Document Type
Article
Publication Date
10-22-2024
Journal Title
Crop and Pasture Science
ISSN
1836-0947
Keywords
exchangeable potassium, plant analysis, potassium, soil analysis, soil test calibration, wheat
Disciplines
Agronomy and Crop Sciences | Soil Science
Abstract
Context
Long-term negative potassium (K) balances in crop production have depleted soil K levels in Western Australia (WA). Previous research has focussed on sand-textured soils, but recently, monitoring of crops grown on loam-textured soils has shown deficient or marginal shoot K concentrations where Colwell K 0–10 cm is above current critical levels.
Aims
The aims were to examine whether grain yield responses to fertiliser K can be detected on loam-textured soils and if soil test calibration curves can be identified for these soils.
Methods
Eight field trials were conducted with wheat on loam-textured soils. The same experimental design was used at all sites; six levels of K applied at sowing, from 0 to 200 kg K ha−1 with one treatment including a split application. Soil and plant test calibration curves were modelled using measurements from the trials.
Key results
Grain yield responses of 0.69 to 1.37 t ha−1 to fertiliser K (P < 0.05) occurred in 4 of 8 trials. Relative yield was closely related to soil exchangeable K and the goodness of fit of the soil test calibration curves increased as the depth of sampling increased. The best soil test calibration curve was for sampling 0–40 cm.
Conclusions
This research confirms that on some loam-textured soils, yield loss is occurring to K deficiency if no K fertiliser is applied. Implications. As soil K reserves are run down, soil sampling at 0–40 cm on loam-textured soils will provide the most accurate monitoring of soil K deficiency for wheat production.
Recommended Citation
Scanlan CA et al. (2024) Subsoil testing required to detect the rundown of soil potassium to deficient levels for wheat production on loam-textured soils. Crop & Pasture Science 75, CP24195. doi:10.1071/CP24195
