Fall Fertilization Strategies

Minimizing yield-limitations caused by crop nutrient deficiencies is top of mind for soil testing and fertilizer decision makers every autumn. Collecting soil samples after harvest is a good place to start. There are several ways to collect soil samples, from random sampling (collecting multiple cores from different areas of the field and creating a composite) and grid sampling (based upon GPS location) to zone sampling (based upon delineated management zones). There are pros and cons to each method.

The soil test report is only as good as the sample provided to the lab for analysis, so no matter the approach — ensure soil samples are administered correctly. Collect samples to the same depth when creating a composite, ensure adequate sample volume to accurately represent average soil nutrient levels, and mix composites thoroughly before collecting samples and depositing to soil bags. These are critical first steps along the nutrient management decision chain.

After submitting the samples to a reputable lab and receiving the results, the next step in the decision chain is to determine which nutrients and what quantity should be applied to ensure that soil levels maximize productivity. The natural place to start is to evaluate the soil pH level. Make certain that soil pH falls within optimum ranges for the crops to be grown. In general, legumes require a slightly higher soil pH to maximize production than grasses. If your soil pH level is below the optimum range, your soil may require neutralization.

When applied to soil, lime neutralizes soil pH, but is among the most expensive soil applications to be made in a single production year. Since adding lime to the soil can be critical to maximizing crop yields next spring, the expense should be considered a good investment.

Soil pH readings only indicate whether or not lime is needed, but lab-conducted buffer pH or lime index tests will determine how much lime is required to optimize soil pH. These tests will also determine the quality and lime grind fineness appropriate for application to fields. University specialists and local experts familiar with lime quality are the best consultative resources for lime application.

Evaluating P And K Levels

Table 1
Grain and stover/straw nutrient removal rates for common agricultural crops.
Crop Grain*  Stover/Straw*
P2O5
removal
  K2O
removal
P2O5 removal   K2O
removal
 
Corn
 
0.38
lb/bu
 
 
0.27
 
 0.16
 lb/ton
 
 
 1.10
Soybeans 0.84   1.30  8.80    37.00
Barley 0.40   0.32  —    —
Canola 0.91   0.46  —    —
Wheat
 
0.60
 
 
lb/bale
0.34
 
 3.30
 
 
 
 24.00
 
Cotton 14.00   19.00  —    —
*-IPNI      

After assessing lime needs, evaluating phosphorus (P) and potassium (K) levels is essential to determine the soil’s ability to supply nutrient levels throughout growing season.

P is required to ensure adequate energy for crops and is critical to the formation of genetic material as the crop grows and develops. K is essential for drought tolerance, multiple enzyme reactions and crop disease resistance. As different crops have different critical P and K soil test levels, lab results will also reveal information about where test results are relative to crop needs.

P and K behavior in soil is dramatically different than mobile nutrients like nitrogen (N) as they can actually be built up in most soils. While this tendency can result in fertilization for more than one crop year, it does not mean continual crop production without nutrient replenishment should be the norm. This is an unsustainable practice that can dramatically decrease crop productivity.

Significant depletion of P and K levels can also be quite costly when attempting to bring soil test levels back in line for crop production, as equivalent or greater levels of these nutrients will have to be applied to see a noticeable reserve accumulation in the soil.

Beyond Soil Testing

Other factors can also be monitored to determine how much fertilizer will be required to maintain P and K soil test levels. Crop removal can either be monitored in a site-specific manner with the use of a yield monitor, or by simply monitoring and logging load weights when delivering grain. All that is required is a crop yield estimate to provide insight into the amount of P and K removed from the soil.

Crop P and K removal can be estimated using crop yield and crop removal values from Table 1 above. For example, a 200-bushel corn crop, where only grain is removed, will remove 76 (200 x 0.38) and 54 (200 x 0.27) pounds of P2O5 and K2O per acre, respectively. Corn and wheat growers who remove stover and straw, respectively, must make sure an estimate of nutrient removal in the stover/straw is included when determining the total P and K removed. Estimates of stover and straw tonnage, as a function yield, are provided in Table 2.

Table 2
Stover/Straw yiuelds based upon grain yields and an assumed harvest index of 0.55 for corn and wheat.
Crop Grain yield,
bu/acre
Stover/Straw yield,
ton/acre
Corn 150 3.4
Corn 200 4.6
Wheat 60 1.5
Wheat 90 2.2

Fall N Application Considerations

N applications planned for this fall also require consideration. Soil temperatures should be below 50°F to minimize conversion of supplied ammonia to nitrate. The same guideline surrounding soil temperature also applies to the application of DAP or MAP. Recent research has shown a significant amount of the N supplied with MAP, DAP or ammonium sulfate may be unrecoverable in the next corn crop-based on soil temperature and rainfall pattern in early spring. Nitrification inhibitors are more likely to reduce N loss in fall-applied systems because fall N application has the highest N loss potential. The use of N in the fall should therefore be considered.

Remember — the key to optimizing crop production is ensuring adequate nutrient availability. Spending a little time evaluating soil test reports and determining crop nutrient removal when making fertilizer decisions will go a long way in ensuring favorable production for years to come.

Leave a Reply

Fertilizer Stories

FertilizerKoch Agronomic Services Launches N-TEGRATION Technology
July 27, 2015
Koch Agronomic Services, LLC (KAS) has launched  N-TEGRATION Technology, a process technology platform designed to enable production of enhanced efficiency fertilizers at Read More
FertilizerWSJ: Cf Industries Exploring Merger With Dutch Chemical Company
July 23, 2015
U.S. fertilizer maker CF Industries is in advanced merger talks with Amsterdam-listed chemical company OCI NV, the Wall Street Journal Read More
Crop InputsH.J. Baker Launches Fall Sulphur Campaign
July 22, 2015
H.J. Baker has launched their “Keep Your Future Green – Use Tiger This Fall and Win Big” campaign. The campaign Read More
FertilizerNew Research Could Lead To Less Reliance On Nitrogen, Eliminate Runoff
July 21, 2015
Farmers often are required to apply nitrogen fertilizers to their crops to maintain quality and improve yields. Worldwide, farmers used Read More
Top 100 Articles
CropLife 100Pinnacle Purchases California-Based Specialty Crops Retailer
July 20, 2015
Pinnacle Agriculture Holdings has successfully acquired California-based NH3 Service Co.  Operating as part of Pinnacle’s Performance Agriculture brand, the new locations Read More
Asmus Farm Supply liquid fertilizer facility features 20,000 square feet
CropLife 100Slideshow: Asmus Farm Supply Shows Off Its New Liquid Fertilizer Facility
July 15, 2015
Asmus Farm Supply, Rake, IA, recently added a new liquid fertilizer facility to its company operations. The new liquid fertilizer Read More
CropLife 100Wilbur-Ellis Feed Division Facilities Receive Safe Feed/Safe Food Certification
July 13, 2015
Wilbur-Ellis Co.’s Feed Division, a marketer and distributor of value-added feed ingredients for the aquaculture, livestock and pet food industries Read More
CropLife 100BRANDT Expands To Brazil With Acquisition
July 8, 2015
BRANDT has acquired a majority interest in Target Brasil Fertilizantes Ltda. through its Brazilian subsidiary. Target Brasil manufactures, distributes and Read More
Milan Kucerak, president/CEO, West Central
CropLife 100West Central Cooperative And Its New President Are A Match Made In Deviation
June 29, 2015
To appreciate just how unique West Central Cooperative is in the world of ag retail, an observer need only consider Read More
Winter Wheat
CropLife 100South Dakota Co-op Member Owners Vote No On Unification
June 26, 2015
The Boards of Directors for North Central Farmers Elevator (NCFE) and Wheat Growers (WG) have announced that member-owners have voted Read More
Latest News
StewardshipOhio Water Quality Project To Determine How Much Phosph…
July 27, 2015
Researchers with the College of Food, Agricultural, and Environmental Sciences at The Ohio State University are looking for farmers in Read More
FertilizerKoch Agronomic Services Launches N-TEGRATION Technology
July 27, 2015
Koch Agronomic Services, LLC (KAS) has launched  N-TEGRATION Technology, a process technology platform designed to enable production of enhanced efficiency fertilizers at Read More
HerbicidesExpert: IARC Herbicide Classifications Leading To Confu…
July 24, 2015
Few people in the crop protection industry had heard of the International Agency for Research on Cancer (IARC) before this Read More
ManagementFCI Trade Summit Update & Precision Tank Turns 50
July 23, 2015
Editors Dave Frabotta and Eric Sfiligoj discuss the upcoming FCI Trade Summit in Las Vegas, NV, and how Precision Tank Read More
Palmer pigweed seedhead in cotton
HerbicidesUSDA Deregulates Dow AgroSciences’ Enlist Cotton Trait
July 23, 2015
The USDA today issued its decision deregulating Dow AgroSciences’ Enlist cotton trait in the U.S. The USDA has now completed its Read More
Industry NewsVerdesian Life Sciences Showcases Versatile Product Por…
July 23, 2015
Technology has revolutionized agriculture by bringing farmers, retailers and distributors to the forefront of the digital age. To meet the Read More
FertilizerWSJ: Cf Industries Exploring Merger With Dutch Chemical…
July 23, 2015
U.S. fertilizer maker CF Industries is in advanced merger talks with Amsterdam-listed chemical company OCI NV, the Wall Street Journal Read More
HerbicidesNufarm Releases New Panther SC Herbicide
July 23, 2015
Nufarm has announced the availability of new Panther SC herbicide. Panther SC is the first liquid formulation of flumioxazin available Read More
EquipmentFarmLink Launches Farm Equipment Sharing Program
July 23, 2015
FarmLink has introduced a new online farm equipment sharing community – MachineryLink Sharing – leveraging this new economy business model Read More
HerbicidesCould The South’s Most Troublesome Weed Represent A Thr…
July 22, 2015
Palmer amaranth is undoubtedly the most troublesome weed in the southern United States, taking a devastating toll on both cotton Read More
Industry NewsH.J. Baker Hires New Director Of International Sales
July 22, 2015
Global Agriculture firm H.J. Baker announced today that Steve Langley has joined the company’s Crop Performance Division and Animal Health Read More
InsecticidesSyngenta Recommends Soybean Scouting To Prevent Economi…
July 22, 2015
Proper soybean insect pest control begins with scouting. As the warm weather continues, Syngenta encourages growers to implement a scouting Read More
Crop InputsH.J. Baker Launches Fall Sulphur Campaign
July 22, 2015
H.J. Baker has launched their “Keep Your Future Green – Use Tiger This Fall and Win Big” campaign. The campaign Read More
Central Valley Ag Randolph, NE
Retail FacilitiesStueve Construction Builds Fifth Facility For Central V…
July 21, 2015
Central Valley Ag partnered with Stueve Construction Co. to successfully design and build its Monroe, Oakland, Wakefield and Royal hub facilities Read More
FertilizerNew Research Could Lead To Less Reliance On Nitrogen, E…
July 21, 2015
Farmers often are required to apply nitrogen fertilizers to their crops to maintain quality and improve yields. Worldwide, farmers used Read More
Seed/BiotechMonsanto Targets Farmers, AFBF In Syngenta Takeover
July 21, 2015
As Monsanto Co. struggles to convince rival Syngenta AG to discuss a potential merger, the seed and agrochemical giant is Read More
CHS Building exterior
Retail FacilitiesSackett Helps CHS Expand Blending Facility, Improve Acc…
July 21, 2015
CHS needed a blend plant that could vastly expand their capabilities in St. Charles, MN. The A.J. Sackett & Sons Read More
Industry NewsH.J. Baker Adds To HR Team
July 21, 2015
H.J. Baker announced today that Barbara Sullivan has joined the company’s executive team as Vice President of Human Resources. Prior Read More