Effects of Elemental Sulfur, Phosphorus, Micronutrients and Paracoccus Versutus on Nutrient Availability of Calcareous Soils (Report‪)‬

Introduction S deficiency is a very common phenomenon in Asia, North America and Western Europe. Elemental S is widely used in Canada, New Zealand, Australia and China to alleviate S deficiency (Slaton et al., 2001; Hu et al., 2003). Most of the agricultural land of United Arab Emirates is calcareous soil that contains relatively high amounts of CaC[O.sub.3] and extremely poor organic matter resulting in high pH (Abdou, 2006; Khaled et al., 2006). Poor availability of nutrients rather than low nutrient content is one of the major factors for the widespread occurrence of plant nutrient deficiency in calcareous soils. The nutrient uptake of plant is governed by numerous soil factors. Among them, high soil pH and CaC[O.sub.3] contents are predominantly responsible for low availability of plant nutrients (Kaya et al., 2009). Under unfavorable soil conditions with high pH and CaC[O.sub.3], only with application of N, P and K fertilizer can't resolve the nutrient deficiency. The nutrient availability of soils can be increased with the application of [S.sup.0]. Thus, there is a growing interest in S applications to improve availability of nutrients and overcome nutrient deficiencies in both alkaline and calcareous soils (Dawood et al., 1985; Neilsen et al., 1993). Because of the high cost and adverse effects of commercial fertilizers especially N, P and K fertilizer, use of natural sources, micronutrients and [S.sup.0] may be used as a nutrient and soil acidifier (Neilsen et al., 1993) and [S.sup.0] fertilizer has recently gained importance in agricultural production (Bender et al., 1998; Erdal and Tarakcioglu, 2000; Atilgan et al., 2008). An individual application of [S.sup.0] or combined with Fe dropped soil pH in calcareous soil (Abbaspour et al., 2004) but application of [S.sup.0] combined with N fertilizer significantly increased the availability of micronutrients (Erdal et al., 2004). Sulfur is a constituent of the amino acids cysteine and methionine and part of proteins that plays an important role in the synthesis of vitamins and chlorophyll in the cell (Marschner, 1995; Kacar and Katkat, 2007). As a result of S deficiency, plants show retarded growth (Motior et al., 2011) and reduction in yield and quality. The efficacy of [S.sup.0] to satisfy the S demand of crops depends, however, on speed and magnitude of its oxidation to S, which is taken up by plants (Yang et al., 2010). The effectiveness of [S.sup.0] is governed by its oxidation rate, which is primarily a microbiological function. Thus physical factors such as soil temperature and moisture play an important role in regulating S oxidation (Janzen and Bettany, 1987). The oxidation of S into [H.sub.2]S[O.sub.4] is especially beneficial for alkaline soils for increasing nutrient availability by reducing pH (Nielsen et al., 1993). Elemental S is the standard acidulant applied to soil for pH reduction (Slaton et al., 1999). The reactivity of CaC[O.sub.3] is considered an important property of soil which influences soil chemical and rhizosphere processes (Loeppert and Suarez, 1996) and management of soil pH for optimum nutrient availability has to be considered for quality crop production (Slatoon et al., 1999). Application of [S.sup.0] increased the availability of P and micronutrients to correct their deficiencies in alkaline and calcareous soils (Hilal and Abd-Elfattah, 1987) and increased the chemically available P from native soil apatite or added rock phosphate (Garcia and Carloni, 1977), while in others it increased available P only when P-fertilizer was added to the soil but soil P was not affected (Gupta and Mehla, 1980). Application of [S.sup.0] has been suggested as an option with regard to reclamation of alkaline solonetzic soils (Rupela and Tauro, 1973). The acidity produced during [S.sup.0] oxidation increases the availability of nutrients such as P, Mn, Mg, Ca, and S[O.sub.4] in soils (Lindemann et al., 1991). The oxidation of [S.sup.0] in calcareous soils is a