Soil compaction research

charlotte.evans@britishgrassland.com

Soil Compaction • 70% of grassland soils in England and Wales

exhibit signs of compaction

Research Partnership

Grassland, forage and soils 20 Research Projects:

Grass

Alternative forages

Soil

Out-wintering

Economics

BGS working with

DairyCo launched the

DEMO FARMS in

2013 to demonstrate

research in practice

Background research

• Deliberately compacted medium soils at Dumfries site in 2011

• Compaction created by both trampling and trafficking

Bulk density & Water retention

• Compaction increased

soil water retention by

c. 17%

• Compaction increased

bulk density

• Most of the increase

caused by the first event

First cut yield

• Both tractor and livestock induced compaction reduced first

cut yield

• Average reduction under trampling = 14%

• Average reduction under trafficking = 22%

Nitrous Oxide losses • Compaction alters soil microbial activity

• Increased emissions of nitrous oxide (N2O)

• Reduced nutrients available to grass N2O losses following March

fertiliser application were

14.9g/ha/day more from tractor

compacted soils and 7.4g/ha/day

from trampled sites compared to the

non-compacted control

Influence of aeration

Bulk density

Influence of aeration

Influence of aeration

Research findings summary

• Compaction is easily caused and identified

• Average first cut yield loss of 14% form trampled and 22% form tractor compaction

• 30% higher N2O emissions from tractor compaction

• Both slitting and sward-lifting reduce bulk density in both types of compacted soil

• More data is needed to understand the influence of aerators on yield

Crathorne Farms, Yarm • Soil lifting and spiking

• Controlled Ttfficking

Ray Brown, Holmes

Chapel • Soil lifting and spiking

• Utilising slurry on gazed grass

Home Farm, Newton St

Cyres • Separated slurry utilisation

• Spike aeration

Chynoweth, Truro • Lucerne as a sustainable

source of home-grown

protein

Trink, St Ives • Surface aeration

• Out-wintering replacement

heifers

Crathorne

Holmes Chapel

Spike = 3.8% yield increase

Lift = 13% yield increase

Combined spike in spring & lift in autumn =

15.1% yield increase

Graze – Silage – Graze – Graze , 2013 & 2014

Demo includes:

1. No aeration

2. Spike aerate only (spring)

3. Spike aerate (spring)

and sward lift (autumn)

4. Sward lift only (autumn)

Quickes Home Farm

7.4 litres more

milk per day

from grass from

the spiked site

Sward-lift

Soil map

Trink • Comparison of two types of surface aerator

• Comparison between spring and autumn aeration

• What was the effect of each on grass growth

• What was the effect of each on herbage quality

A

B

2014 yield results

A = 3.5 % better than B and

5.8% better than no action

Summary

• Demo Farm trials are incomplete and ongoing

• Site specific and farm specific

• Limited control of other influencing factors

• Nevertheless some food for thought:

– Even light soils compact

– Both types of mechanical aeration can improve soil structure and yields

– Sward-lifting + spiking OR aerating in the spring and autumn further increases yields

– But take care with timing!

Events 2015