Response of southern North Island hill pasture to nitrogen, molybdenum and lime

Abstract

of molybdenum (MO), lime and nitrogen on steep (>30°) north-facing hill pasture on the Massey University Hill Farm, "Tuapaka". Treatments included application of molybdenum, lime (L), nitrogen (N) alone and together with MO and lime. MO and lime werre applied in mid May at 0.05 kg/ ha and 2000 kg/ha separately, and N fertiliser was applied as urea in August and October at 60 and 20 kg N/ha respectively. Herbage and soil responses were measured over spring and summer 1992/93. Nitrogen fertiliser increased herbage mass accumulation from 3 to 41 kg DM/kg N applied, and the response was increased by the addition of lime or MO. Ryegrass content increased in the sward and the low-fertility-tolerant grass species content decreased. MO application increased the white clover content in the sward and subsequently resulted in the increase in herbage mass accumulation by 0.4% to 32%. The effect of MO application was larger than that of liming but less than that of N alone application. Liming increased soil pH by 0.24-0.3 pH units per 2000 kg lime applied and soil moisture was increased from 2% to 26% over spring/summer, and the potential mineral nitrogen was increased by 94% in November. These resulted in the increase in herbage mass accumulation from 4.4% to 15%. These results indicate that MO and lime applications would be beneficial on these hill soils. Keywords: herbage mass accumulation, hill country, lime, molybdenum, nitrogen, Trifolium repens