Pea responds well to irrigation and can also be grown under dryland conditions. Field pea has a high water use efficiency and can use moisture in a root zone of about 0.80 m or 2.6 ft. This means it can effectively use moisture on stubble where it is not fully recharged but cannot make use of soil moisture below 1.0 metre.
In the Brown or Dark Brown soil zones, chickpea may prove a useful alternative to pea as chickpea roots deeper than pea and is able to extract more moisture from the soil than a pea crop. Pea is also sensitive to salinity and to waterlogged soils.
Irrigation of Pea Crops
Water use experiments conducted with pea at Vauxhall, Alberta, in 1976 show:
- the maximum average water use is 6 mm (0.24 in.) per day, and this occurs just after flowering
- pea is sensitive to water stress at all stages of growth – a safe depletion of available water should not exceed 30 per cent until pod filling is completed
Water use experiments conducted with pea at Brooks, Alberta, from 1974 to 1976 show:
- water use efficiency was 21 to 28 kg/ha. of total dry matter per mm of water and about 10.9 to 13.3 kg/ha. of seed per mm was produced
- the harvest index (weight of seed/weight of total dry matter) was about 0.46 to 0.51, and this ratio increased when optimum irrigation was supplied
- total water use of pea at Brooks varied from 410 to 440 mm (16 to 17.5 inches) to obtain maximum yield of over 4500 kg/ha. (4000 lb./ac.)
- these processing pea experiments were conducted with Dark Skin Perfection, a late determinate growth variety – early determinate varieties such as Sprite or Sweet 11 required about 80 per cent of the amount of water needed for a late variety
- protein content in pea is maintained under increasing amounts of irrigation (with cereals, protein content declines when irrigation increases)
Salinity & Drainage
- pea is sensitive to salinity
- an Electrical Conductivity (EC) of 4 dS/m or higher in the top 30 cm (1 ft.) of soil severely reduces field pea growth
- poor drainage is also damaging, especially if the waterlogging occurs just before flowering (Greenwood and McNamara, 1985)
- if irrigating by flood irrigation, use short sets of not more than three to five hours, and do not irrigate after the vines collapse
Water Use Under Dryland Conditions
Data from Miller and McConkey, 1998, show that pea is not as effective in using soil moisture below 0.60 m as wheat, chickpea or mustard. Other data, from dryland conditions in Saskatchewan (Miller et al, 1998), indicate pea has water use efficiency equal to wheat on fallow and better on stubble. Semi-leafless varieties of pea are reported to have similar water use as conventional fully-leafed pea in experiments in New Zealand by Zain et al, 1983, and in Spain by Martin et al, 1994. Other authors report differences between varieties in drought tolerance and in water use.
Yield, water use and effective rooting depth of wheat, pea, chickpea, lentil and mustard when grown on fully recharged fallow at Swift Current and Stewart Valley 1996-97 derived from P. Miller and B. McConkey.
Alternative crop yields and water-use efficiency (WUE) averaged for tillage systems in fallow and wheat stubble phases at Swift Current 92-94, 96 and Assiniboia 1994-95. Derived from Miller et al, 1998.