Sulfur Bentonite
Sulfur Bentonite
Manufacture Sulfur Bentonite
Sulphur Bentonite is one of the concentrated source of sulphur. Sulphur is involved in metabolic functions of plants and is a constituent of amino acids. It also helps in chlorophyll synthesis and improves efficiency of other nutrients. Sulphur is a key element in oilseed production. It leads to improvement in yield of crops and oil content. Sulphur bentonite contains 90 % S and 10 % Bentonite clay which serves as binder during manufacture and as a dispersing agent after addition to soils.
Elemental Sulphur
The use of elemental S to reduce soil pH and to reclaim sodic soils is well known. However, its function as a fertilizer source of S has greatly increased its use in agriculture with the limited production and availability of other sulphur-containing fertilizer materials.
Elemental S is a yellow, inert, water-insoluble crystalline solid. Commercially it is stored in the open, where it remains unaltered by moisture and temperature changes. When S is finely ground and mixed with soil, however, it is oxidized to SO4-2 by soil microorganisms. The effectiveness of S in supplying S to plants compared with SO4-2 depends on several factors, including particle size, rate, method, and of application; S oxidizing characteristics of the soil; and environmental conditions. S oxidation rate increases as particle size is reduced. The finer the S particle size, the greater the surface area and the faster the SO4-2 formation. Thus, increases in the S surface area results in increased SO4-2 availability to crops.
When S is finely ground and mixed with soil possessing a high oxidizing capacity, it is usually just as effective as other sources. Time of application is especially important with S products. Finely divided S should be worked into the soil as far ahead of planting as possible. Placement of S can often affect its oxidation rate, with broadcasting, followed by incorporation, being superior to banding. Uniform distribution of S particles throughout the soil will 1) provide greater exposure of S particles to oxidizing microorganisms, 2) minimize any potential concerns caused by excessive acidity, and 3) provide more favorable moisture relationships.
If S is placed on the soil surface and compared with SO4-2 placed similarly, the SO4-2 may initially give better responses. Because of its solubility, it can move into the root zone with percolating waters. The S must first be oxidized to SO4-2 . This is not a rapid process, particularly when left on the soil surface. In the case of granular elemental S products, a period of exposure on the soil surface to wet-dry and freeze-thaw cycles is required to disrupt the granules and disperse the S. This dispersion process prior to soil incorporation is essential for satisfactory conversion of S to plant available SO4-2 . With the exception of perennial crops, topdressing of S sources is not normally recommended, and in all cases, elemental S should be applied well in advance of crop need.
Sulphur Bentonite
A variety of S-bentonite fertilizers have been produced to improve the effectiveness of granular elemental S products by incorporating, typically 10% by weight of swelling clay such as bentonite. Particles of S-bentonite are sized for blending with solid N,P, and K fertilizers. When it is applied to soil, this bentonite component imbibes soil moisture, causing fertilizer granules to disintegrate into finely divided S, which is more rapidly converted to SO4-2 . This material has gained wide acceptance as a source of plant nutrient S for high analysis, bulk blend formulations because it provides elemental S in an acceptable physical form that can be converted easily into the SO4-2 form in soil.
Because of variable oxidation rate of these S sources during the first growing season after application, it should be incorporated into soil prior to planting. When it is applied just before seeding and on severely S deficient soils, some SO4-2 should also be provided. Repeated use of elemental S containing fertilizers tends to gradually enlarge the population of S-oxidizing microorganisms, resulting in a corresponding increase in the rate of SO4-2 formation.
