Field & Feedlot

Field & Feedlot is a monthly newsletter of current educational topics written by Agriculture and Natural Resources Extension and Outreach specialists in Northwest Iowa.

ISU Soil Fertility Recommendations by Joel DeJong

Register for Upcoming Beef Programs by Beth Ellen Doran

Maximizing Manure by Kris Kohl

Indoor Blooms for the Holidays by Margaret Murphy

Archived Issues


ISU Soil Fertility Recommendations

Joel DeJong, Field Agronomist

ISU Soil Fertility specialists Antonio Mallarino and John Sawyer released an updated version of the ISU publication titled “A General Guide for Crop Nutrient and Limestone Recommendations in Iowa” in 2013. Since we are likely looking at narrow margins again for 2019, we need to look carefully at crop costs. If you are cutting expenses on soil fertility, you need to do that wisely, and this research can help you make some of those tough decisions. Knowing the soil fertility of your soil through soil testing is the key for good decisions, but interpretation of those numbers is the next critical step. A copy of this publication, which can be vital on interpreting these results of your soil tests, is available free at this website:

The general concept in these recommendations is for long-term profitability and reducing risk of yield loss by emphasizing response-based applications for very low and low soil test categories, and removal-based maintenance replacing what has been removed with crop harvest in the optimum category. These recommendations do not encourage the rapid build-up of soil test levels when in the low and very low categories, but rather longer-term profitability goals.

This publication also discusses some newer soil tests being run where samples are not dried in the lab; they are analyzed as a moist or slurry sample. The results are now calibrated to determine when yield responses are likely to occur, as has been done with the other soil testing methods. Recent research had also indicated that an adjustment was needed for K (potassium) tests where samples are dried in the lab. Additionally, adjustments were made to both crop nutrient concentrations and default crop yields needed to estimate nutrient removal for maintaining soil-test levels in the optimum category.

The nutrient concentration of the crop removed has changed, and is lower than the nutrient content was 30 years ago. Research studies analyzed in Iowa and other states have shown that to be true for corn and soybeans, plus we also now have better information of nutrient concentrations for many other crops and harvested plant parts.

A couple of examples, the “old” publication indicated that a bushel of corn removed 0.375 pounds of phosphate, and 0.3 pounds of potash. The new table in this publication lists a bushel of corn removing 0.32 and 0.22 pounds respectively. If you removed 200 bushels of corn from a field, you would have hauled out about 64 pounds of phosphate, and 44 pounds of potash. These numbers are set at the level where 75 percent of the samples analyzed would fall below this level, not an average of all samples.

Likewise, soybeans are now at 0.72 and 1.2 pounds of phosphate and potash removed per bushel, where previously they were estimated at 0.8 and 1.5 pounds removed per bushel. Therefore, 60 bushels of beans removes about 43 pounds of phosphate and 72 pounds of potash. Forage nutrient removal amounts in the new report are based on typical harvest moisture levels, not on a dry matter basis like previously reported. Corn stover, per ton removed at 15 percent moisture, has a removal rate of 4.8 pounds of phosphate and 18 pounds of potash under the new standards, down from the older 5.9 and 25 pounds, respectively.

This is a great soil fertility reference. I encourage everyone who grows crops to carefully read the entire publication and get familiar with the nutrient needs of your crops.

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Register for Upcoming Beef Programs

Beth Ellen Doran, Beef Specialist

January 1 Deadline for Beef Quality Assurance (BQA) Certification
January 1, 2019 is the deadline to obtain a current BQA certificate, which is required in order to sell cattle to certain packers.

To comply with this requirement, ISU Extension and Outreach, Iowa Beef Center and Iowa Beef Industry Council are offering a series of “year-end” trainings in Northwest Iowa: 

  • Nov. 19: New Dordt Ag Stewardship Center, Sioux Center. RSVP by Nov. 14 to: 712-737-4230.
  • Nov. 28: NW Iowa Community College, Sheldon. RSVP by Nov. 14 to: 712-957-5045.
  • Dec. 4: Sac County Extension, Sac City. RSVP by Dec. 2 to: 712-662-7131.
  • Dec. 5: Grace United Methodist Church, Spencer. RSVP by Dec. 3 to: 712-262-2264.
  • Dec. 11: Plymouth County Extension, Le Mars. RSVP by Dec. 9 to: 712-546-7835.
  • Dec. 18: Archer Coop Grain Company, Archer. RSVP by Dec. 14 to: 712-723-5233.

All trainings are 10:00 a.m. to noon, except the Archer training which will be 1:00 to 2:30 p.m. There is no cost to attend any BQA training; but, pre-registration is required in order to plan for meals and materials. To pre-register, call the number for the site you plan to attend.

If you are unable to attend one of these six trainings, BQA certification may be completed on-line  by going to A listing of other trainings in Iowa is located on the Iowa Beef Industry Council webpage, which may be accessed at For a flier or more information on the Northwest Iowa trainings, contact Beth at 712-737-4230 or

Cover Crop Tours Feature Fall Grazing

Wondering how to extend fall grazing and your feed resources? Then, plan to attend one of two fall tours featuring the grazing of cover crops. Each tour includes stops at two producers who are successfully fall-grazing cover crops and current research at the nearby ISU Demonstration and Research Farm. Field Days will be: November 30, Castana area. RSVP to 712-423-2175; and December 3, Newell area.  RSVP to 712-662-7131.

Both field days will be 10:00 a.m. to 2:30 p.m. and include lunch ($5 per person), which is payable at the door.nIf you didn’t get a flier, please request one when you RSVP. P.S. Dress warm as we  will be outside the majority of the day!

Save the Date for Feedlot Forum 2019!

Feedlot Forum 2019: Focusing on Marketing in a New Era will be January 15,  2019 at the Terrace View Event Center in Sioux Center.

New Publication

Pricing Forage in the Field (A1-65) – Updated September 2018 — Features how to derive a price for corn silage, oats, hay and haylage, and cornstalks. Available at:

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Maximizing Manure

Kris Kohl, Ag Engineering Specialist

It’s time to get this job done before everything freezes up. To maximize the manure from our livestock operations, we must do the following:

1. Right rate on right place.

2. Minimize compaction.

3. Minimize safety risk.

Right rate on right place. If we have not yet sampled the manure to determine the NP&K content prior to spreading, be sure to sample while you are spreading now. Then send the samples to the lab as soon as possible, so they don’t explode in your pick-up on a sunny day a week later. The results can be used to make adjustments in fertility program next spring if needed. Apply the right rate according to the manure management plan to meet the needs of the crop.  Most of the feedlot cattle manure is applied at a rate to provide 75 percent of the nitrogen needs of next year’s corn with a starter fertilizer applied the following spring. This is because the high organic matter in manure require soil microbes to break them down in the spring and will tie them up when the corn is small. Swine and poultry manures don’t show this problem very often.

Minimize compaction. The wet fall has provided plenty of risk for compaction. Lower tire pressure will cause less damage and radial tires have a much lower working range. It is always a dilemma on what pressure to use as the travel down hard surface roads should be high to reduce tire wear and fuel consumption, while the field pressure should be low to reduce soil damage and ruts. If the soil does not show any sign of the wheel traffic, there is little damage like frozen soil.  This is the issue that will be difficult to work around with the wet spots.

Minimize safety risks. Deep pits always have risk of poison hydrogen sulfide gas that can kill pigs and people. Don’t agitate until there is at least 2 feet of space between the slats and the manure surface and then start slowly with at least mid-range ventilation making sure the jet remains below the surface. We encourage the gas monitoring clips to be worn by farmers and commercial manure haulers to help provide warning prior to high levels being inhaled. There have been more reports of pits foaming again this year with a flash fire report. The foam contains methane that can be explosive if it mixes with air and there is a pre-lit light or spark. Be sure to check this when the pit covers are opened.

Have a safe and productive hauling season.

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Indoor Blooms for the Holidays

Margaret Murphy, Horticulture Educator

Looking for a little flower drama this winter? Amaryllis may be the answer. Amaryllis are popular flowering bulbs grown indoors for winter blooms and are widely available now in stores and garden centers.

Native to tropical areas of South America and South Africa, amaryllis offer impressive, trumpet-shaped blooms – some reaching up to 10 inches in size. The blooms can be single or double in form and come in a range of colors. I have grown the ‘Red Lion’, which as the name suggests, has a large, intensely red bloom. ‘Minerva’ is also lovely with a bi-colored bloom that has a white, star-shaped middle fading into a red border. I have also grown the ‘Apple Blossom’, which has a white flower with pinkish-red hues on the petals just like an apple blossom. Other flower colors include orange, salmon and deep burgundy so you are sure to find a color that will add a festive air to your holiday décor.

Amaryllis are easy to grow. They normally flower February to April but can be forced to bloom anytime. A bulb potted in early November should be in bloom by Christmas. You can buy a kit, which contains the bulb, a pot and a soil disc or you can purchase just the bulb. If you purchase only the bulb, plant it in a pot that is one to two inches wider than the base of the bulb. Amaryllis bulbs prefer to be a bit cramped when growing. Make sure the container has drainage holes. For bulbs, good drainage is essential.

So if you are looking for a burst of living color to brighten the indoors this winter, check out the wonderful blooms of amaryllis. For more information on how to grow and care for amaryllis, view or download Iowa State University Extension and Outreach publication, Amaryllis, ( available at the Extension store.

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