Grass – the greatest asset on your farm

Improved grassland management and making higher-quality silage will increase the economic and environmental sustainability of NI beef farms, attendees at a webinar held last Thursday were told.

Organised by a number of industry organisations, and with speakers from AFBI and CAFRE, along with Kilkeel beef and sheep farmer James Henderson, the event was the first of four planned for this year.

Delivering his presentation under the heading “Grass – your greatest asset”, Dr Francis Lively from AFBI emphasised how good grassland management will increase animal performance, ensure efficient input use and ultimately reduce the carbon footprint of beef.

Quoting results of a recent NI survey which indicated that over 50% of farmers still operate set stocked systems, he urged farmers to consider rotational or paddock grazing, as it can produce over 4t dry matter per hectare (DM/ha) of additional grass with no extra inputs supplied.

With more grass available from the grazing platform, it frees up additional land to cut earlier and make higher-quality silage, so ultimately less concentrate feed is required on the farm to sustain liveweight gains.

“That has economic and environmental benefits,” Lively pointed out.

A small investment in water troughs, electric wire and a little bit of labour can give a high return

He defines rotational grazing as a system where farmers might graze a group of cattle across four or five blocks of land, so the cattle are moved every five to seven days. A paddock grazing system is slightly more labour-intensive, with cattle moved every two to three days. While both rotational and paddock systems deliver a similar yield benefit over set stocking, grass in a paddock system is better utilised.

“A small investment in water troughs, electric wire and a little bit of labour can give a high return,” said Lively.

Ultimately, there is an economic benefit moving to daily paddocks. In a recent study at AFBI Hillsborough, which compared a system where cattle were moved every 24 hours versus an average of every 3.5 days, grass utilisation increased by 19%, and animal production per hectare by 33%. Overall this was worth an additional £656/ha.

However, Lively acknowledged that labour is often a limited resource on farms. A project has just started at AFBI Hillsborough looking at the potential for virtual fencing (where cattle are fitted with a GPS collar) as a means of reducing this labour requirement, and allocating grass on a daily basis.

Turnout

With grass at its highest quality in the spring, it is important to get cattle out as early as possible. Lively quoted results from an AFBI study where a group of steers were turned out on 5 April versus a second group turned out on 22 April. The cattle that went out first were 23kg heavier in the autumn, and 8kg heavier at slaughter the following year.

However, he also maintained that there is potential for farmers to hold light cattle out well into the autumn as late season grass is often as good a quality feedstuff as many silages made on NI farms.

In a study where young cattle were put out after weaning at the end of October, there was very little difference in performance when compared to a group kept inside and fed silage plus concentrates. However, the difference in feed costs worked out at 62p/head/day, or around £9 less per head for every two weeks outside.

Silage

The other main issue that will affect animal performance is silage quality. Where young growing cattle are being fed, Lively said that the aim must be to make higher quality silage by cutting earlier.

He advocates a three-cut system, producing silage with a D-value of 72, versus two heavy cuts of silage with a D-value of 65. “With higher quality grass silage, you will have higher animal intakes, so you will require higher volumes of silage, but overall you can get away with feeding a lot less concentrate, and you will have more profit,” he said.

Ultimately cattle that are fed good quality grass and grass silage, will grow quicker and will be finished at younger ages, and have a lower carbon footprint, he concluded.

Nitrogen – a nutrient easily lost

Nitrogen (N) in chemical fertiliser or in slurry is easily lost if applied in the wrong conditions, emphasised Dr Suzanne Higgins from AFBI at last Thursday’s beef webinar.

“Nitrogen is the most important nutrient, but also the hardest to manage. Potentially you could lose 30-50% of the N you apply depending on conditions,” Higgins told farmers.

Fertiliser N can be washed through the soil or lost in the form of nitrous oxide (a greenhouse gas) or ammonia. CAN in particular, is prone to loss as nitrous oxide, while urea is easily lost as ammonia.

She said that chemical fertiliser or slurry should not be applied when heavy rain is forecast in the next three to four days. In addition, slurry should not be applied on warm windy days as there can be increased ammonia loss, while there is no point applying N in a period of drought as N needs moisture to be taken up by the grass.

“It is better to apply N when there is the most growth and always keep an eye on the weather, because you risk losing it from your system,” Higgins advised.

When putting on fertiliser for silage, she said that farmers should avoid putting it all on at once as there is the potential to lose a lot of the N if conditions turn unfavourable.

Sulphur

Another nutrient easily washed out of the soil is sulphur (S), and it is commonly deficient in NI, and can result in reduced yields of up to 30%.

“Slurry won’t apply all the S you need. You need to put on a nitrogen sulphur fertiliser, particularly in the spring,” said Higgins.

Phosphorus

On phosphorus (P), she pointed out that recent soil-sampling schemes suggest that 50% of soils in NI contain too much P, so applying more in the form of chemical fertiliser increases the risk that it gets into waterways, where it is a major contributor to lower water quality.

“If soil is sitting at 3 or above for P you don’t need to be putting any more P on because it is not going to be needed for growth and it will just build up in the soil and be potentially lost,” she said.

Potash

For potash (K) the aim should be Index 2. K deficiency can reduce yields by 20%, so it is important that it is applied to silage areas either via slurry or chemical fertiliser.

Lime

To improve the utilisation of all nutrients Higgins also emphasised the need to target a pH in grassland of 6 to 6.2.

She pointed out that more than 50% of grassland in NI requires lime. Ideally it is best applied in late summer or early autumn, which will give it time to dissolve into the soil over the winter.

If lime is applied in the spring, farmers should wait at least four weeks before spreading chemical fertiliser, as there is an increased risk of the fertiliser N being lost as ammonia.

Back to the future with clover

Much of the research on clover was done in the 1980s and 1990s, but with farmers under pressure to reduce greenhouse gas emissions associated with chemical fertiliser, there is likely to be renewed interest in growing grass clover swards.

Referring back to that historic research, Dr David Patterson from AFBI pointed out at last Thursday’s beef webinar that clover can fix up to 150kg of N/ha/yr.

However, he acknowledged that one of the drawbacks of the plant is slow growth in the spring as it has a higher temperature threshold than perennial ryegrass.

His advice is for a “tactical use” of 50kg/ha of fertiliser N early in the season, alongside tight grazing in the April to June period, allowing light into the sward and the clover to come through.

“Avoid continuous grazing, especially with sheep. Graze off cleanly late autumn, early winter,” added Patterson.

To highlight the potential to replace chemical fertiliser, he quoted from a four-year study at AFBI Hillsborough in 1995, where a grass clover sward receiving 50kg of N/ha had 86% of the stock carrying capacity of a grass sward receiving 360kg N/ha.

Establishment

When establishing clover, Patterson said this was best done in late spring and early summer, which will give the clover time to get established for the winter.

It is vital that soil pH is above 6, P and K are at index 2, and that any weed issues in the old sward are addressed before you start.

A conventional reseed involving burning off and ploughing will work best.

“Don’t put seed in any deeper than 1cm. Roll before and after to ensure good seed to soil contact,” advised Patterson.

However, oversowing clover into an existing sward is also an option, potentially after a silage cut when the sward is likely to be more open.

The clover seed needs to get in contact with soil, so it may be necessary to use a machine with spring tines.

Graze for seven to 10 days before seedlings emerge with sheep or light cattle, and it should be ready for grazing in six to eight weeks, he said.

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