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Standard operating procedure for boron determination in soil: Hot water extraction








FAO. 2024. Standard operating procedure for boron determination in soil: Hot water extraction. Rome.



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    Booklet
    Standard operating procedure for soil microbial biomass (carbon): chloroform fumigation-extraction method 2024
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    Microbial biomass is considered as an estimation of soil biological activities and the capacity to mediate soil biochemical reactions. It is the most dynamic and labile of soil organic matter fractions, generally accounting for 1 to 5 percent of soil organic matter and very sensitive to soil management. The need to quantify soil microbiota has become increasingly relevant in current times as they are responsible for many different processes like the degradation of organic matter, the stability of aggregates and most of the nutrient cycling that occurs in soils. This standard operating procedure (SOP) focuses on the determination of soil microbial biomass using the chloroform fumigation-extraction method, which is applicable to both aerobic and anaerobic conditions over the whole range of soil pH, regardless of land use type. While chloroform fumigation also affects soil fauna, the carbon aliquot derived from these organisms is generally small (less than 5 percent) and can usually be disregarded.
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    Brochure, flyer, fact-sheet
    Standard operating procedure for saturated soil paste extract 2021
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    Salt-affected soils severely limit crop growth, reduce yield, and cause plant stress and soil structure degradation. Therefore, soil salinity/alkalinity interpretation is essential to develop and apply sustainable agricultural practice and suitable irrigation techniques in semiarid and arid environments. Salinity is a soil condition characterized by a high concentration of soluble salts, generally defined as one in which the electrical conductivity (EC) of saturate soil paste extract (ECe) in the root zone exceeds 4 dS m-1 at 25 oC (Richards, 1954). Sodic soils are those with a percentage of exchangeable sodium (ESP) greater than 15. Because of the considerable experimental errors involved in ESP determination, emphasis has been placed on using the sodium adsorption ratio (SAR) of the equilibrium soil solution instead of the ESP for classification purposes. The electrical conductivity of saturation soil extracts may vary, but usually remains below 4 dS m-1 at 25 °C. The pH of saturated soil paste in sodic soils is 8.2 or higher, and in extreme cases may exceed 10.5. However, many crops exhibit a yield reduction at a lower ECe because soil salinity/alkalinity affects a number of morphological, physiological and biochemical processes and water and nutrient or toxic elements uptake (FAO, 2018; Filipovic et al, 2018). The main aim of this SOP is to prepare a saturated soil paste to measure electrical conductivity (ECe) and soluble salts of a soil from a saturated paste extract.
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    Brochure, flyer, fact-sheet
    Standard operating procedure for soil available micronutrients (Cu, Fe, Mn, Zn) and heavy metals (Ni, Pb, Cd), DTPA extraction method 2022
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    The method provides a potential indicator of the plant available copper, iron, manganese and zinc, which are essential soil micronutrients for plant growth and living organisms. It can be used to extract heavy metals such as nickel, lead and cadmium assisting with conclusions as to their potential bioavailability. This method must be used in combination with suitable determination methods, for example, flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry or inductively coupled plasma – optical emission spectrometry.

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