EFFECT OF SULFUR SOURCES, RATES AND METHODS OF APPLICATION ON GROWTH, YIELD, FRUIT QUALITY, LEAF MINERAL CONTENT AND SOME SOIL PROPERTIES OF "VALENCIA"

Field experiment was conducted to assess the impact of added two sulfur sources [elemental sulfur (S) and sulfur mixture (SM)) with different rates [S or SM equivalent gypsum requirements SR, SMR and SR or SMR +1- 25%] and 2 methods of application [broadcast under the tree canopy (M1) and banded at the edge of the tree skirt (M2)] at two selected alkali "Valencia" orange orchards in kafr El-sheikh Governorate in two successive seasons, 1998 and 1999 on some soil properties, growth, yield, fruit quality and leaf mineral content . Most soil chemical (pH, SAR, Na/CI, and EC) and physical (A.I, I.R, and Cr) properties were markedly improved by SMR or SR with M1 appli-cation. Moreover, total N and P, K, Fe, Zn, Mn and Cu solubility and avail-ability were increased particularly in the surface layer with slightly Ec in-creasing in the deepest layer. Consequently, the greatest fibrous root density with a more typi‌cal distribution, highest vegetative growth (as indexed by shoot length and number and leaf area and ❑.W) and less preharvest fruit drop were noticed, thus, the highest yield with enhanced fruit quality was obtained. SM treatments gave the highest vegetative growth and yield followed by S treatments. Meanwhile, soil physical and chemical properties improvement were decreased, EC and Ca' percentage were increased and the availa‌bility of many macro and micronutrient were negatively affected by more S or SM addition than SR or SMR treatments. Therefore, the vegetative growth and yield were decreased compared to S or SM treatments. SMR or SR application with M1 slightly increased leaf N, P, Fe, Zn, Mn and Cu while K was slightly decreased, however, they were progres‌sively decreased with increasing S or SM particularly rnicronutrients with‌out significant differences among all S or SM treatments. It could be concluded that SMR or SR application with M1 was the best treatment to improve or to conserve, increase fertilizers use effi‌ciency and may overcome salt effects for increasing the productivity of "Valencia" orange trees with best fruit quality.