Minimum phosphorus needs for silage production.

Abstract

Phosphorus recovery in product at the low stocking rates was poor, but improved in the high stocking rates. It is deduced that when the new Teagasc recommendations are implemented, recovery of applied P in product should be very efficient. • Soil should be maintained at Index 2 (3.1 to 6.0 mg P l - 1 ) for optimum silage production • Slurry should be recycled to the silage land early in the year or after 1 st or 2 nd cut silage. • Maintenance fertilizer P should be used to supplement P in the slurry in order to replace removal in milk, meat and other losses • Where slurry is recycled, maintenance fertilizer P for silage land will be less than for grazing land as concentrates are an important source of P input to the farm. The fertilizer P maintenance requirement will normally be between 0 and 10kg P ha -1 yr -1 . • Where slurry is not recycled, maintenance P requirements for silage land are higher at 20 to 30 kg P ha -1 yr -1 • Do not apply insurance P dressings to silage land. It will not increase production and may lead to increased potential for P loss to water.