Field Research & Agronomy

Nitrogen and phosphorus rates in barley on heavy soil

AIM:

‍To assess the response of barley to nitrogen (N) and phosphorus (P) fertilizer application on heavy, red loamy soil in the Nokaning area.

Whilst helping to improve the knowledge and advice provided to local farmers in regards to their sowing and in-season fertiliser choices.

For further details contact your local Area Manager or the Summit Research Team

CONCLUSIONS

• Even with below average rainfall the harvest yield data demonstrated a significantly positive response to both N and P.
  The highest yield was 2.36t/ha from 75kg/ha of N and 12kg/ha of P, whereas the lowest was 0.81t/ha from N4 and P6.
  By applying P6 a yield increase of 24% was achieved, a 37% increase from P12 and 35% increase from P18 when compared to P0.
  A greater yield increase was achieved from N with 86% from N25, 100% from N50 and a 125% from apply N75 compared to N4.
• The grain analysis presented low protein levels and screenings, with high hectolitre weights.
  All treatments went BFED1 as the variety Spartacus is not accredited as MALT.
• The highest economical return was $457/ha receiving a treatment of N75 and P12, with the lowest being $176/ha from N4 and P18.
  When applying P12 an additional $79/ha can be made on P0 and an extra $198/ha on N4 by applying N75
• This trial demonstrated that in order for a crop to fully utilise additional N, there must be sufficient P available.
  The tissue samples display a positive biomass response from applying N and P.
  However, treatments that received higher rates of P had higher dry weight compared to others that received nil P.
• When relating plant dry weights to tissue nitrate levels it shows the poor ability for the crop to utilise the absorbed N for growth when P is deficient.
  Nitrate concentrations remained higher in plants that received lower P rates, as it was not being utilised for plant growth.
• Showing there is little advantage to applying N at sowing and throughout the growing season on crops which have not received ample P at sowing, as this additional N is not efficiently used by the plants and is a financial loss.
• Based on gross margin calculation and response curves the optimum fertiliser rate at this site in 2017 is N50 and P12.