Environmental Systems and Agricultural Practices in New Zealand

Posted on Jan 26, 2026 in Environmental Sciences

Environmental Systems & Agriculture

Agricultural System Components

Inputs:

• land
• water
• fertiliser
• labour
• energy
• capital

Processes:

• cultivation
• irrigation
• grazing
• harvesting

Outputs:

• food
• fibre
• waste
• emissions
• by-products

Key Drivers

Population growth, market demand, policy incentives, technology, climate.

Sustainability Principles

• Efficiency: maximise yield per input.
• Resilience: ability to recover from disturbance.
• Circularity: reuse and recycle nutrients and energy.

Environmental Pressures

• Nutrient runoff → eutrophication
• Greenhouse gas emissions (CH₄, N₂O)
• Water use and scarcity
• Soil degradation
• Biodiversity loss

Department of Conservation (DOC) Functions

Function — Description / Purpose

Conservation management

Manage all land and resources under the Act for conservation purposes.

Freshwater fisheries

Preserve indigenous species; protect recreational fisheries.

Advocacy & promotion

Advocate for conservation and promote its benefits.

Sub-Antarctic & international

Manage Ross Dependency and Antarctic areas under agreements.

Education & publicity

Develop and promote conservation education materials.

Recreation & tourism

Encourage use compatible with conservation objectives.

Advice to Minister

Provide expert advice on conservation issues.

Legal functions

Execute functions under other statutes/enactments.

Resource Management Act (RMA) – Core Principles

Purpose (s5)

Promote sustainable management of natural and physical resources.

Matters of National Importance (s6)

• Preserve natural character of coastal, wetland, lake, and river environments.
• Protect outstanding natural features & landscapes.
• Protect significant indigenous vegetation & habitats.
• Maintain/enhance public access to coasts, lakes, rivers.
• Recognise Māori relationship to ancestral lands, waters, sites, taonga.
• Protect historic heritage & customary rights.
• Manage significant natural hazard risks.

Managing Environmental Effects

Adverse Effects

Assessed by nature, intensity, duration, and location.

Mitigation

Alleviate, abate, or moderate effects. Reduce intensity or duration.

Example: pest control, replanting, buffering edge effects, habitat enhancement. Occurs at point of impact.

Offset vs Compensation

• Offset: positive gain elsewhere (e.g., restore another wetland).
• Compensation: make up for loss when offset not possible.
• Mitigation: reduces impact; offset: adds benefit elsewhere.

Hierarchy for Biodiversity Protection

1. Avoid
2. Minimise
3. Remedy
4. Offset
5. Compensate

Avoid activity if unacceptable.

Biodiversity Maintenance Principles

No net loss in:

• Species population or range
• Ecosystem extent, properties, functions
• Connectivity and buffering
• Ecosystem resilience

Subdivision & Consent Processes

What is a Subdivision (s218 RMA)

Division of land into new titles or long leases (>35 years). Affects hydrology, water use, stormwater, environment.

Key RMA Sections

Section — Focus

• s9: Land use control
• s11: Land use control (other restrictions)
• s13: Subdivision requires consent
• s14: Works in river/lake beds
• s15: Water take/use/diversion
• s106: Discharges to land/water/air

Council can refuse if unsafe or poor access.

Authorities

• District Councils: zoning, land use, design, infrastructure.
• Regional Councils: water, soil, air, hazards, NES & CRPS consistency.

Process

Pre-application → Application (AEE + reports) → Lodgement → Notification → Decision → s223 (survey) → s224 (conditions met) → Title issued.

Consent Activity Status

Notification Pathways

• Public: anyone may submit.
• Limited: only affected parties.
• Non-notified: no public input.

Good AEE Includes

• Site + environment description
• Potential effects (dust, discharge, sediment)
• Mitigation/management plans
• Expert input (ecology, hydro, geotech)
• Plan alignment (District, RPS, NES)

Soil Fundamentals

Definition

Soil: Biologically active, porous medium supporting plants; the upper crust of the Earth.

Functions

• Support: roots, infrastructure
• Regulate: water, gas, nutrients
• Carbon storage: ~2× atmosphere
• Biodiversity: microbes, fauna
• Cultural/archaeological record
• Raw materials: sand, clay, peat

Composition

Approximately 50% solids (minerals + organic) and 50% pore space (air + water).

1 g soil ≈ 1 billion bacteria, ~10,000 species, ~10 m fungal hyphae.

Land Use Capability (LUC) – NZ System

Class — Capability — Typical Use

• 1: Very high versatility — Cropping, horticulture
• 2: Slight limitations — Intensive agriculture
• 3: Moderate limits — Cropping with care
• 4: Significant limits — Pasture, limited cropping
• 5–8: Non-arable — Grazing, forestry, conservation

Soil Organic Matter (SOM)

Components:

• Living biota ≤ 4% (microbes, fauna, roots)
• Active/labile (fast turnover, nutrient release)
• Resistant/humus (stable, improves structure)

Functions:

• Nutrient reservoir (N, P, S)
• Structure: aggregation, infiltration, aeration
• Cation exchange: retains nutrients, immobilises toxins
• Supports soil food web
• Major carbon store (~1.5×10¹⁵ kg)

Soil Contamination & Pollution

Concepts:

• Contamination: above background
• Pollution: causes harm
• Dose–response: impact increases with concentration

Units: mg/kg (soil), mg/L (water) ≈ ppm.

Management: compare to trigger & intervention levels; remove or stabilise contaminant.

Heavy Metals in NZ Agriculture

Tiered Fertiliser Strategy (Cd)

• Tier 1–2: normal use
• Tier 3: restricted use
• Tier 4: stop or remediate

Pathways to Waterway Degradation

Eutrophication Process

Nutrient loading → algal bloom → light loss → plant death → decomposition → hypoxia/anoxia → fish kill.

Waterway Restoration Pathways

Strategy — Mechanism

• Precision agriculture: Targeted fertiliser timing & placement
• De-intensification: Reduce stocking rates, shift land use
• Wastewater upgrades: Tertiary N & P removal
• Riparian planting: Native buffers intercept runoff, stabilise banks
• In-lake treatments: Aeration, alum flocculation
• Native ecosystems: Mānuka/kānuka promote pathogen die-off
• Nitrification inhibition: Keeps N as NH₄⁺ to reduce leaching

Overall: Combine ecological and technological methods for long-term recovery.

Key Numbers & Facts

Concept & Value / Ratio

• Soil organic matter ↑1% → +180 m³ water/ha
• Soil stores 2× carbon of atmosphere
• 12 M ha land lost annually to desertification
• 3–4% global crop loss by 2030 (soil sealing)
• 1 g soil → ~1 billion microbes
• NZ pasture Cd avg = 0.43 mg/kg (bg 0.16 mg/kg)
• SOM ≤4% living biota
• Salinity ECe thresholds: barley 8.0, maize 1.7, wheat 6.0 dS/m