Mineral_N {SoilTesting}

Mineral N i.e., summation of ammonium-N and nitrate-N in soil

Description

This function determines the amount of mineral N (ammonium-N + nitrate-N) in soil as extracted by 2 M KCl, expressed in terms of oven-dried soil mass (Rowell, 1994).

Usage

Mineral_N(W = W, m = m, VA = VA, VE = VE, VS = VS, VB = VB, X = X)

Arguments

W

Mass of moist soil sample (g)

m

Moisture content of the field-moist soil sample (% w/w)

VA

Volume of aliquot of the extract (mL) taken for distillation

VE

Volume of 2 M KCl (mL) added as extractant

VS

Volume of standard sulphuric acid solution (mL) consumed in titration with soil

VB

Volume of standard sulphuric acid solution (mL) consumed in titration without soil (i.e., blank titration)

X

Normality of standard sulphuric acid solution

Details

Mineral N in soil consists of ammonium and nitrate ions present on soil exchange sites or solution or both. It can be extracted by 2 M KCl. The extract is steam-distilled in the presence of magnesium oxide and Devarda’s alloy (Cu: Al: Zn :: 50: 45: 5) to liberate ammonia. The evolved ammonia is absorbed in 2% boric acid solution containing mixed indicator, pH 4.5, and titrated against standard sulphuric acid solution to know the volume of the boric acid consumed during ammonia absorption (Rowell, 1994; Biswas, 2018).

Value

N_mgkg - Mineral N in soil (mg/kg) (expressed in terms of oven-dried soil mass)

References

Biswas, D.R. (2018) Determination of different forms of nitrogen in soil and total N in plant. In Manual on Advanced Techniques for Analysis of Nutrients and Pollutant Elements in Soil, Plant and Human (S.P. Datta, M.C. Meena, B.S. Dwivedi, A.K. Shukla (Eds.)), Westville Publishing House, New Delhi, pp. 57-68.

Rowell, D.L. (1994) Soil Science Methods and Application, Pearson Education Ltd., Essex, England.

Examples

with(data = df_Minearl_N, Mineral_N(W = Mass_Moistsoil, m = Moisture_Percent,
VA = Vol_Aliquot, VE = Vol_Extractant, VS = Vol_Sulphuric_Soil,
VB = Vol_Sulphuric_Blank, X = Normality_Sulphuric))