NITROGEN PENETRATION AND PERSISTENCE IN SOIL UNDER UNCOVERED AND COVERED FARMYARD MANURE HEAPS

After deposition of cattle manure for 308 days neither the total nitrogen nor the nitrate but only the ammonia content in the soil (0-70 cm) was significantly increased. During a 258 days period from autumn to spring the observed microbial oxidation of penetrated ammonia to nitrate was tardy and by no means quantitative. So leaching of nitrate was hardly to be detected during the whole period. In the soil layer 40-70 cm a maximum of 1.6 g NO3--N/M2 was measured, which was in an equivalent range with the amounts detected by large scale investigations in agricultural soils at the same season. Therefore the manure heaps in question did not lead to an uncommon increase of nitrate in soil. The protection of the heaps against precipitation simply brought about small and only a few times significant reductions in soil N(min) content.