The effect of rice straw mulch on evapotranspiration, transpiration and soil evaporation of irrigated wheat in Punjab, India

• Published in: Agricultural water management 2011-10, Vol.98 (12), p.1847-1855
• Main Authors: Balwinder-Singh, Eberbach, P.L., Humphreys, E., Kukal, S.S.
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agronomy. Soil science and plant productions; Biological and medical sciences; biomass production; clay loam soils; Crop factor; Evaporation; Evapotranspiration; field experimentation; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; grain yield; irrigation; Mathematical analysis; Mini-lysimeters; mulching; North-west India; Rainfall; rice straw; Soil (material); Straw; straw mulches; Transpiration; water balance; Water balance and requirements. Evapotranspiration; Wheat; Zero till; Zero till Crop factor Mini-lysimeters North-west India
• ISSN: 0378-3774; 1873-2283
• DOI: 10.1016/j.agwat.2011.07.002

► Mulch suppressed Es and increased T by a similar amount. ► ET was not affected by mulch, under water deficit and non-deficit conditions. ► Under non-water deficit conditions, mulch lowered transpiration efficiency. ► Crop factor was lowered by mulch except towards the end of crop season. Soil evaporation (Es) is considered to be a non-productive component of evapotranspiration (ET). So, measures which moderate Es may influence the amount of water available for transpiration (T), the productive component of ET. Field experiments investigating the effects of rice straw mulch on components of the water balance of irrigated wheat were conducted during 2006–2007 and 2007–2008 in Punjab, India, on a clay loam soil. Daily Es was measured using mini-lysimeters, and total seasonal ET was estimated as the missing term in the water balance equation. Mulch lowered total Es over the crop growth season by 35 and 40 mm in relatively high and low rainfall years, respectively. Much of this “saved water” was partitioned into T, which increased by 30 and 37 mm in the high and low rainfall years, respectively. As a result, total ET was not affected by mulch in either year. In both years, there was a trend for higher biomass production and grain yield with mulch, but with significant differences only in 2006–2007. Transpiration efficiency (TE) with respect to grain yield was 18.8–19.1 kg ha −1 mm −1 in 2006–2007, and 14.6–16.4 kg ha −1 mm −1 in 2007–2008. While wheat grown in the presence of mulch tended to lower TE, this was only significant in 2007–2008. The results suggest that while mulching of well-irrigated wheat reduces Es, it does not “save” water because the crop compensates by increased T and reduced TE.