Use of fertilizers and manures during 1994 were studied at the farm and catchment scale in the largely
agricultural Ythan catchment, north-east Scotland, using farm level census data supplemented by
questionnaire data. Grassland accounted for 40% of the agricultural land, and seven farm types
represented 87% of the total land, having an average size of 90 ha. The average livestock density of
1·2 livestock units/ha was high compared to Scotland as a whole (0·5). Rates of inorganic fertilizer
applied to individual crops in the area corresponded with the national average and current advisory
recommendations. At the catchment scale, most fertilizer N was applied to grassland (47%), whereas
spring crops received the greatest proportion of the fertilizer P (35%). The annual manure production
equated to an average over the catchment of 63 and 16 kg/ha of N and P, respectively. When
calculated for farm types these figures ranged from 27 and 6 kg/ha on ‘cereal’ farms to 384 and
163 kg/ha on ‘pig’ farms. The ratio of applied fertilizer N and P varied from 4[ratio ]1 for ‘general
cropping’ to 10[ratio ]1 for ‘cattle and sheep (lowground)’ farms. There was no significant compensatory
reduction in inorganic fertilizer applications on crops, which also had received manures.
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