Agronomy, by the question you are asking
Every rate and threshold here comes from a university extension guide or a replicated trial, named and dated where it shows. Prices, forecasts and satellite data are named on their cards. Nothing is for sale. Where the trials do not agree or do not exist, the page says so. Checked November 13, 2026.
Fertility: what to put on, and what it costs
Corn nitrogen rate
How much N for corn at posted fertilizer and corn prices, by soil and last crop, with legume credits.
Source: UW Extension A2809 (Wisconsin), 2012 printing, Table 6.1Nitrogen credits
What manure, alfalfa and other legumes give back, so you do not pay for the same pound twice. Soybeans before corn add nothing here, because the rate table already counts them.
Source: UW Extension A2809 (Wisconsin), Chapter 9, 2012 printingP and K by soil test
Enter your soil test, get the phosphate and potash rate, for corn, soybeans, silage and alfalfa.
Source: UW Extension A2809 (Wisconsin), Tables 7.1, 7.2 and 7.4Lime and micronutrients
Soil pH targets, a lime requirement calculator, and which crops need zinc, manganese, boron or sulfur.
Source: UW Extension A2809 (Wisconsin), Chapter 5 (lime) and Chapter 8 (micronutrients)Fertilizer prices
Posted co-op cash prices per ton and per pound of nutrient, and a fertility bill for your own program.
Source: Co-op prices, each dated on its rowNutrient removal
P and K hauled off in grain, stalks, straw, silage and hay, and what it costs to put back.
Source: UW Extension A2809, Table 4.2; Iowa State; PurdueManure value
What the N, P and K in your manure are worth, by type, with a calculator.
Source: UW Extension A2809, Tables 9.1 to 9.3Urea nitrogen loss
How much surface urea can be lost to the air today, and what NBPT does and does not do.
Source: Montana State Extension, EB0209Fall anhydrous timing
Whether the soil is cold enough yet, by county, and what each state's extension says.
Source: Iowa State, Illinois Agronomy Handbook and other state guides, named on the page
Planting and stand
Planting date
The corn and soybean planting window, yield by planting date, and soil temperature.
Source: University of Minnesota (corn); UW Extension (soybeans)Growing degree days and crop stage
GDUs from your planting date on real weather, projected black layer, and frost risk.
Source: Purdue NCH-40 for the corn stage tableCorn and soybean growth stages
What the plant is doing at each stage and what to watch.
Source: Purdue NCH-40
Pests: diseases, insects and weeds
Tar spot of corn
How to tell it from look-alikes, when to scout, whether a fungicide pays, and the break-even.
Source: University extension sources, each named and dated on the pageInsect thresholds
When to treat corn and soybean insects: the count to use for each pest, and when it applies.
Source: UW Extension A3646 and L023; Iowa State; SDSU; University of Minnesota, each named on the pageHerbicide groups
Site-of-action group numbers and what resists what, with the waterhemp resistance record.
Source: Weed Science Society of America classification (checked Oct 16, 2026); Ohio State ANR-78Can I spray?
Wind, temperature, humidity and inversion risk for a spray window at your location.
Source: National Weather Service forecast; label and state rules as the page names them
In season and harvest
Field Scout
Draw a field and see its soils, ten years of crops, and satellite greenness. It points, it does not diagnose.
Source: USDA soil survey and Cropland Data Layer; Sentinel-2 imageryYield estimator
Pod counts for soybeans and ear counts for corn, turned into bushels an acre.
Source: Purdue, Iowa State, Ohio State and Penn State Extension methodsCombine loss
Count beans or kernels in a frame behind the combine and get bushels an acre lost.
Source: Nebraska CropWatch; Iowa State; NDSUHarvest now or wait
The drying bill today against the bill after a week or two of drydown.
Source: NDSU (Hellevang); Iowa State; PurdueAeration fans
When to run fans to dry, cool or hold grain, hour by hour at your ZIP code.
Source: Minnesota, Iowa State and NDSU ExtensionShrink and moisture discount
What wet grain nets at the elevator after shrink and drying charges.
Source: Iowa State; Nebraska CropWatch; Extension FSA1078
How we choose sources
What counts: university extension guides and replicated university trials, each with its date. A product label counts for what the label says, such as a guaranteed analysis.
What does not: company trials, testimonials, dealer claims, and tests that were not replicated.
Products: none is sold here. A product name shows up only where a university table uses it to find a group or a rating, never as a recommendation. We make no claim for biologicals or yield boosters without independent replicated trials.
Your state: the fertility tables are Wisconsin's (UW Extension A2809) unless a table names another source. Other states set their own rates; use your state's guide outside Wisconsin.
Not on this site yet
These are gaps. They are listed so you do not look for them here.
- Corn replant: when a thin stand is worth tearing up. Needs a university replant table read and dated first.
- Soybean stand and replant, the same way.
- Soil test pages for states other than Wisconsin. The P, K, lime and nitrogen tables here are Wisconsin's (UW A2809). Each state sets its own, and a state is added when its guide has been read.
- Hail damage to a crop by growth stage.
- Cover crops.
- Crop diseases other than tar spot.
- Herbicide plant-back intervals and a stand-alone herbicide group page (the group table is in Fast Facts today).
- Biologicals, biostimulants and yield boosters. We make no claim for them without replicated, independent university trials, and we sell none.
Questions
Where do the numbers on these pages come from?
Every rate and threshold comes from university extension guides and replicated university trials. Each page names its source where the number shows, with a date. Prices, forecasts and satellite data are named on their cards. Where trials disagree or do not exist, the page says so.
Does AGSIST sell or recommend any product?
No. Nothing here is for sale. A product name appears only when a university table uses it as a lookup key, such as a fungicide rating or a herbicide group. It is never a recommendation.
Are the rates for my state?
Not always. The fertility tables are Wisconsin's (UW Extension A2809) unless a table names another source. Other states set their own rates, so use your state's guide outside Wisconsin.