Use of a coupled soil-root-leaf model to optimise phosphate fertiliser use efficiency in barley

Abstract

Aims Phosphorus (P) is an essential nutrient necessary for maintaining crop growth, however, it's often used inefficiently within agroecosystems, driving industry to find new ways to deliver P to crops sustainably. We aim to combine traditional soil and crop measurements with climate-driven mathematical models, to give insight into optimising the timing and placement of fertiliser applications. Methods The whole plant crop model combines an above-ground leaf model with an existing spatially explicit below-ground root-soil model to estimate plant P uptake and above ground dry mass. We let P-dependent photosynthesis estimate carbon (C) mass, which in conjunction with temperature sets the root-growth-rate. Results The addition of the leaf model achieved a better estimate of two sets of barley field trial data for plant P uptake, compared with just the root-soil model alone. Furthermore, discrete fertiliser placement increases plant P uptake by up to 10 % in comparison to incorporating fertiliser. Conclusions By capturing essential plant processes we are able to accurately simulate P and C use and water and P movement during a cropping season. The powerful combination of mechanistic modelling and experimental data allows physiological processes to be quantified accurately and Plant Soil (2016) useful agricultural predictions for site specific locations to be made.

Feed the crop, not the soil! : Explaining variability in maize yield responses to nutrient applications in smallholder farms of western Kenya

“…A uniform value of P recovery for this labile pool is then assumed by most P uptake models, e.g. Wolf et al (1987), Greenwood et al (2001), and Heppell et al (2016). Initial yield response to P application is therefore expected to be small as a consequence of the small size of the initial labile P pool in P depleted soils.…”