Influences of Nitrogen and Potassium Fertigation on Nutrient Uptake, Production, and Quality of Pepper Irrigated with Disinfected Urban Wastewater

Summary

This field trial investigated optimal nitrogen and potassium fertigation strategies for pepper cultivation using disinfected urban wastewater in Almería, Spain, to balance water conservation, fertiliser reduction, and crop productivity. Higher NK application rates (N1.5K1.5, N1K1.5, N1.5K1) significantly increased marketable yields and fruit weight compared to unfertilised controls, whilst fruit quality attributes remained unaffected by NK levels. The recommended local rate (N1K1) matched unfertilised regenerated water performance, suggesting scope for tailored nutrient adjustment based on wastewater composition.

Regional applicability

Findings apply primarily to Mediterranean greenhouse horticulture with access to treated urban wastewater. UK applicability is limited by climate, irrigation practice, and wastewater regulatory frameworks; however, the methodology for matching wastewater nutrient composition to crop demand could inform future water reuse strategies in UK horticulture, particularly as pressure to reduce freshwater abstraction and fertiliser inputs increases.

Key measures

Marketable yield, fruit number and weight, fruit quality (pH, firmness, total soluble solids, titratable acidity), macronutrient uptake (N, K, Ca, Mg, P), regenerated wastewater nutrient content (9.8 mM N, 5.4 mM K)

Outcomes reported

The study measured yield, fruit quality attributes, and macronutrient uptake in pepper plants irrigated with regenerated urban wastewater under different nitrogen and potassium fertigation regimes. Production parameters, fruit characteristics (pH, firmness, soluble solids, titratable acidity), and plant nutrient concentrations were quantified.

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