Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
11030414 | Agricultural Water Management | 2019 | 7 Pages |
Abstract
A key determinant of water-limited yield potential in dryland agriculture is the soil's plant available water capacity (PAWC), the difference between drained upper limit and crop lower limit over the rooting depth. To simulate water-limited yield potential (Yw), a crop model must be parameterised for the local edaphic conditions, which require a quantitative description of drained upper limit, crop lower limit and rooting depth. Often, these soil properties have to be estimated from existing soil surveys, which creates uncertainty for drained upper limit, crop lower limit or rooting depth. The impact of uncertainty in these soil properties on the estimation of Yw has not previously been reported. Using the Agricultural Production Systems sIMulator (APSIM), a sensitivity analysis was performed to identify the effect of uncertainties in drained upper limit, crop lower limit and rooting depth on wheat Yw for two contrasting rainfall sites (high and low) with two typical soil types (shallow sandy duplex and clay) in Western Australia. Simulation results demonstrated that the resultant change in PAWC was the dominant driver of a change in the estimate of Yw, irrespective of whether such a change was caused by drained upper limit, crop lower limit or rooting depth. Estimated errors that underestimated or overestimated PAWC by up to 20âmm only had a marginal impact on Yw (less than 200âkgâhaâ1) in all environments (soil typeâÃâlocation). But when this error was more than 20âmm, an underestimation would cause more severe deviation of Yw of wheat than an overestimation. On average, 40âmm underestimation of PAWC resulted into 530âkgâhaâ1 of Yw, while this amount of overestimation caused overestimation of Yw about 290âkgâhaâ1. The bias of underestimated wheat Yw due to underestimation of PAWC was generally increased with rainfall up to 350âmm. We conclude that it is better to estimate soil hydrological parameters towards overestimating PAWC than to underestimate PAWC. However, where possible, all three soil hydrological parameters should be estimated as accurately as possible.
Related Topics
Life Sciences
Agricultural and Biological Sciences
Agronomy and Crop Science
Authors
Renye Wu, Roger Lawes, Yvette Oliver, Andrew Fletcher, Chao Chen,