IT'S been a peculiar growing season for just about all crops and now grass faces up to some unusual challenges to the rest of 2020.

In this article, Dr George Fisher, of CF Fertilisers, gives advice on how to make the most of grass following a first cut of silage:

Careful management of aftercut fertiliser applications will be essential in building vital stocks of high quality forage to provide insulation against market volatility and uncertainty in 2020.

The problem is this needs to be achieved following a very wet winter that will undoubtedly have reduced availability of nutrients in the soil and, now ironically, many producers have endured a lengthy period of low rainfall.

P and K levels shouldn’t be affected too much – P and K do not move much in the soil and supplies should be adequate if you’ve used FYM and slurry in previous years. But N and S move readily through the soil and the high rainfall over the winter could have reduced these and placed what is available lower in the profile than usual.

This is likely to be compounded by small plants with limited root growth so whatever N or S is there is unlikely to be easily accessed. Hopefully, most people will have got some N on their land before first cut but aftercut applications will be essential to ensure grassland does not ‘run out of puff’ as the season develops.

Simply adding a bit of additional fertiliser over your normal practice or relying solely on FYM and slurry won’t work – you need to be prepared to increase N and S levels by 25-30% above usual levels to get the best results.

If you would normally put 50-60kg N/ha and 15-20kg SO3/ha on after your first cut, you need to be thinking of increasing these to around 70-80kg/ha and 20-30kg/ha, respectively. Equally, if your third cut usually gets 40-50kg N/ha, this needs to be 50-60kg N/ha – it’s these sort of levels we’re talking about.

Producers should also be mindful of weather conditions, particularly the prospect of land drying out as the season progresses, and pay particular attention to timing of applications. The longer the time that elapses between when you cut your silage and when you get back in with the fertiliser, the greater the loss in terms of yield and quality.

Delaying application for second cut fertiliser, for example, will lose you 370kg/ha of fresh grass every day, so over two weeks that could be as much as 1 t/ha of dry matter. With every tonne of DM of grass silage at 11.5 MJ ME containing enough energy to produce 1490kg of milk – which at 29ppl is worth £430 – that translates into a saving of 0.7t of concentrate, which at £230/t equals £165.

A range of options for applying N and S exist, but the best approach lies with true granular compounds. The problem is that blends are physical mixes that can separate out in the bag and hopper leading to inaccurate applications – some areas get too much of one or both elements, whilst others get less than they need.

In true granular compounds, every granule contains every nutrient so the spread is much more even with the result that up to 14 times more landing sites for key nutrients are possible than with blends. If you’ve used FYM and slurries and Ps and Ks are good, something like SingleTop (27N+12SO3) would be an ideal choice, whereas if they need a bit of maintenance CropMaster Sulphur (27-4-4+7SO3), or KayNitro Sulphur (25-0-13+7SO3) would be better options.

If you haven’t used FYM or slurry but Ps and Ks are still high, then SingleTop is still a good option but if you’re looking at more frequent cutting then Multicut Sulphur (23-4-13 +7SO3) would suit best.

* CF Fertilisers has launched an online silage 'health check' providing specific advice on managing aftercut applications and product decisions. By answering a simple series of questions, producers can receive information and recommendations for maximising grass production in their individual situations.