Nitrogen Management and Methane Emissions in Direct-Seeded Rice Systems

摘要: Published in Agron. J. 106:968–980 (2014) doi:10.2134/agronj13.0491 Copyright © 2014 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part this periodical may be reproduced or transmitted any form means, electronic mechanical, including photocopying, recording, information storage and retrieval system, without permission writing from publisher. ABSTRACT Rice (Oryza sativa L.) establishment systems based on resource-conserving production practices are gaining popularity globally. To investigate potential for improved N management mitigation methane (CH4) emissions, field experiments were conducted California three crop systems: water-seeded (WS) conventional, WS stale seedbed, drill-seeded (DS) seedbed. Fertilizer nitrogen recovery efficiency (NRE) rice yield as affected rate, source, application timing evaluated 2 yr each system. Methane emissions monitored over a full annual cycle (growing season plus fallow period). Results indicated that neither split applications nor ammonium sulfate increased yields NRE compared with single urea, regardless However, economic optimum rate approximately 30 kg ha-1 seedbed conventional Since generally remained similar across treatments maximized yields, applying appropriate dose before permanent flood would satisfy both agronomic environmental goals within Both resulted growing CH4 emissions. DS system reduced 47% possibly due to decreased period anaerobic soil conditions. This study highlights importance assessing benefits well tradeoffs when evaluating opportunities increasing sustainability direct-seeded respect