Puddling depth and intensity effects in rice-wheat system on a sandy loam soil I. Development of subsurface compaction

Puddling, even though reduces percolation losses of irrigation water in rice production, it also results in yield decline of wheat (Triticum aestivum L.) that follows the rice crop in the cropping sequence because of subsurface compaction. The 3-year field study reported in this paper evaluates the effects of puddling depth and intensity on the development of subsurface compaction in a sandy loam soil (coarse loamy, mixed, hyperthermic Typic Ustochrept). The treatments included two passes of tractor-drawn cultivator followed by levelling with a wooden plank (medium puddling) and four passes of tractor-drawn cultivator followed by levelling with a wooden plank (intensive puddling). Both medium and intensive puddling treatments were imposed at shallow (5-6 cm) and normal (10-12 cm) depths. Increase in puddling intensity from medium to intensive, significantly increased bulk density from 1.63 to 1.67 Mg m(-3) in 16-18 cm and from 1.61 to 1.66 Mg m(-3) in 18-20 cm soil layers. In normal-puddled plots, the average bulk density of 14-20 cm soil layers was significantly higher (1.74 Mg m(-3)) than that of shallow puddled plots (1.57 Mg m(-3)) at the end of 3 years of study. Similar trends were observed in case of soil penetration resistance. (C) 2003 Elsevier Science B.V. All rights reserved.