Managing Crop Rotations

Christi FalenExtension Educator

Critical for dairy cattle rations

Necessary for phosphorous (P) uptake

Need yield maximized for feed production and maximum

P uptake

Corn Importance in South ID

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/Crop_Rotation_Lit_Review.pdf

Yield Reduction

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/2007/Text.htm has corn hybrid performance for grain and silage in Wisconsin

Carefully Choose Corn Hybrid

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.

Carefully Choose Corn Hybrid

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

Importance of Crop Rotation

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

Western Corn Rootworm

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

Western Corn Rootworm

Disease Triangle

Host Environment

Pathogen

Disease

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

Build Up of Pathogens

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

Build Up of Pathogens

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.

Gibberella Ear Rot

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

Remember…

Phosphorous Export

Christi FalenExtension Educator

Cows Eat and Cows …

Where do we go with the … Environmental concerns for livestock operations are critical to everyone. *nutrient and waste mgmt.

*water quantity and quality

*air quality and odor mgmt.

Crop Uptake of Soil P

Previous Cereal

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B. Brown, UI Parma

Winter Forage

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Seeding Rate

B. Brown, UI Parma

Previous Cereal

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99 WF P99 Si P

Crop % P % H2O Yieldlb P

Removed

Canola seed

0.44 10 2000 lb/A

8

Peas 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

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P Content and Removal with Crops

Information from National Research Council (NRC) with modifications for Idaho where data is available from Dr. Brad Brown, UI in Parma

Crop % P %H2O Yieldlb 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

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P Content and Removal with Crops

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 year36 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 ppm44 ppm / 3 ppm = 14.6 years

Predicted Soil Test P IncreaseA 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 matter14,000 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 change91.8 lb net P added/ (12 lb P/ppm) = 7.65 ppm73.5 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!

Crop Import and Manure Export?

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

Aflatoxins in Corn

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

Fungicide Resistance

FRAC = Fungicide Resistance Action Committee

Goal is to provide fungicide resistance mgmt guidelines to prolong effectiveness of “at risk” fungicides.

FRAC Code

Look on label for group number-easier to alternate chemistry

M is when a fungicide acts onmultiple sites and resistance is low

FRAC Code

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

Restrictions for Corn Fungicides

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