Initial irrigation requirements of dry tilth paddy soil

C. S. Chan

Abstract

This study provides information related to the first irrigation requirement in irrigating a dry direct-seeded rice field. Irrigation requirement is the total amount of water applied to meet land soaking requirement, seepage and deep percolation losses. Soil compaction and time of water advance, water flow rate and elapsed time, water flow rate and land soaking requirement, elapsed time and land soaking requirement relationship were studied. The observed and calculated values of the water advance time were compared. Most of these parameters are closely related to each other as expressed by its relatively high coefficient of regression. For instance, when the water flow rate is 1.0 L/s/m, the average time of advance over soil surface is 110 min for an 80-m field run of an average tillage depth of 120 mm. The land soaking requirement is about 80 mm depth of water under such conditions.

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