Up-Scaling Micro Irrigation

Abstract

Micro irrigation (MI) is one of the key interventions in water saving, energy saving, and improving the crop productivity and is gradually emerging as a demand management technology in India. The MI potential in the country varies from 42 to 72 M.ha by various estimates. At all India level, the MI area covered to the potential till 2019 is only about 17.4%. Among the drip and sprinkler coverage, the potential covered under drip is 28.2% and sprinkler is 12.9%. In terms of actual area coverage to the total MI area in the country, five states viz., Rajasthan, Andhra Pradesh, Maharashtra, Karnataka, and Gujarat have shared more than 10% each. Regarding MI implementation models, Gujarat Green Revolution Company (GGRC) model is comparatively performing better. The major suggestions to up-scale the MI adoption include provision of technical support for MI operation after installation, relaxation of farm size limitation in providing MI subsidies, supply of liquid fertilizers, improved marketing facilities and access to more credit, direct benefit transfer (DBT) scheme, MI in canal command area, and better implementation models like GGRC.

Appendices

Annexure 1: Introduction of Micro Irrigation in the Canal Commands—A Sample Worksheet

Parambikulam Aliyar Project (PAP) is one of the major irrigation systems of Tamil Nadu; which serves the area of more than 4.30 lakh acres of the dry part of western Tamil Nadu. The PAP, interstate (Between Tamil Nadu and Kerala), a multi-valley and multi-purpose project was commissioned in the early 1960s and started functioning from the mid-sixties. Since, PAP is a supply-based irrigation system, the farmers’ demand for adequate supply for better cropping is not feasible. This system follows a system of dry irrigated cropping which entails irrigation of a larger area with a given quantity of water (operating at a 120 duty basis). The rainfall in the command area is scanty with an annual average of about 700 mm, which is well below the state average of 960 mm. It is also concluded through different studies conducted so far that difference in productivity per unit of cultivated land with and without irrigation is much larger in this command. In recent years, there has been change in the water allocation management in the system, where the irrigation department controls the supply of water up to distributary/sluices after which farmers themselves manage water through Village Water User’s Association (VWUA) functioning since 2000.

Water Realization for Irrigation System

The average quantity of water realized from the group of reservoirs over the past 35 years is around 15 TMC (Thousand Million Cubic feet). Out of 4.30 lakh acres in the entire PAP system, again this has been divided into two river basins namely Aliyar river basin with a command area of about 0.50 lakhs and the Palar river basin (Thirumurthy dam) with a command area of about 3.80 lakhs acres. The Palar river basin has been again divided into four zones system and each zone is being irrigated once in two years.

Existing Irrigation Method

Currently water is conveyed through concrete lined canals (main, branch, and distributaries) and from the sluice point to the field, water is flowing through earthen channel and in the field traditional irrigation methods like ridges and furrow, beds, and channels for annual crops and basins for perennial crops are used for irrigation. All these traditional methods follow flooding irrigation. To provide irrigation to the 3.80 lakh acres of command area, water is released once in 2 years for 135 days dividing the entire area into four zones. The first two zones are in the first years and remaining 2 zones are irrigated in the next irrigation year (each zone’s average command area is almost uniform ranging from 86,152 acres to 98,558 acres).

This is a unique project in the sense that the farmers get water once in 2 years for growing one dry crop with uncertainty in supplies as the supply is decided based on the many other factors including rainfall at catchments and command area, etc. However, according to the farmer’s demand, from the year 2000 onwards, irrigation water is supplied by Alternative Sluice Irrigation System (ASIS) in order to keep the water flows in the main canal throughout the year so that wells get recharged. ASIS is nothing but regrouping of command area under branch canals, distributaries, and direct irrigation sluices, water is allowed in each zone through alternative sluices in main canal, branch canals, and distributaries having more than 1000 acres where main canal will be functional for the entire irrigation year to distribute the water for irrigation to different branches and distributaries.

Cropping Pattern

It is seen from the table below that 29% area is under coconut, 31% under millets viz., maize, sorghum, and cumbu, 11% under pulses, about 14% under oil seeds, 12% under vegetables, and remaining (around) 3% is under cotton.

S. No	Crop	Area (acres)	Percentage
1	Coconut	97,540	29.05
2	Maize	65,270	19.44
3	Sorghum	38,470	11.46
4	Pulses	36,920	11.00
5	Groundnut	32,550	9.69
6	Gingelly	14,495	4.32
7	Onion	10,470	3.12
8	Cotton	9,755	2.91
9	Vegetables (tomato, Brinjal, Bhendi and others	30,315	9.03
Total		3,35,785	100.00

Proposed Cropping Pattern Under Changed Irrigation Method

The quantity of water realized at Thirumurthy dam was reduced from 18 to 14 TMC in the last 20 years and sometimes water realization may even go less than 10 TMC in drought years. The non-agricultural demand as well as 15–20% conveyance losses should also be accounted for within the available supplies. Rainfall received in the command area over the years is also around 650–700 mm. In order to improve the water use efficiency in the water-scarce irrigation system and also to enhance the income of farmers, micro irrigation with the following crops in the canal command is suggested.

• Low Water Consuming Crops

  Mango, Sapota, Guava, Amla, Tamarind, Jetropa, and medicinal plants.

• Medium Water Consuming Crops

  Coconut, papaya, onion, all vegetables, maize, oil seed crops like groundnut, gingelly, and pulses.

Since, irrigation system is facing shortage of water for distribution to the entire command, water intensive crops like banana, turmeric, and sugarcane cultivation in the command may be discouraged.

Worksheet

9.6.1 Water Use with Proposed Irrigation Method

Water availability for utilization:
Surface water availability in the Thirumurthy reservoir	= 14 TMC
Groundwater availability in the entire command area	= 12 TMC
Assuming that command area as on date is around 3.0 lakhs acres with reduction of 25% area due to urbanization and converted into industrial use, etc.,
Quantity of water available per acre per year = 14,000 M.cft/0.30 M acres
	= 50000 cft
Assuming this water is supplied for about 300 days (assuming the rainy days of three months—effectively around 75 days) the quantity available per day
	= 50000/300
	= 166 cft (or) around 5000 L/acre/day

Irrigation Methods

The water required for matured coconut tree through micro irrigation system is about 60–100 L per day. Variation may be due to season to season and soil moisture content, etc. Among the proposed crops, coconut may require more water. If coconut may be restricted to the 40% of the command area and remaining with other crops which consumes less water compared to the coconut. This calculation has been made without considering the groundwater potential of the location or region or zone. However, it is assumed that 12 TMC of groundwater potential is expected to be available from the command area which can be utilized in the drought years and whenever there is failure of monsoons.

Farmers’ Preference for Micro Irrigation in the Command

It is interesting that majority of the farmers in the PAP system are well aware about the success and efficiency of micro irrigation techniques like drip and sprinkler and also drip irrigation method was already extensively adopted for cultivation of coconut crops (currently almost more than 40% of the coconut area is under drip irrigation in the PAP system) and also many other tree crops (mango, sapota, amla, and wood value tree crops) are cultivated under drip irrigation. Hence there may not be much problem in convincing the farmers and shifting the entire land under micro irrigation methods.

It is also high time to use the support extended by central and state governments for drip and sprinkler irrigation systems. In addition to this, financial sectors (agricultural banks) are also interested in funding for these types of activities.

Agricultural and Non-agricultural Benefits

By changing the crop/cropping pattern under micro irrigation method, farmers can cultivate the crops throughout the year instead of one season in two years irrigation cycle under existing water release pattern. Those areas brought under complete micro irrigation technique will be given water throughout the year and this arrangement will definitely help the farmers in managing their livelihood without much uncertainty in the agriculture since water is a crucial input. Groundwater level will improve due to continuous canal water supply. Equity can be achieved in time and quantity of irrigation water distribution among farmers.

Cost of Conversion to Micro Irrigation Technique

The entire command area will come under micro irrigation system and the ratio of drip and sprinkler may be 70 and 30% respectively.

The cost of drip irrigation per hectare for horticulture crops including water storage tank and pumpsets, etc., (well owning farmers may be educated to use their wells as such for storage of canal water and pumped for irrigation) will be around Rs. 40,000 per acre and Rs. 40,000 for development of water storage tank at farm level.

Initially, this modern irrigation water distribution will be implemented in one of the distributaries with a command area of 100–150 acres. The cost of this programme may be about Rs. 1–1.5 crores and based on the experience of this case, further expansion may be taken up. Already some success stories are done at micro level using drip irrigation in the command and hence this project will be successful if implemented properly. Successful implementation schedule is given below.

Case Study

•	Sluice		1® of veruvedampalayam Distributary of PMC
•	Ayacut area		21.30 Acres
•	Proposed Area		21.30 Acres
•	No. of Beneficiary		4 Nos
•	No. of plants		1600 Nos
•	Length of Hytrohole		1600 × 6 M = 9600 Nos
•	No of Dripper/emitter		9600/0.50 M = 19200 Nos
•	Total Discharge		19200 × 2 Lph = 38400 LPH
•	Peak water requirement		1600 × 100 LPD = 160000 LPD
•	Operating hours		4.16 h/Day
•	Storage tank capacity		((10 + 8)/2) × (10 + 8)/2 × 2.25) = 182250 L
•	Total head		(A) Operating head 10 m
			(B) System Head Loss17 m
			(C) Well Depth (Sump depth)2.25 m
		Total Head	29.25 or 30 m
	Discharge		Q = 38400 L/3600 = 11 lps
	HP 11 * 30/75 * 06(Q * H/75m)		7.3 HP 7.5 hp

Sluice (1R) of Veruvedampalayam Distributary of Parambikulam Main Canal

Total Ayacut Area	20.33 Acres
Total Number of Farmers	4 Nos
Total Number of Coconut Trees	1600 Nos
Total Number of Wells	4 Nos
Total Water Requirement/Tree/Day	100 L
Total Water Requirement/Day	1,60,000 L