Evaluation of factors affecting modulus of rupture as an index of crusting in soils of Haryana
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Date
2017
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CCSHAU
Abstract
The experiment was carried out at Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana
during 2016-2017 to evaluate the factors affecting the modulus of rupture as an index of crusting in soils of
Haryana. The soil samples were collected from 0-5 and 5-15 cm depths from 21 sites located in different
districts of the Haryana State. The texture of soil varied from sand to silty clay loam. The organic carbon, pH,
EC, SAR, saturated hydraulic conductivity, CaCO3, dispersion ratio, aggregate size analysis, mean weight
diameter and modulus of rupture of all the soils were determined using standard methods. The effect of different
soil properties on modulus of rupture of soils was evaluated.
The MOR of different textured soils at both the depths (0-5 and 5-15 cm) was significantly positive and lineally
correlated with the soil organic carbon contents of soils with R2 value of 0.74 and 0.75 for 0-5 and 5-15 cm
depths. The SOC was significantly negative and exponential correlated with saturated hydraulic conductivity of
soils for both 0-5 cm (R2 = 0.81) and 5-15 cm soil depths (R2 = 0.67). The water stable aggregates at 0-5 and 5-
15 cm depths were found significantly positive and linearly correlated with organic carbon content of soils with
R2 value of 0.87 and 0.73, respectively. The water stable aggregates were highest in silty clay loam (67.42%)
and lowest in sand (30.85 %) at 0-5 cm depth.
Aggregate stability index as mean weight diameter (MWD) was observed to be higher in fine textured soils as
compared to coarse textured soils. The silty clay loam soils were found with highest MWD of 1.61 mm and 1.54
mm at 0-5 and 5-15 cm depth amongst all the soils. Dispersion ratio was higher in coarser soils and decreased
with increase in fineness of the texture. Modulus of rupture was significantly negatively correlative with
dispersion ratio which was positively correlated with sand content and saturated hydraulic conductivity.
Hydraulic conductivity was significantly positively correlated with sand content and negatively with clay
content. The modulus of rupture of texturally different soils was significantly positively and exponentially
correlated with saturated hydraulic conductivity at both the depths. There was no role of calcium carbonate,
pH, EC and SAR in influencing the values of MOR of soils. The MOR was found highly dependent on
dispersion ratio, silt + clay, EC and water stable aggregates and the regression equation found to explain the
impact of MOR was: MOR = 4.243 - 3.961 DR + 0.029 silt+clay - 0.0957 EC - 0.0269 WSA (R2 = 0.845).