Quantifying the effect of uncertainty in soil moisture characteristics on plant growth using a crop simulation model

For a given site, most readily available soil information is descriptive, qualitative and classifies soils according to origin, texture, colour and chemistry. Precise prediction of plant responses to lack of water or nutrients requires a quantitative description of moisture holding and release characteristics of soil that are often estimated from these descriptions rather than measured. In this paper we analyse the effect of uncertainty in soil description on the precision of simulated crop growth and development. This analysis suggests that accurate yield estimates depend on site-specific measurements. We demonstrate the significance of this imprecision by calculating the expected range of grain yields from a range of soils representing arable land in the UK using UK weathers and a realistic range of crop N-managements. A maximum grain yield range of 7 t/ha was found, representing a significant level of uncertainty. We conclude that since simulated yield can be so sensitive to the description of soil hydraulic properties, quantitative soil moisture characteristic measurements should be made in order to analyse plant growth in response to its environment.