The first experiment fields were established in 1901 on tracts of rented land. Since 190S fields have been located only on land donated by the community and deeded to the state. In 1916 there were 39 fields, 12 of which were rented and 27 owned by the state. The names and locations of the fields are shown on the accompanying map.
The diagram of the Urbana Experiment Field on page 160 represents a typical experiment field of 20 acres. The field is divided into 5 series corresponding to the different fields of a farm. Each series is divided into 10 plots so that ten methods of soil treatment may be tested on the plots of each series. Each plot covers exactly one-tenth of an acre. The results are then easily converted into acre units.
On this field two dif ferent systems of farm ing are practiced: a live-stock system and a grain system. In the live-stock system, the grains, hay, and forage are fed to live stock; the cornstalks and straw are used for bed ding. The resulting manure is returned to the land and constitutes the important source of nitrogen and organic matter for soil improve ment. In the grain system, the nitrogen and organic matter are maintained by plowing under all crop residues after the seed is removed (cornstalks, the straw from wheat, Oats, soy beans, clover, and some cover crops). Under this system, the grain, the alfalfa, and the clover or other legume seeds are marketed. Alfalfa is regarded as a money crop, since sufficient residues are provided in the regular four-year rotation to supply the needs of the non-legumes for nitrogen.
In both systems of farming there are check plots which do not receive any treatment. The only benefits the soil receives are those which are in cidental to the rotation. Everything is removed from the land, and nothing returned; which means a gradual de crease in productive power and eventual land ruin. The purpose of these plots is to show by comparison the value of the treatment. The other plots receive defi nite treatments in such a way that the definite needs of the soil may be determined; whether it be manure or residues alone, or lime in addi tion, or lime and phos phorus in addition that must be applied in order to insure greater pro duction. To two plots in the series potassium is added in order to obtain information in regard to the possible need for that element. In both systems of farming,
provision is made for the maintenance and the increase of those elements of plant food and those physical conditions necessary for the best plant growth as indicated by the soil survey, the soil analysis, and other sources of knowledge.
It will be noted in the diagram that those plots whose numbers end in 1 receive no treatment; those ending in 3, 5, 7, and 9 receive manure and therefore illustrate live-stock farm ing; those ending in 2, 4, 6, and S receive residues and thus illustrate grain farming; while 10 has residues in the form of cover crops and also manure, thus representing a combination of live-stock and grain farming. The actual yields of the experi ment field, year after year, when studied in relation to soil treat ment, reveals unmistak ably the methods of scientific farming best adapted to the farms of the locality having the same soil type as the experiment field. Very few farms of Illinois are as far as 50 miles from one of the permanent experiment fields.
Some practical re sults.—The Blooming ton Experiment Field is located about two miles northeast of Blooming ton on the brown silt loam prairie soil of the Illinois corn belt.
It is typical of extensive areas of farm lands in central Illi nois. The total crop values per acre during thirteen successive years, 1902 to 1914 inclusive, are shown in Table II, on page 162, and indicate clearly that soil improvement is not only possible, but extremely profitable, on the most fertile tracts of Illinois soils. The prices used in this table are much lower than the war-time prices of later years.
The plot which received no treatment yielded, in thirteen years, crops valued at $266.90 per acre, or an average of $20.53 per acre per year; while the plot treated with lime and phosphorus yielded, during the same period, crops valued at $409.45 per acre, or an average of $31.50 per acre per year, a gain of $10.97 per acre per year, at a cost of $2.50 per acre per year, leaving a net gain of $S.47 per acre per year with a much improved and a much more valuable soil than now found on the untreated plot. Since $8.47 is 6 per cent of $141, land receiv ing the scientific treatment may be capitalized at $141 more per acre than the untreated land.