ISHS Acta Horticulturae 779: International Symposium on Growing Media
MICRONUTRIENT DETERMINATION IN WATER EXTRACTS OF PEAT INCUBATED WITH MINERAL FERTILIZERS |
| Authors: | C.A. Abreu, M.F. Abreu, O.C. Bataglia, A.M.C. Furlani, P.R. Furlani, A. Paz-Gonzalez |
| Keywords: | soilless, substrates, boron, copper, iron, manganese, zinc, analysis |
| Abstract:
Substrates for plants are of varied composition and the non-standardized water extraction methods for nutrient chemical analysis have raised difficulties to adequately interpret results and manage substrate fertilization and/or correction. In the United States (USA), the saturation extract procedure is widely adopted, while in Europe, the water extraction using fixed volumes (1:1.5 v/v; 1:2 v/v; 1:5 v/v; 1:10 m/v) is used. This research aimed at evaluating the current water extraction methods for the chemical analysis of peat incubated with conventional (NPK) and slow-release fertilizers (SRF). The treatments were applied as follows: (1) control; (2) lime; (3) lime + NPK + S; (4) lime + NPK + S + micronutrients; (5) lime + slow-release fertilizer (SRF) + S and; (6) lime + SRF + S + micronutrients. Both, NPK and SRF (formula N – P2O5 - K2O = 14–14–14) were applied at a rate of 6 g L-1 of substrate. Substrate samples were collected at 20, 60 and 120 days after incubation for the determination of micronutrient concentrations, using the following water extraction methods: 1:1.5 v/v; 1:2 v/v; 1:5 v/v; 1:10 m/v; and saturation extract. The micronutrient concentrations were influenced by fertilization treatments (NPK or SRF with micronutrients), especially B. No effect was observed on Cu, Fe and Zn concentrations. Manganese was the most affected by liming, since significant decrease on Mn concentration was observed with the pH increase. The incubation period had little influence on B and Fe concentrations, but affected Cu, Mn and Zn, which concentrations tended to increase with time. Such effect was more evident in the SRF treatments. On the overall, positive and high correlations were found between the several extraction procedures (correlation coefficients > 0.92) for B, Mn and Zn data. There was no correlation between methods for Cu and Fe. The saturation extract best discriminated the fertilization treatments, followed by the 1:1.5 extract. | |
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