Sustainability & Circular Bioeconomy
Biochar in New Zealand Soils
Biochar is gaining increasing attention in Australia and New Zealand as a sustainable soil amendment with the potential to improve soil health, nutrient retention, and carbon sequestration. Produced through the pyrolysis of organic materials under limited oxygen conditions, biochar can enhance soil physical and chemical properties depending on feedstock type and soil condition.
Research indicates that certain biochars may reduce nutrient leaching, improve water-holding capacity, and support microbial activity in certain soil systems. In pastoral and wastewater-irrigated environments, biochar may also contribute to the retention of nutrients and contaminants such as heavy metals.
The successful application of biochar requires careful consideration of feedstock quality, production conditions, soil type, and long-term environmental effects. Our consultancy supports research, field assessment, and practical evaluation of biochar applications within New Zealand land-use systems.
Wastewater Irrigation Risks and Management
Land application of treated wastewater can provide beneficial reuse of water and nutrients when appropriately designed and managed. However, poor irrigation practices may create environmental risks including nutrient leaching, ponding, runoff, soil structural degradation, and groundwater contamination.
Key factors influencing wastewater irrigation performance include soil hydraulic conductivity, drainage characteristics, nutrient loading rates, slope, climate, and seasonal soil moisture conditions. Site-specific assessment is essential to ensure sustainable operation and regulatory compliance.
Our consultancy provides technical support for wastewater irrigation assessments, nutrient loading calculations, soil investigations, land suitability evaluation, and environmental compliance across agricultural, industrial, and municipal systems.
PFAS and Biosolids Management
Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants of international concern due to their persistence in the environment and potential human health implications. PFAS may enter biosolids through industrial discharges, consumer products, and wastewater treatment systems.
As regulatory attention increases globally, the management of PFAS in biosolids and organic wastes is becoming an important consideration for land application programmes and wastewater management strategies.
Current scientific understanding of PFAS behaviour in soils, plants, and groundwater continues to evolve. Risk assessment requires consideration of contaminant sources, concentrations, land use, soil properties, and long-term environmental exposure pathways.
Our consultancy follows current scientific and regulatory developments relating to PFAS and emerging contaminants to support environmentally responsible biosolids management practices.
Soil Nitrogen Dynamics and Nutrient Management
Nitrogen is one of the most important nutrients for plant growth and agricultural productivity; however, excessive nitrogen loss from land can contribute to groundwater contamination, surface water degradation, eutrophication, and greenhouse gas emissions. Effective nitrogen management is therefore essential for the sustainable operation of wastewater irrigation and land application systems.
Nitrogen behaviour in soils is influenced by factors such as soil texture, drainage characteristics, organic matter content, microbial activity, climate, plant uptake, and irrigation management. Processes including mineralisation, nitrification, denitrification, volatilisation, and leaching all affect nitrogen availability and environmental risk. Different New Zealand soils exhibit varying capacities to retain, transform, and transmit nitrogen within the soil profile.
Understanding nitrogen dynamics is critical for nutrient budgeting, wastewater discharge assessment, irrigation design, and long-term environmental sustainability. Our consultancy undertakes nitrogen loading assessment, nutrient modelling, soil evaluation, and environmental risk assessment to support sustainable land-use management and resource consent applications.
Soil Phosphorus Retention and Nutrient Management
Phosphorus plays a critical role in agricultural productivity; however, excessive phosphorus loss to water bodies can contribute to eutrophication and declining water quality. Soil phosphorus retention capacity is therefore an important factor in assessing the sustainability of wastewater irrigation and land application systems.
Phosphorus retention is influenced by soil mineralogy, clay content, iron and aluminium oxides, organic matter, pH, and drainage characteristics. Different New Zealand soils exhibit widely varying phosphorus sorption capacities.
Understanding phosphorus dynamics is essential for nutrient management planning, wastewater discharge assessment, and long-term land treatment design. Our consultancy undertakes phosphorus retention assessment and nutrient management evaluation to support sustainable land-use decisions and resource consent applications.
Composting Systems and Organic Waste Recovery
Composting is an effective biological process for stabilising organic wastes and converting them into beneficial soil amendments. Well-designed composting systems can reduce waste volumes, improve nutrient recycling, minimise odour generation, and support circular bioeconomy objectives.
The effectiveness of composting depends on several operational factors including carbon-to-nitrogen ratio, moisture content, aeration, temperature, and feedstock composition. Different composting systems may be suitable depending on waste type, scale, site conditions, and regulatory requirements.
Our consultancy provides technical advice on composting systems, organic waste characterisation, beneficial reuse opportunities, and environmental compliance for agricultural, industrial, and municipal waste streams.
Climate Change and Land Application Systems
Climate change is expected to influence rainfall intensity, drought frequency, soil moisture dynamics, and nutrient transport processes across New Zealand. These changes may affect the long-term performance and resilience of wastewater irrigation and land application systems.
Extreme rainfall events can increase the risk of runoff, erosion, nutrient loss, and contaminant transport to surface water and groundwater. Conversely, prolonged dry periods may alter soil biological activity and irrigation management requirements.
Sustainable land application systems require adaptive design approaches that consider future climate variability, site resilience, and environmental risk management. Our consultancy integrates climate-related considerations into wastewater management, soil assessment, and land-use planning to support long-term environmental sustainability.
Biofertiliser Application for Environmental Sustainability
Biofertilisers containing beneficial microorganisms such as nitrogen-fixing bacteria, phosphorus-solubilising bacteria, mycorrhizal fungi, and decomposer microorganisms are increasingly recognised as sustainable tools for improving soil health, nutrient efficiency, and environmental performance in agricultural and land application systems. These biological amendments can enhance nutrient cycling, improve root development, stimulate microbial activity, and support long-term soil fertility while reducing reliance on synthetic fertilisers.
Beneficial fungi and bacteria may also contribute to improved soil structure, organic matter decomposition, moisture retention, and suppression of certain soil-borne pathogens. In wastewater irrigation and land treatment systems, biologically active soils play an important role in nutrient transformation, organic matter breakdown, contaminant attenuation, and overall ecosystem resilience. Enhanced microbial activity can support nitrogen and phosphorus retention processes, improve wastewater treatment within the soil profile, and reduce potential environmental risks associated with nutrient losses and contaminant transport.
The integration of biofertilisers, composts, biochar, and other organic amendments within land management systems aligns strongly with circular bioeconomy principles by promoting resource recovery, reducing environmental impacts, and supporting sustainable agricultural production. Our consultancy supports the assessment and application of biologically based soil management approaches to improve environmental sustainability, soil function, and long-term land-use performance.
Research & Publications
Our consultancy combines scientific research with practical environmental management experience. Our work includes contributions to journal publications, technical reporting, conference presentations, and applied environmental research across soil science, wastewater management, nutrient dynamics, and circular bioeconomy systems.
Areas of expertise include:
- Soil and environmental science
- Wastewater management and land application
- Biochar and composting systems
- Nutrient management and phosphorus retention
- Emerging contaminants and PFAS
- Climate change adaptation
- Circular bioeconomy and resource recovery
- Sustainable agricultural systems
We are committed to developing practical, scientifically robust, and environmentally responsible solutions for industry, councils, and the wider community.
Our Senior Environmental Scientist Dr. Shamim Al Mamun’s (Ex professor and head of the department of Environmental Science and Resource Management) Research Profile links are given below: