Abstracts

Caio T. Inácio¹, Segundo Urquiaga², Phillip M. Chalk³

¹ Embrapa Solos, Rua Jardim Botânico 1024, Rio de Janeiro, RJ, 22460-000, www.embrapa.br/solos, caio.teves@embrapa.br

² Embrapa Agrobiologia, Rodovia BR-465 KM 7, Seropédica, RJ, 23891-000

³ University of Melbourne, Parkville 3010, Melbourne, Victoria

Abstract

The remarkable influence of organic inputs, such as manure and compost, on d¹⁵N values of growing plants suggests the possible use of ¹⁵N natural abundance as a tracer of N. Thus, using ¹⁵N natural abundance might be possible to estimate compost-N recovery as an alternative method to the use of ¹⁵N-enriched materials. The objective of this study was to verify the feasibility of using d¹⁵N value to estimate compost-N recovery by plants. Head lettuce, carrots and broccoli were cultivated (randomized blocks) in sequence under increasing levels (0 to 2.5 kg/m², dry matter) of compost application. Pearson correlations were significant and positive between plants d¹⁵N and yield (except lettuce, no yield response). A new equation for estimating compost-N recovery by plants was proposed using differences in d¹⁵N-plant with and without compost application. The compost-N recoveries were 2-8 % for lettuce, 4-9 % for carrots, and 9-18 % for broccoli. Unrealistic estimates were disregarded and assigned primarily to non-representative sampling because of intra-plant d¹⁵N variations. This study showed the theoretical and experimental basis of using d¹⁵N values to estimate compost-N recovery by test plants.