RESPONSE OF RAIN-FED BREAD AND DURUM-WHEAT TO SOURCE, LEVEL AND TIMING OF NITROGEN-FERTILIZER ON 2 ETHIOPIAN VERTISOLS .2. N UPTAKE, RECOVERY AND EFFICIENCY
T. Geleto et al., RESPONSE OF RAIN-FED BREAD AND DURUM-WHEAT TO SOURCE, LEVEL AND TIMING OF NITROGEN-FERTILIZER ON 2 ETHIOPIAN VERTISOLS .2. N UPTAKE, RECOVERY AND EFFICIENCY, Fertilizer research, 44(3), 1996, pp. 195-204
In trials conducted at 2 highland Vertisol sites in Ethiopia in 1990 a
nd 1991, 2 locally popular wheat cultivars, 1 spring bread wheat (Trit
icum aestivum L.) and 1 durum wheat (T. durum Desf.), were supplied wi
th nitrogen (N) fertilizer at 0, 60 and 120 kg N ha(-1) in the form of
large granular urea (LGU), standard urea prills or ammonium sulfate.
N was applied all at sowing, all at mid-tillering of split-applied bet
ween these two stages (1/3:2/3). While durum wheat exhibited the highe
st N concentration in grain and straw, bread wheat, because of its hig
her productivity, resulted in a greater grain and total N uptake. In g
eneral, split application of N and use of LGU as N source enhanced gra
in and total N uptake, apparent N recovery and agronomic efficiency of
N, particularly under severe water-logging stress. Where significant,
the interactions among the experimental factors substantiated the sup
erior responsiveness of the bread wheat cultivar to fertilizer N, and
the beneficial effects of split N application and LGU as an N source.
Split application of N tended to nullify the positive effects of LGU,
presumably by approximating the delayed release of N achieved with LGU
. Considering the potential benefits to Ethiopian peasant farmers and
consumers, split application of N should be advocated, particularly on
wafer-logged Vertisols; LGU could be an advantageous N source assumin
g a cost comparable to the conventional N source urea.