Pesticides, soil erosion and water

Understanding the interactions and some management solutions

Contents

• Background• Pesticides and water• Soil erosion• Managing soils

There is a problem!Frequency of detection above 0.1 ppb of PPP’s since 1995

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

4.5%

5.0%

1996 1997 1998 1999 2000 2001 2002

% o

f a

na

lyse

s

Other

Diuron

Simazine

Atrazine

Chlorotoluron

Isoproturon

Dichlorprop

Mecoprop

MCPA

2, 4-D

IPU levels and River Flow

Intense rainfall on 18-20 Nov increased river flow, water very turbid (soil particles) likely to be surface run off

taking IPU to river

Water movement from Fields

Environmental Quality Triangle

Soil

Air

WaterQ

Soil Quality is the Basement of Environmental Quality

Rilling

Deposition

Runoff

Compaction / Capping => Soil Erosion

Soil Erosion

• In England and Wales, Erosion moves some 2.2 million tonnes of arable topsoil every year

• This contains nutrients &pesticides

• The equivalent of a 1cm layer of soil lost each year!

• It all ends up in water

Minimise Erosion

• Crop or Trash Cover

• avoid bare ground drill early

01020

30405060

708090

0 20 40 60 80 100

Effectiveness

% G

roun

d C

over

Stop raindrop impact!

Small rills in tractor wheelings

Larger rill along a headland wheeling

Minimise Erosion

• Cultivation Type • Don’t create very fine seedbeds which can cap and

slake if heavy rainfall occurs, stopping infiltration

• Soil Organic Matter • Helps keep stable soil structure which is less likely

to be broken by raindrops

Capping and Compaction will promote soil run-off, containing nutrients and pesticides and reduce pesticide efficacy

This headland would be ideal for an ELS buffer strip

Beetle Banks or Grass Strips can slow water movement to watercourses

•at least 6m wide•site across slopes•where gradient increases

Spot the error!This strip runs up/down slope rather than across

High Risk Situations• Soil type

• sandy soils are the least able to retain pesticides and nutrients;

• drained, structured clay soils can rapidly transport pollutants.

• Crop cover

• bare ground over the winter is most at risk.• Capping and compaction

• promotes soil run-off containing nutrients and pesticides.

Things to consider

• Slope – particularly if tramlines are compacted • Use a buffer strip to protect a water course,

provided that the water reaching it is moving at low velocity

• Plough the land way from the buffer strip to leave a furrow (but not a watercourse!)

• Don’t access the field by driving through a buffer strip

• Don’t let wheelings enhance run-off to buffers

Buffer strips against watercourses reduce the loss of pesticides, nutrients and sediment to water.

Use Setaside, ELS, or HLS options

Where buffer strips will not workBuffer strips can’t stop everything!

Buffer strips need time to establish; even this one is better than nothing

Risks and Solutions

Activity Risk Solution

Run-off Moderate Minimise erosionto high Use buffer zones

Drain flow Very high Consider soil, SOM or leaching

Better management

Roads/Tracks

Spray Drift

Drainflow

Run off

Leaching40-60% 5-10%5-10%

5-10%

10-20%

Typical ways in which agricultural pesticides can reach water from the field

Promoting Best Practice

In the Field

• Follow VI H2OK Best Practice Advice• Crop Protection Management Plans• Soil Management Plans• Environmental Stewardship Scheme• Environmental Information Sheets• Decision Support Systems

Use available tools to minimise risks to water

How might Environmental Stewardship help?

Valuable options in ELS include:

• Crop Protection Management Plan• Soil Management Plan• Not growing certain high-risk crops• Creating buffer strips alongside watercourses• Planting beetle banks • Managing hedgerows• Organic management opportunities for higher payments• Targeted areas HLS may provide some solutions too

Avoiding diffuse pollution• Farmers and agronomists need to identify risks to

water from the rotation and crop protection plans• Consider if lower doses and pre-emergent treatments

are appropriate • Listen to weather forecasts pre–spraying • Avoid spraying if soils are heavily cracked• Follow Decision Trees especially if rain is predicted

or soils are near field capacity and drains are likely to flow

• On steeply sloping/poorly drained fields, only spray when run-off risk is low

Soil ManagementManage soils to ensure that water cannot run-off from the treated area onto another field, road, track or other feature from where it could directly enter a watercourse•Do not overwork the soil so that it becomes slaked or capped;•Delay pesticide applications until after the first rains when deep cracks in the soil have closed;•Tramlines should run across slopes NOT down slopes leading to a watercourse;•Drill in tramlines where possible;•50% trash cover and rapid crop establishment can reduce the impact of raindrops which break down soil crumbs and can trigger soil erosion.

Risks can be reduced further by the additional measures listed below. These require long term planning.•Review rotations to avoid cropping practices and cultivations on soils and slopes which are at risk of erosion. This should be part of your Soil Management Plan.•On slopes over 5% (1 in 20) running for more than 200m, establish a beetle bank or at least 6m grass strip across the entire field. Locate this break where the slope increases;•Grass down valley bottoms leading to any watercourse.

Decision TreesIPU CTU and Simazine Mecoprop-p

In Summary• Soil erosion and surface run-off can result in pesticides, nutrients

and sediment reaching water.

• Awareness of the issue, thoughtful planning and good soil management can reduce the risks

• Careful soil management does not solve all pesticide problems because not all pesticide losses are linked with cultivation.

E.g. filling, washdown, disposal, drift

• Soil and water interactions are variable; delivery of environmental benefits requires a constant high standard of management and agronomic skill.

www.environmentsensitivefarming.co.uk

www.voluntaryinitiative.org.uk

www.smi.org.uk

Prepared by Paddy Johnson and Vic Jordan on behalf of SMI, with the help of CPA staff & members, TAG, and AIC members

Photos - from above, AMEWAM, Jim Orson and padre productions