ChileanJAR

ln a pot experiment, fertility deficiencies of 73 soil samples from the Arauco province are detected, using Lolium perenne x Lolium muítifíorum. The fertilization treatments are choosen by the missing element technique. This originates one treatment with complete fertilization and six other treatments, by omiting, one by one, the following nutrients: P, K, Ca, Mg, S, and microelements (B, Mo, Zn, Cu, and Mn). Results from four cuttings are interpreted according a fertility diagrarn. Soil pH is not associated with Ca or Mg cleficiency or its intensity, Ca deficiency occurs only occasionalty, and Mg deficiency is more frequent. Every soil Iow in Ca or Mg has also a severe deficiency in microelements or, if such is not the case, in K. It is believed that Ca or Mg deficiency may be caused by an antagonic effect, due to the Iack of sorne microelementor of K. P, K, S and rnicroelements are identified as the rnain soil deficiencies of these soils. P is the rnost severe and common deficiency; the inclusion of this esernent in ihe correction fertilization is considered rnandatory. The only sample rich in P is found in Meirupe, close to the Arauco city. In many sois co-exist, three or more deficiencies, generating complex fertilization problems. It seems essential to deterrnirie the specific microelement deficient at the farrn leve, before including these elements in the fertilization formula. The steep negative sopes for the fertility unes of P, K, S, and rnicroelernents, indicate that these elernents must be included in the rnaintenance fertilization, to obtain and maintain a high level of fertility. P and K deficiencies show a tendency to increase with depth.