Field Research & Agronomy

AIM

To study the response of wheat to phosphorus (P) and nitrogen (N), whilst examining how soil amelioration activities, of deep ripping and liming help to better improve yields and economical returns from fertilizer applications.

For more details about this trial contact your local Area Manager or our Summit Research Team

KEY MESSAGES

• The in-season biomass assessment and plant tissue samples highlighted a strong growth response to amelioration and to applied N and P.
• Calingiri wheat had a significantly positive yield response to amelioration and to N and P rates.
• The highest yield was 4.18t/ha and the greatest profit was $1145/ha.
• The optimal fertilizer rates on unripped soil is 12 units of P and 90 units of N and on deep ripped soil 18 units of P or higher and 90 units of N.

CONCLUSION

• NDVI readings showed a positive biomass response to applied N and P at both the sites, with greater growth seen on ameliorated plots.
• Plant dry weights did not increase with N application when P was unavailable or low, but when adequate P was provided the dry weights did increase.
  The removal of soil constrains by amelioration resulted in greater dry weights.
• The NO3- analysis shows that plants from both sites take up N at all rates, but data suggests that the ability of plants to utilise this N for plant growth is less when P is deficient.
  Higher NO3- concentrations are in plants from unripped plots, suggesting restricted root growth decreases nutrient uptake even when luxury amounts are applied.
• NO3- concentrations are higher in plants that received low P rates, as it is not being utilised for plant growth, suggesting that there is little advantage to applying N at sowing or throughout the growing season if adequate P has not been applied at sowing.
• Even with below average rainfall the yields demonstrated a significant response to N, P and amelioration.
  The highest yield was 4.18t/ha which had been ameliorated and received P24 and N150.
  The lowest yield was 1.10t/ha and was not ameliorated and received no fertilizer. When comparing yields at both sites the ameliorated site on average had a 31% higher yield.
• The greatest gross margin was $1,145/ha which was at the ameliorated site and received P24 and N150.
  The lowest revenue was $320/ha which was not ameliorated and received no fertilizer.
  The gross margin calculations demonstrate that returns were much greater with amelioration, on average $188/ha higher.
• Based on gross margin calculations and response curves the recommended application of fertilizer on unripped soil is P12 and N90 and on ameliorated soil P18 and N90