Effects of puddling intensity on the in-situ engineering properties of paddy field soil

Puddling may have an effect on the physical and mechanical properties of soil. Puddling intensity (the number of puddler passes) to a required level has always been a challenge for many farmers. Field experiments were conducted to determine the effect of puddling on the hydraulic conductivity, bulk density and penetration resistance at three depths (0-10, 10-20 and 20-30 cm). The treatments were puddling by one pass (P1) and three passes (P3) of a tractor-drawn rototiller and no-puddling (NP). The treatments were replicated three times and experiment was laid out in a randomized block design. Results showed that puddling caused a significant reduction (p<0.01) in soil hydraulic conductivity, bulk density and penetration resistance. Hydraulic conductivity decreased from 5.36 cm h-1 in NP to 1.12 and 0.78 cm h-1 in P1 and P3, respectively. The first level of puddling (one pass of puddler) decreased the penetration resistance of soil by about 53%, whereas puddling to higher levels decreased the penetration resistance by 15% corresponding to three passes of the puddler. The decrease in bulk density by one pass of puddler was about 6%, whereas subsequent puddling to three passes decreased the bulk density by 3%. Increasing in depth increased bulk density and penetration resistance but decreased hydraulic conductivity. Puddling only to the required level will deteriorate less the soil physical condition as compared to more intense puddling.