2024, Vol. 7, Special Issue 1

author(s)
AS Rabari, VJ Zinzala, Narendra Singh, RR Sisodiya, JB Vasave and VA Patel

abstract
An experiment was conducted at Department of Soil Science and Agricultural Chemistry, Navsari Agricultural University during the year 2018-19, with the objectives of (i) to find out suitable extractant and instrument for the determination of sodium from soil and (ii) to establish the relationship of various soil properties with sodium availability. For evaluation of methods of sodium, each Taluka wise one sample; total 46 samples from south Gujarat (Bharuch, Dang, Narmada, Navsari, Surat, Tapi and Valsad) were collected from 0-15 cm depth. Soil physico-chemical properties viz., pH, EC, CEC, organic C, CaCO₃ content and soil texture were determined from these sample soils. These soils were used to evaluate six methods of sodium. The methods of sodium was (i) Extracted through NH₄OAc and determined with FPM (Na₁), (ii) Extracted through NH₄OAc and determined with MP-AES (Na₂), (iii) Extracted through AB-DTPA and determined with FPM (Na₃), (iv) Extracted through AB-DTPA and determined with MP-AES (Na₄), (v) Extracted through Neubauer and determined with FPM (Na₅) and (vi) Extracted through Neubauer and determined with MP-AES (Na₆). The methods of sodium were evaluated through method validation parameters like linearity, sensitivity of instruments, precision and predictability. The available sodium determined from the sample soils were correlated with soil physico-chemical properties. The linear dynamic range of NH₄OAc-FPM (Na₁), AB-DTPA-FPM (Na₃) and Neubauer FPM (Na₅) extractants was between 25 to 100 ppm having Co-efficient of determination (R²) 0.982, 0.988 and 0.994, respectively. The NH₄OAc-MP-AES (Na₂), AB-DTPA-MP-AES (Na₄) and Neubauer-MP-AES (Na₆) had linear dynamic range between 1.0 to 10 ppm with Co-efficient of determination (R²) 0.985, 0.945 and 0.991, respectively. The sensitivity of instruments was identified by measuring limit of detection (LOD) and limit of quantification (LOQ) of FPM and MP-AES for NH₄OAc, AB-DTPA and Di-acid extractant. The LOD of FPM for NH₄OAc, AB-DTPA and Diacid extractants were 0.578, 0.382 and 0.614 ppm, respectively. The corresponding LOQ of FPM for NH₄OAc, AB-DTPA and Di-acid extractants were 1.925, 1.272 and 2.045 ppm, respectively. The LOD of MP-AES for NH₄OAc, AB-DTPA and Di-acid extractants were 1.663, 3.542 and 0.643 ppm, respectively. The corresponding LOQ of MP-AES for NH₄OAc, AB-DTPA and Di-acid extractants were 5.537, 11.79 and 2.142 ppm, respectively. Amongst the chemical methods the measured values were observed in increasing order of Na₂ (685.7 kg/ha) > Na₁ (673.8 kg/ha) > Na₄ (365.1 kg/ha) > Na₃ (255.8 kg/ha). NH₄OAc-FPM (Na₁) extractant of Na determination is accepted extractant. Sodium determined by this extractant was highly positive and significantly correlated with uptake-FPM (r=0.663**) and uptake MP-AES (r=0.674**). In extractant AB-DTPA-FPM (Na₃), highly positive and significantly correlated with uptake-FPM (r=0.630**) and uptake MP-AES (r=0.642**). Na extracted with AB-DTPAMP-AES (Na₄) was highly positive and significantly correlated with uptake FPM (r=0.645**) and uptake MP-AES (r=0.667**). In sodium determination NH₄OAc-FPM has highly positive and significantly correlation with nutrient uptake by wheat on MP-AES instruments.