**3.6 Change in profile moisture (ΔG)**

Profile moisture change is also an important part of the soil water balance equation. For measuring soil profile moisture change, the thermogravimetrical method is used for measuring moisture before sowing and after harvesting throughout the profile up to a depth of 1.5 m.

$$\begin{aligned} \text{Moisture of soil } (\text{g} \,\text{g}^{-1}) &= \text{Fresh soil mass } (\text{g}) \text{-oven-dried soil mass } (\text{g})/ \\ \text{Oven-dried soil mass } (\text{g}). \end{aligned} \tag{12}$$

From the above conversion, above weight basis (g g�<sup>1</sup> ) values of soil moisture to volumetric basis (cm3 cm�<sup>3</sup> ), these values must be multiplied with a respective bulk density.

$$\mathcal{Q}\mathbf{i} = \mathbf{W} \times \mathbf{D}\_{\mathbf{b}} \tag{13}$$

#### *Delineation of Soil Moisture Potentials and Moisture Balance Components DOI: http://dx.doi.org/10.5772/intechopen.92587*

where Øi is the volumetric soil moisture (cm<sup>3</sup> cm�<sup>3</sup> ); W is the mass basis soil moisture; and Db is the bulk density.

For Db determination, generally, core method [22] was used. Under this method, undisturbed metallic soil cores are used for calculating the Db, and fresh core weight was measured. Then, fresh soil + cores weight was recorded, and then, both fresh soil and cores are dried for 1 day in an oven at 105°C. For Db, the dried weight of soil is divided with the internal volume of the metallic cores [15]. Further for a specific depth under consideration, moisture (cm) is determined by

In a specific depth of soil, soil moisture cmð Þ¼ Øi � soil profile depth (14)

Further, for delineating soil profile moisture up to 150 cm, each depth value of soil moisture is added up to have soil profile moisture (cm), which is further multiplied by 10 to get soil moisture of the whole profile in mm, the required units for the soil moisture balance.

By adopting above methodology for calculating different soil moisture components, namely, rainfall, irrigation, evaporation, transpiration, seepage, drainage, and change in profile soil moisture, one could easily delineate the soil moisture components or validate the performance of a particular resource conservation technology, namely, happy seeder, laser leveler, tensiometers, direct-seeded rice, etc., in improving the yield potentials by partitioning the maximum share of the evapotranspiration water from evaporation to transpiration.
