Dr. Kiran Kumar*1 and Dr. Padmakshi Thakur2

*1 R.H.E.O., Assistant Director Horticulture Dist. Kanker (C.G.)
2 Scientist, SG College of Agriculture & Research Station, Jagdalpur, IGKV, Raipur, (C.G.).
*Corresponding Author: kiran.nagraj90@gmail.com

Introduction- When, how much and how to irrigate are important questions for farmers/growers, mainly because of the increasing energy costs and lack of adequate water resources. The rational management of irrigation is, therefore, an indispensable process in irrigated crop production. Many interacting factors determine the frequency of application and the amount of water to be applied. Some of these factors include: the plant's inherent water requirements based on species; the climate of the region (macro climate) and the environment around the specific area (micro climate); the season of year; the type of water delivery (irrigation) system; and the desire or necessity to conserve water. The present article embodies information on irrigation water management approaches, advantages of hi-tech irrigation systems and future needs related to efficient water management in vegetable crops.
The conventional method of irrigation (flooding, furrow, flat bed, corrugation, boarder, ring etc.) revolves around the concept of replenishing the moisture level to field capacity (FC) after 50 to 60% depletion. The plants actually use only 40-50% of the water delivered through these methods. The low efficiencies are attributed mainly to the conveyance losses resulting from seepage, percolation and evaporation. On the other hand, drip irrigation system is for efficient (Table1) owing to precise and direct application of water in the root zone. (Raina, 2000)

Table 1: Irrigation efficiencies (%) under different methods of irrigation

Irrigation method efficiency
Methods of irrigation
Surface
Sprinkler
Drip
Conveyance efficiency
40-50 (Canal)
60-70 (well)
100
100
Application efficiency
60-70
70-80
90
Overall efficiency
30-35
50-60
80-90

Drip irrigation: Drip irrigation is a technique in which water is applied in small and precise amount at frequent intervals, directly near the root zone, through emitting devices via network of PVC/HDPE mains, sub mains, filtration unit, control valves and LLDPE laterals. The technology has the greatest potential where water is either very expensive or scarce or the soils are coarse textured. Micro-irrigation was practiced in India through indigenous methods such as bamboo pipes, perforated clay pipes and pitcher/porous cup irrigation. Drip-irrigation also enables the use of fertilizers, pesticides and other soluble chemicals along with the irrigation water more economically.


Advantages of Drip Irrigation:
Every irrigation method has its own merits and demerits. There are various advantages of drip irrigation method -

1.Water Saving: Due to partial wetting of the soil volume, reduced surface evaporation, decreased runoff and controlled deep percolation losses, the water use efficiency under drip irrigation is markedly higher than traditional flood or furrow irrigation. The comparative results on drip and surface irrigation in some vegetable crops are cited in table 2.

Table 2: Water use and yield under two methods of irrigation.

Crop
Water use (cm)
Yield Q ha-1
Surface
Drip
Surface
Drip
Tomato
49.8
10.7
61.9
88.7
Okra
53.5
8.6
100.0
113.2
Source; Sivanappan and Padamkumari 1987

2.Enhanced plant Growth and Yield: Slow and frequent watering eliminates wide fluctuations in soil moisture content resulting in better growth and yield. Application of mulch in conjunction with drip system proved more beneficial in saving the irrigation water and improving the yield.

3.Saving in labour and Energy: There is a considerable saving in labour as the well designed system needs labour only to start and stop the system. Because of high irrigation efficiency much time is not required to supply the desired quantity of water, thus, it also saves energy.

4.Weed Control: Due to partial wetting of soil, weed infestation is very less in comparison to other methods of irrigation.

5.Most Suitable for poor Soils: Very light (sandy) soils are difficult to irrigate due to deep percolation of water. Like- wise, very heavy soils are difficult to irrigate, even by sprinkler methods because of low infiltration rates.

6.Salinity Hazards: Less moisture content due to frequent irrigations and lesser water requirement over the surface method keep saline concentration below the detrimental levels.

7.Soil Erosion: There is no soil erosion due to drip irrigation.

8.Fertilizer use efficiency: Because of reduced loss of nutrients through leaching, runoff and volatization and also local placement in the root zone, FUE is considerably improved.

9.Disease incidence: Easy installation, minimum tillage and incidence of diseases and pests are added advantages of drip irrigation.

Constraints of drip system:
There is no second opinion about the immense potential and prospects of drip system. But, there are some constraints listed below, which need to be solved by multi- pronged effort:
  • It requires high initial investment.
  • Frequent clogging of drippers. The clogging could be due to algae, salt accumulation or foreign particles.
  • Non availability of technical manpower.
  • Inadequacy of technical input for efficient management of drip irrigation system.
  • It is not suited for frost protection or for cooling during periods of hot weather.

Future Needs: With the ever increasing demand for water in the domestic and industrial sector, the allocation of water for agriculture is likely to decline considerably. This calls for judicious use of water adopting strictly the recommended irrigation schedules and efficient water injection systems such as drip/sprinkler. Application of irrigation water through high tech systems such as sprinkler/ drip is an integral component of protected cultivation. Irrigation water requirement is expected to vary markedly for different vegetable crops being raised under open and polyhouse conditions in different parts of the country. So for, scanty information on these aspects has been generated and documented. There is also a need to popularize the high tech irrigation systems among farmers and growers through demonstrations pin pointing the advantages of such systems related to water savings and improvement in yield and quality of crops.

References
Raina, J.N. (2000) Drip irrigation and fertigation in vegetable crops.HorticultureTechnology (Eds.) V.K. Sharma and K.C. Azad. Deep and Deep Publications, New Delhi,Vol. II: pp339-346

Sivanappan, P.K. and O. Padamkumari (1987) Drip irrigation. Keerthi Pub. House Pvt.Ltd. Coimbatore.