Managing Crop Rotations Christi Falen Extension Educator
Corn Importance in South ID • Critical for dairy cattle rations • Necessary for phosphorous (P) uptake • Need yield maximized for feed production and maximum P uptake
Yield Reduction • 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
Carefully Choose Corn Hybrid • 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.htmhas 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.
Importance of Crop Rotation • 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
Western Corn Rootworm • 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
Disease Triangle Host Environment Disease Pathogen Risk of disease severity higher with continuous corn, but weather conditions in-season still affect disease severity
Build Up of Pathogens • 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 Fusariumgraminearum, which causes primarily scab (head blight) in wheat and barley, stalk and ear rot of corn
Gibberella Ear Rot • Gibberella ear rot is caused by the fungus Gibberellaaeae, also known as Fusariumgraminearum . It usually appears at the ear tip and is red or pink. A vomitoxin can be produced that causes vomiting in monogastrics.
Remember… • 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
Phosphorous Export Christi Falen Extension 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 B. Brown, UI Parma
B. Brown, UI Parma
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
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 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
Crop Import and Manure Export? • 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, struvitecystalization, anaerobic digesters, nursery industry – continue the quest for ways to export P!
Aflatoxins in Corn • Produced by mold fungi – Aspergillusfalvus and Aspergillusparasiticus • 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
Fungicide Resistance • 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 Code • 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 on multiple sites and resistance is low
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
