Conservation Expert Guest Editorial
Conserving Water and Improving
Infiltration with No-Till
U
sing no-till can save you far more than
fuel, labor and equipment costs. The savings in soil moisture can be just as important, especially in years when soil moisture and
precipitation are short or when irrigation is costly
and water supplies are limited. With continuous
no-till, the improved soil structure and moisture
infiltration will enhance productivity and profitability even more.
Effect of Tillage on Rainfall Impact
In addition to drying out the soil on its own, the
tillage also breaks up soil structure, pulverizes the
soil surface and reduces residue cover, making
the soil prone to crusting from raindrop impact.
In fact, tillage actually creates a condition that
allows sealing of the soil, resulting in more runoff
and therefore less effective rainfall or irrigation.
On the other hand, when crop residue is present,
the raindrop impact is absorbed, and
erosion and crusting are reduced. The
Continuous no-till saves 5" to 12" of
residue also slows the runoff, allowing more time for infiltration. More
water. Intensifying a cropping system to about the effects of crop residue on
soil moisture will come in the next
use that water can improve the soil and article.
Reducing the sealing of the soil by
increase profitability.
continuous no-till has drastic benefits. University of Nebraska–Lincoln
Too often soils dry out down to the depth of
(UNL) research with a rainfall simulator at Sidney
tillage. An average silt loam soil holds about 2"
demonstrated the effects of reduced crusting and
of plant-available water per foot of soil. Tilling
improved soil structure in a wheat-fallow rotation.
the soil can result in a loss of 1/2" to 3/4" of soil
More than 3.75" of water was applied in 90 minmoisture with each trip. After multiple tillage
utes on continuous no-till before runoff started,
trips, there may not be adequate soil moisture in
compared to runoff starting after only 1.0" of
the seed zone for uniform germination and emerwater applied in 20 minutes on plowed ground.
gence; this could result in lower yields, even when
there may be sufficient moisture throughout the
No-Till Improves Infiltration
rest of the year.
With the improved soil structure of continuous
Greater yet are the soil moisture losses from evapno-till, infiltration also improves, reducing runoff
oration once tillage destroys residue cover, which
even more. Research at the UNL Rogers Memowe’ll talk about in more detail in the next article.
rial Farm near Lincoln showed a much greater
infiltration rate for no-till (over 4"
per hour) than for tilled conditions
(only 0.4" per hour) after 25 years
Effects of Tillage on Infiltration and Runoff Potential
of continuous tillage system evaluation. Similar results were measured
Soil permeability
Rainfall rate to create
Tillage System
at the UNL South Central Ag Lab
inches per hour
runoff, inches per hour
near Clay Center after 30 years of
Disk & Plant
0.4
1.5
continuous tillage system evaluaRidge-plant
1.5
3.2
tion (see table, first column). With
better infiltration, storms of greater
Slot-plant
4.0
6.4
intensity will have less runoff and
Information provided by a grant from the Howard G. Buffett Foundation
can provide more water in the soil profile for use
later in the season.
Contrary to the belief that crop residue will eliminate evaporation, this evaporation does still take
place from the soil, the residue itself and the crop
canopy every time each of these gets wet. This loss
has been estimated to be around 0.08" to 0.1" each
time. This is why light, frequent rains or irrigations
are less effective than longer, soaking ones.
Many center pivot irrigators have problems with
runoff on tilled soils, so they apply small amounts
quite frequently, typically applying only 0.5" at
a time. One-tenth of an inch evaporation out of
0.5" water applied is a 20% loss—or even more,
if runoff occurs. Luckily, when adopting continuous no-till under center pivot irrigation, the pivot
can apply a greater amount of water before runoff
occurs (see table, second column). With more water being applied less often, the evaporation and
runoff losses are reduced and irrigations can be
scheduled to make better use of naturally occurring rainfall.
Need to Increase Cropping Intensity
By adopting continuous no-till, more water
is available in the soil for crop production. If
producers don’t change their cropping practices
to make use of that water, they may complain
that no-till soils are too cold and wet. Or, if their
soils cannot store all the water there is when it is
available, deep percolation may occur, potentially
leaching nutrients out of the root zone.
Examples of changes to use the “extra” water
include increasing seeding and fertilizer rates for
higher yields; implementing more intense and
Paul Jasa, Extension Engineer with the University
of Nebraska-Lincoln, develops and conducts
educational programs related to crop production that
improve profitability, build soil health and reduce
risks to the environment. He has been working with
planting equipment and tillage system evaluation at
the University since 1978. Jasa has become one of
the best sources of information in the Midwest on notill planting equipment and system management. If
there is a mistake to be made with no-till, Jasa admits
he’s either made it himself or has seen it done. More
importantly, he has learned from those mistakes and
shares information on a systems approach and the
long-term benefits of continuous no-till.
diverse crop rotations; using cover crops, relay
cropping or double cropping; and, for irrigators,
applying less irrigation water. Each of these options can produce significant cost savings or earnings. The water savings with continuous no-till
is there and producers should grow it rather than
lose it.
In an upcoming issue: Conserving Water with Crop
Residue and Cover Crops
About the Howard G. Buffett Foundation
Established in 1999, the Howard G. Buffett Foundation’s primary mission is to catalyze transformational change to improve
the world and the lives of the most impoverished and marginalized populations. The Foundation’s focus is on international
programs that operate in challenging environments, including conflict and post-conflict countries. The Foundation has to
date invested nearly $250 million to support sustainable agricultural development and improved nutrition initiatives in 50
countries around the world, including in the United States. The Foundation believes global food security efforts must include
all countries – both rich and poor – therefore, the United States must consider its domestic agricultural practices and policies
if we are to successfully address hunger, malnutrition and achieve global food security.
To follow this series visit www.HarvestingThePotential.org