קובץ:TVA Results of Fertilizer.gif

מקור http://en.wikipedia.org/wiki/File:TVA_Results_of_Fertilizer.gif

השוואת שדות עם דשן ובלעדיו בטנסי, 1942, הניסוי נועד לבחון את יעילות הדשן כאמצעי לשיפור חיפוי הקרקע למניעת סחף קרקע בדומה לקערת האבק.

Tennessee Valley Authority: "Results of Fertilizer -- This is a test field of a practical operating farm on which TVA-produced phosphate has demonstrated its ability to encourage the growth of a protective vegetable cover and hence build up soil fertility. The thick growth was treated with a mixture of phosphate and lime; the almost bare area was not treated. (53227(1828), 00/00/1942, 27-0921a.gif) Tennessee Valley Authority: "Results of Fertilizer -- This is a test field of a practical operating farm on which TVA-produced phosphate has demonstrated its ability to encourage the growth of a protective vegetable cover and hence build up soil fertility. The thick growth was treated with a mixture of phosphate and lime; the almost bare area was not treated. (53227(1828), 00/00/1942, 27-0921a.gif) Tennessee Valley Authority: "Results of Fertilizer -- This is a test field of a practical operating farm on which TVA-produced phosphate has demonstrated its ability to encourage the growth of a protective vegetable cover and hence build up soil fertility. The thick growth was treated with a mixture of phosphate and lime; the almost bare area was not treated. (53227(1828), 00/00/1942, 27-0921a.gif)הגביר את כיסוי קרקע