August 2019 Monthly Management

Water heating, autumn grass, steps to successful reseeding

21 August 2019

Water Heating

Water heating is a significant cost on dairy farms.

Main areas of energy usage
Milk cooling 31%
Water heating 23%
Milking 20%
Lighting 3%
Water pump 5%
Other 18%
Teagasc research states that it is one of the highest areas of energy usage on farm (see table 1.1)

Carbery are requesting all farms to use chlorine free detergents in the bulk tank from July 1st and in the milking machine from January 1st, 2020. When using chlorine free detergents there will be a bigger emphasis on hot water to keep both the bulk tank and milking plant clean.
The quantity and temperature of hot water available on farm will be important considerations when deciding on a chlorine free wash routine.

Currently electrical water heating is the most common method of heating water on farm. However, there is other options available such as heat recovery, gas and oil boilers. Heat recovery (HR) is a very efficient system but payback varies widely depending on parlour size, hot wash frequency and bulk tank size. HR can meet 40-50% of water heating load without plate cooling and 20-25% with plate cooling. Payback on HR systems needs to be checked on a case by case basis.

Price per 100 Litres of Hot Water (80c)
Day Rate €2.00
Night Rate €1.00
Oil Burner €0.70
LPG (Gas) €0.90
Table 1.2 shows Teagasc estimated water heating costs.

Dairy Geyser diesel water heater

Dairy Geyser
Drinagh now stock Dairy Geyser diesel water heaters and Calor Rinnai Gas water heaters.

Autumn Grass

The aims of autumn grassland management are:

  1. To keep grass in the diet for as long as possible this autumn
  2. To set up the farm for Spring 2020 by grazing out paddocks well and housing cattle at the right time with the right amount of grass left on the farm.
Autumn grazing targets: Stocking rate of 2.5LU/ha
Date Cover/cow AFC Rotation Length
Mid-August 200 500 25 days
September 1 300 750 30 days
Mid-September 400-450 1000-1100 35 days
October 1 400 1000 40 days
Quick guide: On a 30 day rotation approx. 3% of the total grazing area available should be grazed per day – if higher than 3% is being grazed per day then the rotation is shorter the 30 days.

While November may seem a long time away – action is required now to increase the amount of grass on the farm while growth rates are good and highest farm cover should be reached by mid September. Where there is no grass in September there will not be any grass in October or November.

Last Round of Nitrogen & Late season Potassium (K)

Nitrogen will be a driver of grass growth in the Autumn as much as any other time. Spreading up to 30 units per acre in the last round of fertiliser in early to mid-September will help sustain good grass growth rates. Autumn is the ideal time to replace potassium (K) offtakes and build up soil K levels where fertility is low. Normal offtake levels for grazing are typically 30-40 units/acre of K per year. Silage removes a lot more, up to 100 units for first cut, and another 80 units for second cut. Low K soils (Index 1) require 50 units/acre of K to build fertility in the soil.

Soil pH

Lime can be applied in the autumn once it is planned into the grazing rotation and where ground conditions are good.

Steps to Successful Autumn Reseeding

Reseeding is one of the most cost effective on-farm investments, with return on investment generally seen within two years. Reseeded swards have huge growth potential and greater fertiliser efficiency compared to older swards. With a great grass growing season to date, many will avail of the opportunity to reseed a portion of their farms this autumn. Some of the key steps to ensuring a successful reseed are as follows:

1. Timing

With autumn reseeding, timing is critical. Leaving it too late can have severe consequences for the successful establishment of a new sward.

The seed should be sown by the second week of September at the latest. Desirable growing conditions for seed germination start to deteriorate from late September onwards. In addition to this, one must plan ahead to the post emergence weed control and potential first grazing. If the sowing date is delayed, then the opportunities to control weeds and graze the new ground are minimized greatly.

Remember that if the weather breaks around the end of August, you can quickly lose a week or two so err on the side of caution and don’t leave it too late.

2. Spraying Off

Using a glyphosate spray to kill the old sward is important, as this removes competition from the new seedlings as they are establishing. Follow label guidelines and use the higher rate of water to ensure adequate uptake of the spray by the old grasses and weeds. Allow time for the spray to kill the old sward, particularly if docks and thistles are present. Apply lime to help counteract this surface acidity from surface thrash; liming is critical with min-till and direct drilling.

3. Cultivation Method

The method of reseeding in the autumn can have an impact on success and establishment of the sward. Ploughing is the most reliable method, as it creates good soil/seed contact and buries thrash and pests. Discing is also a popular method of surface tilling. This method works well provided the soil is not compacted. In autumn, direct-drilling can be problematic as slugs and pests can be more of an issue with autumn reseeds compared to spring reseeds.

Regardless of the cultivation method, always ensure you are sowing into a fine, firm seedbed and roll adequately after sowing.

4. Fertiliser For Root and Tiller Development

Cows grazing
Cows grazing Drinagh D74 grass seed after reseeding last autumn.

Phosphorous and potassium are essential for root and tiller development of the new grass plants – generally three bags of 10:10:20 per acre are advised on index three soils. It’s advisable to follow with nitrogen about three weeks after sowing. Ensure that you stay within your allowances and spread before the September 15 deadline in accordance with the nitrates directive.

5. Weed Control & Early Grazing

Post-emergence weed control is vital and the most cost-effective opportunity you will have for weed control in the new sward. Apply approximately four to six weeks after sowing when weeds are actively growing. It’s also important to check the label on your post-emergent weed spray to see when the sward can be grazed. In most cases, this is usually one week following application.

Early grazing is critical to help tillering of the new sward. Graze once ground conditions allow and the new grass withstands the pull test. A sward passes the pull test when you pull the leaves and they break off and the root of the plant remains in the ground.

Grazing in autumn, once ground conditions allow, will ensure you have a more dense and settled sward by the following spring.