Field experiment was conducted on red sandy loam soils, during Kharif 2013 at Zonal Agricultural Research Station, University of Agricultural Sciences, Gandhi Krishi Vignana Kendra, Bangalore to find out the effect of drip fertigation with combination of water soluble fertilizers and normal fertilizers or alone on water productivity and economics of aerobic rice during kharif 2013. The experiment was laid out in a Randomized Complete Block Design (RCBD) comprising of 3 replications and 10 treatments. Results show that water use efficiency and economics differed significantly among the treatments. Consistently use of high water potency (91.01 kg/ha.cm-1) was noted when the crop was drip fertigated with 100% recommended dose of fertilizers. High net income (Rs.58104 ha-1) was, however, observed for fertigation with 100% RDF in which 50% applied as basal dose and 50% top dress through water soluble fertilizers.

The most reliable method used to estimate deep percolation is using Lysimeter which proves to be expensive and time consuming as well. In this study, deep percolation has been estimated by using water balance method. The experimental setup consisted of two lysimeters in the Hydraulic Engineering field lab, I.I.T., Roorkee in which maize crop was grown. Regular measurements of soil moisture were made at the depths 0-20 cm, 20-40 cm, 40- 60 cm, 60-80 cm and 80-100 cm using gravimetric method. The evapotranspiration estimates were determined using Penman-Moneith equation. The deep percolation is calculated using the water-balance approach. The deep percolation calculated using the water-balance approach is comparable to the observed values of deep percolation which are obtained from the lysimeters.

Climate characteristics play an essential role in the crop evapotranspiration and therefore affect irrigation. Reference evapotranspiration (ET0) is a climatic parameter that can be computed from weather data and used to a reliable variable for assessing long-term trends of the atmospheric evaporative demand. The study aims to evaluate the effects of the climate change on ET0 and citrus and tomato irrigation scheduling parameters (irrigation depth, length of the irrigation season and number of irrigation) in Calabria, a Region of South Italy. The study covered 89 years (1925-2013) and 9 of the most relevant irrigated areas in the Region. The software CROPWAT was used to estimate the irrigation scheduling parameters. The time series were analyzed at yearly and seasonal scale using standard trend analysis tests (Mann-Kendall and linear trend test). The results showed a slight decreasing trend for maximum temperature and both increasing and decreasing trends for minimum temperature. Due to the asymmetric behavior of temperatures, impact on ET0 resulted in a decreasing tendency (-5.51 mm.decade-1). There was a slight decrease in the seasonal irrigation depth for both citrus and tomato. The average annual magnitude of decreases throughout Calabria were 2.40 and 5.51 mm.decade-1 for citrus and tomato, respectively, corresponding to -7% and -11% of the mean irrigation depth of the period considered. This trend depended on both the decreased ET0 and precipitation trend: precipitation decreased at yearly scale, but increased in summer, the season when irrigation requirements are higher in the environment considered. The positive trend in summer precipitation also caused an advance of the last watering, resulting in a slight decrease of the length of the irrigation season. The results, on the whole, showed the importance of studies at regional scale considering the detection of trends even opposite with respect to those founded in studies on other areas in the same Mediterranean region. The elaboration of more local studies is useful in order to deepen knowledge on the problematic of each zone and to plan concrete actions.

Bi-level drainage system, in which alternate shallow and deep subsurface drains are laid, seems to be an economical option as compared to the level drainage system due to substantial reduction in cost of excavation. Mathematical solutions are available to describe fall of water table between two bi-level drains located at some distance above the horizontal impermeable barrier. But, if the barrier is semi-impermeable, little information is available to account for the vertical upward leakage in the soil system and its effect on spacing, fall of water table and discharge of drains. In the present study, a boundary value problem consisting of one dimensional linearized Boussinesq equation incorporating vertical upward leakage from semi-impermeable barrier with appropriate initial and boundary conditions was formulated. Analytical solution of such linearized equation has been obtained after devising a simple transformation through which boundary value problem was transformed to a heat transfer problem for which a solution was available. Spatial and temporal variation of water table between two bi-level drains was obtained employing this solution. A special case of the proposed solution (without vertical leakage) was verified with the existing solution and identical values of water table heights were obtained. The effect of hydraulic resistance of semi-impermeable barrier on spacing, water table heights between two bi-level and level drains and discharge of drains was studied by considering a numerical example based on assumed and experimental data. It was observed that with increase in the value of hydraulic resistance the spacing and fall of water table between two drains increases. Discharge of the drains is also influenced due to vertical upward leakage. An increase in hydraulic resistance, discharge of the drain decreases. The solution can be employed to determine discharge, spacing and fall of water table between two level or bi-level subsurface drains considering the semi impermeable barrier.