Crop residue decisions affect soil life

Date:
June 17, 2020
Source:
American Society of Agronomy
Summary:
New findings share how prescribed fire and no-till management
impact soil microbes.



FULL STORY ==========================================================================
In some ways, farming is like cooking. Cooking would be much easier if
we could leave the kitchen after eating and not come back until we make
the next meal.

But someone needs to put away the leftovers, do the dishes, and clean
up the table.


========================================================================== Similarly, there's work to do in farm fields after harvest and before
planting the next spring.

After harvest in the fall, farmers take the harvested crops to market
or store them on their farm. They don't take the whole plant from the
field, though.

The leftover parts of the plant, like the stalk and leaves from corn,
remain in the field. This debris is called crop residue.

Using no-till and prescribed fire management are two potential ways to
manage crop residue. Both practices help keep organic matter and nitrogen
in the soil.

However, research was needed to understand how these two practices can
affect long-term soil health.

Lisa Fultz and her team want to help farmers determine the best way
to manage their residue between growing seasons. To do this, her team
decided to learn more about how no-till and prescribed fire management
affect nutrients and microbes in the soil. Fultz is a researcher at
Louisiana State University AgCenter.



========================================================================== No-till is a practice where farmers plant directly into the crop debris
from the previous year. Prescribed fires are used to purposely burn off
the previous crop debris with controlled fire. "Both of these practices
have minimal physical disturbance to the soil," says Fultz.

Both of these practices also come with drawbacks. No-till can cause poor conditions for crop growth like low spring temperatures and increased
moisture, which promotes disease. Prescribed fire can leave bare soil vulnerable to erosion.

The team focused the research on wheat and soybean rotations and
continuous corn production systems. "These are common practices not only
in the mid-south, but across many areas of the world," explains Fultz.

"Wheat and corn production leave behind residue," she says. "Common
practices, like conventional tillage, are highly disruptive. The need
to identify viable conservation practices is growing in importance."
Crop residue and its degradation by soil microbes is an important part
of the carbon cycle. Plants store carbon during the growing season, then microbes use the plant residue for food. The carbon then gets stored in
the soil in a chemically stable form.



========================================================================== "Fresh, green material in no-till fields is easy to breakdown and
provides rich nutrients for soil microbes," says Fultz. "Ash from
burned residue is more chemically stable, but it doesn't provide a
nutrient source for microbes." The team found that impacts from crop management practices, like crop rotation or fertilization, outweighed
the influence of prescribed fire for residue management. Researchers
found some decreases in microbial activity after yearly prescribed burns.

Findings show prescribed fire had some possible short-term benefits for
soil nutrient availability, but timing is crucial. Prescribed burning of
wheat residue provided an increase of nitrogen for about 7 days. These
benefits should be weighed against other possible impacts, like carbon
dioxide production and crop yield.

We still need to learn the long-term influence of prescribed fire on the
soil biological community," says Fultz. "While short-term impacts were measured, the long-term influence on soil nutrients, biological cycles and
soil health are not known." No two farm management systems are the same,
and their success is defined by the user. Scientists continue to examine possible scenarios to provide accurate and sustainable recommendations
to farmers.

"I have always been interested in soil conservation and the potential
it has to impact many facets of life," says Fultz. "By improving soil
health, we can improve air and water quality, store carbon, and provide
stable resources for food production."

========================================================================== Story Source: Materials provided by American_Society_of_Agronomy. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Autumn Acree, Lisa M. Fultz, Josh Lofton, Beatrix Haggard. Soil
biochemical and microbial response to wheat and corn stubble residue
management in Louisiana. Agrosystems, Geosciences & Environment,
2020; 3 (1) DOI: 10.1002/agg2.20004 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200617091007.htm

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