Quest of Water Extract Analysis of Micronutrients in Soilless Organic Substrates

Abstract

This research was aimed at evaluating the current water extraction methods for the analysis of four substrates treated with and without micronutrients. Black peat, coir, rice hulls, and pine bark (Pinus elliotis) were treated as follows: 1) control, 2) nitrogen, phosphorus, and potassium (NPK), and 3) NPK+M (micronutrients). Substrate samples were collected at 20 and 120 days of incubation for the determination of micronutrient concentrations. After 120 days of incubation, B, Mn, and Zn were easily detected in the SE, 1:1.5 v/v, and 1:2 v/v extracts from treatments with added micronutrients. Cu and Fe concentrations did not differ among treatments, irrespective of the extraction method used. Pine bark and black peat showed the lowest micronutrient concentrations for B and Zn; coir showed high values for B, Fe, and Zn concentrations; and rice hulls showed the highest Mn and Zn concentrations. SE and the 1:1.5 water extract were the best methods for substrate micronutrients evaluation.

Keywords:

• Laboratory procedures
• micronutrient diagnosis
• saturation extract
• substrates
• water extraction

Acknowledgments

The authors acknowledge Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), “Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (Proc. 00/01635‐0), and Empresa Brasileira de Pesquisa Agropecuária’ (EMBRAPA—Prodetab) (Proc. 065‐02/99) for financial support and grants.