Improvement of Supplementary Irrigation Water Quality for Rain-Fed Agriculture in the Semi-Arid Region Using Magnetization Techniques

Rain-fed agriculture depends on the groundwater as a supplementary source of irrigation. The poor quality of water from the hard rock area is applied to the crops to save the crop. Continuous irrigation leads to degradation of soil, drip irrigation system as well plants. This study assessed the damages on the drip irrigation system and soil, inflicted by the use of low-quality irrigation water. The quality of water was improved with reference to raw water in terms of pH (1.57% 5.88%), EC (3.08% 10.08%), ions (0.96% 46%) by using magnetization method, without disrupting the existing irrigation system in the basaltic aquifer in semi-arid to the arid condition. This was demonstrated before the farmers in central India.


Introduction
About 60% of the total net sown area in India is under rain-fed agriculture and 48% of food crops is generated from this practice. Rain-fed agriculture is practised in areas receiving an annual rainfall of 375 to 1125 mm by using supplementary irrigation from groundwater. The success of rain-fed agriculture depends on the onset of monsoon, the periodicity of rainfall, rainy days, wet and dry spells during the growing period. Hence, hard rock aquifers are subjected to intensive abstraction mostly from rural areas of 1) weathered zone of the Deccan Traps Basalt underlying Maharashtra and in Andhra Pradesh and 2) low-storage variably weathered crystalline basement aquifer underlying most of droughtprone Tamil Nadu, India. These areas experience drought situations once in two years, as well water stress at regular interval. The depletion of the water table is attributed to uncontrolled and excessive exploitation in saving the crop growth and yield. There is a widespread depletion of irrigation wells before the end of Rabi (winter) season and no groundwater even for drinking after January till the onset of monsoon in June.
The quality of groundwater varies from season to season and place to place depending on the depth of water table, extent and composition of dissolved solids. The hydrological imbalance has triggered the geochemical processes expressed as a spatiotemporal variation in groundwater chemistry [1]. Groundwater contains dissolved salts and traces elements from the natural weathering. Groundwater contains dissolved salts and traces elements from the natural weathering. Groundwater chemistry depends on geology, the degree of chemical weathering of rock types, and quality of recharge water [2]. In recent years, an increasingly significant threat to groundwater quality is from human activities [3] [4]. The most critical factor in agriculture is the prediction and managing and forecasting the crop production using the low-quality irrigation water. There is a need to optimize the use of groundwater, improve the quality to permissible limits and apply as supplementary irrigation in preventing long-term impacts.
The objective of this study is to 1) assess the quality of irrigation water with their impacts on the irrigation delivery system & soil 2) improve the quality by the magnetized method & assessment of the impacts.

Water Quality Parameters
The salts in irrigation water affect both the soil structure and crop yield. Salts and other dissolved substances begin to accumulate/deposit as water evaporates from the surface. High concentrations of salt in the soil result in physiological drought condition -even though the field appears to have plenty of moisture, the plant's wilt because the roots are unable to absorb the water. These impacts attributed to pH, Salinity hazard (total soluble salt content), Sodium hazard (proportion of sodium (Na+) to calcium (Ca 2+ ) and magnesium (Mg 2+ ) ions, Alkalinity -carbonate and bicarbonate and presence of specific ions like chloride (Cl), sulfate ( 2 4 SO − ), boron (B), and nitrate-nitrogen (NO 3 -N). The anticipated impact of poor quality irrigation water on soil and plants that could affect the sustainable agriculture and food security are listed in Table 1.
The prevalent effects of the application on low-quality water the delivery system (nostril, delivery pipes), soil surface, and structure in these areas are shown in Figure 1.
pH affects the toxicity of other elements and pronounced effect on many chemical reactions. The ranges of pH of the groundwater in basaltic aquifers are D. Bornare et al.  The total hardness of groundwater samples from basaltic aquifers was found in the range of 55 -300 mg/l. Electrical conductivity (EC) is the conductance of the one-centimetre cube of the substances in micromhos/cm at 25˚C. The presence of ions in solution increases the conductivity of water from all the ions dissolved such as negatively charged ions (Cl¯, 3 NO − ) and positively charged ions (Ca++, Na+). The effect of high ECw water on crop productivity is their inability of the plant to compete with ions in the soil-water solution (physiological drought). The usable plant water in the soil solution decreases significantly as EC increases. The long-term impact of EC high water is the salt loading through the irrigation water.
Ions Different ions and their concentration level plays critical role as far as water quality is concerned. Olivine, biotite, hornblende, serpentine are the major magnesium-bearing minerals. Crops grown on soils having an imbalance of calcium and magnesium exhibit toxic symptoms. High concentrations of potassium may introduce a magnesium deficiency and iron chlorosis. The sources of calcium in groundwater from basalt are plagioclase and pyroxene. The range of calcium content in groundwater is largely dependent on the solubility of calcium carbonate, sulphide and rarely chloride. Magnesium's solubility in water is around five times that of calcium. The maximum acceptable limit of calcium for domestic use is 75 ppm.
The contributions of various parameters in aquifers of hard rock are: Most sodium salts are readily soluble in water, but take no active part in chemical reactions. Sodium is released into groundwater by weathering of plagioclase feldspar, clay mineral and amphiboles. Potassium minerals orthoclase, microcline and biotite etc., are resistant to decomposition by weathering. Slow circulation, a longer period of contact between aquifer and water, dissolving of minerals at the time of weathering, residential time, drainage pattern etc. and surface water link is responsible for the variations in chemical concentrations of groundwater. Sodium in irrigation water cause toxicity problems for some crops. The amount of water transpired through a crop is directly related to yield. The sodium content of groundwater from basaltic and granitic aquifers ranges between 16 to 150 mg/l and 32 to 129.3 mg/l respectively. The potassium content of ground waters from basaltic and granitic aquifers ranges between 1.0 to 66 mg/l and 11 to 54.4 mg/l respectively.
High salt concentration in water leads to the formation of saline soil. Sodium in irrigation water is absorbed by the soils and high sodium leads to the development of an alkaline soil. An imbalance of magnesium and potassium may be toxic, but the effects of both can be reduced by high calcium levels. Many crops have little tolerance for salinity during seed germination, but significant tolerance during later growth stages. Barley, wheat and corn are more sensitive to salinity during the early growth period than germination and later growth periods. Journal of Water Resource and Protection Evaporation rates from water surfaces often exceed 0.25 inch a day during summer.
Sulphate salts affect the crops by limiting the uptake of calcium and increasing the adsorption of sodium and potassium, resulting in a cationic imbalance within the plant. Sulfate content in basaltic and granitic aquifers range between 12.0 to 56.1 mg/l and 14.0 to 62.0 mg/l respectively. They are found to be within the desirable limit in basaltic and granitic aquifers. In the presence of CO 2 , Calcium bicarbonates can normally be dissolved up to 20 ppm at atmospheric pressure and up to 100 ppm at higher pressure. The bicarbonate ion in soil solution harms the mineral nutrition of the plant through its effects on the uptake and metabolism of nutrients. Sodium absorption ration (SAR) The risk of high sodium content in irrigation water is due to the tendency of the clay particles to absorb sodium and release the magnesium and calcium ions. This results in reduced soil permeability due to this ion exchange and eventually, the soil has a weak internal drainage. The unit area specific capacity of dug wells ranges from 0.77 to 18.9 lpm/dd/sq.m; permeability from 12 to 65 m/day; transmissivity of phreatic aquifer between 18 and 89 m 2 /day; specific yield between 1.7% to 9.7% in the district. Groundwater level rises after monsoon due to natural recharge and water level ( Table 2) and falls down in accordance with withdrawal leading to salt concentration [5].

Deccan Basalt Aquifer
As the level of salt concentration increase with a reduction in depth to water level, there is a need to improve the water quality prior to irrigation.

Improvement in Water Quality
The prevailing and predicted scarcity situation warrants the optimization of water consumed by agriculture per unit area. Use of low quality of irrigation hampers the plant growth and crop yield. The methods available to improve the quality of irrigated water is given in Table 3.
Chemical treatment methods require additional facilities at the farm for reaction time and new structures. There is a time delay between the uptake from the well and the application to crops, in addition to the loss of precious water by storage, release and evaporation. Even though, physical and mechanical conditioning methods are in continuity with pumping, filtration methods are applicable to turbid waters, leaving magnetic water conditioning suitable for the application. It is reported that even a low magnetic field can change the water [6] density, salt solution capacity, pH, electrical conductivity, dielectric constant etc [7]. The magnetized water can improve water productivity [7] and crop yield [8]; increased germination percentage of seeds [9], emergence rate [10], and root growth [11]. The benefits of magnetically treated water depend upon the plant species, pathway in the magnetic unit and flow rate [12]. Magnetic fields change the physicochemical properties of water [13]; [14].

Water Improvement Device
The water quality improvement device was fixed between the take-off point from the well and irrigation water delivery system. The various components of the Water quality improvement device consisting of the electrolysis unit, dynamic pulse unit and the electromagnetic unit is shown in Figure 2.

Field Trials
Trial tests were carried out on the agriculture fields at four sites without disturbing the existing delivery system (Site of the plot were present during the entire activity. Field setup described above is shown in Figure 3. Irrigation (untreated) water prior to treatment and post-treatment were collected using standard protocol methods of ICAR & FAO. After installation of the water quality improvement device and water passing through the device (untreated) and outlet (treated) water collected and analyzed at MIT-CARS laboratory (@ Maharashtra Institute of technology, Aurangabad), with the help of standard protocol and the results are presented in Table 4 and Table 5.
In order to understand the quality of individual parameters with reference to the duration of processing/treatment by the device, water samples were collected every 30 minutes from the inception of pumping. It is assumed that 4 hours (maximum) of pumping fulfils the irrigation requirement of crops over 1 acre.
The observations are shown in

Conclusion
In most of the irrigation practices in semi-arid/arid regions experiencing water stress and drought, is concerned with salinity levels that affect the soil structure and crop yield. The salts in the irrigation water are from the natural weathering.  Table 5. Treated water quality is assessed for three sites in static condition which shows percent improvement of water quality parameters after treatment i.e. pH 5.88% (+) & 1.57% (+) of site 1 and site 3 respectively, whereas it is reported that pH value slightly increased on site 2 i.e. 4.15% (−). Electrical conductivity reduced in 10.97% (+), 7.39% (+), and 3.08% (+) in site 1, 2, 3 respectively. Na ion reduced to 0.96% (+), 1.00% (+) and 4.74% It may be concluded that • This study has demonstrated that parameters that have a significant impact on the delivery system and soil causing a detrital impact on the crop yield could be improved at the field level.
• By using this device detrimental parameters found in the irrigation water were reduced to acceptable limits. The successful reduction in chemical pa-Journal of Water Resource and Protection rameter in percentage in terms of treated water are pH (1.57% -5.88%), EC (3.08% -10.08%) & Ions (0.96% -46%).