EXECUTIVE SUMMARY
3. CROP AND RESOURCE MANAGEMENT AND ENVIRONMENT
3.3 WATER MANAGEMENT
3.3.1 Meteorological Studies
3.3.1.1 Application of CLIMGEN model in climate change investigations and development of drought indices for agricultural water management
Daily rainfall data from 1972 to 2007 (36 years) of the WTC observatory were digitized and processed as an input to CLIMGEN model. These data were analysed using Fourier’s transformation, and the data bases of the years 2010, 2020, 2030, 2040 and 2050 were generated using the capability of CLIMGEN model to study the decadal changes in daily precipitation. The non-parametric statistical methods, viz., the Mann-Whitney-Pettitt (MWP) method and Mann-Kendall rank correlation (MK) method were employed to test the existence of climate change pattern in the daily rainfall data.
3.3.2 Watershed Based Studies
3.3.2.1 Modelling watershed hydrologic responses using soft computing tools
Multivariate Adaptive Regression Spline (MARS) concepts were used to model the surface runoff and sediment yield from rainfall events in the watersheds under DVC, Hazaribagh, Jharkhand. MARS uses a “divide and conquer” approach through generation of splines and knots to automatically classify the training data into several groups. In each group, a regression line or hyperplane is generated for a specific spline and knot value and represented by basic functions. Compared to other soft computing technologies, MARS is fast, flexible, and capable of determining the important inputs to the model.
In this study, MARS models were developed for two watersheds, i.e., Banha (17.61 km2) and Pokhariya (64 km2) using the data of daily rainfall, runoff and sediment yields of 7 years period. The validation results of MARS were compared with those of the best-fit regression models obtained using the “LabFit” tool. It was revealed that the MARS models for runoff prediction for both the watersheds performed better (0.75 < R2 < 0.92) than the regression models (0.45 < R2 < 0.68). Also, the MARS model developed for prediction of sediment yield for Banha watershed performed better (R2= 0.82) than that of the regression model (R2=0.56). It can be concluded that MARS can be successfully used for the prediction of watershed runoff and sediment yield from daily precipitation events.
3.3.2.2 Water harvesting and irrigation methods plan for Moolbari micro-watershed in Shimla district of Himachal Pradesh
Hydrologic monitoring and subsequent analysis of rainfall and runoff hydrograph revealed that water availability for utilization within the watershed could be increased as substantial amount of infiltrated water flow as base flow for considerable period. Normally the topography of the watershed in hills may not permit for large surface storage structures within the micro-watershed, and if large water harvesting structure is created at some location in the downstream side of main stream, pumping and conveyance would be a problem and uneconomical for small cultivated area. Looking at the prospect of stream water harvesting, the construction of a few small check dams in the primary and secondary channels at appropriate location to harvest the sub- surface flow was suggested. Tanks constructed near stream can be connected to sub-surface reservoir created upstream of the sub-surface dam to collect the sub-surface flow. By adopting the suggested measures, water availability in the micro-watershed can be increased by 0.02 mcm. Harvested water can be utilized efficiently through drip and sprinkler irrigation systems. Even small diameter flexible pipe can also be used to irrigate the vegetable crops. The irrigation system could be operated under gravity as sufficient head would be available to operate this.
3.3.3 Irrigation Agronomy
3.3.3.1 Performance of pearl millet-based cropping system under irrigated condition and its residual effect on succeeding wheat
In this study, wheat was grown after the harvest of pearl millet under the same field layout to asses the residual effect of different treatments. The treatments for pearl millet were two irrigation levels, i.e., rainfed and 2 irrigations applied each at flowering and dough stages, and 3 cropping systems, i.e., sole pearl millet (var. Pusa 383), pearl millet intercropped with mungbean (var. Pusa Ratna) and cowpea (var. Pusa Sampda) in additive series of intercropping. The experiment was laid out in split plot design with 3 replications. The irrigation schedule was allotted in main plots and cropping system in sub-plots. It was observed that pearl millet grown either as sole crop or intercropped with cowpea or mungbean produced similar grain yield. Additional yields of intercrops were obtained without any adverse effect on the yield of main crop. But pearl millet equivalent yields were significantly
higher with intercropping compared to sole crop under both rainfed and irrigated conditions. Soil moisture contribution from deeper soil depths towards the total water use was more under rainfed compared to irrigated crop. Total water use was higher in irrigated crop but the crop water use efficiency was more under rainfed conditions.
3.3.3.2 Aqua-ferti-seed drill studies
Under rainfed conditions, sowing by aqua-fert-seed drill (AFSD) gave significantly higher grain yield of wheat (2.44 t/ha) compared to that given by conventional method (CS) of sowing (1.68 t/ha). Under AFSD, germination and growth were better than those under conventional method.
Performance of wheat variety HD 2865 was maximum (2.86 t/ha) followed by HD 2285 and HD 2687 (2.05 t/ha and 2.03 t/ha). The least grain yield was recorded with HD 2329 (1.69 t/ha). Moisture use by wheat under AFSD (in respect of seasonal consumptive use, moisture use rate and crop water use efficiency) was higher compared to that under conventional method. On an average, three irrigation, resulted in maximum seed yield (1.96 t/ha), which was 12.69% higher than that of one irrigation (1.74 t/ha) and 9.76% more than that of two irrigations (1.91 t/ha). Similarly nitrogen applied
@ 90 kg/ha produced 1.98 t/ha, followed by 60 kg N/ha (1.88 t/ha) and the least with 30 kg N/ha (1.76 t/ha). Application of 40 kg S/ha enhanced the seed yield of mustard by 40.8% in comparison with no S (1.55 t/ha) followed by 20 kg S/ha which registered 21.63% increase over no S application. Moisture use in terms of seasonal consumptive water use and moisture use rate was maximum with three irrigations.
3.3.4 Pressurized Irrigation Studies
3.3.4.1 Response of summer groundnut to drip irrigation in semi-arid region
A study was carried out in summer 2007 with 5 irrigation schedules, viz., daily irrigation (As per ETcrop), alternate day, 30% of management allowed deficit (MAD), 40% MAD and 50% MAD and methods of sowing, viz., normal flat bed, paired row flat bed and paired row raised bed. Effects of irrigation schedules remained consistent with yield and water use efficiency, irrespective of the sowing methods. Daily irrigation as per the ETcrop produced the maximum pod yield.
This was comparable to the pod yields obtained from the plots irrigated alternate day and at 30% management allowed deficit.
However, the pod yields were significantly less if irrigation events were scheduled at greater than 30% management allowed deficit.
3.3.4.2 Response of garlic to different crop geometry under the influence of micro-irrigation and its economics
An investigation was carried out to evaluate the performance of garlic under micro-irrigation. The treatments consisted of six geometries and two methods of micro- irrigation, namely, drip and micro sprinkler. Maximum yield of garlic was found under drip irrigation (8.07 t/ha) compared to that under micro-sprinkler (6.61 t/ha). Amongst the crop geometries, 15 x 10 cm spacing produced significantly higher yield (9.23 t/ha). However, the yields obtained under 10 x 15 cm, 5 x 30 cm and 25 x 10 cm were on a par. Crop water use efficiency and irrigation water use efficiency were higher with drip irrigation compared to those under micro-sprinkler.
Economic analysis indicated that drip irrigation gave maximum net returns and benefit cost ratio as compared to micro- sprinkler. The crop geometry of 10 x 15 cm under drip irrigation was found to be most economical.
3.3.4.3 Effect of drip fertigation on garlic yield A field experiment was conducted on garlic var. G 50 with 3 irrigation levels, viz., 60%, 80% and 100% of the crop evapotranspiration (ET); and 4 fertigation frequencies, viz., biweekly, weekly, fortnightly and monthly. Yield of garlic was not significantly affected by biweekly and weekly fertigations, though there was a trend of lower yields with monthly fertigation. The highest yield was recorded in biweekly fertigation (18.7 t ha-1), followed by monthly fertigation (10.4 t ha-1).
3.3.4.4 Effect of deficit irrigation and its frequency on yield and quality of potato
An experiment was conducted on potato var. Kufri Badsah during October to February to study the effect of different levels of irrigation water and its frequency on potato yield and quality. Drip tape was buried manually in the middle of ridge at a depth of 15 cm. Three irrigation levels of 60%, 80% and 100% of the crop evapotranspiration and four frequencies of irrigations (daily, alternate day, biweekly and weekly) were maintained in the crop. Optimal or ‘no stress’
irrigation was calculated as the net amount of irrigation required to refill the soil moisture deficit with daily application of irrigation water. The water requirement of the potato was estimated as 23.5 cm. Maximum potato yield (46.5 t/ha) was obtained in the alternate day irrigation with no water stress.
Maximum specific gravity (1.09) was observed with alternate irrigation. Maximum starch content (15.98%), and dry matter
content (21.6%) were observed in daily irrigation with no water deficit. Yield reduction was less for cultivation of potato under deficit irrigation.
3.3.4.5 Effect of deficit irrigation during crop growth stages of onion
In this study, onion was irrigated with subsurface drip irrigation involving nine treatments, viz., one period stresses at second, third and fourth growth stages and continuous partial stresses of 60% ETc and 80% ETc of the irrigation requirements. Minimum yield (28.7 t/ha) occurred in the fully-stressed treatment at 60% ETc. While maximum yield (37.7 t/ha) was obtained in the full- irrigation treatment. It was observed that water deficit at fourth growth stages gave non-significantly different yields from that in the optimum application. However, in no case the yields were higher than that in the optimum (full) irrigation. If the water deficit was in the second and third growth stages, or during all stages as 60% ETc and 80%ETc water deficit, the yields were significantly different from that in the optimal irrigation.
3.3.4.6 Effects of shading nets on micro-climate Twelve shade nets of dimensions, 3m x 4m x 5m, of different colours and shade factors were constructed in the month of September and October. Temperature, solar insolation, wind velocity, relative humidity and ultraviolet radiation were measured at 10 a.m., 12.0 noon, 2.0 p.m. and 4.0 p.m. inside and outside the shade nets during winter season.
Observations recorded are given below:
Maximum temperature of 28.5oC, 23.2oC and 21.6oC in the months of November, December and January (at 12 noon) was recorded in the shade net having shade factor of 35% (BxW), while minimum was recorded in black colour shade net having 75% shade factor.
Maximum humidity and solar insolation were observed in the BxG shade net having 35 % shade factor in the months of November, December and January
Shade net having shade factor of 90% (Green) had minimum light intensity, while maximum was recorded in the shade net having shade factor of 35% (BxW and BxG).
The shade net having shade factor of 90% (Green) received minimum ultra-violet radiation, while
maximum was recorded in the shade net having shade factor of 35% (BxW and BxG).
Wind velocity was maximum, ranging from 0.5 -1.00 m/s in shade net having shade factor of 35% and the rest of the shade net with different shade factors had negligible wind velocity.
Shading reduced mean solar insolation by more than 40%, and the screen transmissivity was varying with solar elevation angle. Wind speed inside the shade net was reduced by more than 60%. Wind speed inside the screen house was reduced and ultimately crop water requirements would be lower than those under open field condition.
3.3.5 Groundwater Studies
3.3.5.1 Performance evaluation of filtration unit of ground water recharge shaft
Recharge shaft models were fabricated using acrylic sheets and filled with filtration material, viz., coarse sand (CS), gravel (G) and pebbles (P) of varying depths to study the recharge rate and sediment concentration of the filtered water. The investigation was designed for five different thickness combinations of filtration materials, i.e., coarse sand (CS), gravel (G) and pebble (P) with varying depth ratios of 1:1.5:3, 1.5:1:3, 3:1:1.5, 3:1.5:1, 1:1:1 (CS: G:
P). It was observed that higher depths of coarse sand in the filtration unit were very effective in reducing the recharge rate of the effluent. Also, the effect of change in the thickness combination of gravel and pebble layers with higher depth of coarse sand was observed to be minimal.
Overall, the depth of the coarse sand layer in the filtration unit was responsible for controlling the recharge rate of the effluent. But, the rate of change in the outflow rate was not in proportion to the variations in the depths of the layers of coarse sand, gravel and pebble. The best thickness ratio of the filtration unit for obtaining the highest flow rate was observed to be 1:1:1 (CS:G: P). The combination of the filtration unit to perform the best filtration for all inflow sediment concentrations was 3:1.5:1 (CS: G: P). Analysis of the results of both the recharge rate and sediment concentration of the effluent revealed that the filtration layer thickness ratio of 1.5:1:3 (CS: G: P) would be the optimal design of the filtration unit of the recharge shaft for attaining higher recharge rate and better filtration of
the turbid water.
3.3.6 Aerobic Rice Cultivation
3.3.6.1 Aerobic rice system: A water-wise rice production system
Rice production under traditional puddle-transplanted lowland uses more than 50% of irrigation water used in agriculture. A change from traditional rice production system to aerobic rice system is imperative to increase water productivity of rice. Since no aerobic rice variety is released
for north Indian region, 28 rice genotypes were evaluated for their potential aerobic adaptation and high yield with three irrigation regimes, viz., irrigation at zero kPa, 20 kPa and 40 kPa soil moisture tension. Drought tolerant upland variety Nagina 22, aerobic rice varieties, namely, APO and MAS946- 1 released by IRRI, Philippines and UAS, Bangalore, respectively, were used as checks. The total amount of water applied was 1345mm, 1045mm and 845 mm under the three irrigation regimes, respectively. Thus, aerobic rice method saved about 30-50% (~800 mm less water) as compared to 1800 mm water applied in transplanted rice. Pusa Rice Hybrid 10, Proagro 6111 (hybrid), Pusa 834, IR 55423-04, IR 72875-94-3-3-2 produced a grain yield similar to that of APO (4.8 t ha-1) but higher than that of aerobic rice variety MAS946-1 (4.08 t ha-1) under zero kPa. Pusa Rice Hybrid 10 and Pusa 834 showed a combination of aerobic adaptability similar to APO and better than Nagina 22 at 40 kPa, as they produced a grain yield of about 4 t ha-1.The potential of aerobic rice in water saving was demonstrated in farmer’s field in three villages of Bhulandshar district (U.P.).
3.3.7 Water Quality Studies
3.3.7.1 Spatio-temporal variability of groundwater quantity and quality parameters
Keeping in view the deteriorating ground water quantity and quality of National Capital Territory (NCT) of Delhi owing to higher population density and over-exploitation of ground water, efforts were made in this study to map the spatial and temporal variability of ground water depth and quality parameters using geostatistical concepts. The ground water depth and quality parameters were analyzed from the existing tubewells, and the spatial variability and probability maps were generated using geostatistical concepts. Ordinary kriging method was used to analyze the spatial variability of groundwater depths. Indictor kriging method was used to analyze the groundwater quality parameters such as chloride, electrical conductivity (EC), fluoride, magnesium and nitrate concentrations equal to or greater than that of the groundwater pollution threshold levels. It was revealed that the exponential semi-variogram model fitted well with coefficient of determination (R2) equaled to 0.996 for water table depth, whereas the spherical semi-variogram model fitted well for the water quality parameter such as chloride (R2 = 0.915), EC (R2 = 0.897), fluoride (R2 = 0.505), magnesium (R2 = 0.920) and nitrate (R2 = 0.656). The water quality parameters, viz., chloride and EC were inversely related with water table depth, whereas the magnesium concentration in groundwater was directly related to the depth of water table, and nitrate concentration had no correlation with the depth. The areas with potential salinization were in the northern part of NCT, whereas the chloride concentration was higher in the southern part and the nitrate pollution in the western part of NCT. The indicator kriging revealed that 50% of area within NCT was having polluted ground water resources.
3.3.7.2 Temporal variability of quantity and quality parameters of the waste water carrying channel in IARI farm and its use in agriculture
In continuation of the periodic reading of the flow depth and collection of water samples of the waste water-carrying channel at IARI farm, it was observed that for an average depth of 5 m from the culvert surface, the quantity of water flowing past the channel is about 48.5 million litres per day.
By diverting about 50% of water from the channel and permitting the rest to flow past the channel to downstream regions, one can harvest about 24.25 million litres of water per day, which can meet the irrigation requirement to a large
Grain yield production of rice varieties in three levels of irrigation (Io, okPa; I20 , 20 kpa; I40, 40 kpa)under aerobic production system at IARI during kharif 2007
extent. Further, to ascertain its use for agriculture, the water quality parameters were investigated by analyzing the collected samples from the channel at different times and days of the month throughout the year. It was observed that sodium absorption ratio (SAR) varied from 2.5 to 7.5 units, and was within safe limit for irrigation purposes. The residual sodium carbonate (RSC) value of less than 1.25 indicates that the water is safe for irrigation and a value more than 2.5 restricts its use for irrigation. It was observed that 20% of the collected waste water samples exceeded the safe limit (RSC > 2.5) for irrigation. The EC and pH of waste water were within the safe limit for irrigation purposes. Overall, the waste water was safe for irrigation with specific amendments to reduce the RSC or can be used safely in conjunction with fresh water.
However, there is a need to estimate the content of heavy metals in the waste water and conduct long-term irrigation experiments to determine its impact on the soil and underlying ground water resources for sustainable agricultural production.
