August 2018 Monthly Management

Late season Fertiliser for Autumn and Spring Grass, Winter Forage & Autumn Grass

29 August 2018

Late season Fertiliser for Autumn and Spring Grass

spreading fertiliser

Both grass growth and grazing management in the late summer and autumn period are important to ensure a good supply and utilisation of available grass. This is especially relevant this year with low fodder stocks giving a necessity for extending the grazing season both at the back end, and in the spring. The right approach now with fertiliser is critical to achieving good autumn and spring growth rates if weather conditions come good.

Last Round of Nitrogen

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 to take maximum advantage of any good growing conditions that come in the Autumn. Including sulphur with the nitrogen can be also help boost the nitrogen efficiency. Higher rates are unlikely to offer much advantage at this timing as Nitrogen utilisation usually decline in the autumn as grass growth rates start to decline. Excess Nitrogen in the soil will be prone to high risk of leaching losses at this time, especially as soils become wetter.

Late season Potassium (K)

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 over and above normal offtake levels if you want to build fertility in the soil.

There are 3 options for supplying K at this time.

  1. Slurry: 1000 gallons of thick slurry will have approximately 30 units of K per 1000 gallons. Target any late slurry applications to fields that are low in soil K and/or cut for silage. Match application rates to the needs of the fields, and apply higher rates if slurry is dilute, as this will have lower nutrient levels.
  2. Use a compound with K in the last round of fertiliser: Options with either NPK or NK products are available to add additional K when applying the last round of Autumn Nitrogen. Choose an NPK where phosphorus (P) is also required. Where P is sufficient, NK products such as 19-0-15 can be a good option without adding an extra work of having to go with an extra round of the spreader.

Soil pH and Phosphorus

Having soil pH and phosphorus (P) levels correct in the soil will be a big help in getting grass growth moving again next spring. Lime can be applied in the autumn once it is planned into the grazing rotation and where ground conditions are good. Phosphorus can also be applied in Autumn (up to the Nitrates cut-off date) in advance of spring growth. Phased release phosphorus products such as PHYSALG 27 can be particularly effective for this as it is released more slowly from the granule and therefore more protected from fixation by the soil and from losses over winter.

Nitrates cut-off dates extended in 2018

To help build low winter-forage supplies, there is an extension in place for fertiliser and slurry spreading dates for this autumn. Normal dates for fertilisers containing N or P is extended from 15 September out to 30 September. This gives an opportunity to take advantage of potentially good growing conditions in the autumn. The closing date for slurry is also extended from 15 October to 31 October for 2018.

Plan now for next spring

Autumn is the time to be thinking about next year's fertiliser plan. To build a good plan, you need baseline soil fertility information from soil tests. If you haven't got up to date soil samples within the last 2-3 years, then book you soil sampler now to take samples in October/Novemver so that you have results in good time to plan for the spring.

Winter Forage & Autumn Grass

Where winter fodder stocks are currently low on farm, early action is essential, careful planning and management will yield the best results. The first step is to carry out a fodder budget. This is a vital tool in calculating how much winter feed is on the farm and how much additional feed is needed to fill any possible deficits. Co-op advisors can assist in completing a fodder budget and give recommendations if a deficit is identified and we encourage anyone that is concerned about their feed demand for the coming winter to do so. In addition to a fodder budget it is also recommended to carry out a silage test to determine the dry matter content and nutritional aspects of the feed in the yard.

What to do if short of winter fodder?

If you are short or fodder this winter, it is best advised to source additional fodder now rather than in 3-4 months’ time. As well as sourcing fodder from outside your own farm, feed stocks can be conserved significantly by targeting the diets of certain cattle groups within the farm.

The best cattle groups to focus on winter feed savings on are young stock and dry cows. A typical weanling diet will comprise of 5-6 kg grass silage and 1-2 kg of concentrates on a dry matter basis. A portion of silage can be replaced by increasing concentrates to 3kg thus reducing the quantity of silage by 25% in the diet.

In a dry cow diet, it is also possible to replace a significant portion of silage from the diet without having an adverse effect on performance. Just after drying off, a cows’ dry matter intake will continue to remain high (~17kg/DM), and they will consume large quantities of silage without the need to. As a result, it is often seen that late calvers and cows with high body condition scores tend to gain excessive weight during the dry period. One option for cows far off from calving (greater than 8 weeks) is a diet comprising of 5-6kg of hay or straw and 4-5kg concentrates (dry matter basis). This will satisfy nutritional requirements in the dry period, however, silage needs to be in the diet 2-3 weeks prior to calving.

Cull Cows

When fodder stocks are low it is advised to cull or sell any non-productive/surplus stock off the farm in order to save feed. However, in the present climate, the price and demand for cull cows is very poor. Situations will vary from farm to farm but if feed reserves are tight it is best to reduce the stocking rate now to try and allow the farm build up covers and carry as much grass in to the Autumn as possible.

If feed stocks are adequate and stocking rate is reasonable then cows that may have turned up empty but are milking well could be milked once a day and fed a high level of concentrates (e.g. 8kg/day). The efficiency of weight gain is much better during lactation rather than during the dry period. While gaining condition from the high feeding levels, the cull cow is also generating income through milk produced. For example, a cow milking 15 litres/day at 4.2% butterfat and 3.60% protein will generate a milk price of 39.92 c/l. As a result, that cow is grossing €5.98/day with a total feed cost of €2.70 per day.

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 2018 by grazing out paddocks well and housing cattle at the right time with the right amount of grass on the farm

See table below for target rotation length at different stages during the autumn.

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.