Effects of cattle dung and urine on nitrogen uptake and yield of perennial ryegrass.

Effects of artificially placed patches of cattle dung and artificial urine on nitrogen (N) uptake and herbage dry matter (DM) accumulation were studied in perennial ryegrass swards on a sandy soil at fertilizer inputs of 250 and 400 kg N ha 'yr" 1 over a period of ten months after application in mid-summer. Positive effects were only observed in the 250 N sward and were confined to 15 cm from the edge of the dung and urine patches. Apparent N recovery (ANR) of dung was 8.3 % in the 250 N sward and nil in the 400 N sward. The N effect of dung was 3 g DM per g dung N applied in the 250 N sward and nil in the 400 N sward. The effects lasted until the end of the experiment (i.e. 10 months after application). ANR of urine was about 16 % in the 250 N sward and insignificant in the 400 N sward. In the 250 N sward the N effect of urine was low and lasted two months (on average 1.7 g DM per g urine N applied). In the 400 N sward the N effect was even negative due to scorching (on average -2.5 g DM per g urine N applied). The scorching effects were still evident at the end of the experiment.