1Division of Agricultural Physics, ICAR-Indian Agricultural Research Institute, New Delhi, India
2Department of Soil Science & Agricultural Chemistry, Institute of Agricultural Science, BHU, Varanasi, India
3Division of Agronomy, ICAR-Indian Agricultural Research Institute, New Delhi, India
*Corresponding author: raivikas48@gmail.com (ORCID ID: 0000-0003-3249-2567)
Online published on 5 April, 2018.
To achieve the potential crop yield, time and amount of irrigation required for a particular crop under field condition should be quantified. Since soil water stress occurs after few days of irrigation, it affects root water uptake and hence transpiration rate. This stress effect can be quantified by soil water stress coefficient (Ks). Whenever, total available water (TAW) and readily available water (RAW) data are available, a simple Ks calculation can be done. To present a more realistic scenario, Ks can also be computed from simulated root water uptake (RWU) using HYDRUS-2D model. To check the reliability of model, our study was conducted under permanent raised bed with residue (PBB+R) and conventional tillage (CT) system in a pigeonpea (Cajanuscajan (L.) Millsp.)-wheat (Triticum aestivum) cropping system with the objective to compare actual measured transpiration rate with those simulated from model and calculated from FAO method. Soil water balance simulated (100–125 DAS) from HYDRUS-2D model showed higher cumulative root water uptake (CRWU) (1.72 cm), lower cumulative evaporation (CE) (0.34 cm) and higher soil water retention in PBB+R than in CT. Ks calculated from both the methods showed that under low soil moisture condition in root zone, Ks significantly reduced RWU whereas when root zone is sufficiently wet, Ks have very negligible effect. Model simulated actual transpiration rates were comparable with observed values whereas values computed from FAO method showed substantial deviation. Thus Ks obtained from model output showed the better soil moisture stress condition of the profile as it takes into account root growth parameters, radiation interception and crop canopy conditions. So, this model may be adopted for evaluating different management practices in terms of improvement in soil water use.
Permanent raised bed along with residue retention improves root water uptake in pigeonpea.
Average transpiration rate obtained from HYDRUS-2D gives better results
Conservation agriculture, HYDRUS-2D, actual transpiration, root water uptake, stress coefficient
