1. Assessment of suitability of different extractants for estimation of available boron status in Soils ARITRA SAHA, PABITRA KUMAR MANI & GORACHAND HAZRA
Department of Agricultural Chemistry and Soil Science
Bidhan Chandra Krishi Viswavidyalaya Mohanpur , Nadia, West Bengal
ID:
Fig 1: Effect of different levels of B application to wheat on Dry matter yield (g pot-1) at different growth stages.
INTRODUCTION
Boron Extractant
Soil:
extractant
Procedure
0.02 M hot CaCl2 (HCC)
1:2
Reflux 10 Min
0.5 M Potassium dihydrogen phosphate (PDP)
Shake 1 hr
0.01 M Tartaric acid (TA)
Shake 1hr
0.01 M CaCl M Mannitol (pH 8.5) (MCC)
Boron deficiency affects crop growth in light textured acidic Inceptisols and Entisols which receives a larger amount of annual precipitation causing leaching loss.
Initial available B status should be estimated with utmost care because excess B application above optimum dose poses toxicity problems in plant. Several extractants have been reported by many researchers which differ in their mechanisms to extract B from soil exchange phase.
Therefore, no single extractant could be used for predicting B status of all soils or all crops. The present investigation aims to screen out few extractants for predicting the available B status of soil.
Fig 2: Effect of different levels of B application on B uptake (µg pot -1) of wheat plant at different growth stages.
RESULTS & DISCUSSION
Table 1: Some important physico-chemical properties of the Experimental soils.
Districts (Coochbehar, Jalpaiguri, Dinajpur (N), Nadia,
Hooghly, Burdwan, Bankura) pH
Org. C
(g kg-1)
Clay
content
( g kg-1)
Range
Mean
5.86
8.4
261
OBJECTIVES
To assess the relative suitability of four extractants for assessment of available B status in the experimental soils of West Bengal.
Table 4: Pearson correlation coefficients(r) between BPY and uptake of B by Wheat and extractable B content of the experimental soils.
MATERIALS AND METHODS
Table 2: Extractable B contents (mg kg-1) of the Experimental soils.
21 Bulk soil samples from seven districts of West Bengal has been collected and used for pot culture experiment at Central Research Farm, BCKV, WB.
Extractant
Growth
Stages
BPY
B uptake
HCC PI
0.681**
0.906** S
0.553**
0.914** G
0.763**
0.918**
PDP
0.597**
0.727**
0.516**
0.711*
0.606**
0.717** TA
0.552*
0.686**
0.514*
0.674**
0.518*
0.669**
MCC
0.136
0.386
0.022
0.397
0.172
0.348
Avail. B (HCC)*
Avail. B
(PDP)*
(TA)*
(MCC)*
Range
Mean
0.660
0.487
0.391
0.211
POT CULTURE EXPERIMENT:
Treatments (4)
0, 0.25, 0.5, 1.0 mg kg-1 B
No. of Replication 4
N:P:K
150:60:40
Experimental Design
CRD
Crop
Wheat ( CV K-1006)
Sampling Stages
Panicle Initiation & Maturity
Parameters Recorded
Dry Matter Yield, B Concn. of Shoot & Grain
Table 3. Pearson correlation coefficients (r) between extractable B content and soil properties:
Extractant pH
Org. Carbon
Clay content
HCC
0.442*
0.554**
0.737**
PDP
0.459*
0.421
0.701** TA
0.428
0.587**
0.571**
MCC
0.210
0.334
0.304
SOIL ANALYSIS :
( ** and * correlation is significant at 0.01 and 0.05 probability levels respectively.)
Oxidizable Organic Carbon
Wet digestion Method (Walkley and Black, 1934) pH
Soil: water 1::2.5 (Jackson, 1973)
Mechanical analysis
Boyoucous hydrometer method (Gee and Bouder, 1986) )
Available B
Azomethine-H method (Wolf, 1971)
[BPY = Bray’s percent yield.
PI, S, G = Plants at panicle initiation, straw at harvesting and grains of wheat respectively.]
CONCLUSION
Hot Calcium chloride has been found to have highest correlation among all the extractants with almost all plant parameters.
Order of the Efficiency of the extractants : HCC > PDP > TA > MCC
Available B (HCC extractable) was found to be correlated with organic carbon and clay content. This suggests that Organic carbon and clay content have major influence in determining the availability of B.