Changes in the N recovery process from ¹⁵N-labeled swine manure compost and rice bran in direct-seeded rice by simultaneous application of cattle manure compost

The N recovery from ¹⁵N-labeled swine manure compost and rice bran with or without simultaneous application of unlabeled cattle manure compost was examined in a paddy field with direct-seeded rice during a 1-year period (1 crop season). In all the ¹⁵N-labeled materials including ( ¹⁵NH₄)₂SO₄, the processes of N recovery from the ¹⁵N materials by rice plants were different between the plots with and without application of cattle manure compost. At the tillering stage, the N recovery rates from the ¹⁵N materials in the plots with application of cattle manure compost were significantly lower than those in the plots without application of cattle manure compost. These recovery rates, however, became close and no significant differences were observed at the maturity stage. Thus, simultaneous application of cattle manure compost could impede the N recovery from swine manure compost, rice bran as well as (NH ₄)₂SO₄.