Development of a bund strengthening implement for paddy wetland based on soil - machine parameters

Abstract

Three models (BF1, BF2 and BF3) of a low cost, tractor drawn bund strengthening implement were developed and their performance was evaluated at three test locations, viz., Pullazhi kolepadavu in Thrissur kole lands, Kolothumpadam kolepadavu in Ponnani kole lands and Athalur, Tavanur (non-kole). The forming board type design was chosen. The major dimensions of the developed models, viz., top width, bottom width and rear height are 150, 250 and 150 mm for BF1, 200, 350 and 150 mm for BF2 and 250, 400 and 250 mm respectively. The main parts of the implement were the MS angle bar tool frame and hitch assembly of size 1150 mm x 500 mm, implement frame made of MS angle bars to connect the forming board assembly to the tool frame, modified forming boards with gathering boards attached in the front, and a 400 mm long, three sided forming case at the rear which provided a plastered finish to the formed bund. All the elements, including the forming boards and the forming case, acted like a single unit. Analyses of the various soil properties at the three test sites were also performed. The soils at Pullazhi kolepadavu and Kolothumpadam kolepadavu were silty clay while the soil at Tavanur was sandy loam in texture. The dimensions of the bunds drawn by the implements were suited to the prevalent farmers’ practice at Pullazhi and Ponnani. At Tavanur, new bunds could be drawn using the implements. At Pullazhi kole fields, models BF1 and BF2 showed a better performance in terms of strength measured as cone index. The performance of BF3 and BF4 gave the best results at Ponnani. BF2 or BF4, operated by NH 3230, were suitable to the Tavanur fields, in terms of strength of bund as assessed by cone index. Shear strength values exhibited by the manual bunds were always lesser than that by mechanically formed bunds at Pullazhi. Bunds formed by BF2 showed the highest value of 46.02 kPa at 0.2 m depth which went upto 40.81 kPa on the seventh day. The same trend was seen in Ponnani also but the bunds formed by BF3 and BF4 had the highest shear strength values.The average speed of operation ranged from minimum of 1.24 km h -1 when BF1 was operated by KTT at Tavanur, in sandy loam soils to 2.98 km h -1 when BF2 was operated by JD 5042 at Ponnani. Draft was least for BF1 operated by KTT and highest for BF3 and BF4 operated in Ponnani silt-clay. The minimum fuel consumption was noted as 2.53 L h -1 for BF1-NH 3230 combination at Tavanur while the maximum was 3.76 L h -1 for BF3-JD 5042 at Ponnani. The BF4 trials had higher consumption of 7.71 L h -1 in silty clay at Ponnani and 5.62 L h -1 in sandy loam at Tavanur. The maximum capacity of 2984.24 m h -1 was observed for BF2 operated by JD 5042 at Ponnani kole. BF4 had lower capacities as two passes of the tractor were required to complete the operation. The minimum capacity of mechanical bund strengthening implement is 906.86 m h -1 . The manual operation has a capacity of 62.5 m h -1 . Thus there is a 14 times increase in capacity of bund formation by mechanical implements. Wheel slip is within the acceptable range of 5 to 15 per cent. The cost of mechanical formation of bunds ranges from Rs. 18/- to Rs. 30/- per 100 m. while it ranges from Rs. 178/- to Rs. 227/- for manual operation. The developed implement had a FOS of 2.17. Hence, taking all observations into account, it can be summarised that the bund strengthening implement model BF2 was found suitable to Pullazhi kolepadavu in terms of size, strength, lower moisture content and higher bulk density. At Ponnani, the models BF3 and BF4 performed well. However, as BF4 operation involved a higher fuel consumption and lower capacity of bund formation, the model BF3 can be recommended. At Tavanur fields, the prevalent manual bunds showed better performance parameters. However, new bunds can be formed in the fields using the developed implements. Trial BF4 and BF3 gave better performance in these soils.