Posts tagged ‘fertilizer’

OSU Agronomists Recommend Fertilize Now, Avoid Frozen Ground

Reblogged from the November 10, 2009 OSU CORN Newsletter

As you continue to harvest crops, plan on getting your fertilizer down this fall prior to frozen ground setting in or plan on waiting until spring after the thaw. Considering the number of acres that did not receive phosphorus or potassium last year with the prices we were facing, some of you may be in a situation where soil test indicates that you should make the application this year. If that describes your situation there is still time to make your applications this fall. The reason we would rather see applications made this fall is because we do not want to make applications on frozen ground. Applications made to fields with any appreciable slope can result in significant fertilizer losses. Not only do these losses represent an environmental concern, but they also represent an economic loss for your operation. Remember, if you soil test levels are still above our current critical levels (60 pounds per acre phosphorus, and 175-300 pounds of potassium, depending on soil CEC) then your risk of yield loss is small. Thus, you still do not have to make an application for next summer’s crops.

Another issue that producers are bring up is our current phosphorus and potassium recommendations and critical levels. Since at least some producers avoided applications of phosphorus and potassium last year and the crop season was as successful as it has been, growers question if our recommendations are too high. The Tri-State Fertilizer Recommendations are designed to ensure that phosphorus and potassium are not limiting production based upon soil test. A soil test value below the critical does not guarantee a yield loss, so those fields with low tests that performed well may have been those instances where enough phosphorus and potassium was made available (due to chance and weather) to allow for a relatively high yield. Additionally, since no fertilizer was supplemented, we do not know how much yield could have been made with an application (some yield may have been lost, but we have no way of measuring it without non-limiting control treatments replicated in the same field). Operating on low soil test levels is a risky venture, especially with potassium. We have documented yield losses of 35% and 50% on soils with below-critical phosphorus and potassium, respectively. You may be able to produce great yields on soils with low soil test levels, but the one time you do not will be a year you will remember.

November 13, 2009 at 1:19 pm

Nitrogen Fertilizer Options and Technologies

Below is an article I wrote for the August 24, 2008 Lima News.

The financial cost of fertilizer used in agriculture is intimately linked to the oil market. As the cost of a barrel of oil rises, so do agricultural fertilizer prices. One of the most basic sources of fertilizer is ammonium nitrogen, also referred to as anhydrous ammonia. Used directly in corn to supply nitrogen to a growing corn crop, anhydrous ammonia is also used to develop other nitrogen-containing fertilizers for corn, soybeans and wheat. Anhydrous ammonia costs have risen sharply in the past year and farmers are looking for technologies and other options to supply nitrogen. Below I have summarized some of these options and technologies.

Optical Sensors. Optical reflectance sensors can be used to measure light reflectance from leafy corn crop canopies, which can be used to estimate the nitrogen status of plants and ultimately estimate how much additional nitrogen needs to be applied. Healthy, large plants reflect light differently than struggling, smaller plants and plants with adequate nitrogen reflect light differently than nitrogen deficient plants. Optical sensors help farmers recognize and quantify differences in the nitrogen content of plants in areas of a field. The nitrogen rate can be controlled manually or electronically to change application rates based on reflectance differences in a field. There are two primary commercialized sensors in use in the United States, Crop Circle™ and GreenSeeker™. Both units emit near infrared rays and visible light wavelengths. Currently, Purdue leads the Midwest in research on this subject.

Cover Crops. There are some research publications that show nitrogen contributions from legume cover crops. Late July/early August is an excellent time to be planting a cover crop into wheat stubble fields. Summer seeded legume cover crops include: winter pea, red clover, crimson clover, hairy vetch, soybean, and cowpea. Many of the legume species require overwintering and producing significant spring growth in order to supply significant amounts of nitrogen. Establishment of cover crops solely for the purpose of supplementing nitrogen should be approached with caution. The earlier the crop is established the greater the chance of good growth prior to the onset of winter, and the greater the chance that the cover crop can contribute nitrogen. Ohio State University Extension has resources in this area, and the CORN Newsletter ( is a good place to get the latest information on cover crops.

Manure Application. Sidedressing pre-emergent corn in the spring with swine manure produces yields comparable to applying commercial fertilizer. Manure application, mostly practiced in the fall, can be just valuable in the spring, and place the available nitrogen nutrient much closer to when the corn crop can utilize nitrogen. Also in consideration is dry poultry manure, which can be brokered, delivered, stored and spread easier than liquid manure. Livestock manure is a source of nitrogen for growing crops. Manure can be an inexpensive option farmers have for applying fertilizer – especially in no-till situations. Bulletin 604, published by OSU Extension, is a good place to start for information on manure use (

Hyper-Efficient Crops. The next big thing coming out of the laboratory is hyper-efficient crops. These are crops that are bred and altered to produce the same amount of yield on 25% less fertilizer than would normally be required to achieve similar yield. In some cases, single genes are being inserted in to soybeans, canola and rice which increase yield by 10%. There is an obvious push to introduce these genes in to corn, one of the most nutrient intensive crops grown in Northwest Ohio. Expect this technology to be introduced in to the marketplace by 2014.

August 25, 2008 at 7:00 am

Nitrogen Deficiencies in Corn — Easy to See Now

Emerson Nafziger, Extension Agronomy Specialist for the University of Illinois, wrote an article on nitrogen deficiencies in corn. The article is very timely as many growers are now seeing the effect of nitrogen deficiency appear in their corn fields in NW Ohio. Unfortunately there isn’t much that can be done at this stage to assist the corn crop; Emerson writes:

There is little to be done to correct N deficiency in corn following pollination, especially when we have to count on uncertain rainfall to move fertilizer N into the soil so the roots can take it up. Root systems are also starting to decline in size and activity once ears reach the roasting ear stage. It is unlikely that 10 lb or so of N applied using a foliar-safe form will do much to cure deficiency this late.

Listen to my podcast on his article here:

August 13, 2008 at 7:00 am


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