Monaro Legume Nodulation Survey Preliminary Results

Transcription

1 Monaro Legume Nodulation Survey Preliminary Results Jo Powells Senior Land Services Officer (Pastures)

2 What did we want to find out? What is the current nodulation status of legumes across the Monaro? Is a healthy looking legume plant (above-ground) actually fixing nitrogen? Are the current rhizobia strains performing or not? Can we manipulate nodulation & nitrogen fixation in existing pastures? What are the limiting factors affecting legume production (including nodulation) and how can we address them?

3 Survey Locations North Slap Up South Delegate Station West Rocky Plains East Countegany

4 Site methodology A 20m X 20m grid was established on a representative area within the selected site (paddock). A GPS reading was taken at centre of the grid. Soil samples (0-10cm) collected and bulked together for a site sample. Pasture composition was assessed. Chunks of pasture & soil collected and taken away.

5 Methodology what you didn t see! The chunks of pasture & soil were carefully washed by hand with a minimum of 15 legume plants retained. Nodule scores were assigned to each of the 15 legume plants from each site. 2 legume samples from the 15 washed samples were then photographed, root material (including nodules) removed and sent to the Centre for Rhizobium Studies for MALDI-ID processing.

6 Guide to assessing legume performance Check roots + Nodule scoring Nodule score 4-8 Healthy? Not Healthy? Nodule score 0-3 Correct inoculant No inoculant Soil analysis Change species Plant disease control ph P Mo and S Al Herbicides NO SU s Inoculate: - Drill in - Re-sowing - Top dress?

7 Nodulation scores Absent Ineffective Rare (Effective) Scarce Moderate Adequate Ample Abundant Very Abundant Extremely Abundant No nodules White ineffective nodules 0-5 small pink nodules 6-10 small pink nodules small pink and/or 1-2 large pink nodules small pink and/or 3-4 large pink nodules < > 40 small pink 10 large and/or 5-9 large pink pink nodules nodules Crown nodulation < 5 mm diameter Crown nodulation 5 mm diameter Source: Ron Yates, DAFWA

8 Preliminary results (more to come!) Subterranean, white, suckling, haresfoot, arrowleaf, red, caucasian and strawberry clover and lucerne (<1 year old) all sampled and nodule scored. Nodulation scores for the Monaro samples ranged from 0 8 Average nodulation score for the Monaro region was 2.6

9 Nodulation scores Absent Ineffective Rare (Effective) Scarce Moderate Adequate Ample Abundant Very Abundant Extremely Abundant No nodules White ineffective nodules 0-5 small pink nodules 6-10 small pink nodules small pink and/or 1-2 large pink nodules small pink and/or 3-4 large pink nodules < > 40 small pink 10 large and/or 5-9 large pink pink nodules nodules Crown nodulation < 5 mm diameter Crown nodulation 5 mm diameter Source: Ron Yates, DAFWA

10 Previous results in other LLS regions In spring 2015, 140 paddocks surveyed across Central West and Riverina LLS regions - Central West (60 paddocks) - 22% of paddocks had no nodules - 63% of paddocks scored <2/8-90% of paddocks scored <4/8 - Average score 1.8/8 - Riverina (80 paddocks) average score 2/8 Central Tablelands LLS region, spring 2016 (30 paddocks) average score 2.3/8

11 Low scoring plant

12 High scoring plant

13 But it s more than just presence of nodules Over 100 species of true Rhizobium For perennial and most annual clovers we need Rhizobium leguminosarum (group B & C inoculants). How do we know we have them?

14 Guide to assessing legume performance Check roots + Nodule scoring Nodule score 4-8 Healthy? Not Healthy? Nodule score 1-3 Correct inoculant No inoculant Soil analysis Change species Plant disease control ph P Mo and S Al Herbicides NO SU s Inoculate: - Drill in - Re-sowing - Top dress?

15 What is??? A tool developed by Dr Sofie DeMeyer (Murdoch University) Extracts bacteria directly from the nodule(s) without the need for culturing Quickly identifies bacteria present Identifies most likely strain of bacteria. - Newest strain - Older strains or mix of old and new - Exotic strain

16 Guide to assessing legume performance Check roots + Nodule scoring Nodule score 4-8 Healthy? Not Healthy? Nodule score 1-3 Correct inoculant No inoculant Change species Plant disease control Soil analysis ph P Mo and S Al Herbicides NO SU s Inoculate: - Drill in - Re-sowing - Top dress?

17 Factors affecting nodulation & N-fixation Specificity Soil texture Soil ph Soil fertility Herbicides Waterlogging Fungicides Insecticides Time since last inoculation Desiccation Time of sowing Drought

18 Specificity WU Source: Ron Yates, DAFWA WSM WSM present

19 Soil ph Rhizobia species Group - Host legume ph 4.5 ph 5.0 ph 5.5 ph 6.0 ph 7.0 ph 8.0 Bradyrhizobium spp. Rhizobium l. bv. trifolii Rhizobium l. bv. viciae Rhizobium l. bv. viciae Mesorhizobium spp. Sinorhizobium spp. G,S serradella, lupins C - Clovers E peas, vetch F faba, lentils Bis Biserrula, chick peas AM, AL - Medics Red = low N fixation, Orange = sub-optimal N fixation, Green = optimal N fixation Source: Ron Yates, DAFWA

20 Soil ph - Monaro Red = low N fixation, Orange = sub-optimal N fixation, Green = optimal N fixation Monaro average soil ph (CaCl2) (7 years of MFS soils club data)

21 Soil fertility - Phosphorus Mark Peoples et al Bungendore 3yr trial Surface applied Lime & Phosphorus > soil ph < available aluminum and manganese Drew et al. 2012

22 Soil fertility other nutrients Rhizobia N-fixation can also be limited by: High soil Nitrogen levels Sulphur deficiencies Molybdenum deficiencies - Mo is a component of Nitrogenase, which is essential for N-fixation. - Low Mo availability linked to low soil ph

23 Herbicides Group B (triasulfuron, chlorsulfuron, metsulfuron-methyl etc.) Group K (pyroxasulfone) Group I (clopyralid)

24 Herbicides 3g 0.3g 0.03g 0.003g g control 1/10 1/100 1/1000 1/ / of recommended rate Triasulfuron (LG) application on Sub clover (18 days growth) DAFWA Crop Pasture Group (Yates, Nutt & Loi)

25 What next? Finalise sampling and testing Analyse results All producers will get individual results (soil tests, images of plants, nodule scores and MALDI ID results) Field Day planned for early 2017 Full results Findings Guest speakers

26 Thankyou to: - Nancy Spoljaric (MFS) & Doug Alcock (Graz Prophet Consulting) - Belinda Hackney & Janelle Jenkins (Local Land Services), Oli Cay (MFS) - All our participating farmers across the Monaro!