Pasture production and transfer of fertility within a long-established hill pasture

Abstract

A long-established, moderately steep hill pasture was visually mapped into five strata (A to E) according to occurrence, colour, and vigour of pasture species and distribution density of obvious urine patches. Annual pasture production and major nutrient concentrations of the pasture, except magnesium, decreased markedly from stratum A to stratum E. Phosphorus and potassium soil tests were distinctly higher in stratum A than in the remainder of the paddock. From the measured nutrient uptake in pasture and from dung counts carried out on each stratum, it was estimated that large quantities of P, K, and N were transferred into camp areas, mostly from the least productive two-thirds of the paddock. Because of the irregular distribution of the strata it is not practicable to compensate fully for the observed transfer of nutrients by differential aerial topdressing; but phosphatic topdressing of 10 percent of this paddock could probably be omitted without measurably affecting total production. The significance of the five strata in soil sampling and the incidence and correction of potassium deficiency are discussed.