HILL LAND STUDIES IN THE GRAMPIAN REGION OF SCOTLAND

Abstract

SummaryFactors affecting the growth of mixed grass swards in the Upper Don Basin were studied in two phases: in 1967–68 within the altitude range 260–440 m and in 1969–70 in the range 330–550 m O.D. In the first phase the interaction effects of altitude, aspect and soil parent material on herbage yields and mineral element contents were studied using 24 sites in a 3 × 2 × 2 factorial design, without fertilizer in 1967 and with nil, N. P and NP treatments in 1968. Total yields from 3 cuts at 2 monthly intervals averaged 4.84 tonnes D.M. ha−1 in 1968 with no overall significant altitudinal differences. Application of 75 kg N ha−1 as Nitrochalk raised the yield by over 40 per cent, slightly more in the presence of P on soils derived from mineralogically acidic parent materials. Overall, yields from soils on ‘basic’ materials were at least 25 per cent greater than from the ‘acidic’ ones. Sites with southern aspects mostly oulyielded the northern ones but not significantly so. In the second.phase 3 pairs of ‘acidic’ sites only were used, with an NPK treatment added to the 1968 treatments, and lime for the most acid soils at 550 m O.D. On these highest sites the yields were much reduced by the adverse climatic conditions.Samples of the dry matter from each treatment, replicate and cut at each site were analysed and the offtakes of N, P, K, Ca and Mg determined as well as the apparent recoveries of N, P, K and Ca from the fertilizers. The constraints of altitude on yield and composition were strongly correlated with the prevailing air and soil temperatures. The practical implications of the findings for upland livestock production are discussed but the detailed correlation and factor analyses of the data are presented in another paper.