Puddling depth and intensity effects in rice–wheat system on a sandy loam soil: II. Water use and crop performance

The effect of puddling in reducing water losses and increasing rice yields is thought to be a function of its intensity. However, increased puddling intensity may have a negative effect on yield of succeeding wheat crop due to subsoil compaction. A 3year field experiment was conducted on a sandy loam soil (coarse loamy, calcareous, mixed, hyperthermic Typic Ustochrept) to study the effect of puddling intensity and puddling depth on irrigation water use in rice (Oryza sativa) and the performance of rice and wheat (Triticum aestivum) crops. The treatments on main plots included (i) no puddling, (ii) and (iii) medium puddling-2 passes of a tractor-drawn cultivator followed by leveling with a wooden plank and (iv) and (v) high puddling-4 passes of a tractor-drawn cultivator followed by leveling with a wooden plank, each at shallow (5–6 cm) and normal (10–12 cm) depths. Percolation losses decreased by 14–16% with the increase in puddling intensity from medium to high, whereas the amount of irrigation water required decreased by 10–25%. Puddling depth did not affect percolation losses or the amount of irrigation water applied. Intensive puddling intensity resulted in higher root mass density (RMD) in 0–5 and 5–10 cm soil layers. In 0–5 cm soil layer, the RMD in the shallow-puddled plots was 17% more than in deeply puddled plots. Puddling treatments had no effect on total dry matter and grain yield of rice in any of the 3 years of study. During the third year, the RMD of wheat in the 0–15 cm depth of the deeply puddled plots was 7% larger than in shallow-puddled plots. At depths greater than 15 cm, the RMD was 11–68% less in the deeply puddled plots than in the shallow-puddled plots. RMD of wheat in the 0–15 cm soil layer increased from 302(mu) g cm-3 in 1994–1995 to 319 (mu)g cm-3 in 1996–1997 whereas in the 15–30 cm layer it decreased from 85 to 47 (mu)g cm-3. High puddling intensity increased the canopy temperature of wheat by 0.5–1.7 °C and decreased average xylem water potential by 4–7%. During the 1996–1997 season, the total dry matter and wheat grain yield of wheat were, respectively, 19 and 8% greater in the shallow-puddled plots than the deeply puddled plots.