Person: Tim Sieren
Small grains are a unique crop in the Midwestern system because they are harvested early – around July – leaving the field open for different field operations and cover crops. This longer window makes it possible to grow a legume cover crop that can synthesize nitrogen and offset purchased fertilizer costs for the following crop […]
February 19, 2018
A roller-crimper presents farmers the
opportunity to mechanically terminate
cover crops without chemicals or
tillage. This method is dependent on
a large amount of cover crop growth
and the cover crop reaching the
flowering stage before crimping.
• Farmer-cooperator Tim Sieren
compared soybean seeding dates
relative to cover crop termination
(before and after) as well as cover
crop termination techniques (chemical
• Cover crop termination date had
the strongest effect on soybeans.
Soybeans yielded best when the cover
crop was chemically terminated on
May 5 and the soybeans were seeded
on Apr. 24 or May 7.
• Roll-crimp termination of the cover
crop was a challenge and this was
attributed to a thinned cover crop
stand resulting from drilling soybeans
on May 7 before roll-crimping on May
November 30, 2017
Successfully raising corn after a
cover crop requires timely cover
crop termination and N fertilization.
Commonly, farmers terminate a cover
crop 2-3 weeks prior to planting corn
but generally do not need to apply any
more N than if they did not use a cover
• Farmer-cooperators Dick Sloan and
Tim Sieren compared terminating their
cover crops approx. 3 weeks prior to
planting corn with terminating their
cover crops within 3 days of planting
corn. They also investigated N fertilizer
timing and rates across the cover crop
• Delaying cover crop termination
until a few days before planting
corn increased cover crop biomass
production in the spring.
• Terminating the cover crop a few
days before planting corn generally
resulted in reduced yields at both farms
regardless of N strategy.
• Fall manure with 35 lb N/ac at corn
planting and 90 lb N/ac at side-dress
resulted in no yield drag at Sloan’s
when the cover crop was terminated 3
days before planting corn.
November 20, 2017
Various green manure cover crop mixes can successfully be established following the harvest of a small grain crop in mid-summer. Following cereal rye seed harvest in July 2015, farmer-cooperator Tim Sieren seeded a brassica mix into one field and a legume mix into another field. He then compared 2016 corn yields resulting from a Low […]
November 21, 2016
Various green manure cover crop
mixes can successfully be established
following the harvest of a small grain
crop in mid-summer.
• Following cereal rye seed harvest
in July 2015, farmer-cooperator Tim
Sieren seeded a brassica mix into one
field and a legume mix into another
field. He then compared 2016 corn
yields resulting from a Low and High N
fertilizer rate that followed the green
manure mixes in the separate fields.
• Regardless of the green manure mix it
followed, corn yields were significantly
greater with the 145 lb N/ac (High) rate
compared to the 95 lb N/ac (Low) rate.
• Wet summer months likely contributed
to the superiority of the High N rate
in terms of both yield and financial
returns in 2016.
November 18, 2016
• Two farmers tested Spray strips and
No-Spray control strips of cereal rye for
• This project was a secondary project
within “Fungicide and Plant Growth
Regulator Effect on Cereal Rye
Production” (Gailans et al., 2016).
• At Sieren’s farm, no propiconazole
residue was found above the
detectable limit of 0.05 ppm in No-
Spray control strips.
• At Sloan’s farm, metconazole residues
of 0.02 ppm were found in both control
strip samples, compared to the 1.30
ppm baseline residue level in the
October 20, 2016
In recent years, a growing number of farmers have become interested in raising their own cereal rye seed to use as cover crop seed. However, fungal diseases and lodging can present challenges to raising small grain crops, like cereal rye, in Iowa. Warm and humid conditions during heading and grain fill periods are conducive to fungal […]
October 10, 2016
In a Nutshell
• Fungal diseases and lodging can
present challenges to raising small
grain crops, like cereal rye, in Iowa.
• Farmer-cooperators investigated the
use of fungicides and plant growth
regulators on cereal rye seed crops
to determine effects on yield and
• Across four fields at three farms, in only
one instance, when a fungicide was
paired with a growth regulator, were
cereal rye seed yields and financial
• Germination percentage of harvested
seed was generally greater than 90%
regardless of treatment.
September 30, 2016
Cultivation of cereal rye for cover crop seed offers the possibility of frost-seeding a legume into the standing rye crop in early spring, where the legume can produce biomass and fix N following rye harvest. In 2014, farmer-cooperators Tim Sieren and Dick Sloan grew corn in rotation following cereal rye frost-seeded with red clover and […]
December 16, 2015
In a Nutshell
• Cultivation of cereal rye for cover crop
seed offers the possibility of frost-seeding
a legume into the standing rye crop
in early spring, where the legume can
produce biomass and fix N following
• Farmer-cooperators Tim Sieren and
Dick Sloan grew corn in rotation following
cereal rye frost-seeded with
red clover and compared this to corn
grown using synthetic N fertilizer applications.
• Tim and Dick invited Iowa State University
graduate student Will Osterholz
on to their farms to quantify N uptake
by corn as well as two measures of N
release from soil organic matter: net N
mineralization and gross ammonification.
• Red clover did not improve corn
growth, N content or grain yield compared
to synthetic N fertilizer.
• Soil N mineralization rates in August
tended to be higher with red clover
compared to synthetic N fertilizer, but
differences were not statistically different.
• Fertilization with supplemental N at
planting could provide corn with early
season N before clover decomposition
can provide sufficient N to the corn
crop in late summer.
November 30, 2015