The following graphs show total harvested acres for certain crop types within the COHYST study area. Also included are graphs showing irrigated vs. non-irrigated acreage totals for selected harvested crops. These graphs show trends in crop types and irrigation usage for each county within the COHYST study area from the 1946 to 1997. Also, this crop data is summarized in 5 designated areas as seen in the handout presented at the last Technical Meeting.

For this analysis, historic crop production for each county and the five designated areas is based on data from the dnr website and the annual Nebraska Agriculture Statistics Report from 1946 to 1997. Certain crops are grouped together for developing the graphs. In one category, 'Corn', includes corn for grain and corn for silage. The second category, 'Hay', includes all alfalfa and natural grasses used for hay. The third category is 'Soybeans', and the fourth category, 'Sorghum,' consists of both grain sorghum and sorghum silage. The fifth category, 'Others' includes oats, sugar beets, and dry beans. Each graph now includes 'Wheat', which is all wheat harvested in the county or area for that time period. Wheat was not included in the graphs for all areas in the first set developed.

 Harvested Acres Databases and Graphs for COHYST Areas

For the Irrigated vs. Non-Irrigated Harvested Acre graphs, data was obtained from the Nebraska Agricultural Statistics (NAS) annual distributed by the Nebraska Department of Agriculture. The crops selected for these graphs were chosen since they had the most consistent data on both irrigated and non-irrigated harvest totals. The definition of the crop types used for the graphs changed over time in the NAS annual. For example, only certain types of corn and sorghum contained irrigation data. For the 1955 and 1958 data, the NAS annuals designated irrigation and non-irrigation data as 'corn for all purposes.' In the 1967 - 1997-98 NAS annuals, irrigation data for corn was divided into 'corn for grain' and 'corn harvested for silage'. These values were thus added to get a total of corn acres irrigated or non-irrigated for each area.

For sorghum, no irrigation data was available for 1955. For the1958-1967 annuals, sorghum data was categorized as 'all sorghums harvested for grain.' For the 1970-1980 annuals, data was compiled from the categories 'all sorghums harvested for grain' and 'all sorghum harvested for silage.' Later issues of the annual only included irrigation data on 'all sorghums harvested for grain.' Therefore, not all harvested acres for a certain crop are included in some of the data compilations. However, the bar graphs show definite trends in irrigated versus non-irrigated crops even without all of the harvested acres included in the data. Irrigation data for wheat was not available until 1964, therefore the graphs show an apparent jump from zero to thousands of acres at this time.

Also included are graphs showing the harvested crop and irrigation trends on a COHYST-wide basis. Data from each category and area was compiled to show trends over the entire study area from 1946 to 1997.

 Irrigated vs. Non-irrigated Databases and graphs for COHYST Areas 

Some items to note:

- Data for irrigated vs. non-irrigated soybeans on the Area 1 graph was not included due

to the lack of acres planted. The records show that the only soybeans planted in this

area were 600 acres in 1985, 1100 acres in 1988, and 300 acres in 1991, all on irrigated

land.

- Irrigation data for irrigated and non-irrigated acres of wheat was not available until

1964.

- Irrigation data for soybeans and sorghum was not available until 1958.

- Although approximately 20% of Grant County is within the COHYST area, the only

crop planted on a year to year basis is hay. The county averaged 550 acres of corn and

silage from 1974 to 1993, had 200 acres of sorghum and wheat each and 70 acres of oats

over the entire 51-year time span. The lack of diversity and changing trends in crop

practices led to Grant County being excluded in the data compilation.

 Trends in Crop Practices

Here are some trends I noticed from the charts:

-Over the entire COHYST Study area, there is a decline in corn production from 1946

until the mid-1960's. Corn production rose significantly from 1964 to the late 1970's,

leveled off, then increased again in the 1990's. This trend was quite apparent in many of

the county graphs.

-Corn production remained the most steady in Area 1 counties (panhandle area).

-Significant amounts of soybeans appeared on the scene around 1970 and increased each

year after.

-Wheat production remained relatively steady over the time period.

-Counties within Areas 4 and 5, (the eastern half of the study area), showed significant

decrease in harvested acres of 'Others' (sugar beets, oats, dry beans) from 1946 to the

1960s. Conversely, Area 1 (panhandle) showed a very consistent trend in crops

designated 'Others', while counties within Areas 2 and 3 showed consistent or increasing

trends as the century progressed.

-Sorghum production in all areas but #4 appears to peak in the early to mid 1960's and

decline steadily until 1997. Area #4 shows slight declines, but relative to the other areas,

decline in production is much less pronounced.

- A very obvious trend in corn production for the entire area is non-irrigated corn

dominating production from in the late 1940's and early 1950's, with an explosion of

irrigated corn production occurring in the late 1950's and 1960's. During this time,

non-irrigated corn production decreased dramatically. However, in all areas but #1,

non-irrigated corn made a slight comeback from the 1980's to the present. In area #1,

once irrigated corn production took over, the practice remained and very little non-

irrigated production occurred thereafter.

- In all areas, non-irrigated sorghum dominates production of this crop. The same trend is

apparent with wheat.

- Irrigated and non-irrigated soybean production began simultaneously, with a trend of

irrigated soybeans being more prevalent, however, in many areas, the number of acres

of each appears to be even.

- In the eastern half of the study area, non-irrigated alfalfa was dominant, while in areas

#1 and 2 irrigated alfalfa was typically produced at a higher volume.

- Irrigated wheat production appears to increase significantly in the late 1970's.

For the compilation of data for historical crop acreage and irrigation use, 5 areas were used based on the locations of NRDs in Nebraska. The North Platte and South Platte NRDs are designated as area no. 1. Counties within the Twin Platte NRD are designated as area no. 2. The Upper and Middle Republican NRDs are designated as area no. 3. The fourth area is comprised of counties in the Tri-Basin, Little Blue and Lower Republican NRD's, and the fifth includes counties within the Central Platte and Upper Big Blue NRD's.

Counties within each area are:

Area 1 - Deuel, Cheyenne, Kimball, Garden, Morrill, Banner, Scottsbluff, Box Butte, Sioux, Sheridan

Area 2 - Lincoln, Keith, Arthur**, McPherson**, Logan*

Area 3 - Perkins, Chase**, Hayes, Frontier, Red Willow*, Hitchcock*

Area 4 - Gosper, Phelps, Franklin**, Furnas*, Harlan*, Nuckolls**, Webster**

Area 5 - Adams, Buffalo*, Clay, Custer, Dawson, Hall, Hamilton, Howard*, Kearney, Merrick, Nance*, Platte*, Polk, York

* counties that have less than 50% of land area within the designated area.

** counties with less than 100% but over 50% of land within the designated area.