A comparison of N and P inputs to the soil from fertilizers and manures summarized at farm and catchment scale

Abstract

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.

Assessing nitrogen and phosphorus efficiency at farm and catchment scale using nutrient budgets

“…It is therefore important to notice that the calculated area-weighted fertiliser rates, which were based on the Farm Nutrient Questionnaire, closely represented the actual practice. 12 Similar nutrient surpluses based on very detailed farm level information have been reported elsewhere in the UK. 1,5 Since small inputs or a small nutrient surplus are not necessarily a re¯ection of ef®cient practices, 7 ef®ciency indices, expressing the nutrients in the output products as a percentage of those in all inputs, were calculated.…”

“…There is a mixture of arable and livestock farming in the catchment, with the main land cover type in 1994 being grass, followed by spring crops and winter crops. Livestock density in the area in 1994 was shown to be high, 1.2 livestock units per hectare, 12 compared with Scotland (0.5) and the UK (0.9). 6 Farm types were distinguished based on the national and European system, which groups farms related to the cropping or livestock enterprises that account for at least two-thirds of the total farm income.…”

“…13,14 Seven main farm types in the area together represented nearly 90% of the agricultural land. 12 For the budget calculations, each farm type was characterised by the average areas of crops and average livestock numbers. Crop areas (Table 1) were summarised from the agricultural census data (June Census) for 1994 obtained from the Scottish Executive Rural Affairs Department.…”

“…12 These were used to calculate area-weighted fertiliser application rates for individual crops per farm type. If insuf®cient information was available for a particular crop on a farm type, the average application rate over the whole catchment was assumed and average N and P applications per farm type were calculated.…”

Variation in carbon footprint of milk due to management differences between Swedish dairy farms

“…Supporting this conclusion is the fact that we found no correlation between purchased N in synthetic fertiliser and livestock density (and thereby access to manure) on the farms studied. This expected correlation was also found to be weak in earlier studies by Domburg et al (2000) and Swensson (2002). The efficiency of N used in feed production can be improved, and thereby also the CF of feed, if the use of N in manure is optimised and adjusted to the N-fertiliser rate.…”