At last the weather has changed though now into April the soil temperatures are only now rising above 10ºc. Anyway, after a wet winter and the recent dry spell there is much to be done. We have a short spell when good growing conditions with the increased warmth are still accompanied by moist soil conditions when the gains from rainfall exceed the losses from evapotranspriration.
Into May and the reverse happens when the losses in moisture begin to become greater than the gains. On standard coarse turf areas such as football and rugby pitches, normally not equipped with irrigation much will depend on the rainfall over the next six weeks. The period between stopping play at the end of the season and the beginning of the following one is very short.
The narrow window makes the outcome of this immediate task on sports pitches a very difficult one. Initially, scarification is needed to remove accumulated debris and as much of the annual meadow grass that has invaded during the season. It is also vital to prepare the surface for over-seeding. Decompaction with the earthquake or vertidrain is also essential to loosen the top 200mm after heavy use. The seed must be drilled to at least 8 to 10mm to ensure good warm moist conditions vital for germination and establishment. Most over-seeding implements capable of drilling the seed satisfactorily are limited to 50 to 70 mm row spacing and the density of grass cover can just not be obtained unless there are at least two passes in two directions to reduce the effective spacing.
To create any density of grass sward, plants need to tiller and harden before full use and in the case of football and rugby, this renovation treatment determines the grass cover that can be expected in the autumn. Records show that May warms significantly and unless there is sporadic rainfall during the month, over-seeding remains a lottery. This is a major concern and the delay in this treatment also influences spring fertilisation. Ideally, nutrition should be available once active growth begins in April. However, with over-seeding only possible in May it is preferable to knock back the competition and gain successful germination before applying fertilisers. It is a case of one or the other. Favourable conditions before it becomes too warm favour the earlier application but there can be no real gain before soil temperatures rise above 10ºc.
To summarise one thing is clear – the need to concentrate all expertise available for the renovation procedures as soon as possible during this narrow window. Secondly, where scarification is carried out, every effort should be made to carry out the operations properly with adequate opening of the surface for over-seeding. Thirdly, the proper placement of the seed after reducing the competition is vital. Finally, judicious mowing and the use of controlled release fertilisers will help to attain the most dense cover possible for the new season.