Field Research & Agronomy

Potassium interpretative methods & response in wheat

AIM

This trial investigates the response of wheat to potassium (K) fertilizer application on sandy soil in the Eradu area.
Additionally, looking at the capacity of different interpretative methods at measuring soil K concentrations accurately.
Also apart of series of yearly trials looking to determine a more accurate critical value for K.

For further details contact your local Area Manager or our Summit Field Research team

CONCLUSION

• With the bulk of pre sowing soil samples having levels below 40-50mg/kg Colwell K a yield response to K would be expected.
  A notable variability between K measuring methods of Colwell K and Exchangeable K was apparent.
• Post sowing soil samples demonstrated that K application had altered the levels of K in the soil.
  Showing an increase in soil sample Colwell K values with increasing K application.
• The NDVI data showed a significant biomass decrease with increasing K rates (p
• Scepter wheat had a significant yield response to applied K.
  The highest yield was 2.71t/ha which received 50kg/ha of K.
• Plant biomass was considerably less at higher K rates earlier in the season, this decrease is not express as strongly in yield.
• Higher K rates did have an unfavourable effect on early plant growth and harvest yields.
  MOP can have a toxicity effect on germinating crops, especially in low rainfall seasons.