National Agricultural Innovation Project was launched at Duphad cluster and another seven hamlets in Penpahad Mandal, 160 km away from Hyderabad. The population of nine Schedule Tribe (ST) thandas was 2,326. Around 92% populations are living below poverty line.
The major source of irrigation in the cluster was open wells (165) and tube wells (67). Farmers preferred to grow paddy with the support of open wells and tube wells during Kharif and, paddy and vegetables depending on water availability during the Rabi season. Greengram, red gram, groundnut and vegetables were mostly grown in the rainfed area while paddy was practised under open wells and bore wells. The vegetables were cultivated under rainfed during Kharif season, while they are grown with the support of irrigation during Rabi and summer seasons.
Rainfall situation in the cluster
Duphad cluster falls under Penphad mandal which is the nearest rain gauge station for the study area. Rainfall data were collected analyzed and compared with normal rainfall. Normal rainfall of the mandal is about 609 mm which is lower than district average (753 mm). Eleven years annual rainfall was plotted and compared with normal rainfall (Fig.1). Study area received deficit rainfall in eight years out of eleven years. Lowest rainfall was received in 2002 with a deficit of 68%. There was a continuous deficit in rainfall from the year 2001 to 2004 with a deficit of 44 to 68%. In the year 2010, study area received 908 mm of rainfall with excess rainfall of 49%.
Groundwater status in the cluster
Depth to groundwater levels data was accessed from Central Ground Water Board (CGWB) web site. The data was plotted against seasonal rainfall. Maximum seasonal fluctuation in Ground Water Level (GWL) of +11.37 m was found in 2010 where the annual rainfall was recorded about 906 mm. During the five years period, depth to groundwater level reduced to as low as 14.3m in pre-monsoon of 2010. Depth to groundwater level was raised to close to as 2 m during post-monsoon season in the year 2007 and 2011. The average depth to groundwater level during pre-monsoon season was about 6 m and during the post-monsoon season it was about 2.9 m.
A) Renovation work of Jalamalakunta percolation tank
Jalamalakunta tank is situated at N 17o 0′ 26.6″ and E 79o 42′ 53.3″ between Jalamalakunta Thanda and New Banjara Hills Thanda in Dupahad cluster of Nalgonda district. The tank was constructed two decades ago to harvest the runoff from the catchment area of 15 ha. The present tank does not have enough capacity to accommodate all the runoff from the catchment. After discussion with the farmers it was proposed to enhance the storage capacity by increasing the height of bund and surplus weir ). With the provision, there would be a significant increase of groundwater level at the surrounding area. The tank is surrounded by 15 open wells and bore wells some of them are defunct. If the tank is renovated, all the wells would get recharged and will enhance cropping intensity.
a)Total earthwork involved to achieve design storage capacity: 3695 cum.
At the middle of the water spread area of tank (an extent of 0.75 ha), the soil needs to be excavated to a depth of 0.5 m and heaped on the bund uniformly to achieve required dimensions of the bund.
b) To construct surplus weir of 6 m length.
Impact of Intervention
The above work was included in “Shelf of Works” of NREGS programme in the year 2009. Budget (Rs. 2,50,000) was sanctioned for deepening and bund strengthening based on the estimate submitted to the department. The work was carried out through labour as per the norms of NREGS. Construction of surplus weir was taken up by project funds and it was also constructed in April that year. The very same year rainfall was very distributive and catchment area of the tank received a good amount of rainfall, percolation tank filled with designed excess volume 3695 cum.
Impact on groundwater recharge nearby open well
The percolation tank has a good significant impact on the water table in nearby open wells. The below Google image is showing the location of percolation tank and open wells under observation in the downstream side of the tank. Depth to groundwater levels (GWL) of six open wells was plotted, the results show that there was a tremendous increase in recharge of groundwater (8 to10 m) and depth to groundwater increased from 15 m to 5m in five borewells. Borewell 3 got recharged by 15 m and depth to groundwater was reached from 27 m to 8 m In downstream of the tank there are 21 farmers having open/bore wells.
All the groundwater resources got recharged by the percolation tank. Before the intervention, the paddy grown areas under all the wells were about 11 ha with an average of 0.52 ha per open well. After this intervention, the areas under all wells have gone to 16.4 ha with an increase of 50% additional area under irrigation facility. The corresponding yields have also increased from 50 t to 92.6 t with a yield growth of 83%. The production per unit area was increased from 4.5 t ha-1 to 5.6 t ha-1 with an increase of 25%
B) An economic design for recharging dug wells with rainwater
Design and estimate
In initial PRA and baseline survey, it was observed that the groundwater level was declining season by season and some of the open wells and bore wells were defunct. Even crops under irrigation got affected due to this. In the initial period of the monsoon season, after sowing operation, if any dry spell occurred, crops suffered from moisture stress even under open wells because it required some time to recharge naturally.
In the cluster of villages, open wells which have either gone dry or whose water levels have declined considerably could be recharged directly with surface run-off. Rainwater that was collected from the surrounding area was diverted by approach channel to a settlement or silt trap, from which it was diverted by conduit into the open well. Open wells were thus recharged with runoff water from nearby waterways or surrounding catchment area. This initiative met immediate water requirement of crops as well as improved groundwater levels.
In areas where considerable de-saturation of the aquifer have already taken place due to over-exploitation of groundwater resources, it resulted in the drying up of dug wells and lowering of piezometric heads in bore/tube wells, therefore an alternative simplified and economic design was made to recharge dug wells with rainwater.
C) Monitoring of groundwater resource use through water meters
Water meters were fixed to two pump sets in the cluster in order to monitor or quantify the water used by a farmer for a particular crop in a season. Daily water pumping from a bore well was monitored by taking the initial and final reading of the water meter. This study indicates whether the farmer is over irrigating or under irrigating his field in a season. Water pumping in rice fields and tomato fields was monitored.
Irrigation application in paddy fields
It was observed that total pumping of water was around 2075 m3 to irrigate 0.5 ac of paddy Irrigation application is estimated as 1066 mm in addition to contributed rainfall of 628 mm in Kharif season. Water productivity of rice is estimated at 2.92 kg ha-1 mm-1 with water use of 1694 mm and productivity of 5 t ha-1.
Application of irrigation water in a tomato field
Daily pumping of water was plotted. Total pumping of water in m3 was recorded for the entire crop period which was observed to be1853 m3 for 0.5 ac of tomato crop. Application of irrigation water for whole crop period was estimated at 923 mm in rabi season
D) Efficient use of water sources through micro-irrigation
Micro irrigation system (drip) was installed in watermelon field which was inaugurated by the horticulture minister, Govt. of AP system was introduced for demonstration purpose which influenced the farmers to adopt micro-irrigation techniques. Drip-irrigated field was compared with a controlled field where conventional irrigation system was adopted. The results were found to be significant. Effect of irrigation application method was studied in watermelon crop with the conventional method and drip irrigation method.
Under this study, one hectare of watermelon crop was considered. Observations like irrigation application, period, and irrigation interval, the area covered in a day, production and gross income were noted down. It was found that the productivity increased by 16%in drip irrigation when compared to conventional irrigation. Drip irrigation system could cover one-hectare area with 6 mm of irrigation application with pump discharge of 3 LPs for 6 hours pumping. Whereas, conventional irrigation method could cover only one-tenth of a hectare per day with same discharge and operating hours.
E) In-Situ rainwater harvesting through furrows
In-Situ conservation is the key intervention to enhance moisture availability to plants through retention of rainfall in low to medium rainfall zones. Presently, conservation measures are mostly taken up during crop growing season after weeding that result in loss of precious rainfall as runoff, as there is less crop cover on the surface. Ridger planter is developed to make deep furrow (25 cm) of 60 cm width with paired row planting and fertilizer application simultaneously.
This system can store about 250 cu.m of water to the field per hectare. Combined operations such as furrow making, sowing and fertilizer application also result in lower cost of cultivation. Threshold rainfall for initiation of runoff is also higher with this practice. The In-Situ conservation paired row furrow system was found to enhance the crop productivity by 15- 20%. The different In-Situ water conservation interventions followed in the cluster are illustrated.
F) Water productivity of crops
Water productivity of crops was calculated based on the area, production and water used in the growing period. This was worked out for farmers who were benefited by the project. Water productivity of tomato was found to be 19.9 kg ha-1 mm-1 with the productivity of 13.91 t ha-1 during 2008 Kharif season which is higher than that of the earlier season (2007) with water productivity of 17.0 – 19.9 kg ha-1 mm-1. Water productivity of Bhendi was found about 8.2 kg ha-1 mm-1 during Kharif season of 2008 which was 67% higher than the earlier season (Kharif 2007). Groundnut water productivity was found to be 14.1 kg ha-1 mm-1 with the production of 8.47 t ha-1. Jowar water productivity was about 9.1 kg ha-1 mm-1. Water productivity of green gram was about 10.4 kg ha-1 mm-1
- Central institue of dryland agriculture