Evaluation of four soil amendments in ameliorating toxic conditions in three orchard subsoils.
Baugher T. A., Singh R. N.
Author Affiliation: Div. Plant and Soil Sci., West Virginia Univ., Morgantown, WV, USA.
Applied Agricultural Research 4 : 111-117
Abstract : Rock phosphate was compared with limestone, superphosphate and lime plus superphosphate for controlling Al and Mn toxicities in acid soils of apple orchards. Rock phosphate was acidulated in three soils (pH range 3.5-5.5). Soil pH increased, soil and plant contents of Ca, Mg and P increased and soil and plant contents of Al and Mn decreased to nontoxic levels. Root and shoot growth improved and the incidence and severity of internal bark necrosis decreased. Rock phosphate was less effective than lime or lime plus phosphate in increasing pH and decreasing Mn and Al; exchangable Al and available Mn were well below the toxic range, however, and nutrient levels were satisfactory. Eight years after application, rock phosphate still affected soil Ca and P levels. Some lime plus phosphate treatments affected soil pH and soil Mn, although lime and phosphate alone had no residual effects.