Enhancing Sulla (Hedysarum coronarium L.) introduction to different soil types through inoculation with rhizobia strain

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1 27 TH EUROPEAN GRASSLAND FEDERATION GENERAL MEETING Sustainable Meat and Milk Production from Grasslands Cork, June 2018 Rochestown Park Hotel - Douglas, Cork Ireland Enhancing Sulla (Hedysarum coronarium L.) introduction to different soil types through inoculation with rhizobia strain Sitzia M. 1, Manca C. 1, A. Pintore 1, Epifani GP 1, Loi A Servizio Ricerca per la Zootecnia, Agris Sardegna, Olmedo, Italy; 2 - Department of primary industry and regional development Baron-Hay Court, South Perth WA 6151

2 CHALLENGE To help farmers improving farming income by reducing the off-farm feed purchases through increasing forage production and quality Introduction well adapted perennials and legume species

3 SULLA Is one of the most productive, short-lived perennial pasture legume that is grown throughout Mediterranean countries Sulla commonly grows into clay calcareous soil with alkaline ph; Its perenniality allows rapid regrowth in the second autumn

4 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

5 When effectively nodulated, Sulla plants have the ability to biologically fix large quantities of N, increasing paddock fertility

6 Sulla spontaneous diffusion is limited to areas where its native specific rhizobia is available Inoculated Uninoculated

7 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

8 MATERIAL AND METHODS Paddocks of Sulla (Hedysarum coronarium L.) Sulla was introduced for its first time in autumn 2014 in 43 dairy farms 53 paddocks of 1 or 2 ha located in different areas Altitude range: m a.s.l A small area in each paddock was seeded with un-inoculated Sulla seeds as control

9 Before seeding Sulla was inoculated with a Rhizobium sullae - strain WSM1592 (Australia) IN INOCULATION WITH PEAT LIME 5 kg/ha SPECIFIC RHIZOBIA STRAIN ADHESIVE INOCULATED SEED

10 Material and methods - measurements Full soil analysis for each site was conducted Soil texture and chemical composition 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.);

11 Material and methods - measurements 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)

12 Statistical analysis Soil ph is considered the main constraint to optimal Sulla nodulation and growth (Yates et al, 2015) then it was used as classification factor. Data were analyzed by Anova model. Differences between treatments were assessed by Duncan T tests (P < 0.05, SAS Institute, 2002).

13 Results Number of paddocks per class Soil ph range and ph average per class 30 ph ph (H 2 O) 23 Range Average Paddocks (n ) < > <6,5 6,5 7,5 >7,5 P 5,4-8,5 < 0.001

14 paddocks n. Results Soil texture per class < >7,5 Clay Loam Clay Loam Sandy Loam Clay Sandy Loam Sandy Clay Silty Sandy Loam Silty Loam ph

15 RESULTS Soil chemical characteristics ph ph (H 2 O) 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 < b 4.8 b 1.93 b b a 12.7 b 8.47 b a > ab a a a P 5,4-8,5 < ns ns ns < Values with different letters within column are significantly different (P < 0.05) Soil fertility was generally high

16 RESULTS Seedlings establishment, nod efficiency and crop scores Nodulation efficiency Sowing year Second year-2015 ph Seedling (n m -2 ) Inoculated score Uninoculated score Vigor score Ground cover score Vigor score Ground cover score < b 2.17b 2.38b 3.2b 1.34b ab 2.09b 3.27ab 3.44ab 1.57ab > a 3.07a 3.43a 4.26a 2.35a P ns ns Values with different letters within column are significant different (P < 0.05). 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

17 Conclusions 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).

18 Thank You 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.