Author:
GRYLLS J. P.,WEBB J.,DYER C. J.
Abstract
From 1985 to 1987, 20 experiments were carried out on shallow chalk
soils, in which soil N reserves
were expected to be small, to assess seasonal variations in the response of
winter cereals to applied
fertilizer N, and to relate these responses to measurements of soil mineral
N (SMN), temperature and soil moisture deficits (SMD).Soil mineral N measured in autumn varied from 21 kg/ha (1986) to
73 kg/ha (1985), while SMN
in spring ranged from 19 kg/ha (1987) to 91 kg/ha (1985), these values
were typical of soils in long-term arable rotations. Estimates of apparent net
N mineralization (AM) during the growing season
were small at c. 26 kg/ha and suggested large seasonal variation.
The small AM is considered to be
due to the shallow topsoil drying out during the growing season. Whole crop
N offtake without
fertilizer N was only c. 40kg/ha. Crop N offtake, grain yield
without fertilizer N and AFR (apparent
recovery of fertilizer N) could not be reliably predicted by regression
on SMN in autumn, SMN in
spring or AM. Little or none of the variation in crop yield could be
accounted for by regression on
accumulated temperature over winter, maximum SMD in April to July or
mean temperature in April to July.Despite optimum grain yields being only moderate at 6·59 t/ha for
winter wheat and 6·78 t/ha for
winter barley, response to applied fertilizer N was large, between
3·77 and 5·38 t/ha. In consequence
the requirement for fertilizer N (c. 240–250 kg/ha) was also
large, but differed little between seasons.
This large requirement is concluded to be a result of limited fertilizer
recovery and mineralization of soil N during the growing season.
Publisher
Cambridge University Press (CUP)
Subject
Genetics,Agronomy and Crop Science,Animal Science and Zoology
Cited by
8 articles.
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