Night heat, water, the loss record and what the land is worth

How each layer is measured

Night heat. NOAA NCEI's nClimDiv county dataset gives, for every county, the monthly mean of each day's minimum temperature since 1895. I keep July, the silking month across most of these states, and August, the grain-fill month where the cited harm from warm nights is measured. The recent level is the mean of the last ten Julys (at least eight must be present). The trend is an ordinary least squares line through the Julys since 1976, reported in degrees per decade with a 95% confidence interval; a county gets a direction only when that interval, as printed, excludes zero, and no trend at all with fewer than forty of the years present. 1976 sits at the cold end of the record, which flatters a warming slope, so the slope through the whole record from 1895 is printed beside it in the arithmetic. Decade means run from the 1900s; a decade needs five Julys to print and ten to count as complete. A hot July is one whose average low was at or above 70 F: extension research puts the harm line for corn at nightly lows above 70 F, and a monthly average at that line means most nights were over it. North of Kansas that is rare, and the count says so; the decade means and the slider carry the Corn Belt story.

Water. Two official sources, neither produced by AGSIST. The irrigated share is irrigated harvested cropland over all harvested cropland from the 2022 Census of Agriculture; where NASS suppressed the irrigated figure it stays suppressed here, and where NASS published no irrigated row at all, which is what happens when no farm in the county reported any, the county shows none reported. The groundwater share is crop-irrigation withdrawals from groundwater over all fresh crop-irrigation withdrawals in the USGS county water-use estimates for 2015, the latest county release; USGS builds those from irrigated acreage and application rates, not meters, so they are estimates. Water withdrawn per irrigated acre comes from the same file and includes conveyance losses, so surface-water districts read high. The irrigated rent premium is separate: it is NASS's own survey of what tenants pay, and it needs at least six paired years before a trend is printed.

The loss record. USDA RMA's cause-of-loss files, one per crop year from 1989. Every crop indemnity dollar in the county is grouped by the peril that caused it and summed by period: 1989 to 1999, the 2000s, the 2010s, and 2020 on. Pasture, rangeland and forage rainfall-index policies are left out, because they pay on a rainfall index rather than a destroyed crop and in ranch counties they would swamp everything else; the dollars left out are printed. Area and index plans on crops (GRP, GRIP, ARPI, SCO, STAX) pay on a county outcome and RMA assigns them no peril; they are carried as peril not assigned rather than guessed into drought. Price decline stays in the denominator, so a revenue-protection county's 2014 and 2015 show up as price, not weather. Prevented planting sits inside excess moisture. Dollars are nominal and participation grew sharply after 1994 and 2000, so the shares by period are the comparable numbers, not the dollars. The heat-and-drought share by period is the number to watch. Irrigation failure is its own group: it is failure of the irrigation supply or equipment within the policy period, and aquifer decline is not an insured cause, so it is a narrow signal, not the Ogallala. The current crop year is partial until RMA closes it and is marked. The cause-of-loss files carry premium only for policies that had a loss, so no loss ratio is computed from them; that comes from the next layer.

Loss ratio. RMA's Summary of Business county files (sobcov, one per crop year from 1989) carry every policy in the county whether it paid or not: liability, total premium, subsidy and indemnity by crop, plan and coverage level. Indemnity over that premium is the loss ratio as RMA defines it, and 1.00 means the county's book paid out exactly what it took in. It is summed over the whole record, over the last ten crop years, and by the same periods as the loss record; it prints only above $1,000,000 of premium, and a period prints only with at least five of its years present. Rainfall and Vegetation Index plans are left out here too, so the two RMA layers describe the same book, and the ratio of the two files' indemnity totals is printed as a check. The premium is the whole premium, farmer-paid plus federal subsidy, because that is what the ratio means to the program; a farmer's own premium is a fraction of it.

Land value. The Census of Agriculture asks every operator the market value of their land and buildings; NASS publishes the average per acre by county for 2012, 2017 and 2022. It is the only county land value on one method across all fifteen states, and it is what it is: operators' estimates, buildings included, five years apart. Beside it, the county's non-irrigated cropland cash rent for the census year divided by that value, printed as a gross percentage. No modelled value, ever, unless it ships with a backtest beside it; the one vendor that prints an accuracy for its model prints ±25%.

CRP. FSA's county statistics: acres enrolled by year since 1986, and acres whose contracts expire by fiscal year. The share is CRP acres over CRP acres plus 2022 harvested cropland, the county's arable base. Acres expiring in the current and next two fiscal years are summed and printed against the enrolled total. FSA publishes county names; they are joined to FIPS by name and a name that does not match is listed, never guessed.

Drought. The U.S. Drought Monitor's county statistics, one record per weekly map since January 2000. A week counts when at least half the county's area was in D2 (severe) or worse; D3 (extreme) or worse is counted the same way. Weeks are summed by year, over the record, and over the last five full years; a year needs forty weekly maps to count as full. The Monitor is a map drawn by people from many indicators, not a rain gauge, and it is the map that USDA's disaster designations and livestock forage payments key off, so it is the drought that the program world recognises.

Solar and wind. EIA's Form 860 lists every generator of 1 MW or more at a grid-connected plant, with the plant's county and coordinates; the Operable tab gives what runs and the Proposed tab what developers have reported with a planned year. Solar, wind and battery nameplate MW are summed by county, with the year the first solar and first wind generator came online. A county with no plant in the file reads zero, not missing, because the file is a census. Proposed is not the interconnection queue; much of it is never built, and the queue itself is a later layer.

Wells and water rights. Two states publish an open register that this page has read and verified: Nebraska's registered wells (every well, with use, status, depth, static level at completion and completion date) and Kansas's WIMAS points of diversion (every point, with use, active flag, source of supply and the right's priority date). Nebraska counties show wells, irrigation wells not decommissioned, median depth, median static level and completions by decade; Kansas counties show points, active irrigation rights, the median priority year and the source split. Every other state reads "no open register read yet", which is the truth: some have one behind a login or a fee, some have none. Water-level change over the High Plains aquifer (USGS) is a layer to add once its file can be fetched from a runner.

Rent and yield. County cash rent and county corn yields are the same NASS series that drive Cash Rent by County. The yield trend here is fitted on every published year since 2008 and labelled with its window; that page's own trend uses the last fifteen years, which as of 2026 starts on the 2012 drought, and the two are different windows, not two answers. The rent change is nominal dollars over about ten years, using the closest published year at or before ten years back, because NASS published no county estimates for 2015 or 2018 and some counties skip years. The worst year is an observation, not a fit: the lowest published yield since 2008 as a share of the county's median over the same years.

What is never done. No number is interpolated from a neighbour. No layer is scaled, weighted or added to another. No owner name appears on this page. No land value is modelled. A county with nothing published shows a dash and the reason. The states covered are Iowa, Illinois, Indiana, Ohio, Michigan, Wisconsin, Minnesota, Missouri, Nebraska, Kansas, South Dakota, North Dakota, Oklahoma, Colorado and Texas.

Sources