Fertilise by the book – tip for silage makers

11 July 1997




Fertilise by the book – tip for silage makers

By FWlivestock reporters

PRODUCERS should stick to recommended fertiliser guidelines after second cut silage, and apply it as soon as possible.

According to ADASs Peter Dampney, recent high rainfall and good second cut yields mean theres unlikely to be a surplus of residual nitrogen in soil.

"Fertilise aftermath as you would normally. Soil moisture levels are good, so nitrogen will be used efficiently compared with uptake in last years drought conditions."

Signet consultant Ian Ross also believes that current soil moisture will guarantee a good regrowth following N application. "Its as good as money in the bank," he says.

Dumfries-based SAC grassland specialist Johnny Bax echoes these views. "Apply 80-100kg N/ha, using slurry where possible, and taking its fertiliser value into account. Where effluent is included in the slurry ensure its well mixed to minimise scorch."

Theres likely to be little response to phosphate, but tissue testing may help gauge whether potash and sulphur fertilisers have been applied in the correct amounts, says Mr Dampney.

"Potash requirement depends on soil type, manure and fertiliser applied and soil analysis, and should be gauged on a field-by-field basis.

"Sulphur deficiency is increasing, and later cuts are more responsive to application than earlier cuts. Deficiency is most likely on shallow or sandy soil but all soil types may be affected. An application of about 15kg/ha of S is recommended."

Producers with plenty of grass and thinking of cutting back on nitrogen should first consider other options. Check whether stock, such as heifers, could use more grass, advises Genus Management nutrition consultant James Shenton. Alternatively, make silage from excess grass even when it is not needed this year, he says. Well clamped silage will keep and a smaller area will be needed for first cut next year – allowing more spring grazing.

ADAS beef and sheep consultant Elwyn Rees also stresses that summer nitrogen applications give an efficient response and can allow concentrates to be reduced, if grass can be grazed or conserved.

That extra home-grown forage could allow cattle to rely on forage alone next winter, claims Dr Rees. But small silage cuts may be more expensive than straw and concentrate diets for beef or sheep, he warns. He also cautions against over-estimating the quality of late harvested second cut silage or hay fed to highly productive stock. Although these crops should be well made they may be low in digestibility. Also be aware that when a heavy hay crop is cut, and there is dead material at the base, sward regrowth will be slow if there is little rain from now on.

Silage aftermaths should recover faster, he adds.


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