Dairy Notes April 2010
Between 1 April and 1 May grass growth rate normally increases rapidly, from approximately 15 to almost 100 KG dry matter per hectare per day. Most grazing swards are carrying similar grass covers at the moment but this surge in growth rate could mean that by the time you reach the end of the first grazing cycle covers are too heavy for cows to graze out cleanly.
For most of the grazing season the ‘ideal’ grazing cover is 3000-3300 KG dry matter per hectare (grass height 150mm). At the start of the season, however, you must graze swards with a cover of 2500-2700 KG dry matter per hectare (grass height 100mm) to give you a chance of completing the first cycle before covers are too heavy. Turning cows out to graze at the correct time is critical to ‘control’ grass growth and maintain grass quality throughout the season.
Turn cows out for two to three hours per day as soon as possible. In addition to the immediate financial benefits of reduced feed costs, improved milk protein levels and higher yields, early turn-out makes it easier to maintain grazing quality throughout the grazing season.
To control nutritional stress at turn-out:
- Reduce the amount of concentrates fed through TMR or out-of-parlour feeders and increase parlour feeding levels a few days before turn-out.
- Order a 16 -18 percent grazing concentrate before turn-out and allow it to mix in the storage bin with the winter ration.
- Graze for only two to three hours per day at first, increasing gradually to eight to nine hours by day ten
- Increase the level of silage being fed to compensate for any sudden changes in weather conditions.
There are a number of key points to consider if you are thinking about growing forage maize this year:
- Trials carried out by the Agri-Food and Biosciences Institute (AFBI) Hillsborough, have consistently shown that, even in the most favourable growing areas of Northern Ireland, the extra yield achieved using plastic mulch for early establishment justifies the expense.
- Crops should be sown as early as possible, when ground conditions are suitable as ‘forcing’ a seedbed can lead to soil compaction, causing yield loss. Field headlands will benefit from a run with a ‘shakerator’ before ploughing. For crops sown under plastic, drilling can commence in mid - April as the crop should be emerging after the danger of late frosts has passed.
- The Forage Maize Recommended Varieties booklet 2010 produced following trials carried out by the DARD Plant Testing Station at Crossnacreevy is now available from your local DARD Development Centre. Varieties recommended for establishment under plastic on the best sites (mainly Down and Armagh) include Kaukas, Salgado and Award. For more marginal sites use early maturing varieties such as Kaukas, Award, Mas 12A and Surprise.
- In the past land intended for forage maize received bagged fertiliser along with heavy coatings of farm-yard manure and/or slurry for crop growth. This practice is likely to have resulted in a significant oversupply of nutrients relative to the recommendations given in the Fertilisers Recommendation book - RB209. Under the Nitrates Action Plan this could constitute a breach in cross compliance.
Ongoing research at AFBI, Crossnacreevy and technology work by CAFRE confirm that supplying nutrients above the recommended levels will not give an increase in yield. In the current economic climate the excess nutrients could probably be put to better use elsewhere on the farm reducing the fertiliser bill or treating deficiencies.
Check the fertiliser recommendations for your maize crops by entering your fields soil nitrogen status and phosphate and potash indices on the Crop Nutrient Management calculator on the Ruralni.gov.uk web-site or contact your local Dairying Development Adviser.
- Weed control strategies are mainly based on the use of Stomp and Calaris at sowing. A follow up treatment may be needed to control weeds developing between the rows before the crop emerges from the plastic, for example, applying a tank mix of Stomp, Calaris and Bromoxinil. An alternative but more expensive chemical treatment is the application of the pre-emergent spray Cadou Star (Bayer) at planting.
Turn out cows early to manage grass quality
Forage maize – early establishment is essential