crop development

[robert pufall]

CROP DEVELOPMENT
Variation of Microbial Communities in Soil, Rhizosphere, and
Rhizoplane in Response to Crop Species, Soil Type, and Crop
Development
Gabriele Wieland, Regine Neumann, and Horst Backhaus*
Federal Biological Research Centre for Agriculture and Forestry,
Institute for Plant Virology, Microbiology and Biosafety, 38104
Braunschweig, Germany
Received 23 May 2001/Accepted 20 September 2001
We investigated the influence of plant species, soil type, and plant
development time on the shaping of microbial communities in soil and
in association with roots. The sample group consisted of a total of 32
microcosms in three habitats: soil, rhizosphere, and rhizoplane.
Communities were represented by the patterns of a sequence-specific
separation of rRNA target sequences. Effects of experimental
parameters were classified by a cluster analysis of pattern
similarities. The type of plant species (clover, bean, or alfalfa) had
the greatest effect in plant-associated habitats and also affected
soil patterns. Plant development had a minor habitat-dependent effect
that was partly obscured by replicate variation. The results stress
the applicability of biased community representations in an analysis
of induced variation.

EPA Recalculates Land Use Changes, Gives Corn Ethanol Thumbs Up
U.S. Biofuels Struggling to Meet 2022 Goal by SolveClimate Staff - Feb
3rd, 2010
in
Cap on Emissions
American Clean Energy and Security Act
Biofuel
Collin Peterson
corn ethanol
EPA
Ethanol
Farmers
Lisa Jackson
Vilsack
Farm state lawmakers and agribusiness have been hammering the EPA
since it announced a plan last year for evaluating biofuels by their
lifecycle emissions — including indirect land use changes.
It appeared then that corn-based ethanol wouldn’t make the cut. The
proposed rules, based on the 2007 Energy Independence and Security
Act, required renewable fuels’ lifecycle emissions to be at least 20
percent less than gasoline's. An early EPA review calculated that,
with greenhouse gases from indirect land-use changes included, most
corn ethanol wasn't much better than regular gas.
The EPA has now finalized the renewable fuel standard, and agency
Administrator Lisa Jackson announced today that corn ethanol will
qualify after all.
“EPA has found that it is indeed 20 percent less greenhouse gas
emitting than gasoline,” Jackson said. “Based on what we know now,
including indirect land use analysis, there is no basis to exclude
these fuels.”
What changed in less than a year?
Jackson told reporters that the agency wasn't trying to appease any
industries, and she rejected the suggestion that the EPA had changed
the science to meet an outcome.
U.S. crop productivity, the amount produced per acre, is at record
levels, and “the numbers used in the proposal were not right,” she
said. With updated numbers, the agency came up with different
results.
The EPA also recalculated its estimates of emissions from indirect
land-use changes, known to be a large contributor to emissions but
difficult to track. An example of indirect land-use changes, or ILUC,
would be the greenhouse gases emitted from the razing of forests to
grow food in Brazil because land that could have produced food in the
United States was shifted to fuel crops instead. The EPA’s initial
assessment took land use in 40 countries into account; the new
calculations were based on 160 countries, Jackson said.
"This is, at its root, an effort to reduce greenhouse gas emissions,"
she said. That effort is expected to cut oil imports by $41.5 billion
and reduce emissions the equivalent of taking 27 million vehicles off
the road.
The White House is “sending a very positive, very specific, very
direct message that the Obama-Biden administration is highly
supportive of the biofuels industry,” Agriculture Secretary Tom
Vilsack told reporters.
That message came in three measures announced by President Obama
during a meeting today with governors at the White House. First was
the EPA’s finalization of the renewable fuel standard, designed to
provide guidance in meeting a congressionally mandated goal of 36
billion gallons of biofuel a year by 2022. The second was guidance
from the Agriculture Department on rules for funding under the Biomass
Crop Assistance Program to help meet that target. And the third was
the release of a report by a government panel led by Vilsack, Jackson
and Energy Secretary Steven Chu describing a national strategy for
advancing biofuel development and commercialization.
The president also announced that he was creating another interagency
task force to develop a strategy for developing carbon capture and
storage for emissions from coal, with a goal of having five to 10
demonstration projects in operation by 2016. Chu said the target was
commercial deployment in 10 years.
“We’re intent on showing that science and technology can drive down
the cost to where it’s becoming an affordable solution,” the energy
secretary said.
Behind on the Biofuels Targets
The DOE determined last year that the United States was unlikely to
make its 2022 target for biofuel production. So far, only about 12
billion gallons of biofuels are being produced annually.
Production of cellulosic ethanol, such as from wood chips and plant
waste, was supposed to hit 100 million gallons by 2010 but is only
about 6.5 million gallons now. Advanced biofuels such as algae are in
their infancy. Instead, the bulk of today's biofuel is corn ethanol.
Existing corn ethanol production was grandfathered in under the 2007
energy law, which calls for 15 billion gallons of corn ethanol by
2022, but new operations faced the barrier of meeting the 20 percent
rule under the EPA initial land-use change estimates. The new EPA
assessment changes the landscape.
Jackson stressed, however, that those new biofuel operations will
still have to meet the lifecycle emissions limits. The percentages are
even higher for advanced biofuels, at 50 percent less, and 60 percent
less for cellulosic biofuels.
“To get to that level, you have to be smart. You have to be energy
efficient,” Jackson said. “And that is where we see the industry
going."
The executive director of the Iowa Renewable Fuels Association, Monte
Shaw, echoed that vision of the industry's future in a speech last
week.
"I believe better science will clear up the current indirect land use
debate," Shaw said. "Plant technology will continue to improve
production efficiencies. Seed technology and better agronomic
practices will continue to boost commodity yields at an increasing
rate. In short, it won’t be long until corn ethanol achieves the
scientific benchmarks of an advanced biofuel."
The government panel’s report suggests several strategies for
increasing biofuel use in environmentally sound ways, including
replacing higher-risk, less productive crops or abandoned lands with
lower-risk and more productive cellulosic biofuel feedstock, and
implementing better management strategies to get greater production
from the same amount of land.
The panel calls for more support of research and development — the
president’s 2011 budget proposal includes five Regional Feedstock
Research Centers — and greater government use of biofuels to create
reliable markets, particularly in the Midwest. However, the panel also
warned:
“As more farms and forests are utilized for biofuels production,
careful consideration of feedstock production practices and location
of biomass conversion plants will be required to avoid serious impacts
on existing food, feed, and fiber markets and the quality of natural
resources upon which we all depend on for clean air and water."
That the EPA didn’t bow to pressure to remove land-use change
calculations entirely drew praise from Sierra Club Executive Director
Carl Pope and the Union of Concerned Scientists.
“Despite intense pressure from the corn ethanol industry to exclude
emissions from indirect-land-use change, the EPA found that such
emissions are a major source of heat-trapping pollution from corn
ethanol and other food-based biofuels,” the UCS wrote. “This finding
affirms the view of 200 scientists and economists with relevant
expertise who sent a letter to the EPA in September 2009 arguing that
‘grappling with the technical uncertainty and developing a regulation
based on the best available science is preferable to ignoring a major
source of emissions’.”
Hostile Environment
The EPA still faces hostility in Washington, where Rep. Collin
Peterson (D-Minn.) made clear this week that industrial agriculture
wants absolutely no regulation of their greenhouse gas emissions.
Peterson and fellow Democrat Ike Skelton of Missouri joined the
introduction of legislation that would prevent the EPA from regulating
greenhouse gas emissions under the Clean Air Act, especially when it
comes to biofuels.
“Americans know we’re way too dependent on foreign oil and fossil
fuels in this country — and I’ve worked hard to develop practical
solutions to that problem — but Congress should be making these types
of decisions, not unelected bureaucrats at the EPA,” Peterson said.
Those “unelected bureaucrats” are tasked with considering the good of
the entire country, though. Unlike members of Congress, they aren’t
angling for one region’s interests and they aren’t lavished with
campaign contributions and advertising support that now promises to
balloon under the Supreme Court’s recent ruling in Citizens United v.
FEC.
Peterson’s top campaign contributors? Donors connected with the crop
production and basic processing industry have given him close to
$700,000 over his career, and those connected with agricultural
services and products have contributed about $392,000, according to
data compiled by the Center for Responsive Politics. In this election
cycle, Peterson is the No. 3 recipient of agribusiness money in
Congress, receiving $185,500 so far. No. 1, Sen. Blanche Lincoln (D-
Ark.), is also co-sponsoring legislation to block the EPA.
Clean fuel standards are also facing challenges in the courts.
California, which has been leading the way on renewable fuel standards
and lifecycle emissions calculations, was hit by another lawsuit this
week over its low-carbon fuel standard.
The state’s LCFS requires fuel providers to reduce the average carbon
intensity of their fuels 10 percent by 2020, and takes into account
land use changes. The National Petrochemical and Refiners Association
and American Trucking Associations filed a complaint claiming that the
rules violate commerce law and discriminate against Canadian oil and
Midwestern corn ethanol.

Statement from Agriculture Secretary Tom Vilsack on the Proposed
FY2011 Budget
VIDEO Link
WASHINGTON, Feb. 1, 2010 – Below is a statement from Agriculture
Secretary Tom Vilsack on the proposed FY2011 budget:
"I don't need to tell the American people that in 2009, America
struggled through the most serious economic recession since the Great
Depression. Families were forced to make difficult decisions. And more
and more Americans had to rely on USDA to help put food on the table.
"The challenges facing rural communities for decades have grown more
acute, which is why the Obama Administration is committed to new
approaches to strengthen rural America. Rural Americans earn less than
their urban counterparts, and are more likely to live in poverty. More
rural Americans are over the age of 65, they have completed fewer
years of school, and more than half of America's rural counties are
losing population.
"This year, President Obama took steps to bring us back from the brink
of a depression and grow the economy again. But with the unsustainable
debt accumulated over the past decade, it's time to get our fiscal
house in order.
"Our proposed FY 2011 budget is a reflection of that reality,
essentially freezing funding for discretionary programs at the FY 2010
level. However, limits we placed on select programs and efforts to
eliminate earmarks and one-time funding actually result in a bottom
line reduction to our discretionary budget authority of over $1
billion.
"This budget uses taxpayer dollars wisely, taking common-sense steps
that many families and small businesses have been forced to take with
their own budgets. We are investing in American agriculture and the
American people without leaving them a mountain of debt.
"We care deeply about farmers and ranchers and have worked hard to
maintain the agricultural safety net, while instituting some targeted
reductions in farm program payments. Just as importantly, this budget
pursues priorities that will have the greatest impact in our efforts
to address the challenges facing rural America and lay a new
foundation for growth and prosperity.
"This budget will assist rural communities create prosperity so they
are self-sustaining, economically thriving, and growing in population.
We have already taken important steps in this effort. With help from
the Recovery Act, we supported farmers and ranchers and helped rural
businesses create jobs. We made investments in broadband, renewable
energy, hospitals, water and waste water systems, and other critical
infrastructure that will serve as a lasting foundation to ensure the
long-term economic health of families in Rural America. This budget
includes almost $26 billion to build on that down payment and focuses
on new opportunities presented by producing renewable energy,
developing local and regional food systems, capitalizing on
environmental markets and generating green jobs through recreation and
natural resource restoration, conservation, and management.
"We will promote the production of food, feed, fiber, and fuel, as
well as increased exports of food and agricultural products, as we
work to strengthen the agricultural economy for farmers and ranchers.
America's farmers and ranchers are the most productive and efficient
in the world, and this budget maintains the policies that help
maintain our nation's food security. This budget increases our funding
for export promotion as part of President Obama's National Export
Initiative and provides more support than ever before for competitive
research, which can lead to gains in agricultural productivity.
"We will ensure that all of America's children have access to safe,
nutritious, and balanced meals. The budget fully funds the expected
requirements for the Department's three major nutrition assistance
programs – WIC, the National School Lunch Program, and SNAP – and
proposes $10 billion over 10 years to strengthen the Child Nutrition
and WIC programs. It also invests over $1 billion for efforts to
reduce foodborne illnesses from USDA-inspected food products.
"We will ensure our national forests and private working lands are
conserved, restored, and made more resilient to climate change, while
enhancing our water resources. This budget will enroll more than 300
million acres into Farm Bill conservation programs, an increase of 10%
over 2010. It will support our efforts to strategically target high
priority watersheds. And it focuses efforts on forest restoration and
hazardous fuels reduction in the wildland-urban interface, where they
will offer job-creation opportunities and reduce the chance of
catastrophic wildfires.
"There is no doubt that these tough times call for shared sacrifice.
The American people have tightened their belts and we have done so as
well. We made tough decisions, but this budget reflects our values,
and common sense solutions to the problems we face. It makes critical
investments in the American people and in the agricultural economy to
set us on a path to prosperity as we move forward in the 21st
century."
#
USDA is an equal opportunity provider, employer and lender. To file a
complaint of discrimination, write: USDA, Director, Office of Civil
Rights, 1400 Independence Avenue, SW, Washington, DC 20250-9410 or
call (800) 795-3272(voice), or (202) 720-6382 (TDD).

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract
Publication Acceptance Date: May 30, 2008
Publication Date: October 5, 2008
Citation: Rice, W.C., O'Shaughnessy, S.A., Evett, S.R. 2008. Influence
of cotton crop development and level of irrigation of microbial
community structure [abstract]. 2008 Joint Meeting of American Society
of Agronomy, Soil Science Society of America, and Crop Science Society
of America, October 5-9, 2008, Houston, Texas. Paper No. 745-15. 2008
CDROM.
Technical Abstract: Soil microbial population densities can easily
reach one billion cells per gram of soil;and soil microbial diversity
has been shown to exceed fifty thousand individual species per gram of
soil. Soil type and underlying soil structure are considered primary
determinants of microbial community structure in soils. Disturbance of
soil due to agricultural practices (tillage) has been shown to reduce
or alter microbial diversity while long term agricultural production
also can influence microbial diversity. The objective of this study
was to evaluate the effects of cotton crop development and four levels
of irrigation (0, 33, 67 and 100% of well-irrigated crop water demand)
on microbial community structured during the course of the growing
season. We use denaturing gradient gel electrophoresis-polymerase
chain reaction (DGGE-PCR) assay employing universal PCR primers that
target prokaryotic (16S) and eukaryotic (18S) ribosomal genes and
other non16S DNA primer sets to evaluate microbial diversity.
Community DNA samples were obtained from four sampling dates beginning
at planting and ending prior to harvest. Both cotton crop development
and the level of irrigation influenced general microbial community
structure. Microbial diversity tended to increase over time and was
positively influenced by the level of irrigation.

GMO

The abbreviation for genetically modified organism. A GMO is an
organism whose genome has been altered by the techniques of genetic
engineering so that its DNA contains one or more genes not normally
found there.

Crop Water Use and Growth Stages
by M.M. Al-Kaisi and I. Broner1 (2/09)
Quick Facts...
Water stress during critical growth periods reduces yield and quality
of Crops.
Crop water use (ET) at critical growth stages can be used in
irrigation scheduling to avoid stressing Crops.
Crop water use (ET) is weather dependent as well as soil, water and
plant dependent.
Periodically check soil water at different depths within the root zone
and at different growth stages to avoid stressing the crop during
critical growth stages.
Crop water use, also known as evapotranspiration (ET), is the water
used by a crop for growth and cooling purposes. This water is
extracted from the soil root zone by the root system, which represents
transpiration and is no longer available as stored water in the soil.
Consequently, the term "ET" is used interchangeably with crop water
use. All these terms refer to the same process, ET, in which the plant
extracts water from the soil for tissue building and cooling purposes,
as well as soil evaporation.
The evapotranspiration process is composed of two separate processes:
transpiration (T) and evaporation (E). Transpiration is the water
transpired or "lost" to the atmosphere from small openings on the leaf
surfaces, called stomata. Evaporation is the water evaporated or
"lost" from the wet soil and plant surface.
Significant evaporation can take place only when the soil's top layer
(1 to 2 inches) or when the plant canopy is wet. Once the soil surface
is dried out, evaporation decreases sharply. Thus significant
evaporation occurs after rain or irrigation. Furthermore, as the
growing season progresses and canopy cover increases, evaporation from
the wet soil surface gradually decreases. When the crop reaches full
cover, approximately 95 percent of the ET is due to transpiration and
evaporation from the crop canopy where most of the solar radiation is
intercepted.
Crop water use (ET) is influenced by prevailing weather conditions,
available water in the soil, crop species and growth stage. At full
cover, a crop will have the maximum ET rate (reference ET) if soil
water is not limited; namely, if the soil root zone is at field
capacity. Full cover is a growth stage at which most of the soil is
shaded by the crop canopy.
In a more technical term, the crop is at full cover when the leaf area
is three times the soil surface area under the canopy. At this growth
stage, the crop canopy intercepts most of the incoming solar
radiation, thereby reducing the amount of energy reaching the soil
surface.
Different crops reach full cover at different growth stages and times
after planting (See Scheduling Irrigations: A Guide for Improved
Irrigation Water Management Through Proper Timing and Amount of Water
Application, USDA, Natural Resources Conservation Service,
Agricultural Research Service and Colorado State University Extension,
1991, page 32).
In order to standardize ET measurements and calculations, a reference
crop ET (ETr) is used to estimate actual ET for other Crops. In humid
and semi-humid areas where water usually is not a limiting factor,
grass is used as a reference ET crop. In arid or semi-arid areas,
alfalfa is more suitable as a reference ET crop because it has a deep
root system, which reduces its susceptibility to water stress
resulting from dry weather.
Actual evapotranspiration (ETa) is the water use of a particular crop
at a given time. ETa of an annual crop reaches its maximum at full
cover, and can be higher or lower than ETr, depending on the crop. In
Colorado, alfalfa is used as the reference crop. Corn at full cover
has a maximum water use rate, ETa, of 93 percent of alfalfa ETr, while
sugar beets have a maximum ETa rate of 103 percent of alfalfa ETr.
Estimating Crop Water Use
Actual crop water use, ETa, can be measured directly by using several
research methods or indirectly by measuring changes in soil water
content with time. However, these methods are expensive, tedious and
can be done only in research settings. Therefore, ETr is theoretically
and empirically correlated to weather parameters to generate ET models
that estimate ETr from weather parameters.
ET equations most often used in Colorado are the Penman and Jensen-
Haise models. These models were checked and calibrated for local
conditions and give reliable estimates of ETr. The Jensen-Haise
equation uses temperature and solar radiation measurements, while the
Penman equation uses temperature, solar radiation, wind run and
humidity.
Actual evapotranspiration, ETa, can be calculated from reference ET by
multiplying ETr by the crop coefficient (KC). A crop coefficient is
the ratio between ETa of a particular crop at a certain growth stage
and ETr. If the crop coefficient is smaller than one, the crop uses
less water than reference ET and vice versa.
Crop coefficients depend on the stage of growth and usually are
presented as a function of time following planting. Crop coefficients
are measured using lysimeters for different Crops and are shown in
fact sheet 4.707, Irrigation Scheduling: The Water Balance Approach.
These coefficients represent average conditions -- namely average
weather.
In years that are significantly different from the average year,
actual crop development may exceed or lag behind the average crop
development rate. Therefore, when using crop coefficients in an
irrigation scheduling scheme, some adjustments of the average curve to
actual crop development may be needed. The crop coefficient of an
annual crop is small at the beginning of the growing season, gradually
increases as the crop develops, and may decline as the crop matures.
Effect of Soil Water on ET
Crop water use also is influenced by the actual soil water content. As
soil dries, it becomes more difficult for a plant to extract water
from the soil. At field capacity (maximum plant-available water
content), plants use water at the maximum rate. When the soil water
content drops below field capacity, plants use less water. This
phenomenon is described by the soil coefficient (KS), which is a
function of soil water content (see 4.707). The soil coefficient often
is used in irrigation scheduling schemes to adjust the actual ET to
reflect soil water conditions.
After rain or irrigation, actual ET is higher than when the soil or
crop surface is dry. When the soil or crop surface is wet, the
evaporation portion of ET increases significantly, resulting in a
higher actual ET, especially early in the growing season. This actual
ET rate can be larger than reference ET. This phenomenon is described
in irrigation scheduling schemes as an additional evaporation
coefficient (KW). This coefficient adjusts actual ET (upward) to
reflect wet soil surface conditions.
Each soil type can hold different amounts of water while acting as a
water reservoir for plants. Estimating the soil water content and
information on maximum water holding capacities of different soils are
given in 4.700, Estimating Soil Moisture.
Managing Irrigation According to Growth Stages
Crops are different in their response to water stress at a given
growth stage. Crops summarized according to their sensitivity to water
stress at various growth stages (Tables 1 and 2) reveal the importance
of these stages in making the irrigation decision.
Crops that are in the sensitive stage of growth should be irrigated at
a lower soil water depletion level than those that can withstand water
stress. If a crop is last in the irrigation rotation and is at a
sensitive stage of growth, the recommended strategy may be to apply
partial or lighter irrigations in order to reach the end of the field
before the sensitive crop is subjected to water stress.
Such a strategy can be used with sprinkler systems, but this may lead
to unfavorable soil moisture conditions at the lower soil depths. When
soil is repeatedly watered to only shallow depths, the lower soil
depths tend to develop a soil moisture deficit that exceeds the
allowable soil moisture depletion level at that particular growth
stage. Therefore, quick soil moisture assessment at various soil
depths to determine the actual water use is essential in irrigation
scheduling as related to growth stages.
Crop appearance is considered one of many field indicators that can be
used in irrigation scheduling. A crop suffering from water stress
tends to have a darker color and exhibits curling or wilting. This is
a physiological defense mechanism of the crop that is evident on hot,
windy afternoons when the crop cannot transpire fast enough, even if
the water is readily available in the soil. If the crop does not
recover from these symptoms overnight, the crop is suffering from
water stress. Any changes in crop appearance due to water stress may
mean a reduction in yield. However, using this indicator alone for
irrigation scheduling is not recommended if a maximum yield is
desired.
This indicator is inferior for modern agriculture due to the inability
to determine the actual crop water use. However, ignoring it at the
critical growth stages may lead to yield reduction. Using the growth
stage as a field indicator in irrigation scheduling should be coupled
with more sensitive and accurate methods of determining the crop water
use such as soil moisture measurements and ET data. The main advantage
of this indicator is to provide direct and visual feedback from the
crop.
Different Crops have different water requirements and respond
differently to water stress. Crop sensitivity to water stress varies
from one growth stage to another. Table 1 is a summary of critical
growth stages during which major Crops in Colorado are especially
sensitive to water stress.
A good irrigation scheduling scheme should consider sensitivity of the
crop to water stress at different growth stages. This is accomplished
by using a coefficient termed the Management Allowable Depletion
(MAD), which is the amount of water allowed to be depleted from the
root zone before irrigation is scheduled. The MAD is usually given as
a percentage of maximum water-holding capicity of the soil. At the
time of irrigation, the soil water deficit should be less than or
equal to the MAD.
The goal of any irrigation scheduling scheme is to keep the water
content in the root zone above this allowable depletion level. This
ensures that the crop will not suffer from water stress and will
produce maximum potential yield. In Table 2, suggested MADs for
selected Crops are given for different growth stages. This information
can be used in an irrigation scheduling scheme by using the
appropriate MAD for each growth stage to trigger irrigation.
Table 1: Critical growth stages for major crops1.
Crop Critical period Symptoms of water stress Other considerations
Alfalfa Early spring and immediately after cuttings Darkening color,
then wilting Adequate water is needed between cuttings
Corn Tasseling, silk stage until grain is fully formed Curling of
leaves by mid-morning, darkening color Needs adequate water from
germination to dent stage for maximum production
Sorghum Boot, bloom and dough stages Curling of leaves by mid-morning,
darkening color Yields are reduced if water is short at bloom during
seed development
Sugar beets Post-thinning Leaves wilting during heat of the day
Excessive full irrigation lowers sugar content
Beans Bloom and fruit set Wilting Yields are reduced if water short at
bloom or fruit set stages
Small grain Boot and bloom stages Dull green color, then firing of
lower leaves Last irrigation at milk stage
Potatoes Tuber formation to harvest Wilting during heat of the day
Water stress during critical period may cause cracking of tubers
Onions Bulb formation Wilting Keep soil wet during bulb formation and
dry near harvest
Tomatoes After fruit set Wilting Wilt and leaf rolling can be caused
by disease
Cool season grass Early spring, early fall Dull green color, then
wilting Critical period for seed production is boot to head formation
Fruit trees Any point during growing season Dulling of leaf color and
drooping of growing points Stone fruits are sensitive to water stress
during last two weeks prior to harvest
1Taken from Colorado Irrigation Guide, Natural Resources Conservation
Service.

Table 2: Management allowable depletion (MAD) at the root zone of
selected Crops at different growth stages.
Crop Growth stages MAD(%) in root zone Effect of water stress
Alfalfa Emergence-lst cut
lst cut-2nd cut
2nd cut-3rd cut
3rd cut-4th cut 65
50
40
60-70 Yield reduction
Pinto beans Emergence-aux. budding
Flower-bud filling
Bud filling-maturity 60-70
55
60-70 Yield reduction
Potatoes Early vegetative period
Tuber bulking period
Ripening period 40-60
30-40
65 Many jumbo and lower yield
Corn Emergence-12 leaf
12 leaf-dough
Dough-maturity 60-70
50
60-70 Yield reduction of 11.5 bu/A-in water deficit
Small grains Emergence-first node
First node-flowering
Milk ripe-maturity 65-70
40-60
50-70 Yield reduction of 6-8 bu/A-in of water deficit
Soybeans Before flowing
First flower-first pod
First pod-maturity 65-70
60-65
60-70 Yield reduction

1M.M. Al-Kaisi, Colorado State University Extension regional water
management specialist, Akron, Colorado, and I. Broner, former
Extension irrigation specialist and associate professor, chemical and
bioresource engineering. 9/92. Reviewed 2/09.