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Estimating losses in the yield of winter wheat as a result of drought, in England and Wales
Author(s) -
Weir A.H.
Publication year - 1988
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/j.1475-2743.1988.tb00733.x
Subject(s) - winter wheat , crop , yield (engineering) , environmental science , soil water , water content , agronomy , transpiration , irrigation , crop yield , distribution (mathematics) , mathematics , hydrology (agriculture) , soil science , biology , geology , mathematical analysis , materials science , geotechnical engineering , photosynthesis , botany , metallurgy
. A simple model for droughtiness, when linked to the distribution of soil types in England and Wales, is potentially valuable for estimating drought‐induced losses of yield in winter wheat at either particular places or in larger areas of the country. The model defines droughtiness, D , in terms of the soil water extractable by the crop, AP , and the adjusted potential moisture deficit, MD : D = AP − MD . The model should represent well the growth of actual crops of winter wheat if AP , which is based on laboratory measurements, accurately simulates the extraction of soil water by roots, if MD represents the cumulative transpiration of water by wheat crops by mid‐July, and if the latter is an appropriate date for testing the effect of drought on grain growth. These three assumptions have been investigated using measurements of artificially draughted crops of winter wheat. The results indicate that mid‐July is a good choice for a single date and MD a good representation of the water requirement of a wheat crop that has been draughted to the point where yield is beginning to be affected. For the deep‐rooting crops studied, AP underestimates the soil water extracted by the crop, and therefore overestimates the susceptibility of the soil to drought If average MD values are replaced by means and a standard deviation the resulting normal distribution of D ‐values can be used to assess the probability that drought will limit yields. When applied to a droughtiness map of England and Wales with AP ‐values used for the soils the model predicts that the soils growing wheat will be susceptible to drought in 16–84 years out of every 100. Our results suggest, however, that this probably applies to shallow rooting or diseased crops and that for deep‐rooting, healthy crops the drought risk is much less serious.