Evaluation of infiltration rate on various compaction levels in climate smart villages adopted by RPCAU
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Date
2022
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DRPCAU, PUSA
Abstract
The current study entitled "Evaluation of infiltration rate on various compaction levels in climate smart villages adopted by RPCAU" was conducted in the farmer's villages of Samastipur district, Bihar, in the year 2022. In this research, an overall 40 soil samples from different villages were collected for laboratory analysis at 0 to 60 cm soil depth. The soil texture of the study area ranged from loam soil to sandy loam soil to sandy clay loam soil under various cropping systems. The sand, silt, and clay content varied from 47.20 to 65 %, 8.25 to 50 %, and 10 to 40 %, respectively. Bulk density ranged from 1.05 to 1.42 g cm-3. At 0.3 bar suction, FC ranged from 15.10 to 34.58 %, and at 15 bar suction, PWP of soil ranged from 12.33 to 23.41 %. The WHC of soils ranged from 32.09 to 84 %, and OC ranged from 0.15 to 0.89 %, generally decreasing with depth and the percentage of water holding capacity also decreased. A field study was carried out to establish the infiltration rate using an instrument called double-ring infiltrometer. The results showed that the values of initial infiltration rate (mm h-1) for Kalyanpur, Akbarpur, Tira, Rampura, Ladaura, Mirzapur, Basudeopur, Birsingpur, Kabargama, Phulhara were obtained as 12.99, 10.19, 10.11, 5.91, 9.77, 6.79, 6.96, 7.39, 9.73 and 7.13, respectively. Meanwhile, the values of final steady infiltration rate (mm h-1) were 0.18, 0.12, 0.12, 0.12, 0.10, 0.12, 0.12, 0.12, 0.10 and 0.12, respectively. The four infiltration equations, namely, the Green-Ampt equation, Philip equation, Kostiakov equation and Horton equation, were
used in this study. The performance evaluation of all developed equations between observed and predicted infiltration rate were analyzed based on the highest values of r ranged from -0.59 to 0.99, R2 ranged from 0.52 to 0.99, and NSE ranged from -28579.30 to 0.99, with WI ranging from 0 to 0.99 and the lowest values of RMSE ranged from 0.1 to 441.08, MAE ranged from 0.08 to 281.43. The results showed that the Green Ampt, Kostiakov, and Philip equations were more appropriate than the Horton equations. The results reveal that Horton's parameters do not fit the conditions for given locations.
The average values of penetration resistance for given locations were observed 2067.20, 121290, 1859.68, 1904.32, 109681, 80863, 2432.83, 2196.45, 1524.75 and 1642.65 kPa at 0 to 60 cm depths, respectively. Linear relationship between (weightage mean of PR and constant infiltration rate) shows the value of R2 was 0.45 and significant correlations were obtained. A graphical nomograph was framed to represent three interrelating variables viz. soil texture, final infiltration rate and weighted mean of penetration resistance. A regression analysis was done between infiltration rate as dependent variables and soil parameters as independent variables including soil strength data in developing Pedotransfer Function (PTF). A regression equation had generated to show good relationship between them as R2 = 0.91.