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mended have often given poor results in the
demonstrations.
Morocco and Tunisia are the first largescale
development projects with the Mexican
varieties under dryland conditions. Less of
the accumulate experience with these varieties
under irrigation is directly transferable here
from elsewhere. Yet the increased yielding
ability of these varieties on dryland even under
very low rainfall conditions is relatively
as great as that of the same varieties under
irrigation.
Stand density is a major problem adversely
affecting the dwarf varieties. Many farmers
seed by hand and cover with a disc harrow,
and resulting thin stands permit increased
weed competition and decrease fertilizer efficiency.
The Mexican varieties in the cooler
northern regions have not tillered as well as
elsewhere. The reasons are not c.ompletely
understood; possibly inadequate nitrogen nutrition
or loss of applied preplant nitrogen, and
in some cases long periods of saturated soil
conditions.
A date of planting study was initiated during
1969-70 to attempt to verify the observation
that the Mexican varieties profit from a later
planting date than that recommended for the
local varieties. Fertilizer response has been
irregular, especially in the higher moisture
areas, and calculated coefficients of nitrogen
utilization have been low. Phosphate response
has not been as evident on farmer's fields as
in experiment station trials.
Fertilizer Research
As the amount of field information on fertilizer
requirements of the Mex'ican varieties
in Moroc~o is very limited and the number of
climatic, soil and management factors influencing
response are large, the soil fertility program
used only two basic trials during 1969-70
and distributed them over as wide a geographic
area as feasible. One was a nitrogen use
study consisting of all combinations of three
preplant rates (40, 60 and 80 kg/hal and three
topdressing rates (0, 20 and 40 kg/hal. The
second trial consisted of different rates of several
phosphorus-potassium formulations.
The treatments in the nitrogen trial were se- ­
lected to obtain information on several points:
(1) the effect of different rates of nitrogen applied
at planting on tillering; (2) the response
to topdressing on different preplant rates, and
(3) the effect of different ways of splitting the
higher doses. Local nitrogen fertilization practices
stress the importance of topdressing as
a means to limit early growth of tall, easily
lodged local varieties, and develop large heads,
especially on the durum varieties. The important
consideration for dwarf varieties, however,
is that conditions during the early stage of
growth are adequate for tillering, which in
turn is necessary to obtain high yields. Fields
of these varieties fertilized with 20 kg/ha of
nitrogen at planting and topdressed with 20
to 40 kg/ha have tillered poorly. This suggests
the need to develop new recommendations
adjusted to the specific needs of the dwarf
varieties. Higher rates of early nitrogen applications
appear to be indicated.
The phosphate-potassium trials consisted of
45 to 90 kg/ha of K 2 0, combined with 0, 45
and 90 kg/ha of P 2 0 5 plus several heavy rates
of P 2 01\. Combinations were chosen to take
advantage of phosphorus-potassium formulations
available locally. Phosphorus is widely
recognized by both farmers and technicians
as benefitting Moroccan soils; its use in most
areas is more common than that of nitrogen.
The need for potassium fertilization has not
been clearly established by results obtained in
field trials. It has been suggested that both,
previous crop and yield level, may influence
the need for these two elements.
The experimental results obtained this year
showed no significant response to either phosphorus
or potassium. The failure to observe
a response to phosphorus fertilization was
possibly due to the fact that the trials were
generally conducted on large farms that had
been fertilized with phosphorus for many years.
Phosphate fixation by these soils is presently
being investigated by the national research
service. Their results indicate that
very heavy rates of P 2 0 5 are necessary for
obtaining maximum yields of crops other than
cereals. The effect of phosphorus fertilization
on the entire rotation rather than on a single
crop is being studied. Results obtained in
this work should eventually permit the use of
information on previous cropping history to
arrive at a more precise phosphate recommendation.
Rainfall distribution played an important
role in determining yield response to nitrogen
at a number of locations (Table W22). The
general precipitation pattern for the country
was a very rainy early winter season followed
by a dry spring. Locations in the normally
wetter parts of the country suffered from an
excess of moisture early in the season. The
trial at Toulal (Meknes) received 290 mm during
the 30 days immediately following planting
resulting in satured soil conditions for a period
of at least a month. Under these conditions, the
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