Enhancing Sulla (Hedysarum coronarium L.)

introduction to different soil types through

inoculation with rhizobia strain

Sitzia M.1, Manca C. 1, A. Pintore1, Epifani GP1, Loi A. 2

1- Servizio Ricerca per la Zootecnia, Agris Sardegna, 07040 Olmedo, Italy;

2 - Department of primary industry and regional development Baron-Hay Court, South Perth WA 6151

27TH EUROPEAN GRASSLAND FEDERATION GENERAL MEETING

Sustainable Meat and Milk Production from Grasslands Cork, 17-21 June 2018

Rochestown Park Hotel - Douglas, Cork Ireland

To help farmers improving farming income by

reducing the off-farm feed purchases through

increasing forage production and quality

CHALLENGE

Introduction well adapted perennials and legume

species

SULLA

Sulla commonly grows into clay calcareous soil

with alkaline pH;

Its perenniality allows rapid regrowth in the

second autumn

Is one of the most productive, short-lived

perennial pasture legume that is grown

throughout Mediterranean countries

High nutritive value of Sulla improves milk

production and, due to its condensed tannins

content, has anti-bloating and internal parasite

control properties in sheep

When effectively nodulated, Sulla plants

have the ability to biologically fix large

quantities of N, increasing paddock fertility

Inoculated Uninoculated

Sulla spontaneous diffusion is limited to areas

where its native specific rhizobia is available

The objective of this work was to demonstrate that Sulla can grow successfully in different Sardinian soil types as long as the seed is inoculated with the appropriate rhizobia strain

53 paddocks of 1 or 2 ha

located in different areas

MATERIAL AND METHODS

A small area in each paddock was seeded with

un-inoculated Sulla seeds as control

Sulla was introduced for its

first time in autumn 2014 in

43 dairy farms

Altitude range: 1 - 650 m a.s.l

Paddocks of Sulla (Hedysarum coronarium L.)

Before seeding Sulla was inoculated with a

Rhizobium sullae - strain WSM1592 (Australia)

INOCULATED SEED

INOCULATION WITH PEAT

INOCULATED SEED

LIME 5 kg/ha

SPECIFIC RHIZOBIA STRAIN

ADHESIVE

pH (1:2.5 soil:water suspensions);

organic matter (Walkley & Black method; 1934),

total N (Kjeldahl);

available P (Olsen methods),

exchangeable K and Ca (flame atomic absorption spectroscopy following

ammonium acetate extraction);

total calcium carbonate (quantity of CO2 produced after acid dissolution);

active carbonate (ammonium oxalate method.);

Material and methods - measurements

Soil texture and chemical composition

Full soil analysis for each site was conducted

Plant establishment numbers:

45 days after seeding in 30 quadrats (900 cm2 each)

randomly positioned in each paddock.

Nodulation score (1-10): three months after seeding, in 15

plants per paddock were carefully removed and roots

washed and scored as reported by Howienson & Dilworth

(2016)

Sulla ground cover score (1-5) and vigour score (1-5):

in three occasions during the first and the second year (2014

and 2015)

Material and methods - measurements

Soil pH is considered the main constraint to

optimal Sulla nodulation and growth (Yates et

al, 2015) then it was used as classification

factor.

Statistical analysis

Data were analyzed by Anova model.

Differences between treatments were assessed by Duncan

T tests (P < 0.05, SAS Institute, 2002).

Results

15 15

23

0

10

20

30

<6,5 6,5 – 7,5 >7,5

Paddock

s (n°)

pH pH (H2O)

Range Average

< 6.5 5.4–6.4 5.99

6.5 – 7.5 6.5–7.5 6.94

> 7.5 7.6-8.5 8.04

P 5,4-8,5 < 0.001

Number of paddocks per

class

Soil pH range and pH

average per class

Results

Soil texture per class

0

1

2

3

4

5

6

7

<6.5 6.5-7.5 >7,5

paddock

s n.

pH

Clay Loam Clay Loam

Sandy Loam Clay Sandy Loam Sandy Clay

Silty Sandy Loam Silty Loam

RESULTS

pH pH (H2O) Organic

matter Total N

Exchangeable

K Available P

Total

carbonate

Active

carbonate

Exchangeable

Ca

Range Average g kg-1 g kg-1 mg kg-1 mg kg-1 g kg-1 g kg-1 mg kg-1

< 6.5 5.4–6.4 5.99 28.65 1.80 242.7 13.5b 4.8b 1.93b 1960.1b

6.5 – 7.5 6.5–7.5 6.94 31.5 2.02 246.7 21.2a 12.7b 8.47b 3593.3a

> 7.5 7.6-8.5 8.04 23.85 1.78 314.7 19.0ab 130.9a 30.20a 4431.6a

P 5,4-8,5 < 0.001 ns ns ns 0.054 0.003 0.024 < 0.001

Values with different letters within column are significantly different (P < 0.05)

Soil fertility was generally high

Soil chemical characteristics

Nodulation efficiency Sowing year -2014 Second year-2015

pH Seedling

(n m-2)

Inoculated

score

Uninoculated

score Vigor score

Ground

cover score Vigor score

Ground

cover score

< 6.5 182.9 2.26 0.43b 2.17b 2.38b 3.2b 1.34b

6.5 – 7.5 205.6 3.06 0.85ab 2.09b 3.27ab 3.44ab 1.57ab

> 7.5 198.6 2.97 1.47a 3.07a 3.43a 4.26a 2.35a

P ns ns 0.065 0.046 0.057 0.030 0.062

Seedlings establishment, nod efficiency and crop scores

Values with different letters within column are significant different (P < 0.05).

RESULTS

Inoculated plants were all moderately nodulated showing a better

nodulation in pH 6,5-7,5

The un-inoculated plants shown suboptimal levels of nodulation

suggesting that the background rhizobium levels were inadequate

Sulla can be grown successfully in different soil types

where the species is not traditionally recommended.

Proper inoculation practice of sulla seed seems to have

partially overcome problem linked to low soil pH < 6.5

Further studies are currently underway with a specific

project financed by Sardinia Region to select elite rhizobia

strains for acidic soils (Progetto strategico Sulcis_Delibera

Cipe n.31/2015) .

Conclusions

Acknowledgements:

The authors are grateful to S. Mastinu and S. Fancellu for their

technical contribution and N. Fadda and all staff of the soil

analysis laboratory for their collaboration.

Thank You