Study On Test Method Of Soil Available Sulfur

The form of sulfur in the soil is different in different time.Some sulfur are available in the direct absorption of plants, and some have longer effect on plants-growing. So it is difficult to give a reasonable estimate method for the available sulfur in the soil.At present, there is no uniform manner in which we can reasonably estimate it. In this article, we researched the characteristics of different soils, filtered the better method from different manners of estimating the available sulfur and improved it, and found out the suitable one for our country's soil in order to offer a guidance on spreading the fertilizer contained the surfer reasonable.Four extractant were chosen in this research. They were 0.01mol/L Ca (H₂PO₄)₂ (pH=4.0) medium 2 mol/L HAC, 0.15%CaCl₂, Morgan reagent, 0.5 mol/L NaHCO₃ respectively.And three kinds of representative were treated with the four extractant. The correlation of the efficient sulfur in soil and the total sulfur in plant was compared through the pot experiment, and the best extractant was chosen. This research contained eight kinds of soil samples obtained from different areas in our country. The original method was improved and got a more reasonable and pratical method of testing the efficient sulfur in soil through this experiment. The findings indicated that:1, The correlation of the available sulfur extracting from acid soil and neutral soil and the total sulfur in plant was better when 0.01mol/L Ca (H₂PO₄)₂ (pH=4.0) medium 2 mol/L HAc was chosen as extractants. And for alkaline soil, it was better to choose 0.5 mol/L NaHCO₃ (pH=8.5) as extractant.2, The effect of eliminating the organic matter with oxydol was better compared with active carbon.3, The correlation coefficient of the standard curve was better with 0.5% polyvinyl alcohol (PVA) as defloccuant compared with 0.25% Arabica glue.A, The temperature had little influence on the testing of available sulfur in soil when chosed the 0.5% polyvinyl alcohol (PVA) as defloccuant. And the operation could carry on under the room temperature.5, The steady time of the suspension could reach to one hour With 0.5% polyvinyl alcohol (PVA) as defloccuant.6, The precision and accuracy of the improved testing method for the available sulfur in soil were better than the original's.