Nitrate leaching through oxisols of the Loyalty Islands (New Caledonia) under intensified agricultural practices. Geoderma

Scope of the journal The primary intention of the journal is to stimulate wide interdisciplinary cooperation and understanding among workers in the different fields of pedology. Therefore, the journal tries to bring together papers from the entire field of soil research, rather than to emphasize any one subdiscipline. Interdisciplinary work should preferably be focused on occurrence and dynamic characterization in space and time of soils in the field. . For 1998 volumes 81-86 are scheduled for publication. Subscription prices are available upon request from the publisher. Subscriptions are accepted on a prepaid basis only and are entered on a calendar year basis. Issues are sent by surface mail except to the following countries where air delivery via SAL is ensured: Argentina, Australia, Brazil, Canada, Hong Kong, India, Israel, Japan, Malaysia, Mexico, New Zealand, Pakistan, PR China, Singapore, South Africa, South Korea, Taiwan, Thailand, USA. For all other countries airmail rates are available upon request. Claims for missing issues must be made within six months of our publication (mailing) date. For orders, claims, product enquiries (no manuscript enquiries) please contact Customer Support Department at the Regional Sales Office nearest to you: Publication information G E O D E W ELSEVIER Abstract For the uplifted coral atolls of the Loyalty Islands (New Caledonia), the prime source of potable water is the freshwater lenses that underlie the islands. The recent adoption of more-intensive agricultural practices, particularly the use of nitrogeneous fertilizers, may, however, represent a threat for these fragile Pacific ecosystems. To assess the risk posed by nitrate leaching, experiments have been conducted on the permeable oxisols of the island of Maré, using both cropped and bare soil sites. Drainage below the root zone was found to be very important, about 50% of the rainfall, even on the cropped site. The soils are thin and permeable, and the frequent tropical storms have high rainfall intensities. Nitrate fertilizers thus have potential to be leached, in large amounts, even up to 100% of the nitrate supply, especially if fertilizers are not supplied according to weather conditions and in concert with the plant's ability to extract them. O 1998 Elsevier Science B.V. All rights reserved