Tillage Update April 14th 2022
Over the last number of weeks, the planting of spring crops has progressed very well with very good weather and seedbed conditions. Many crops are emerging to fully emerged as soil temperatures are quite good. Mark Plunkett Soil & Plant Nutrition Specialist, has advice on planting.
Spring crop planting making good progress
Soil pH & Lime
Cereal crops are quite sensitive to soil pH especially barley and require a soil pH +6.5 for successful crop establishment. Soil pH’s <5.5 can result in manganese toxicity and poor crop establishment. Maintaining soil pH +6.5 provides a suitable environment for rapid crop development and the foundation for good grain yield production. Optimum soil pH is critical for the availability of both soil and applied N, P, K & S as either organic (manures) or chemically (fertilisers) nutrients. Where soil pH’s are low based on a soil test aim to apply recommended lime to pressed / rolled ploughing and work well into the top 7.5 to 10cm of soil before sowing.
Select a suitable compound fertiliser such as 10-10-20 / 13-6-20 etc. On very low to low (Index 1 or 2) fertility soils, 10-10-20 would be the product of choice. On medium fertility soils (Index 3) 13-6-20 is a well balance fertiliser product for spring barley/ wheat. Aim to apply ~ 370kg/ha (3 bags/ac) and where possible combine drill at sowing time to increase the efficiency of all 3 major nutrients. For oats aim for a 10-5-25 at 500kg/ha (4bags/ac) to deliver sufficient K rates as oats requires 30% more K than either barley of wheat.
Applying sufficient phosphorus (P) is essential for rapid root and tiller development and is critical in spring barley in the first 3 to 6 weeks of establishment. Trial work carried out in spring barley clearly shows the benefits of combining P especially on low P Index sites (1 & 2). While potassium (K) is very important for N efficiency, grain yield development and straw strength and quality. A number of trials carried out in 2016,17 & 18 in Arklow, Co. Wicklow clearly showed the importance of K in grain yield formation and reducing the effects of straw brackling (breakdown) prior to harvest. Potassium untreated plots were more tolerant to foliar diseases such as powdery mildew infection.
Watch fields that are being ploughed out of long-term grass silage / hays as these fields may have very low soil P & K levels, resulting in crop P and K deficiencies. It will be very difficult to correct especially a P deficiency, as the P is needed in the seedbed zone and close to the rapidly developing seed / roots. Therefore, ensure sufficient available fertiliser P and K are applied at sowing time.
Nitrogen & Sulphur (S) applications to spring barley
Aim to supply ~ 30% of the crops N requirements in the seedbed. For early sown malting barley crops aim to top-dress with N + S once tramlines as visible. For feeding barley crops aim to apply remaining crop N + S requirements at mid-tillering in a single application or alternatively split 70:30 and complete N applications by stem extension (GS 31/32). Aim to apply 15kg S/ha.
Where organic manures have been applied, adjust final N applications to take account of N supplied from organic manures. For example an application of 25mᶾ/ha of cattle slurry by LESS and ploughed in rapidly can supply ~ 25kg N/ha offering a saving in chemical N of ~€100/ha at today’s fertiliser N prices.
Trace Elements (Mn, Cu & Zn)
Soil test results are a very good indication of the soil supply of both copper (Cu) and zinc (Zn). The soil test is not as reliable for manganese. Manganese (Mn) deficiency tends to be most prevalent on:
- sandy or lights soils
- recently limed or high pH soils
- poorly consolidated seedbeds or under dry and cold weather conditions.
Ensure seedbeds are well consolidated after sowing for example on fields ploughed out of grass leys ideally flat roll 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 inclusion of trace elements in base fertilisers at sowing is a very good strategy on soils with recurring trace element deficiencies. Alternatively, foliar treat crops once sufficient leaf is present for uptake e.g. 2 to 4 leaf stage.
Find out more information and advice from the Teagasc Crops team here. The Teagasc Crops Specialists issue an article on a topic of interest to tillage farmers every Thursday on Teagasc Daily. Find your local Teagasc office here