ISO 16075-6:2023

Overview

ISO 16075-6:2023 - “Guidelines for treated wastewater use for irrigation projects - Part 6: Fertilization” provides practical guidance to evaluate and use the fertilizer value of treated wastewater (TWW) in irrigation. The standard explains how nutrient quantities and forms in TWW (N, P, K and trace elements) affect crop nutrition, how to calculate the contribution of TWW to crop fertilizer needs, and how to monitor water, soil and plant parameters for safe, efficient nutrient management.

Key topics and requirements

• Assessment of nutrient supply from TWW
  • Evaluation of macronutrients (nitrogen, phosphorus, potassium) and trace elements at different treatment levels.
  • Example data ranges for municipal wastewater: total N commonly ~20–70 mg/L (typical ~40 mg/L); organic N 8–25 mg/L; ammonium 12–45 mg/L.
• Nutrient availability and soil reactions
  • Behaviour of nitrogen (mineralization, nitrification, denitrification), phosphorus fixation/mobility, potassium and micronutrient dynamics in soils.
• Calculation and scheduling
  • Methods to calculate nutrient contribution of TWW (N, P, K) and to synchronize nutrient supply with crop growth and seasonal demand.
  • Guidance on total seasonal nutrient loading and distribution across the irrigation season.
• Adjustment of fertilizers and amendments
  • How to adapt synthetic fertilizers and organic amendments (manure, sludge) when using TWW to avoid over‑application.
  • Considerations for combining TWW with other nutrient sources.
• Monitoring and sampling
  • Requirements for monitoring nutrients in water, soil and crops, including sampling and analysis considerations to track nutrient availability and environmental risk.
• Risk linkage
  • Risk assessment and management for safe TWW use are referenced to ISO 20426 and ISO 16075-2.

Practical applications

• Optimizing fertilizer programs for crops irrigated with TWW to reduce input costs and environmental impact.
• Designing irrigation-fertilization schedules that synchronize nutrient supply with crop demand.
• Guiding wastewater utilities, irrigation engineers and agronomists to quantify the nutrient value of different TWW treatment levels.
• Informing regulators, farm advisors and consultants about monitoring needs to prevent nutrient leaching, eutrophication and soil degradation.

Who should use this standard

• Water reuse planners, wastewater treatment plant operators, irrigation managers, agronomists, soil scientists, farm managers, environmental regulators and consultants involved in TWW irrigation projects.

Related standards

• ISO 16075-2 (risk assessment/management for irrigation reuse)
• ISO 20426 (risk assessment for safe use of TWW)
• ISO 20670 (water reuse vocabulary)

Keywords: ISO 16075-6:2023, treated wastewater (TWW), irrigation fertilization, nutrient management, nitrogen phosphorus potassium, water reuse standards, soil monitoring.