Diffusive gradients in thin films predicts crop response better than calcium-acetate-lactate extraction

Abstract

Soil P testing has been widely used to predict crop yields, P uptake, and fertilizer demands in agriculture. Diffusive gradients in thin films (DGT) provides a zero-sink soil P test which mimics diffusion-controlled plant uptake and has previously been found to predict P availability to crops better than conventional quantity-based P tests in highly weathered Australian, though not in European soils. Here we tested the performance of DGT and the Austrian and German standard P quantity test calcium acetate lactate (CAL) to explain the variation of crop yield and P uptake response of winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) in long-term P fertilization experiments at four different sites in eastern Austria. Phosphorus extracted with DGT (P-DGT) and CAL (P-CAL) correlated well in similar soils but not across sites with large variation in soil and site properties such as carbonate equivalent and water availability. The predictive power of DGT for barley (R2 = 0.42) and wheat grain yield (R2 = 0.32), and P uptake in wheat grains (R2 = 0.36) was clearly superior to that of the CAL, and less dependent on soil properties. The better performance of DGT compared to the quantity test is consistent with diffusion-limited P uptake in the water-limited cultivated soils of eastern Austria. The critical values of P deficiency derived from the Mitscherlich-type fits for barley and wheat at 80% relative yield are 64.9 and 26.2 µg L−1, respectively, consistent with differential P demands of the crops.

Use of diffusive gradients in thin-film technique to predict the mobility and transfer of nutrients and toxic elements from agricultural soil to crops—an overview of recent studies

“…The DGT technique and calcium acetate lactate have been used to predict crops (winter wheat and spring barley) response in long-term P fertilization experiments. DGT was found to be superior in predicting P transfer to the two crops ( r 2 = 0.42 for barley, r 2 = 0.32 for wheat grain yield, and r 2 = 0.36 for wheat grains) (Hill et al 2021 ). The DGT technique has been used to assess the bioavailability of P and other nutrient elements in flooded soils cultivated with rice crop.…”

Phosphorus dissolution and diffusion from struvite and its impact on phosphorus availability in Acrisol and Cambisol soils

“…To accurately measure and estimate the available P content in soils, the diffusive gradients in thin films (DGT) technique has proven to be a reliable approach (Mason et al., 2010; Six et al., 2013; Zhang et al., 1998). This method mimics the diffusion‐limited process of P uptake by plant roots from the labile P pool in the rhizosphere and has demonstrated a stronger correlation with plant‐available P compared to conventional chemical extraction tests (Hill et al., 2021; Hong & Lu, 2018; Mason et al., 2010; Six et al., 2013). The DGT device contains a hydrogel layer and a binding resin, which accumulates phosphate by diffusion from the soil over a specific period.…”