Production and botanical composition of leys in a long-

term cropping system experiment in Northern Sweden

Parsons, D., Zhou, Z. and Palmborg, C.

Background

• Agricultural land use in Sweden was historically

dominated by leys (a forage phase in a crop rotation)

• During the second half of the 20th century, farming

activities became increasingly specialized in Sweden,

leading to the separation of cropping farms and livestock

farms.

• Concern arose as to how this specialization would

influence soil properties and crop yields

• A cropping system experiment was initiated in the 1950s

in Northern Sweden, and is one of the oldest of SLU’s long-

term experiments.

0 20 40 60 80 100 120 140 160 180

Energy crop

Other annual crops

Unspecified

Potatoes

Other green fodder

Fallow

Cereal

Leys and pastures

Area ('000 ha)

Agricultural Land Use, Northern Sweden (2015)

Total of 4 Northern counties

Experimental Locations

Site Initial

year

Latitude

and

longitude

Röbäcksdalen 1958 63.81 N

20.24 E

Offer 1956 63.14 N

17.75 E

Ås 1955 63.25 N

14.56 E

Climate

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11 12M

on

thly

pre

cip

itat

ion

(m

m)

Month

-10

-5

0

5

10

15

20

1 2 3 4 5 6 7 8 9 10 11 12

Mon

thly

air

tem

pera

ture

(oC

)

Month

Röbacksdalen

Ås

Offer

• Monthly average temperatures

• Monthly accumulated precipitation (half falls as snow)

• Annual precipitation is 558 mm (Ås), 606 mm (Offer)

and 637 mm (Röbäcksdalen)

Cropping systems

• A: Livestock-focused system.

– Five years of ley and one year of barley with ley under-

sown.

• B: Also focused on livestock production

– Typical length ley (three years) with three years of annual

fodder crops.

• C: Balanced between crop and livestock production

– Shorter than normal ley (two years) and four years of annual

crops (including cereals, grain legumes, and potatoes).

• D: Completely annual cropping system

– One year of ley cultivated as a green manure

– The results are not included in this presentation.

Cropping systems (more detail)

Cropping

System

Phases of crop rotations in different year (Phases)

1st Year 2nd Year 3th Year 4th Year 5th Year 6th Year

A Barley

under-

sown with

ley

Ley 1 Ley 2 Ley 3a Ley 4a Ley 5a

B Barley

under-

sown with

ley

Ley 1 Ley 2 Ley 3a Oats/peas (barley

fodder)

Forage rape

(rape/barley/peas

mixtureb)

C Barley

under-

sown with

ley

Ley 1 Ley 2 Winter

rye

(barley)

Oats/peas

(potatoes)

Potatoes

(rape/barley/peas

mixtureb)

D Barley

under-

sown with

ley

Ley as

green

manure

Winter

ryec

(barley)

Peas

(potatoes)

Potatoes (barley) Carrots/swedes

(potatoes)

Crop rotations of the four cropping systems at Röbäcksdalen, Offer and Ås. The crops

in parentheses are those grown after 1987, when the plan was revised.

a Manure (20 t/ha) was applied in the autumn.

Other details

• All six phases of each cropping system were present

each year

• Two replicates per site.

• Ley species used were red clover (Trifolium pratense L.),

timothy (Phleum pratense L.) and meadow fescue (Festuca

pratensis Huds.)

• Leys were initially sown under barley and harvested two

times per year.

• Soil, plant, and manure samples are stored

Results – soil properties

Soil properties Comparison of ley

dominated systems (A and

B) and annual crop

dominated systems (C and

D)

Year of soil

sampling

or measurement

Reference

Bulk density (A and B) < (C and D) 1987

2013 and 2014

Ericson, 1994

Jarvis et al., 2017

Porosity (A and B) > (C and D) 1987 Ericson, 1994

Saturated hydraulic

conductivity

(A and B) > (C and D) 1987 Ericson, 1994

Topsoil organic

carbon

(A and B) > (C and D) 1972 and 1987

2010

Ericson, 1994

Jarvis et al., 2017

Barley root depth (A and B) > (C and D) 1987 Ericson and

Mattsson, 2000

Comparison of soil physical and chemical properties between ley dominated (A and B)

and annual crop dominated systems (C and D)

Source: Zhou et al. 2018

Revisions to experiment

• 1987

– Change in crops (updated to reflect current cropping options)

– Reduced to one replicate

• 1994

– Reduced to one site (Offer)

For simplicity, this presentation will focus on Offer, but the

results are similar for the other sites

Aims

• Aims of overall experiment

– Examine the effect of increasing annual cropping on yield

and soil characteristics.

• Aim of this presentation

– To assess the long-term effects of the different cropping

system treatments on the yield and composition of the ley

phase

Yield

Boxplot of first to fifth year ley yields, in cropping systems A, B, and C. The box

and whiskers represent the 5th, 25th, 50th, 75th and 95th percentiles.

0

2000

4000

6000

8000

10000

12000

A B C A B A B A A

Year 1 Year 2 Year 3 Year 4 Year 5

Tota

l yie

ld (

kg D

M/h

a/y

ea

r)

Clover content

Percentage clover content in the first harvest of first to fifth year leys. Error bars

are one standard error.

0

10

20

30

40

50

60

Year 1 Year 2 Year 3 Year 4 Year 5

% C

lover

Year of ley

A B C

Cropping system

Clover content

Percentage clover content in the first and second harvest of first to fifth year leys.

Data for cropping systems A, B, and C are combined. Error bars are one standard

error.

0

10

20

30

40

50

60

70

80

90

Year 1 Year 2 Year 3 Year 4 Year 5

% C

lover

Year of ley

H1 H2

Ley harvest

Conclusions

• There were minimal effects of cropping system

treatments on ley yields, suggesting that systems with an

annual cropping focus can still include a productive ley

component.

• Ley yields are relatively stable regardless of the cropping

system.

• Results confirm the dynamics of ley clover content within

and between years.

• It is a challenge to maintain the legume component in

longer term leys.

• Side note: Agricultural in Northern Sweden has not (as

was feared) become dominated by annual crops

Acknowledgements

• Staff from Ås, Offer and Röbacksdalen since the beginning, for their work

on the management and measurement of the experiment.

• The experiment is financed by the Faculty of Natural Resources and

Agricultural Sciences, SLU.

• Data and material from Röbäcksdalen, SITES (Swedish Infrastructure for

Ecosystem Science), a national coordinated infrastructure, supported by

the Swedish Research Council