Christi Falen
Extension Educator
Critical for dairy cattle rations
 Necessary for phosphorous (P)
uptake
 Need yield maximized for feed
production and maximum
P uptake

Examination of 26 different
studies showed decrease in yield
 Corn yield reduced 5 to 15% for
corn following corn compared to
the first year corn
 www.agecon.purdue.edu/pdf/Cr
op_Rotation_Lit_Review.pdf

Choose the corn seed hybrid most
desired for your farm – considering soil,
rotations, insect/disease pressures,
residues, manure or compost
applications, emergence concerns etc.
 http://corn.agronomy.wisc.edu/HT/200
7/Text.htm has corn hybrid performance
for grain and silage in Wisconsin

Dale Baker has variety trial on
corn grain from Kimberly
 Then look at cost and
necessity of seed treatments
included on the seed for
insect and disease control.

We need to minimize insect and
disease concerns to maximize
corn yield and P uptake
 Crop rotation is an effective
management tool for reducing
hosts for pathogens

Eggs laid in soil during the fall
– hatch in spring
 Larvae feed on corn roots
 Adults emerge from soil
 Adults beetles feed on female
flowers (silks) and soft kernels





Repeated efforts to control rootworm has
led to resistance to methyl parathion and
carbaryl
www.areawiderootworm.info/final_report
.pdf
Crop rotation is an important option to
prevent large rootworm infestations
Consider chemical and transgenic
control when it is economically required
Host
Environment
Disease
Pathogen
Risk of disease severity higher with
continuous corn, but weather conditions
in-season still affect disease severity
Long term buildup of soil born
pathogens can reduce corn stands,
vigor, yield, plus decrease nutrient
uptake potential.
 Pathogens survive on corn residues
and/or in the soil.
 Crop rotation beneficial to break the
cycle


Increased corn acreage = more stubble,
roots, and crowns = potential for
increasing Fusarium graminearum,
which causes primarily scab (head
blight) in wheat and barley, stalk and
ear rot of corn

Gibberella ear rot is caused by the
fungus Gibberella aeae, also known as
Fusarium graminearum . It usually
appears at the ear tip and is red or
pink. A vomitoxin can be produced
that causes vomiting in monogastrics.
To stop, look, and carefully evaluate
the best corn hybrid and
insect/disease control for your farm
 Practice good crop rotation to
minimize costs and mgmt. intensity
for corn production in Idaho, while
maximizing P uptake
 Keep accurate records when using
transgenic seed and chemicals

Christi Falen
Extension Educator
Environmental concerns for livestock
operations are critical to everyone.
*nutrient and waste mgmt.

*water quantity and quality

*air quality and odor mgmt.

70
60
win forage P removal
sum corn P removal
a
ab
ab
50
b
c
c
40
30
20
B. Brown, UI Parma
Previous Cereal
fallow
win bar
spr wht
win wht
0
spr trit
10
win trit
Annual P removal (lb/A)
Parma, 1999
Parma, 1999- 2001
Seeding Rate
200 lb/A
150 lb/A
100 lb/A
60
50
40
30
20
B. Brown, UI Parma
Winter Forage
win bar
spr wht
win wht
0
spr trit
10
win trit
W Forage P removal (lb/A)
70
Parma, 1999, 2000, 2001
200
99 WF P
99 Si P
180
00 WF P
00 Si P
01 WF P
01 Si P
160
140
120
100
80
60
40
Previous Cereal
win flw
win bar
spr wht
win wht
0
spr trit
20
win trit
Total P removal (lb/A)
220
P Content and Removal with Crops
Crop
%P
% H2 O
Yield
lb P
Removed
Canola
seed
Peas
0.44
10
2000 lb/A
8
0.38
13
2000 lb/A
7
Beans
0.60
40
28 cwt/A
10
Potatoes
0.20
80
500 cwt/A
20
Sugar
beets
0.13
77
35 tons/A
21
Information from National Research Council (NRC) with modifications
for Idaho where data is available from Dr. Brad Brown, UI in Parma
P Content and Removal with Crops
Crop
%P
%H2O
Yield
lb P
Removed
Wheat
grain
0.43
10
120 bu/A
28
Barley
grain
0.39
10
120 bu/A
20
Oat grain
0.40
10
160 bu/A
18
Corn
grain
0.30
15.5
180 bu/A
25
Corn
silage
0.26
67
30 tons/A
51
Information from NRC with modifications for Idaho where
data is available from Dr. Brad Brown, UI in Parma
Soil Test P Decline
John Brown's annual corn removes 36 lb P per
acre. For his soil, the soil test declines 1 ppm
for every 12 lb of P removed each year. His
manured field has a soil test P value of 84 ppm.
How many years will it take with his current
cropping system to lower soil test P to 40 ppm
based just on the crop P removal with no
additional P applied?
Soil Test P Decline Question
STP change in one year
36 lb P a year / (12 lb P/ppm) = 3 ppm P
Difference in ppm P
84 ppm - 40 ppm = 44 ppm
Years to change STP 44 ppm
44 ppm / 3 ppm = 14.6 years
Predicted Soil Test P Increase
A new dairy wants to apply composted manure
at the rate of 10 tons per acre annually to a
field. The compost is 70% dry matter and
0.92% P (dwt basis). Initial soil test P for the
field is 20 ppm. He can remove 37 lb P annually
with corn silage but is wondering about a
double cropping system that would remove 55
lb P per acre annually. Assume soil test P
changes 1 ppm for every 12 lb P applied per
acre.
How many years for STP to reach 40 ppm P?
Predicted Soil Test P Increase Question
Net P added per acre?
10 tons x 2000 lb per ton = 20,000 lb
20,000 lb x 0.70 = 14,000 lb dry matter
14,000 lb x 0.0092 = 128.8 lb compost P per acre
128.8 lb P added - 37 lb P removed = 91.8 lb P
= net P gained annually with single crop corn
128.8 lb P added - 55 lb P removed = 73.8 lb P
gained annually with double cropping
Predicted Soil Test P Increase Question
Soil test P change?
40 ppm P - 20 ppm P = 20 ppm P
Annual soil test change
91.8 lb net P added/ (12 lb P/ppm) = 7.65 ppm
73.5 lb net P added/ (12 lb P/ppm) = 6.125 ppm
Time required?
20 ppm P change / 7.65 = 2.6 yrs with SC
20 ppm P change / 6.125 = 3.26 yrs with DC
Hauling hay from east Idaho here and
exporting compost back
 High fertilizer prices making the export
farther away more economical
 High quality compost marketed for
organic producers
 Lime, struvite cystalization, anaerobic
digesters, nursery industry – continue
the quest for ways to export P!

Produced by mold fungi – Aspergillus
falvus and Aspergillus parasiticus
 Aflatoxins are harmful or fatal to
livestock and are considered
carcinogenic
 No aflatoxins allowed for milk from
dairies
 See Aflatoxins in Corn, PM1800 Iowa
State University, for sampling
procedures and control methods

Highly effective compounds like the
triazoles and Qol fungicides (e.g.
strobilurins) with specific modes of
action developed
 These affect one specific site in one
metabolic pathway of fungus
 Fungi only have one barrier to
overcome

FRAC = Fungicide Resistance Action
Committee
 Goal is to provide fungicide resistance
mgmt guidelines to prolong
effectiveness of “at risk” fungicides.

Look on label for group number-easier
to alternate chemistry
 M is when a fungicide acts on multiple
sites and resistance is low

Product
Rate (fl oz/acre)
REI (hours)
PHI (days)
Headline
6-12
12a
7
Quadris
6-15.5
4a
7
Quilt
7-14
24a
After brown silk
Statego
7-12
24a
After silking
Tilt
2-4
24a
After silking
aREI
is 7 days for bare-hand detasseling activity
*Headline and Quadris are strobilurin fungicides
*Considered “high risk” for fungicide resistance
*May result in yield increases, even in supposed absence of
any disease pressure, in short term
*Exercise caution-use only when required to minimize
selection of fungicide-resistant strains of fungal pathogens.
*http://www.ipm.iastate.edu/ipm/icm/node/2529/print