Sources and pathways for nutrients and to water and means of intervening CSG 14th August 2014

• Sources , Pathways and Variability

• Targeting interventions

• Whatawhata case

Presentation format

Water Quality What is Water Quality?

A variable, often defined by communities, but good

quality may be water that is safely drinkable,

swimmable and fishable, supports cultural values

and healthy ecosystems. The three main issues

affecting water quality in rural settings are:

• Suspended sediments: that smother the beds of

rivers and estuaries

• Nutrients (nitrogen, phosphorus): that encourage

excess plant growth, algal blooms

• Faecal microbes: that affect human, and often

animal, health.

N 2 fixation

3

Urea - N Organic - N

NH 4 rapid

slow

Fertiliser N

120

60

370

Milk

Meat 65

250 75

dung urine

Feed N

20

On Farm Nitrogen cycling and losses

Values are kg N/ha/year

NO3

35

leaching

N2 O 5

ammonia

35

N2 fixation

Meat

Wool

Urea Organic - N - N

rapid NH4 NO3

slow

Fertiliser N 20

60

200

15

125 60

leaching

15

dung urine

N2O, N2

5

ammonia

15

Values are kg N/ha/year

Nitrogen cycling and losses

Sources

Nitrogen

(1) urine patches, (2) fertiliser, (3) effluent irrigation, (4) clover N-fixation, (5) rain/atmosphere

On Farm Sources of N

1 2 3

4

Sources of nitrogen entering streams in the Waikato region

Point Sources 3%

Dairy68%

OtherPasture

21%

Trees8%

Non-pasture<1%

Niwa data

Phosphorus

(1) fertiliser, (2) soil erosion, (3) animal excreta/effluent irrigation

Farm Sources of P

1 2 3

Point Sources 7%

Dairy42%Other

Pasture35%

Sediment9%

Non-pasture,trees7%

Niwa data

Sources of phosphorus entering streams in the Waikato region

Farm Sources of Sediment

(1) grazed pasture, (2) stream bank/bed erosion, (3) animal excreta, (4) animal tracks, (5) unpaved roading

1,2

3 4 5

Faecal microbes what are they?

faecal microbes

viruses bacteria protozoa

Indicator:

enteroviruses,

phages

Pathogens: human

enteroviruses and

adenoviruses,

noroviruses,

rotaviruses,

hepatitis A

Indicator: E.

coli

Pathogens:

E. coli,

Campylobacter

, Salmonella

Indicator:

Clostridium

perfringens

spores

Pathogens:

Giardia,

Cryptosporidium

Campylobacter

Crytosporidium

Rotavirus

(1) grazed pasture, (2) effluent irrigation, (3) wild and feral animals, (4) livestock in, or close to, waterways, (5) laneways connected to drains

Sources of Faecal Microbes

4

3

2

1

5

source

pathway

Critical source area

80% of losses come from 20% of area

CRITICAL SOURCE AREAS

Illustrating CSA

Pathways

The driving force behind contaminant transfer from land to

waterbodies is water, because it provides the energy and the

carrier for contaminant movement.

Location where a water quality

objective/ limit

has been set

The Challenge….Managing contaminant movement to waterways

H e a l t h y R i v e r s P L A N F O R C H A N G E

Technical Leaders Group

W a i o r a H E R A U T A K I W H A K A P A I P A I

The Water Cycle

Attenuation

Attenuation is the permanent loss or temporary

storage of nutrients, sediment or microbes during the

transport process between where they are generated

(i.e., in the paddock) and where they impact on water

quality (i.e., a downstream water body, such as a

lake).

Attenuation

• Generic attenuation processes include flow

attenuation, deposition, microbial transformations,

vegetation assimilation and other physical and

biogeochemical processes.

Attenuation

• These processes can alter pollutant concentrations

and loads by:

• (i) decreasing the mean concentration or load,

• (ii) decreasing variability of concentration or load,

• (iii) increasing the total

Time Lags

• Hydrological and biogeochemical processes that

result in long residence times of nutrient and

sediment pools in catchments, stream channels

and lakes and reservoirs.

• Such time lags, sometimes referred to as legacies,

reflect the fact that the land-cover conversion and

nutrient and sediment pollution may have occurred

for decades to centuries prior to what you see

today.

0

1

2

3

100

300

500

1995-97 2002-04 2005-07 2008-10

TP

loa

d (to

nn

e/h

a y

r-1) S

S lo

ad

(to

nn

e/h

a y

r-1)

SS

TP

Variability in time (Dairy monitor catchments)

Lag in response of suspended sediments (SS) and total phosphorus (TP)

to improved stock exclusion and reduced pond discharge in 1996

Variability through space and time Consequences for what and where

• Different land use types

result in different

contaminant losses

adding further spatial

variability

• The wide range of losses

within a land use is due to:

• climate

• soil type

• topography

• management

• Infers much gain can be

made

P lo

ss (

kg P

ha

-1 y

r-1)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

8.0

10.0

N lo

ss (

kg N

ha

-1 y

r-1)

0

5

10

15

20

25

30

35

40

45

50

55

60

Land use

None Sheep Mixed Deer Dairy Arable/Veg

Se

dim

en

t lo

ss (

kg h

a-1

yr-1

)

0

1000

2000

3000

4000

5000

6000

None Sheep Mixed Deer Dairy Arable

Variability and land use types

Variability in performance

Farm nutrient efficiency and N losses to waterways

0

5

10

15

20

25

0 10 20 30 40 50 60 70 80 90

% offarms

N leached (kg N/ha/yr)

a) Waikato

Room for improvement

to low leaching levels

Targeting interventions; what are they? • An instrument (e.g. a sensor)

• A system (e.g. climate forecasting)

• A farm management practice (e.g. time of application of N

fertiliser)

• A product

• A catchment intervention (e.g. Riparian margins)

• Infrastructure (e.g. Irrigation scheme)

Included also are enablers of technologies such as decision

support tools e.g. Crop calculator

Farm Scale

Good Management Practice

Good

Managemen

t Practice

Numeric

catchment

limits for

nutrients

But how much when you’re farming well?

Good Management Practice

Examples:

• Whole farm (map, plan, skills)

• Land (erosion control, ground cover)

• Plant (fertiliser use, irrigation, crop residues)

• Animal (effluent, grazing)

• Other (waste, agrichemicals)

H e a l t h y R i v e r s P L A N F O R C H A N G E

Technical Leaders Group

W a i o r a H E R A U T A K I W H A K A P A I P A I

Nitrogen Interventions: Cost-effectiveness Low Impact (0-10%) Medium Impact (10-30%) High Impact (>30%)

High

Cost

• Restricted grazing

• Enhanced waste

water treatment

systems

• Winter housing and

manure management

Medium

Cost

• Supplementary

feeding, low N diet

• High sugar grass

• Improved irrigation,

farming practice

• Greater root activity

• Lipids or ionophores

• High tannins

• DCD North Island

• Duration control grazing

• Environmental

forecasting

• BioChar

• Soil processes, new

products & formulations

(commercial)

• Ryegrass N use

efficiency

• Constructed and

managed wetlands,

denitrification systems

• DCD South Island

• Match land to agricultural

use

• Diuretic supplementation

or N modifier

• Low N pasture

• Change Animal Type

• Optimal fertiliser

management

• Effluent management

• Gain in nutrient efficiencies

by nutrient management,

farm systems approach,

overseer,

• Precision agriculture -

targeted mitigation high N

areas

• Optimise timing of pasture

grazing / feed to lower N in

diet

• Groundwater assimilative

capacity

Low cost

Improve Production Efficiency: e.g. N

Improved production efficiency of N can be achieved with

higher genetic gain animals, better pastures and efficient use

of artificial N, optimizing stocking rates and use of animal

shelter e.g.: Scenario Profit

($/ha)

Productio

n

(kg MS/ha

N loss

(kg N/ha)

Baseline Canterbury dairy farm

(modelled)

2000 1500 40

Current breeding worth & better N

management

2150 1600 35

High breeding worth, low stocking

rate & better N management

2450 1750 20

High breeding worth, high stocking

rate & better N management

2500 2000 35

H e a l t h y R i v e r s P L A N F O R C H A N G E

Technical Leaders Group

W a i o r a H E R A U T A K I W H A K A P A I P A I

Phosphorus Interventions: Cost-effectiveness

Low Impact (0-10%) Medium Impact (10-30%) High Impact (>30%)

High Cost

• Buffer strips

• Natural and constructed

wetlands

• Aluminium sulphate to

pasture / cropland

• Sorbents in and near

streams

• Irrigation water use and

recycling

Medium Cost

• Effluent pond storage /

low rate application

• Tile drain • Restricted grazing

• Stream fencing

Low Cost

• Fertiliser management -

Optimize soil P, low

water soluble P fertiliser

Tools developed that provide real-time monitoring to

match the supply of water & nutrients with crop demand

to maximise productivity:

2013 • Crop calculators

• Water & irrigation management tools

• Variable rate irrigation

2016 • New crop calculators developed (e.g. onions, kiwifruit)

• Advanced climate and weather forecasting

• Advanced irrigation scheduling

Precision Farming Technology Options and Timeline

Next generation dairy farms P 21 II

• Waikato:

• Higher genetic merit cows, lower

stocking rate, lower replacement rate,

off-paddock periods in autumn/winter,

reduced N fertiliser inputs and

improved dietary balance

Catchment Scale

Buffers & contaminants

Stream bank stabilisation

RIPARIAN ZONE LIVESTOCK STREAM RIPARIAN ZONE LIVESTOCK STREAM

Setback

Filtering surface runoff

RIPARIAN ZONE LIVESTOCK STREAM

RIPARIAN ZONE LIVESTOCK STREAM

Filtering subsurface flow

Riparian fencing

Subsurface flow filtering

Grass filter strips

0 10 30 50 100 %

low medium high

sediment

phosphorus

nitrogen

sediment

phosphorus

nitrogen

sediment

phosphorus

nitrogen

Seepage wetlands sediment

phosphorus

nitrogen

Performance comparison

Waiokura WQ trends 2001/08

Parameter Trend Reasons

Sediment 40%

Riparian management

Faecal

bacteria 40%

Riparian management

Fewer Pond discharges

Nitrate N

14%

More cows/Increased N

fertiliser use

Total P

30%

Riparian management

Fewer pond discharges

Less P fertiliser used

More milk from catchment AND

environmental expectations being met

H e a l t h y R i v e r s P L A N F O R C H A N G E

Technical Leaders Group

W a i o r a H E R A U T A K I W H A K A P A I P A I

Catchment Interventions: Cost-effectiveness

Low Impact (0-10%)

Medium Impact (10-30%) High Impact (>30%)

High Cost

• Constructed wetland

and managed natural

wetlands

• Improved waste

water treatment

technologies

Medium Cost

• Catchment-wide

riparian management

• Storm-flow mitigation

Low Cost

• Riparian

management

guidelines

• Environmental

forecasting, detailed

time and space

• Critical source area

mapping and targeted

controls

Intervention

Sediment capping Lake Okaro (30 ha) modified zeolite application c.

$75,000 p.a. over 3 years

Phosphorus inactivation Lake Rotorua alum dosing $1M p.a.

Dredging Expensive although costs will vary considerably

depending on circumstances

Oxygenation/destratificati

on

Destratification trial in lake Rotoehu (790 ha):

$524,000

Hypolimnetic withdrawal Limited application so far in NZ but proven to be “low

cost” in Europe and USA.

Weed harvesting

Hornwort harvesting in Lake Rotoehu (790 ha):

$52,800 p.a.

$22/kg N and $165/kg P

Diversions Ohau Channel wall in Lake Rotoiti (124 ha):

$10 million

Ambulance at the bottom of the cliff- Catchment

Restoration interventions

Whatawhata Case

Whatawhata Case