THE CLIMATIC AND AGROCLIMATIC CHARACTERIZATION OF THE AUTUMN
ON THE TERRITORY OF THE REPUBLIC OF MOLDOVA
From calendar point of view, the spring starts on 1st
March, but from meteorological point of view the beginning of
spring conventionally is considered along with the stable
transition of the average daily temperature through 0ºÑ towards its
increase. In the Southern part this transition takes place generally at
the end of February, on the rest of the territory – in the first
decade of March.
Depending on the particularities of the meteorological processes, in
some years the spring start date may significantly divert. Since the
beginning of observations the earliest spring was recorded on the
biggest part of the territory of the country on 10 January (1989),
and the latest on 26 March (1963).
In late March– early April mainly there takes place the
transition of the average daily temperature through 5ºÑ, between
16-23 April – through 10ºÑ (beginning of crops active grow and
development), and between 7 and 19 May the transition through 15ºC
is recorded (start of the meteorological summer).
The transition of the atmospheric circulation from the winter conditions
to the summer one leads to a strong weather variability: sudden change
of warm and cold periods, of rainy and dry one.
The average air temperature in spring
oscillates between +8ºC and +10ºC.The coldest spring was
registered in 1987, with the average air temperature of +5..+6ºC,
that is 3-4ºC lower than the norm. The warmest spring was registered in
1983 and 2007. The average air temperature during the
mentioned seasons constituted +11..+13ºC, exceeding the long term
average by 2-3ºC.
Since the beginning of observations the lowest spring temperature
was recorded on 4March 1955 – -26ºC (Bravicea),
and the highest constituted +37ºC (Cahul, 17 May 1969
and Ştefan Vodă, 20 May 1996).
occur often in spring. In the air they continue until 5-21
April, on the soil surface – until 22-30 April.
Nevertheless, in the last years, the frosts may occur even in
May. The latest date of frost stop in the air in the Northern
and Central parts is 21-24 May(1980), and in
the Southern - 1-10 May (1990). On the soil surfacethe frosts may occur evenon 1 June (1955). The
snow layer usually completely melts between 15-27
March, and thelatest date of its melting was between
20-27 April (1997). The snow may be noticed until 27
April-20 May (1952).
unlike in winter, the heavy rains fall more often and sometimes
they are accompanies by thunderstorms. During spring there may
fall in average 105-150 mm, or circa 24% of the total
annual precipitations. The most arid was the spring of 2003. During
that season the quantity of fallen precipitations was twice lower than
the norm and constituted 30-60 mm. During the 1991 spring,
on contrary, the total fallen precipitations (200-280 mm)
exceeded twice the norm. The maximum daily quantity of
precipitations constituted 30-100 mm.
The fog (in average 6 days) and thunderstorm (in average 8
days) are frequent phenomena in spring. Thefrosts and
the strong winds are the most dangerous meteorological phenomena
in April. They are registered in average once in 3 and 5 years.
The beginning of the spring agricultural works depends on the dates of
snow melt and soil thaw.
The soil thaw up to 30 cm depth, is usually recorded between 10-17
March, the total thaw –11-20 March. The soildry upis
usually noticed on 18-28 March and it indicates the optimal dates for
the beginning of tillage before the sowing works.
The restart of the vegetation period of the autumn crops takes place
between 16-25 March.
During the early springs, the vegetation period may restart in late
February, during the late one – in the middle of April. The
productive soil humidity reserves in 1 meter depth at the beginning of
the restart of autumn crops vegetation period are generally fine
(140-160 mm), the Southern region – satisfactory (125-135 mm). Such
humidity reserves boost the autumn crops growth. During the very arid
springs, the productive humidity reserves are insufficient and
constitute 60-70 mm.
The favorable conditions for the beginning of early crops sowing (barley
and oats) appear when the average daily temperature (on the date of
sowing) constitutes +5°C and higher, the soil has a plastic and soft
texture and gets warm up to +5..+6°C.
Such conditions occur almost yearly (75% of years) in late March – early
April. During this period of time, the long term average productive
humidity reserves in the plowed soil layer in the Southern part
constitutes 25-30 mm, in the rest of the territory – 35-40 mm. In early
springs, the beginning of the spring crops sowing starts in late
February–early March, and in late springs – in the second decade of
Usually, the multiannual plantations on the territory of the country
restart their vegetation period between 23 March and 4 April
(along with the stable transition of the average temperature through
+5°C). Usually, the tree bud swelling starts in the second half of
March, the sap circulation in vineyards starts in late March. In
early springs, the beginning of bud swelling and the flowering of
apricot tree takes place between 15-28 March.
The usual period for flowering of apricot tree is between 15-23 April.
The bud swelling for plums, apples, pears is noticed in the first decade
of April. The vineyards bud swelling is noticed between 5-22 April,
when the stable average daily air temperature transits through +10°C,
towards its increase.
The sowing dates for the sugar beet are determined by the soil warming
up to +7..+8°C and disappearance of frosts that may cause damage to
During the warmest springs the sugar beet sowing is carried out usually
at the end of March – beginning of April, and in the coolest springs –
at the end of April – beginning of May. During the sugar beet sowing
period in the Northern part of the republic the humidity reserves in the
plowed layer of the soil usually constitute 30-40 mm.
The most appropriate terms for sunflower sowing are between 7-18
April (the soil warms up to +10°C). The productive humidity
reserves in the plowed layer of the soil for this period are more than
20 mm everywhere.
The most optimal datesfor maize sowing are in the third decade of April. The
productive humidity reserves in the plowed layer of the soil for this
period are usually fine and constitute 25-40 mm.
In the last pentad of April – beginning of May the sunflower rises up,
the sugar beet rise up in mass, the autumn wheat straw gets longer and
the flowering of apples and pears begins.
is characterized by the beginning of the active growth and development
of thermophilic crops. In the first decade of May, the twinning phase
spring barley starts everywhere. The mass rise of the maize plants is
recorded between 13-17 May and for the potato - on 12-22 May. The
flowering of the lilac is noticed between 5-9 May and of the white
acacia around 30 May.
According to the long term data the crops seedlings are planted in
opened soil in the first half of May.
The mass autumn wheat spike forms in the period 24 May-2 June.The productive humidity reserves in the1 meter depth soil on
the fields with autumn wheat during the spike formation stage
constitutes, basically, 85-115 mm, in some South and Central
regions – 65-75 mm.
The risk climatic phenomena that represent a threat for crops in May are
droughts and hot dry winds.
The unfavorable spring conditions have a negative impact especially on
autumn crops, they partially reduce the weeding crops and trees yield.
In May the hot dry winds are recorded in average in 3-7 days. The spring
drought is recorded in April – May. Its frequency is 15% of year.
Also a big threat for crops in spring represents the frosts that may
occur in May. They are recorded in average once in 10 years
and lead to damaging and even dying of flower buttons, flowers, trees,
buds, grapes and walnuts inflorescences, maize, beans, potatoes, peas,
tobacco, vegetables and other thermophilic plants.