Evaluation of multi-nutrient extractants for determination of available P, K and micronutrient cations for soil analysis in Himachal Pradesh
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Date
2015-08-14
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Publisher
CSHHPKV Palampur
Abstract
Multi-nutrient extractants offer alternative for conventional methods as more nutrients can
be extracted in one go. However, the suitability and accuracy of such extractants for the
determination of available nutrients must be verified. Therefore, sixty soil samples (0-0.15 m
depth) collected randomly from different districts of Himachal Pradesh were used to evaluate the
efficiency of AB-DTPA and AAAc-EDTA in comparison to their standard methods for P, K and
micronutrient cations. Soil pH (1:2.5), EC (µS cm-1
), OC (g kg-1
), textural class, and CEC (cmol (p+
)
kg-1
) soil under study ranged from 5.67-7.56, 61-695, 2.8-27.7, sandy loam to clay loam and 4.1- 15.0,
respectively. Available P (kg ha-1
) extracted by four methods viz., Olsen P, Bray P1, AB-DTPA P and
AAAc-EDTA P varied from 7.8-44.3, 9.5-61.1, 6.5-38.8, 10.5- 52.1; available K (kg ha-1
) extracted by
three methods viz., NH4OAc, AB-DTPA and AAAc-EDTA ranged from 103.6-372.3, 86.6-364.9 and
74.6-362.5. Likewise, DTPA, AB-DTPA and AAAc-EDTA extractable contents of Cu, Fe, Zn and
Mn ranged from 0.3-5.8, 1.0-6.3 and 1.2-5.0; 3.9-42.2, 8.1-58.8 and 7.3-32.7; 0.2-6.6, 0.3-6.7 and 3.3-
26.2, 5.1-27.2 and 7.7-38.3, respectively. Bray P1 method of phosphorus determination extracted
more amount of available P followed by AAAc-EDTA, Olsen and AB-DTPA methods. Likewise
NH4OAc extracted more K followed by AB-DTPA and AAAc-EDTA. In case of micronutrients
cations, AB-DTPA in general, extracted more amounts as compared to DTPA alone.
Overall, phosphorus showed highly significant correlations with physico-chemical properties.
Among methods of extraction for P, AAAc-EDTA showed higher correlation with the standard
method (Olsen P) of determination. Available K contents determined by AB-DTPA and AAAc-EDTA
were well correlated with standard method (NH4OAc) however; AAAc-EDTA had higher correlation
with AB-DTPA method for K extractability. In case of micronutrients, all the methods correlated
positively and significantly with each other Highest significant correlations were observed between
AB-DTPA and DTPA for Cu, Fe and Zn. However, in case of Mn, the highest correlation was
observed between AB-DTPA and AAAc-EDTA. Both, AB-DTPA and AAAc-EDTA methods were
more economical compared to the conventional methods.