Fabio Arsego1 and Helena Oakey2
1SARDI, 226 McKenzie Rd, Minnipa, South Australia, 5654, email@example.com;
2University of Adelaide; Waite Rd, Urrbrae, South Australia, 5064
Irregular and infrequent winter rainfall patterns coupled with low soil fertility provide a challenging environment for growers in the Upper Eyre Peninsula (UEP). Proximal sensing (PS) technologies have the potential to support growers’ nutrient management decisions by monitoring in-season variations in soil water content together with water and nutrient status of the crop. The development of small, portable PS devices has now allowed the use of this technology in the field, enabling PS to be utilised by growers in their paddocks. In this research, two years of UEP nutrition trials have been combined to calibrate PS (SR-3500 spectroradiometer from Spectral Evolution) for crop nutrient content, and one year of data has been examined for soil moisture and nutrient content. PS absorbance data predicted soil moisture and nitrogen with reasonable accuracy (R2 = 0.6-0.8) at depths (0-10, 10-30, 30-90 cm) on the upper Eyre Peninsula in 2018. In-crop PS reflectance data at stem elongation (Growth Stage 31 = GS31, Zadoks et al., 1974) predicted (R2 = 0.5-0.8) the amount of crop macronutrients, including but not limited to nitrogen, phosphorus, potassium and sulphur. Further experimental data are required to use soil absorbance and crop reflectance as a means of predicting nutrient content, because some environmental parameters can confound the results.