Suitability of Extractants for Predicting Available Sulfur in Natural Grassland in the Inner Mongolia Steppe of China

Abstract

It was the objective of this study to compare the suitability of different extractants for predicting the availability of sulfur (S) in natural grassland in a sulfur response trial on three different soil types in the Inner Mongolia steppe of China. For soil analysis, seven different extractants have been employed. The inorganic SO4-S concentration was determined by ion chromatography. Additionally, in the Ca(H:P04)i extract the total soluble S was determined employing turbidimetry. Weak salt solutions (0.15% CaCI., Ca(H2PO4)2, and KH2PO4) extracted similar 721 722 X. Y. Cui et al. amounts of SO4-S. Extraclion with 0.025 M KCl provided the lowest SO4-S values.Deioni/ed water dissolved significanily more SO4-S in Ihe conlrol plots than most weak salt cxtraclaiits. The concentration of soluble organic S decreased in Ihe control plots after 1 (X) days of plant growth, indicating that the organic S pool contrihuted significantly to the S nutrition of the forage crops. Significant relalionships among the SO4-S in the soil determined in different exti'acts and crop yield, sulfur content in the forage, and total sulfur uptake were only found for the Ca(H2PO4)2 extract. In general, the correlation coefficients proved to be unsatisfactory for field experimentation.

Effect of Sulfur on the Yield and Essential and Nonessential Element Composition of Alfalfa Determined by Polarized Energy Dispersive X‐ray Fluorescence

“…This implies that S could have been limiting for plant growth without added gypsum, and some at least of the yield increase with supplemental gypsum came from enhanced S nutrition. Similar increases in tissue S concentration have previously been reported for alfalfa and many other crops (Carter and Cutcliffe 1990;Toma et al 1999;Inal et al 2003;Prasad 2003;Cui et al 2006). …”

“…Toma et al (1999) have previously reported a positive response of alfalfa to applied gypsum S, and Prasad (2003) reported yield increase when gypsum was applied to groundnut. Additionally, increases in forage yield in response to S application to natural grassland (Cui et al 2006) and Brassica rapa L. (Pascale et al 2007) have been reported.…”

Variations in essential and non-essential element composition and yield of silage corn fertilized with sulfur

“…Similar increases in tissue S concentration were also reported for corn (Rehm 2005;Weil and Mughogho 2000) and many crops (Carter and Cutcliffe 1990;Toma et al 1999;Inal et al 2003;Prasad 2003;Cui et al 2006).…”

“…Previously, Rehm (2005) and Weil and Mughogho (2000) was also reported positive effect of S fertilization on silage corn. Additionally, Toma et al (1999), Prasad (2003) and Cui et al (2006) reported positive response of alfalfa, groundnut and natural grassland to applied gypsum-S, respectively. Applied gypsum as an S source supply also Ca to soils and plants.…”

Comparative evaluation of Ca chloride and Ca phosphate for extractable sulfur in soils with a wide range in pH

“…On the suitability of various extractants, it has been stated that Ca phosphate seems to be one of the best extractants, because phosphate ions displace the adsorbed sulfate, especially in acidic-pH soils and Ca 2+ ions flocculate the soil colloids (Fox et al, 1964;Harward and Reisenauer, 1966;Maynard et al, 1987;Schmalz et al, 2001). Among the several factors that influence sulfate sorption-desorption and its extractability by various reagents used for sulfate extraction, soil pH plays a dominant role, and generally the sorption of sulfate is low in soils with pH > 6 (Ensminger, 1954;Curtin and Syers, 1990;Shahsavani et al, 2006;Cui et al, 2006).…”