Making sure later cut silages deliver on yields and quality

Aiming to take two to three cuts of silage through the later part of summer and into autumn could boost low forage stocks considerably but will require careful management.

This is the message from David Howard, Wynnstay head of dairy services. He says: “From the analysis we have received so far first cut silage has been of exceptional quality for the most part, however second and third cuts, if taken, are low in both yield and quality.”

There are several important management steps producers should now be taking if they are to address this, he says.

“One of the biggest questions revolves around the land’s ability to support further cuts of silage with many producers not quite sure what the nutrient status of their soil is and whether it has what is needed to support optimum growth and large offtakes of grass.

Nitrogen levels

“For those who managed to get some muck and slurry on and were able to apply fertiliser as planned, nitrogen levels could be okay, but it is a bit of a lottery.”

Dave Mitchell, Wynnstay fertiliser manager, says phosphorus (P) and potash (K) levels should not change because of the weather. He explains P and K do not move much in the soil and supplies should be adequate, especially if farmyard manure and slurry have been used in previous years.

He says: “The elements that can move through the soil and that could have been affected by the high levels of rainfall at the start of the season are nitrogen and sulphur (S).

“Nitrogen will be key but it is important not to limit potential growth by missing out on other key nutrients. Grass has been hard hit and it is likely P, K and sulphur levels will also need addressing.

“Even if P levels have been maintained at an index of 2 or 3, trials have shown yield responses of 1.2t/ha DM from fertility maintenance applications of 80kg P2O5/ha and it is always beneficial to supply additional S for yield, as well as to lift crude protein levels.”

According to George Fisher, of CF Fertilisers, improving crude protein levels could be a particular priority this year.

“In recent years silage crude proteins around the 10-12 per cent mark have been common where the target for a good forage base to a dairy ration is 16 per cent.

Sulphur

“Sulphur use is key in achieving adequate crude protein levels in silage, with trials in Lanarkshire using a 23N 4P 13K plus 7S granular compound fertiliser producing a 1t/ha yield lift over urea in first cut material, while also lifting proteins by 5 per cent.

“Elsewhere, we have seen sulphur compounds lifting grass yields by over 2t/ha at the same time as lifting proteins by up to 7 per cent without reducing dry matters.

“If you get your later cut silages working properly then these will help balance out any quality problems with first cut and give you a better base for winter rations and optimum cost-effectiveness of bought-in feeds.”

But keeping all key nutrients in balance so they promote maximum nitrogen utilisation and consistent uptake across the grass crop is key, he adds.

“You need to be mindful of the last permitted date for inorganic fertiliser application which is September 15 and you should also be careful about the type of fertiliser you use.

“One of the most popular choices is likely to be a 27-4-7SO3 compound which is ideally suited to late season fertiliser applications on grass providing low levels of P and K with added sulphur.

“Rates and number of applications will vary by system, location and the compound chosen, but as a general guide, applications of 130-185kg/ha can be made after each cut or grazing round.”