Focus on fields to maximise grass growth after a drought period

January 9, 2023

It is well known that well-managed grassland produces the cheapest feed throughout the year, whether it is cut to make silage or grazed by livestock. However no two years are ever the same and with weather patterns constantly changing seasons are becoming more extreme, with drier summers and milder sometimes wetter winters. Last year has been no exception with a cold late spring, followed by a dry summer, with drought conditions in many areas of the country. Coupled with high fertiliser prices, increased fuel costs and uncertainty created by events in Eastern Europe have created challenges never seen before in global farming let alone UK farming.

From a dairy farming perspective, these challenges have exerted extra pressure on grass crops to produce good yields of high-quality forage with reduced N inputs in many cases. Yet ryegrasses, in particular Westerwold, Italian and Hybrids, are all hungry species that will respond to higher rates of N and utilise all of any nitrogen applied to produce good yields with decent protein, ME and D value levels. Perennial ryegrasses will also utilise 100% of the nitrogen applied. Consequently, starving the plants of N will result in a lower yield of poorer quality forage, along with the faster deterioration of the sward in terms of density and persistency. Add prolonged drought conditions to the mix and it’s a multiple whammy of factors that will have serious negative effects on grass production.

Establishing grass

What can be done to counter these factors?

There are a number of key actions that can be used to offset and counter these factors; Where nitrogen is the limiting factor consider using clovers to offset the supply of N from the application of artificial fertilisers. Remember clovers take time to establish so allow 6 months for white clovers in grazing leys to start fixing any amount of N. A sward needs 30-40 % white clover content at this level, white clover can fix up to 150kgs/ha of N a year. White clover is reasonably drought tolerant too.

Red clovers will improve protein levels of cutting leys and help mitigate reduced N inputs in cutting leys. An inclusion of 3kg/acre (7.5/ha) is needed in a mix and can fix up to 250kg of N/Ha a year. Red clover has a protein content of 20-22% and is fairly drought tolerant. Be careful when introducing livestock to clovers as they can cause bloat.

Lucerne is a really useful crop on free-draining, light, drought-prone land due to its deep tap roots. It is a perennial crop that will last for 5-6 years and will give 3 cuts a year when established producing 17.5tDM / Ha being a legume it also fixes N, up to 200kg / Ha per year. The N is a real benefit to following crops.

Legumes require a pH of 6.5 and like to be sown between mid-March and mid-August. We can also utilise the benefits of a number of other grass and herb species for drought tolerance such as soft-leaved tall fescues, Cocksfoot, Timothy which have deep root structures, particularly the soft-leaved tall fescues which produce deep roots with high biomass enabling them to access nutrients and moisture deeper (over 1metre) in the soil profile. The herbs Chicory and Plantain both have deep tap roots which help them cope with drought conditions well, they also have high mineral content, double that of perennial ryegrasses, and have anthelmintic properties which give additional benefits to animal health. Sward Management Maintaining good ground cover and dense swards to prevent evaporation of moisture from bare ground will help grass crops hang in there when it gets dry. During drought periods it is tempting to try and cut or graze every last bit of grass from a field, however, doing so will induce even more stress and have a massively detrimental effect on the grass’s ability to recover once it receives adequate moisture. Adapt the management of swards accordingly to alleviate some of the stress, this can be done by reducing stocking rates and increasing the length of the grazing rotation. Look after the residuals, this is key for good recovery leaving a longer post-grazing residual. When cutting lift the cutter bar on the mower to leave a longer stubble, an extra couple of inches has much more value in terms of energy and photosynthetic area to the plant for regrowth. Having a reseeding policy will also help as recent reseeds coped much better and recover with less long-term damage.

Catch crops

Utilising catch crops of Westerwold or Italian ryegrass following whole crop and cereal harvests will help fill the forage gap if silage has been fed through the summer months.

Managing drought stressed swards after rainfall

When the rain falls it will take time for a perennial ryegrass sward to fully recover from drought stress. Usually about 21 days, as during the stress period the grass plants have been forced to use their root reserves and deplete them so it is really important to look after the sward during this time. The recovering grass plant will not be able to utilise large amounts of N straight away. It will need to reach the 3rd leaf stage before it will start fully photosynthesising so apply lower applications of N from the first flush of growth and repeat again at 10-day intervals to maximise regrowth. Newer reseeds will recover quicker and probably fully whereas older poor-performing swards may be outcompeted by unproductive weed grasses and therefore will be more cost-effective to reseed.

For further information on SCF Grass Seed, please contact our experts at 01829 797100.

Thanks to Barenbrug for their contribution.

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