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| April 2004 |
| The Interactive Online Magazine for Groundsmen and Greenkeepers |
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If you’re looking to re-seed this spring, British Seed Houses amenity seeds manager Richard Brown offers some timely advice. As sports grounds look forward to coping with the legacy of water logged winter pitches, attention turns to their rejuvenation. For many - and where event schedules allow - this will mean starting again and reseeding the grounds. This crucial operation has many potential pit falls, but attention to detail in just five key areas should ensure good seed germination and establishment. |
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The ideal time for sowing grass seed is traditionally the early autumn when, although air temperatures may be dropping, soil is still relatively warm. Spring soil takes time to warm up – April temperatures are typically no higher than in November. As a result, spring germination and establishment may be slower than for a late September sowing though they are perfectly adequate. Rainfall is the other consideration. Autumn conditions always guarantee adequate moisture for seed germination and establishment. Rain we need, but continuous downpours for what seems like months on end, we don’t! Newly sown seed is prone to run off; and slow establishment in water-logged conditions has been made worse by the build up of seedling fungal pathogens which love the wet and warm conditions. Right now, spring sowing (or re-sowing those areas that failed to establish this winter), when, just maybe, the rain might let of for long enough to dry the soil, might seem like the better option. Grounds managers should be ready to sow by the end of April when soil temperatures will be starting to rise and subsequent germination and establishment can get underway. It may seem ironic now, but by May and June it may be necessary to irrigate spring-sown pitches. |
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AberImp in particular features excellent wear tolerance under both low and high nitrogen fertiliser regimes. In addition, it brings the added benefits of unrivalled shoot density and exceptional slow re-growth characteristics under regular mowing. Perennial ryegrass has been consistently shown in trials throughout the temperate world to be the most wear-tolerant grass species – equalled only by smooth stalked meadow grass (Poa pratensis) – yet it scores over meadow grass in that it establishes very quickly from seed. Even in swards sown with a mixture of meadow grass and ryegrass, the proportion of the former rapidly declines, especially under high rainfall conditions. Strong creeping red fescue (Festuca rubra) such as Camilla is sometimes also included in sportsground mixtures to give the turf a bit of “bottom” (eg. Grade A9 General Outfield and the Grade A14 Racecourse and Polo Grounds mixtures). But in swards sown with as much as 40% red fescue, the proportion at establishment is halved and declines rapidly to 1% after wear and shade treatment in the first year. Some mixtures also include Poa supina (eg. 5% in Grade A8 SUPRA Sport) – a grass that performs well in areas of high wear and shade. Wear tolerance is an important attribute but should not be considered in isolation. This is because shoot density – affecting both appearance and laying quality – is often negatively associated with wear tolerance. The factor that seems to influence wear tolerance more is above-ground biomass and biomass is usually greatest in swards with relatively small numbers of large shoots. There are some varieties like AberImp that buck the trend and have high biomass, and hence, wear tolerance combined with shoot density. These not only look good and play well in the short term but can also take the rigours of a long playing session. These are the ones that should be considered. Most varieties are sown in combination with other varieties of the same species. The underlying, and unproved, principle being that it is best not to put all your eggs in one basket – if one variety happens to prove weak in one area of performance, then another variety in the mixture will step in to take its place. For sports pitches, combinations of varieties of a single species do not necessarily have such an economic benefit. In most circumstances the inclusion of a variety for a particular trait will only serve to bring the performance of the mixture down in other ways if that variety has significant weaknesses. I would like to see adventurous groundsmen use simple two-variety mixtures or even top performing single varieties and dropping the lower performing “filler” varieties |
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Immediately before sowing, the surface can be broken up to a depth of 10-15cm and levelled, taking out large stones. Rake the ground to produce a reasonably fine tilth and then leave it to settle to a firm surface. For specialist applications and in arenas – where there are exacting demands on the pitch in terms of turf surface quality and durability under play – the natural grass pitch will be produced on a specially constructed root zone with appropriate drainage. Seed should be sown at the recommended rate (ryegrass at 20g/sqm) – no lower – using a proprietary seed spreader in two passes at right angles to each other to ensure better seed distribution. Seed can be sown by hand broadcasting in which case marking off and sowing in smaller squares within the whole area will ensure more even spread of seed. |
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It is always useful to have taken samples to test for levels of the major nutrients so that any deficiencies can be rectified. Grass will grow healthily at pH ranges of between 5.5 and 7.5 and the optimum is slightly lower than 7.0. Liming may be necessary if the pH is particularly low and, as a rule of thumb, 20kg/ha lime (calcium carbonate) should be incorporated into the top 100mm during initial cultivations to increase pH by 0.1. A granular fertiliser with a quick release source of nitrogen will help establishment, so use ammonium nitrate or ammonium sulphate if pH needs to be reduced. Excessive fertiliser application can lead to poor germination and seedling damage. As a general rule, 100kg/ha of N, P and K should be applied to the seedbed as less bulky high analysis fertilisers and mixed into the top 100m of the rootzone, as P is especially immobile in the soil. It may also be worth applying nitrate at 25-50kg/ha a few days before the first mowing to give establishment an extra pep. |
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The new turf will not be functional for two or three months but it should be mown regularly. For this reason it may be worth considering over seeding existing pitches depending on the condition of the sward in terms of its density and Poa annua population. The first cut of a newly established pitch is best made when the grass is fairly tall. Use a rotary initially as a cylinder mower tends to pull out newly established grass plants from the seedbed. A cylinder mower can be used for subsequent cuts. Mowing frequency should be increased in step with grass growth rates, which will increase in late spring, and the height of the blades should be reduced gradually to the final desired height of 2-3cm. By checking that no more than 33% of the vegetation is removed, the turf can maintain its photosynthetic gain – not only producing new leaves and tillers but also maintaining an adequate root system. |
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If you order your spring grass seed requirements from Grade A Direct by 30th April, and take delivery by 14th May, British Seed Houses will give you 20% extra seed absolutely FREE. For example, if you need 25kg you’ll only pay for 20kg. If you need 50kg, you’ll only pay for 40kg. If you need 100kg, you’ll only pay for 80kg. And so on. Alternatively, if you do not want the extra seed – why not take a FREE bag of Grade A granular fertiliser for every bag of seed you order. To discuss your requirements and take advantage of this superb offer, call the British Seed Houses’ Grade A Direct FREEPHONE number on 0800 328 8276 by 30th April 2004. Alternatively, if you know exactly what Grade A mixture you require, order on-line via Pitchcare's shop and we’ll give you the discount. |
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