Laboratory and field calibrations of a neutron moisture meter were carried out separately for a sandy loam soil in a special drum and in the field respectively. The drum calibration was made by monitoring the neutron counts at preselected depths after packing the soil in the drum layer by layer with stepwise increase in soil water content from natural dry soil to saturated state. The field calibrations were performed by measuring the neutron counts at preselected depths after saturating the soil by flooding and subsequent drying by gravity draining. Soil samples collected were analysed for gravimetric water content (8g) and bulk density of soil (p,,). Calihration relations of volumetric water contents (Bv) & 8g with count rate ratio (n) & corrected count ratio (n') for density were studied by fitting linear regressions at the preselected depths in the drum and field. Generally the bulk density correction did not improve the slope of regression and coefficient of determination significantly, both In drum and field. Results reveal that a separate calibration is required for surface routine field/and or drum calibrations. Application of some of the regressions in the field indicate that drum calibrations converted for field use after corrections for soil constitutional hydrogen content and p" estimate the soil water with minimum error compared with field calibrations.
Javed Akhtar, M.A. Chaudhri,. (1995) COMPARISON OF LABORATORY AND FIELD CALIBRATION OF A NEUTRON MOISTURE PROBE FOR WATER ASSESSMENT OF SANDY LOAM SOIL, , Volume 32, Issue 2,3.
