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Wetted Soil Volume as a Design Criteria in Drip Irrigation

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  2010 Pittsburgh, Pennsylvania, June 20 - June 23, 2010  1008590.(doi:10.13031/2013.29663)
Authors:   Claudinei Fonseca Souza, Bruno Lima Santoro, Lucas Massayuki Sato, José Geanini Peres
Keywords:   Fertigation, Wetted soil volume, TDR.

The principal objective of a drip system design is to choose the appropriate layout and components to obtain adequate soil solution distribution throughout a field. In addition to maximizing crop production, modern fertigation practices must consider environmental sustainability and rigorous water management. These often conflicting considerations require significant changes in irrigation system design and operation (relative to traditional designs for maximum crop production). We conducted experiments to characterize dynamics and patterns of soil solution within the wet bulbs formed by drip fertigation for pepper (Capsicum annum, L). Time domain reflectometry (TDR) probes were used to monitor the distribution of potassium nitrate (KNO3) and water distribution from drippers discharging at constant flow rates of 2 and 4 L h-1 under field conditions. Considering results from different profiles, it was observed greater (large) solute storage near the dripper decreasing gradually towards the wetting front. About half of the applied KNO3 solution (65%) was stored in the first layer (0-0.10 m) for all experiments and 22% was stored in the next layer (0.10-0.20 m). Comparing different dripper flow rates higher solution storage was found for 4 L h-1 by means of 72% of applied KNO3 solution was accumulated in the first layer (0-0.10m) compared with 60% for 2 L h-1. The chemical analysis of leaf showed no differences between N and K concentrations for different flow rates. These results suggest that based on the volume and frequency used in this experiment, it would be advantageous to use flow rate of 4 L h-1 to reduce deep percolation losses of applied water and solutes.

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