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Saturated hydraulic conductivity of soils in the presence of vermicast

Table 1. Treatment arrangement with different Table 2. Physico‑chemical properties of
types of vermicast experimental soils

No. Treatments (Loam and sandy loam soils) Parameters Soil‑1 Soil‑2
1. Control (Soil without vermicast) pH 5.28 5.18
2. Soil+vermicast (Raw) Organic matter (%) 1.87 1.32
3. Soil+vermicast (1.0 – 2.0 mm) Sand (%) 44 62
4. Soil+vermicast (0.5 – 1.0 mm) Silt (%) 36 23
5. Soil+vermicast (<0.5 mm) Clay (%) 21 16
Texture Loam Sandy loam
H − H
Q = Ks 1 2 (I) 3. Results and discussion
L

V V 3.1. Effect of soil texture on Ks in the presence of
Q = = (II)
At π r t vermicast
2
Figure 2 shows the Ks of loam and sandy loam soils
VL *60
K = (III) treated with different rates of vermicast incorporation.
s
2
π rt (H − H 2 ) Sandy loam soils had significantly higher Ks than loam
1
where, soils’ for all the application rates (p < 0.01). Irrespective
K = Saturated hydraulic conductivity (cm/h); of the size, the applications of vermicast at the rates of
s
Q = flux of the water (cm/h); 5 t/ha, 10 t/ha, 15 t/ha, and 20 t/ha resulted in 113.67 –
V = Volume of water (mL); 196.79%, 135.47 – 442.76%, 10.0 – 150.0%, and 29.63
L = Height of soil column (cm); – 135.47% higher Ks in the sandy loam soils relative to
R = Radius of the core (cm); the loam soils. The lower Ks of loam soils, irrespective of
T = Time (min); the size of the vermicast could be ascribed to higher clay
H = Constant water head (cm); content and lower sand content in loam soils compared
1
H = Gravitational head (cm). to sandy loam soils. The filling of large soil pores with
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2 fine organic materials leads to reduced Ks. Pulat
Before setting up the experiment, the soils were 30
analyzed for physicochemical assay. The pH was et al. reported that the application of 1% biopolymer
solution to a 70% sand-containing soil sample resulted
measured with a pH meter after preparing the in a 25-fold decrease in hydraulic conductivity. García-
suspension at a 1:5 soil-to-water ratio (w/v). The Gutiérrez et al. stated that the Ks is subjected to
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percentage of sand, silt, and clay was measured by the particle size and changes with the distribution of soil
hydrometer method as described in a paper by Huq particles. Sari found a significant negative relationship
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and Alam, and the textural class was determined of Ks with that of clay, while a significant positive
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from Marshall’s triangular coordinates. The amount relationship with that of the sand particles. The bulk
of organic carbon in soils was determined by the density of soil is another determinant that influences the
Walkley and Black wet oxidation method, and the Ks, with higher Ks with a decrease in the bulk density of
amount of organic matter was estimated indirectly soils . However, in our study, bulk density could have
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by multiplying the organic carbon content by the van very little effect on Ks as a uniform bulk density of both
Bemmelen factor of 1.724. Soil-1 and soil-2 were soil types was maintained. Under natural conditions,
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loam and sandy loam in texture, respectively (Table 2). however, the change in bulk density modifies the
All the statistical analyses were performed using SPSS distribution of soil pores, affecting the ability of soils
16 software (SPSS Inc. Version 16.0. Chicago). One- to conduct water. The differences in Ks between loam
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way analysis of variance was performed to compare and sandy loam soils treated with vermicast could be
among the treatments for 5 t/ha, 10 t/ha, 15 t/ha, and due to differences in geometry between sand and silt
20 t/ha rates of loam and sandy loam soils and the particles, and the larger-size strong aggregates formed
difference between loam and sandy loam soils for in the presence of vermicast induce large pore size
different rates was performed through a paired-sample distribution to facilitate the transport of more water.
t-test. The geometry of the soil particles determines the size

Volume 22 Issue 1 (2025) 117 doi: 10.36922/ajwep.7526