Many growers may now be unfamiliar with the management of these crops. This article looks at the basics of the different aspects of early husbandry to help growers prepare for the months ahead.

ESTABLISHMENT

It is preferable to establish close to 300 plants per square metre for spring barley and above 250/m2 for spring wheat. While this may have been the target seeding rate, many fields may not hit these plant populations. And the general reports from the field indicate below average establishment with pest damage responsible for decreasing establishment. The problem is not so much bad patches as a reduction across the field, as manifested in gaps along the row.

Where plant population is low, one might consider applying a CCC-based product (CCC or K2) to help break apical dominance and encourage more tillering to fill the gaps. Barley needs to be dense at the grass-corn stage to have high yield potential but this is not so important with wheat. With barley, 250 plants need to have three tillers per plant to give 1,000 ears/m2 (Figure 1).

Where signs of ongoing leather-jacket damage persist, consider rolling with a heavy roller post emergence to slow pest movement and encourage tillering. But keep sprays away for 10 days. If this is not possible, then spray with chlorpyrifos or apply Draza pellets.

NITROGEN

As with all other crops, the maximum rate of nitrogen allowed is governed by the Nitrates Directive. These rates are shown in Table 1. These are the basic rates and they can be adjusted where proof of higher average crop yield is available for one of the past three years. But if either of these are new crops on your farm, you do not have this proof of yield which might justify higher N rates. So, be careful with your quantities.

Where proof of historic yield is available, an additional 20 kgN/ha can be applied per tonne of historic yield above 6.5t/ha in the case of barley and 7.5t/ha in the case of spring wheat. Proof of a 7.5 t/ha recent farm average for spring barley would justify 155 kgN/ha.

The amount of nitrogen allowed is also governed by historic land use. Index 1 soils can receive the highest level of nitrogen and Index 4 the least. Most tillage soils are either Index 1 or Index 2. Index 1 is continuous cereals or other cereal crops. Index 2 tends to be following a break crop.

Milling wheat can receive an additional 30 kgN/ha where it is grown under contract to help achieve the required grain protein level. A similar top-up is allowed for contract malting barley growers, subject to being advised to do so.

The timing of nitrogen application is different to winter cereals. I must assume here that all growers have applied an amount of N as a compound with P and K into the seedbed, either broadcast or combine drilled. On the assumption that the quantity of P and K is adequate, the amount of N in the seedbed will be variable. But this really doesn’t matter because the general rule is that the less that is in the seedbed, the quicker the need to topdress post emergence.

All nitrogen rates should be adjusted downwards where organic manures or composts were applied to a field in recent years.

SPRING BARLEY

The objective is to drive early season growth to bulk up the crop. This is done by applying the balance of the allowed nitrogen to the crop by the three leaf stage and, for most, this means application post emergence. So, if you are allowed 108 units/acre total and you have 30 units in the seedbed, that means another 78 units to apply. This can all be applied in a single application but, if you know your land is ‘strong’, there is something to be said for holding 25 units until the end of tillering to help with grain fill later in the season.

The objective should be to apply all the N soon after emergence but it is better to hold some until late tillering where the land is very fertile.

SPRING WHEAT

Spring wheat is a different plant and can be managed differently. If you are not targeting milling, the objective should be to have the total N applied by stem extension, opting for something over half the total earlier to drive tillering through a combination of the seedbed N and an early post emergence dressing. If there are over 50 units of N in the seedbed, you could opt for mid to late tillering as a compromise timing for the balance of the total nitrogen.

Where milling is the objective, the advice on early timings remains broadly similar but with slightly more of the total N applied closer to stem extension. The remaining additional 24 units (30 kgN/ha) allowed for milling can be applied post flag leaf emergence to help drive both yield and protein.

GROWTH REGULATION

This could be needed in both wheat and barley crops this year. Growth regulation is about helping to reduce or prevent lodging and involves both the shortening of the stem and the thickening of the cell walls. We may also need manipulation to help increase tiller numbers.

Judging whether or not it will be needed in spring barley depends on the growth pattern from here on. The more growth and warmth we get in the next few weeks, the quicker crops will arrive at stem extension stage and, as a result, the less pressure will be on them to extent rapidly when that time comes. But slow growth in the coming weeks may well delay the beginning of stem extension and increase the risk that this will be rapid and weak when it occurs.

The final risk factor is the temperature and growth levels during stem extension itself. Slow to normal growth levels during this phase will help keep stems strong and reduce lodging risk. Lots of wind will help ‘harden’ the stems. The next two to three weeks will be the major influence on the need, or not, for PGR in spring barley but it will also be influenced by the amount of nitrogen applied, how much was applied early, how dense the crop canopy is, the natural fertility of the field, whether or not you have used growth manipulation etc.

Growth regulation should always be carried out on wheat crops. This has traditionally been CCC at 1.0 l/ha to 1.5 l/ha (75%) at the start of stem extension. If crops become excessively rank, a second application could be used using either a Modus/CCC mixture at mid stem extension or Terpal or Cerone to help shorten the final stem length.