Continuous rain and poor ground conditions have recently brought all field work to a halt but Met Éireann today (Monday, April 17) said weather conditions should improve this week with “increased sunshine”.
The meteorological service has also advised that there will “be some opportunities for spraying this week when moderate winds ease up at times”.
According to Mark Plunkett, a specialist in soil and plant nutrition with Teagasc, the poor weather has significantly impacted on tillage operations.
Plunkett said many winter crops still await their main nitrogen (N) application, which should be a priority as the weather improves and field conditions recover.
He also said that early sown spring crops are at, or close to requiring their main N split.
According to the Teagasc specialist, for spring crops not sown yet, farmers should use a suitable compound fertiliser such as ‘10-10-20’ or ‘12-8-20’ or ‘13-6-20’ on Index 1 or 2 fertility soils.
On Index 3 sites, 13-6-20 is a well-balanced fertiliser option for spring barley.
Growers should aim to apply 370kg/ha (3 bags/ac) at sowing time and, where possible, combine drill.
This would be especially the case on low-index soils to increase fertiliser phosphorous (P) efficiency and supply.
Applying sufficient P is essential for rapid root and tiller development. It is critical nutrient in spring barley during the first three to six weeks of establishment.
Trial work carried out in spring barley clearly shows the benefits of combining P, especially on low-P-Index sites.
Potassium (K) is very important for N efficiency, grain yield development and straw strength and quality.
A number of trials carried out in Arklow, Co. Wicklow confirmed the importance of K in grain yield formation and N efficiency.
The trials also highlighted the role of K in reducing the effects of straw brackling prior to harvest.
However, they suggested that K untreated plots were more tolerant to foliar diseases such as powdery mildew infection.
According to Plunkett, growers should keep a close eye on fields that are being ploughed out of long-term grass.
These sites may have very low soil P and K levels, resulting in crop nutrient deficiencies.
The reality is that P is needed in the seedbed zone and close to the rapidly developing plant roots.
Growers should, therefore, ensure sufficient available fertiliser P and K are applied at sowing time.
Plunkett also advised that for spring crops still to be sown, growers should aim to supply approximately 30% of a crop’s N requirements in the seedbed.
The remaining N and sulphur (S) should be applied, once tramlines are visible.
For early sown malting barley crops, these should be top-dressed with N and S, once soil conditions are suitable.
For feeding barley, crops growers should aim to apply remaining crop N and S requirements at mid-tillering in a single application or, alternatively, on the basis of a 70:30 split.
All N applications should be completed by stem extension or growth stage (GS_ 31/32). The recommended application rate for S is 15kg/ha.
Where organic fertilisers have been applied, growers should adjust final applications to take account of N supplied.
For example, an application of 33m3/ha of cattle slurry by low emission spreading equipment – and ploughed in rapidly thereafter – can supply approximately 33kg of N/ha.
This represents a saving in chemical N of approximately €65/ha at today’s fertiliser prices.
Plunkett has highlighed that test results are a very good indication of the soil supply of both copper (Cu) and zinc (Zn).
However, the soil test option is not as reliable for manganese (Mn), deficiencies of which tend to be most prevalent on sandy or light soils.
Plunkett said this issue is similarly prevalent in recently limed or high pH soils, poorly consolidated seedbeds or under dry and cold weather conditions.
Growers should therefore ensure that seedbeds are well consolidated after sowing, where possible.
For example, sites ploughed out of grass leys should be flat-rolled after sowing to improve seed to soil contact to reduce the incidence of Mn and other nutrient deficiencies.
Where trace element deficiencies are anticipated, based on soil test results, the inclusion of trace elements in base fertilisers at sowing is a very good strategy.
Alternatively, crops can be foliar-treated with trace elements, once sufficient leaf is present for uptake.