sown crops, followed by 50% at GS 30-31 and 20% between 32/37. As a general rule, the 2-rows should receive 40-50kg/ha by early March at the latest and receive the balance around GS 30/31. Some will hold back 30-40 kg/ha to apply between GS32/37 on 2 rows also. Don’t forget to apply some sulphur in the first couple of splits. This will be very important to increase the utilisation of nitrogen by the crop.

The winter wheat crops coming up mainly after break crops are looking particularly forward, especially the early sown crops which have tillered really well during the winter. In some cases they may be considered too good as there is an increased risk of lodging with excessively thick crops. Depending on sowing date, the slot within the rotation, and plant counts, wheat crops should receive 20-25% of their total nitrogen around early March with the earlier application (late February) going out on 2nd wheats or backward crops. Again this is a decision that should be made on a field by field basis.

Green Area Index (GAI)

Winter oilseed rape is also looking good and so far have seen little threat from pigeons. This is in stark contrast to this time last year where they really had started to hit crops. In relation to the stronger crops with Green Area Index (GAI) of 1 or higher, an application of 45-50 kg/ha plus sulphur should be made by the first few days in March. Any backward crops will require a higher total nitrogen application than more advanced crops. Crops with a GAI of around 1 will in general receive around 210-220 kg/ha of N(175 units/acre) in 3 splits of 50/90-100/70 kg/ha as a guide about 3 weeks apart, with last split going on around yellow bud stage. Calculate the GAI for each field to achieve the most accurate nitrogen programme.

I strongly advise to take some leaf samples which our agronomy team will be doing with our customers over the next couple of weeks. Place the sample taken in a plastic bag, leaving them in the hot press for 3 to 4 days to assess for light leaf spot levels. If there is evidence of leaf spot in the sample taken, the crop will need to be taken care of straight away or before end of February at the very latest.

A quick look at winter oats

Winter oats is looking quite forward and growers should hold off with nitrogen on these crops until March, unless the crop is very thin or backward. It should have received all its nitrogen by GS 31-32.
The agronomy team at Connolly’s RED MILLS are happy to assess any crop that you may be unsure of.

For more information or assistance, contact the Connolly’s RED MILLS agronomy team.

  • Tags:
  • Agri
  • barley
  • crops
  • fertiliser
  • leaf
  • oats
  • oilseed rape
  • spot
  • Tillage
  • wheat
  • Winter