Daily based quantitative nutrient management in rockwool hydroponics: Growth and yield of tomato and nutrient use at elevated CO2

Summary

This study evaluated the efficacy of an automated daily quantitative nutrient management system for rockwool-grown tomatoes under CO2-enriched greenhouse conditions, comparing three levels of nutrient supply (0.5×, 1.0×, and 1.5× optimal) against conventional electrical conductivity-based management. Daily QNM treatments achieved equivalent or superior marketable fruit yields and fruit quality whilst substantially reducing nutrient inputs (to 10–42% of conventional levels), with the 1.0× treatment offering optimal balance between yield and nutrient use efficiency. The findings suggest that precision nutrient management tailored to daily plant water uptake can maintain commercial productivity under elevated CO2 whilst minimising nutrient waste.

Regional applicability

The study was conducted in Japan and used rockwool hydroponic systems typical of controlled-environment agriculture globally. The findings are transferable to United Kingdom greenhouse horticulture, particularly commercial tomato production, though UK growers would need to adapt QNM protocols to local climate conditions, CO2 availability and electricity costs. The nutrient use efficiency gains are most relevant to regions where water quality or nutrient recovery is a regulatory or economic concern.

Key measures

Cumulative total fruit yield, cumulative marketable fruit yield, fruit dry matter content, fruit soluble solid content, total nutrient use, nutrient use efficiency (NUE) defined as marketable fruit yield per unit nutrient used

Outcomes reported

The study compared daily quantitative nutrient management (QNM) at three supply levels against conventional EC-based management, measuring cumulative total and marketable fruit yield, fruit quality (dry matter and soluble solids content), and nutrient use efficiency in tomato rockwool hydroponics under CO2 enrichment.

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