Soil Profile Water Use and Mean Daily Actual Evapotranspiration from Permanent Bed Planted Wheat (Triticum aestivum)

An experiment was conducted at New Delhi, at an elevation of 228 m (28°36′ N latitude, 77°12′ E longitude) on wheat (Triticum aestivum L.) during late winter (rabi) season (December to April) of 2001–02 and 2002–03 to investigate the water balance components of a permanent bed system in a rice-wheat cropping sequence. Grain yield production in bed-planted wheat with two rows per bed reduced by 15–18% compared to conventional flat system with 20 cm row spacing. However, irrigation water requirement was less (24–42 mm) in bed-planted wheat. Extraction of soil profile water in meeting the actual evapotranspiration (AET) was also 9–15% less in beds, with major amount (55–59%) being contributed by the 0–15 cm root zone while in flat systems it was the 0–30 cm root zone contributing the maximum amount (>60%) of soil water use. Similarly, the total AET value was also 10% less in beds compared to flat system. Mean daily AET value also reflected a distinct pattern, being significantly higher (>14%) in beds at CRI to tillering stages compared to flat systems. However, at flowering stage onwards, a reverse trend of 10% less was observed in bed. Loss of grain yield production was, however, offset by reduction in irrigation water input in bed; as a result, the water use efficiency between the bed and flat system was quite comparable.