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Soil Management
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Increasing
soil organic matter makes more water available to crops by improving
infiltration.
Photo by Edwin Remsberg |
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How you manage your soil can significantly impact water availability.
Some soil management practices increase the amount of water available
to crops, while others will degrade soil and decrease available
soil water.
Good soil structure improves water infiltration and decreases runoff
and erosion. Well-structured soils are porous and allow water to
enter easily, rather than running off to be lost to streams and
rivers. While you are somewhat limited by your soil texture, you
can improve soil structure and water-holding capacity, storing water
for future use by plant roots. (See Figure 1) On the contrary, when
a soil has poor tilth, soil aggregates break down, increasing compaction
and decreasing aeration and water infiltration.
Most soil-improving strategies work slowly over several years,
although some produce results sooner. In contrast, management practices
that degrade soil are often apparent immediately. For example, working
your soil when it is too wet will compact the soil and degrade its
structure.
Soil organic matter plays a vital role in soil quality and soil
water availability. Organic material applied to soil and maintained
on the surface protects the soil from the impact of raindrops, a
major erosive force. Surface residue and mulches also reduce evaporation
and smother weeds, leaving more water for plant use.
Studies show that as organic matter increases, soils develop more
macropores. That happens because, as plant residue and other organic
amendments decompose, sticky substances bind soil particles and
create pore spaces between them. Moreover, organic matter itself
can hold water.
“You can change a soil’s pore size distribution, and
with that, you can change the available water-holding capacity,”
said van Es, a Cornell crop and soil science professor who co-wrote
the book, Building Soils for Better Crops. (Resources)
“There’s more water available to plants when you have
a well-structured soil than if it’s compacted.”
Strategies to increase organic matter content include:
 Spreading
manure or letting livestock deposit their own manure in well-managed
pastures.
Applying
composts (from a variety of materials ranging from poultry litter
to leaves).
Seeding
cover crops, which provide nutrient-rich residue after they die.
Reducing
tillage, because plowing breaks down soil aggregation and accelerates
organic matter loss.
Van Es is collaborating with other researchers at Cornell in a
SARE-funded study examining ways to improve soil health. As part
of the project, county extension educators collect data and demonstrate
strategies such as reducing tillage, adding cover crops and diversifying
from continuous corn to rotations with grass.
Results are promising. On average, and across a range of soil types
from clay loam to loamy sand, the researchers found a 10- to 20-percent
increase in the soil’s available water content by reducing
tillage or adding another crop to the rotation. On a Cornell experiment
station site, researchers saw soil improvements after just two seasons
of adding a hairy vetch cover crop between cash crops.
Compost |
Conservation Tillage | Cover
Crops | N.Y. Farmer Profile
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