Tillage: Low light levels big factor in poor winter barley yields
Published 27/07/2016 | 02:30
The start of the winter barley harvest gave some very disappointing yields but as we progress, yields and bushel weights have improved.
However it does appear that many fields are yielding 0.7-1.0t/ac less than last year despite having good crop establishment and low disease levels.
Good agronomy is not enough; crops must get light and with solar radiation data for Met Eireann (Gutreen) showing that June levels were 14pc less than last year good plants could not fill grain.
The only consolation is that demand and price for straw is strong. While a lot of the six row varieties have been cut there are some two row varieties which will not be fit for harvest for another week. Most crops sown for whole crop have now been harvested.
Avoid the temptation to harvest what appear to be poor crops as whole crop as a crop which has poor yield potential will not make a good wholecrop. Virtually all winter oilseed rape has been desiccated with harvesting due to start in the first week in August.
After harvest give shed oilseed rape seed time to germinate before cultivating. If you bury seed by you will find volunteers coming through for up to 10 years. The Department recommended list of oilseed rape for sowing 2016 has just been released naming Compass 98, Flash 103 and Sensation 97.
Where glyphosate is used preharvest you must, within six weeks, either sow a crop or take measures to provide green cover. Green cover can be encouraged by stubble cultivation.
Ploughing or the application of a second non selective herbicide on the green cover cannot take place before December 1 unless a crop is sown within two weeks.
If you had either a seed crop or a crop destined for human consumption which prohibited the application of a non-selective herbicide preharvest the requirement for green cover is reduced to 75pc of the area.
Ramularia, rust, leaf spot and powdery mildew reduce yield and quality of fodder beet. A fungicide application early in august will increase yield by 4-5t/ac in preventing/controlling disease and will also have physiological effects.
Increased leaf retention will result in reduced harvest losses. Tillage farmers who joined GLAS and selected 'Catch Crops' must establish their catch crops by September 15.
The requirement is to sow a cover crop which must consist of at least two species in an integral mix - a mix purchased rather than made up on farm.
You should order your seed mix now as it is unlikely that merchants will be in a position to supply suitable mixes unless ordered well in advance.
The seed rate and cost/ha is prohibitive for most of the species listed in the specification. The most acceptable mix on a cost basis is 5kg/ha leafy turnip combined with 3kg/ha of fodder/forage rape. It is not ideal either for agronomy or biodiversity that both species are brassicas.
If you are growing other brassicas such as oilseed rape, the use of a brassica as a catch crop adds an additional restriction to your farm rotation. It is advisable to have at least four years before sowing a second brassica crop so as to minimise disease carryover.
If you propose to graze your catch crop it is important to apply adequate nitrogen, phosphate and potassium depending on soil fertility at sowing time. Remember that no chemical nitrogen or phosphorus is allowed after September 15. Catch crops must be sown following light cultivation, shallow grubbing.
It is preferable to remove all straw from fields before sowing catch crops as establishment, even where straw has been chopped, can be difficult.
Ploughing is not permitted. You may use a graminicide after the crop is established to control volunteer cereals and grasses including sterile brome. If in any doubt as to what is required you should contact your GLAS advisor.
PJ Phelan is a tillage advisor based in Tipperary and is a member of the ACA and ITCA