Errors in Measuring Nitrogen and Dry–matter Content of Plant and Faeces Material

Abstract

The N content of pasture species {Trifolium repens L. and Lolium perenne L.) was much less affected hy drying temperatures over the range 70° to 100°C, and hy the density of packing of the pasture sample, than was the amount of hrown colour resulting from these treatments. The DM content of faeces was measured with equal accuracy at temperatures of 80° and 100°C and in samples which varied in weight over a four-fold range. The N lost while drying faeces at 80°C was considerable, with large variations in the amount lost by different animal species fed on particular diets. The results confirm that analyses of the N content of faeces should be carried out before drying.

Mineralization and herbage recovery of animal manure nitrogen after application to various soil types

“…During the 1st and 2nd harvest, plants were clipped with a scissor 4 cm above soil level, whereas during the 3rd harvest they were cut at ground level. Each time, fresh shoot biomass from the pots was measured and representative samples were oven-dried at 70°C for 48 h (Sharkey 1970), weighed, ground to pass a 1 mm sieve and analysed for total N content after Kjeldahl digestion as described by Houba et al (1989). Finally, shoot N uptake from each pot was calculated by multiplying the shoot DM yield with its N content.…”

“…In addition, the remaining roots were recovered by decanting the soil-water mixture through a sieve with the same mesh size. After separation from the soil, the root material was dried in an oven at 70°C for 48 h (Sharkey 1970), weighed, ground to pass a 1 mm sieve and analysed for total N content through Kjeldahl digestion (Houba et al 1989). Subsequently, root N yield of each pot was calculated by multiplying the root DM yield with its N content.…”

Nitrogen balance in Holstein steers grazing winter oats: effect of nitrogen fertilisation

“…Some possible errors of this overestimation are detailed. Fecal N could be underestimated due to volatile losses of ammonia from feces in the field (Spanghero and Kowalski, 1997) and/or during the drying of samples (Sharkey, 1970). Another source of error may be the N loss from the urine collection, due to the use of a wide-specter antibiotic as a preservative, instead of using strong acids (H 2 SO 4 ) in situ so as to prevent N losses (Spanghero and Kowalski, 1997).…”

Bedding additives reduce ammonia emission and improve crop N uptake after soil application of solid cattle manure

“…Grass was weighed in field and the herbage weight of each field was recorded to calculate fresh herbage yield. After mixing the whole grass, an auger was used to take a representative herbage sub-sample of 200 g. Herbage DM yield was determined by oven drying all samples at 70 C for two days (Sharkey, 1970). Subsequently, the grinding mill was used to grind the samples by passing them through 1 mm mesh screen.…”