“…Soil analysis. For soil analysis the following methods were used: texture (Bouyoucos,195 1); cation exchange capacity (Richards, 1954); total nitrogen (Jackson, 1962); available phosphorus (Olsen et al, 1954); potassium and sodium (Richards, 1954); calcium and magnesium (Chapman and Pratt, 1961); zinc (Stewart and Berger, 1965); copper (Bould et al, 1949); iron (Olson, 1948); boron (Silverman and Trego, 1953); manganese (Hoff and Mederski, 1958); molybdenum (Purvis and Peterson, 1956).…”