Climate and Cropping Systems
Thomas G Chastain
CROP 200 Crop Ecology and Morphology
Climate and Cropping Systems
• Successful cropping systems are adapted
to the local climate and soil conditions.
• The distribution of land on earth suitable
for agriculture is determined by climate
soil, and topography.
• There are 3.5 billion acres of potential
cropland on earth:
1. >20 inches/year 1.65 billion acres
(47%) – most of this is in the Amazon
Basin.
2. <20 inches/year 1.5 billion acres
(43%) - this farmland includes most of
the earth’s developed cropland.
3. Irrigated cropland 350 million acres
(10%).
Climate and Cropping Systems
• Climatic Factors and Cropping Systems:
1. Water (Precipitation) – water
determines the type of cropping
system that can be employed. Also, in
a dry climate, the variability in annual
rainfall is greater than in a wet
climate.
2. Temperature. Together with water,
these factors most limit the
productivity of the cropping system.
3. Solar Radiation – not a limiting
factor in most cropping systems except
in multiple cropping systems.
4. Wind
5. Humidity
Climate and Cropping Systems
• Much of the land mass of
the Eastern US is wetter
than the Western US.
• There are individual areas
within the west that are arid
or semi-arid whereas a few
areas have a wet climate.
US Average Annual Precipitation
Map Source – Oregon Climate Service
US Wheat acreage
US Soybean acreage
Climate and Cropping Systems
• Crops are grown in the climate
where they are best adapted and
economically competitive.
• While wheat is grown throughout
the US, the greatest acreage is
concentrated in the driest part of
the Great Plains states and the
Western US.
• Soybeans are mostly grown in the
Midwest and the Mississippi Valley,
but not in the Western US. Low
night temperatures and lack of
summer rainfall restrict the
production of soybeans in the
Western US.
Climate and Cropping Systems
Corvallis Oregon Climate
Wet and Cool
Winter
Warm and Dry
Summer
TG Chastain, Oregon State University
Climate favors winter annuals and cool-season perennials, crops that
actively grow over winter and can be harvested early in summer. Rainfall
subsides as crops mature in early summer facilitating harvest.
A
Climate and Seed Production
Oregon Average Annual Precipitation
C
A
B
B
C
A - Annual ryegrass production in Willamette Valley
B - Roughstalk bluegrass with aid of surface irrigation in central Oregon
C- Kentucky bluegrass under center pivot in Grande Ronde Valley
TG Chastain photos
Climate
Classification
Köppen-Geiger climate
classification system
(Peel et al.,2007)
A – Tropical
B – Arid
C – Temperate
D – Cold
E - Polar
Climate Classification
A. Tropical – can be found within 20⁰ latitude
of the equator. Characterized by high
temperatures with all monthly averages
greater than 64⁰F. Near constant
temperatures and photoperiods year around.
• Rainforest (Af) high rainfall – more than 35
inches per year, and has a year-round
distribution.
• Monsoon (Am) has dry season alternating
with wet season.
• Savannah (Aw) drier than Af and also with
a dry season, tree-studded grasslands.
• Subsistence farming, intercropping, and
plantation agriculture are generally
practiced in these climates. Common
crops include sugar cane, banana, coffee,
cacao bean.
Pineapple (TG Chastain photo)
Climate Classification
B. Arid – dry climates found over a wide
range of latitudes.
• Hot desert (BWh) tropical and
subtropical regions. High
temperatures and very dry. Phoenix
Arizona is an example with 7.9 inches
rainfall per year. Many crops can be
grown in this climate when irrigated.
Salinity problems may limit long-term
productivity.
• Cold desert (BWk) temperate regions.
Cold winters, warm summers and very
dry. Yakima Washington is an example
with 7 inches precipitation per year.
Many crops can be grown if irrigated.
West Texas desert (TG Chastain photo)
Climate Classification
B. Arid –
• Cold Steppe (BSk) semiarid climate in
the temperate latitudes that has warm
summers and cold winters. Palouse
region of eastern Washington and north
Idaho, and Columbia Plateau of Oregon.
Also found in the plains of eastern
Montana, Wyoming, and Colorado.
• Hot Steppe (BSh) grasslands of Arizona
and south-central Texas.
• Grasslands dominate these regions in
the natural state, but when developed
for agriculture, cereals such as wheat
and barley are the dominant crops.
Both rainfed and irrigated agriculture is
practiced in region’s with this climate
type.
Climate Classification
C. Temperate – Found at higher latitudes
than 20°
• Mediterranean Hot Summer (Csa) a
climate with hot dry summers with
mild wet winters. Annual precipitation
ranges from 15 to 25 inches per year.
• Found in the southern Mediterranean
region, California, and Australia. Many
crops can be grown if irrigated, but
also some dryland agriculture is
practiced.
• Mediterranean Warm Summer (Csb) –
a temperate climate with warm dry
summers and mild to cool wet winters.
Found in the northern Mediterranean
region, western Oregon and western
Washington.
Wheat field in Tasmania,
Australia (TG Chastain photo)
Climate Classification
C. Temperate –
• Humid Subtropical (Cfa) rain in all
seasons with hot wet summers and
mild moist winters. Baton Rouge
Louisiana is an example with 58
inches rainfall per year. Crops such
as rice and cotton are common.
• Maritime Temperate (Oceanic) (Cfb)
precipitation in all seasons, but with
cool summers and mild winters.
Coastal locations on windward side
of continents – coastal Washington
and British Columbia.
Climate Classification
D. Cold – Found at latitudes above 35⁰ average
temperature of the coldest month is less than
32⁰F
• Hot Summer Continental (Dfa) rain in all
seasons with hot wet summers and cold moist
winters. Characteristic of the US corn belt in
the midwest. Ames Iowa has 31 inches of
precipitation.
• Warm Summer Continental (Dfb) warm
summers with rainfall and cold winters with
snowfall. Found in the Great lakes states, New
England, and the Canadian Prairie Provinces.
• Boreal (Dfc) cold summers with precipitation in
all seasons and very cold winters at high
latitudes. Some cereals, and grass and legume
seed production in the southern parts of this
climate type.
Climate Classification
E. Polar – cold summers with low
precipitation, and very cold and dry
winters. Not conducive to
profitable agriculture.
• Tundra (ET)
• Icecap (EF)
Climate Change: The Evidence
• The mean temperature
anomaly (or deviation) from
a periodic mean has
apparently increased with
the industrialization of
human society.
• This increase is correlated
with an increase in CO2
concentration and other
“greenhouse gases” in the
atmosphere.
Temperature Data Source – NASA GISS
Climate Change – A Local Perspective
Corvallis - Industrial Revolution to Present
• Incremental increases in
temperature in the region has
Warm
been observed over the last 120
years of record-keeping.
• Periodic warm and cool periods
are found in the temperature
record. This cycle seems to be
related to temperatures in the
Pacific Ocean.
• These warm and cool periods have
impacts on crop production such
as extending or contracting the
Cool
frost-free growing season.
Climate Change – A Local Perspective
• Temperatures in Oregon
have varied between
warm and cool periods
and apparently follow the
phases of the Pacific
Decadal Oscillation (PDO),
an index of sea surface
temperatures in the
Pacific Ocean.
Climate Change – A Local Perspective
• Increased variability in annual
Corvallis - Industrial Revolution to Present
precipitation and its seasonal
distribution has been a matter of
Wet
concern.
• Average annual precipitation has
increased by 81 mm over the last
120 years but most of that
increase has been distributed in
spring where higher rainfall can
interfere with pollination of
winter crops and planting of
spring crops.
• Early autumn rainfalls have been
Dry
on the decline; these are
important for regrowth of
perennials.
Climate Change – A Long-term Perspective
A. Industrial Revolution to Present
B. Last 1000 years to Present
Medieval Warm
Period
Post-industrial
Warming
Little Ice Age
Climate Change – A Long-term Perspective
C. Last 10000 years to Present
D. Last 50000 years to Present
Interglacial
Post-industrial
Warming
Crop Domestication
Ice Age
Climate Change – The Urban Heat
Island
• Urbanization and industrialization
have contributed to increases in
temperature. Temperatures
recorded at airports and city
centers have seen the greatest
change in temperature.
Graph source NASA GISS
Climate Change – Rural Locales
• Recording stations in rural areas
dominated by farms and forests
have seen much less in the way of
warming and in some cases no
change or even reductions in
temperature.
Graph source NASA GISS
Climate Change – Potential Impacts
• Plant growth, yield, and water-use efficiency
have increased and will continue to do so as
CO2 levels rise.
• The effects of increasing CO2 and possible
climate change on pests (weeds, pathogens,
insects and other arthropods) are largely
unknown.
• Some general circulation models predict that
weather variability will increase, introducing
yet more uncertainty and risk into agricultural
production. Droughts, floods, storms, and
periods of excessive heat or cold may occur
more frequently, with impacts on agricultural
operations, alterations in agricultural water
supplies, and increased crop insurance costs
and disaster payments.
Source USDA