Show I Soil Building I IThe The difference between soil building building building build build- ing and soil mining is shown in the chart below Soil building means increasing the soils soil's organic matter matterand matterand matterand and plant food supply and maintaining maintaining maintaining maintain maintain- ing high crop yields It means feeding feeding feeding feed feed- ing the soil and letting the soil feed the crops rather than trying to feed each individual crop The comparative results shown here were obtained at the Ewing soil experiment field in Illinois One plot has had no soil treatment since the field was established in 1910 Theother The Theother Theother other plot has had large amounts of TREATED WITH MANURE LIME PHOSPHATE SOIL NOT TREATED cOr i 02 l 20 acm p n 2 o s rr NORE 16 TONS OF 5 ORGANIC MATTER Of PER ACRE OM lime phosphate and potash to get heavy stands of rooted deep-rooted legumes leg leg- umes Corn stalks have been returned returned returned re re- re- re turned to this plot The rotation on both plots has been corn oats clover clover clover clo clo- ver and wheat Cr Crop p yields covering a year four-year rotation tell the story Corn production production production pro pro- on the fertilized plot was four times greater than on the untreated untreated untreated un un- treated field oats nearly four times and wheat about eight times great great- er Clover yield on the fertilized plot was 19 tons per acre the untreated untreated untreated un un- treated plot is too acid to grow legumes Despite the greater amounts of nitrogen and organic matter used in producing the higher yields the fertilized fertilized fertilized fer fer- plot still contains 4 4 tons more organic matter and pounds more nitrogen than the untreated field |