Field Research & Agronomy

SUM19-19: Form and efficacy of manganese supply to lupin varieties, Eradu

Aim

On light, sandy soils, Mn deficiency can be prevalent. In narrow leafed lupin, Mn deficiencies can cause split seed and reduce grain yield. Split seed occurrence in the Jurien lupin variety has been observed in 2018, but links with Mn are unknown. This trial aimed to assess Mn rates and sources to combat the split seed issues.

Trial Details

Location: Matt Freeman’s, Eradu

Trial Size: 18 treatments x 6 reps =108 plots.

Soil Type: Yellow Sand.

Crop Sown: Jurien and Barlock Lupins, 90 kg/ha, 6/05/2019.

***Table 1:*** *Pre-trial soil nutrient analysis.*

Results

***Figure 1:*** Manganese concentration in lupin stems on 12/09/2019 showing higher concentrations in Barlock stems at lower Mn rates, but higher concentrations in Jurien samples at higher application rates. Deficiency level of 20 mg/kg indicated.

***Figure 2.*** *Yield response curve showing the mean treatment yields for applied Mn, in Jurien and Barlock varieties. Mitscherlich function fitted.*

***Figure 3.****Lupin split seed assessments for three Mn rates and Sources.*

***Figure 4.*** *Split seed and lupin seed size had a strong relationship with the concentration of Mn in the stems sampled at flowering stage.*

Key Notes

Barlock and Jurien lupin varieties appear to respond differently to Mn application.
Stem samples at flowering showed higher Mn concentration in Barlock than Jurien at rates 3 kg/ha or lower Mn applied.
Jurien produced higher yields than Barlock, averaging 1.3t/ha compared to 1.0 t/ha respectively, but Barlock had stronger yield responses to increasing Mn rates than Jurien.
3 kg/ha Mn was adequate to optimise Jurien yield and profit, whereas >6 kg/ha was required by Barlock.
Form of Mn applied is important. Supplying Mn in the MnO2 form appears completely ineffective for Barlock lupin production. The impact of MnO2 on Jurien lupin yield was not as pronounced.
In contrast to yield, MnO2 increased prevalence of split seed in Jurien, not Barlock.
Split seed was strongly correlated with stem test concentrations below 20 mg/kg.
Foliar Mn application was effective and highly profitable for Jurien but much less so for Barlock lupins.
Maintaining adequate Mn status plants is not only important for decreasing incidence of split seed but producing large seed size which translates of higher yield.

Contact your local Area Manager Shane Turner for more details on this trial, sturner@summitfertz.com.au, 0429 947 919.

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Grain Legumes