Effects of inundation period and tillage option on field performance of self-propelled rice transplanter

Manual transplanting of rice seedlings in puddling condition is a common method of crop establishment in the irrigated rice systems of Asia though it is time consuming. Rice transplanters are outmost need to overcome the labor crisis in the peak transplanting periods. But, self-propelled transplanter requires an ideal field conditions to obtain better performance. Hence, a self-propelled rice transplanter (Model: DP480 and S3-680) was evaluated in clay loam (CLS), loam (LS) and sandy loam soil (SLS) during the irrigated dry season (Boro) of 2012-13 and 2013-14 under three inundation periods of 12, 18 and 24 hrs and three tillage options as strip tillage (ST), zero tillage (ZT) and conventional tillage (CT) to identify a suitable inundation period and tillage option. Soil penetration resistance decreased with the increased of inundation period in both the seasons and in three soil types. In CLS and SLS, CT showed lower penetration. In LS, ST gave higher resistance in strip compared to ZT and CT. 2-way interaction of tillage and inundation period as well as single effect of inundation period showed significant outcome in SLS during Boro/2013-14 where 18 hr inundation period for ST and CT and 24 hr for ZT gave significantly higher rate of area coverage. Average of two seasons, ST gave more rate of area coverage for 18 hrs inundation period irrespective of soil types whereas ZT gave more for 24, 18 and 24 hrs inundation period in CLS, LS and SLS respectively. ST and ZT saved 22 to 13% and 8 to 13% fuel requirement for transplanting in CLS and SLS compared to CT, respectively whereas CT saved fuel requirement by 2 to 7% over ST and ZT in LS. Contrary, ST reduced the percentage of missing hills (9.7%) compared to ZT (13.0%) and CT (10.7%) while percentage of missing hills reduced (13.7 to 9.2%) with the increased of inundation periods irrespective of seasons and soil types. Highest percentage of picker missing hills was observed for ZT in LS (4.8%) and SLS (4.6%) while 12 hrs inundation periods in SLS gave the highest and 18 and 24 hrs inundation periods in CLS and 24 hrs inundation periods in SLS gave the lowest picker missing hills. Damage hills increased in ZT from 2.6 to 3.0% compared to CT (1.0 to 1.6%) and ST (1.6 to 2.1%). Damage hills also increased in 12 hrs inundation period (2.4%) followed by 24 hrs (1.8%) and 18 hrs (1.7%) inundation periods. Highest floating hills were also observed for ZT followed by ST. Floating hills decreased with inundation periods in all types of soil. CT increased the buried hills significantly during the both seasons. However, highest percentages of buried hills were observed for 12 hrs inundation periods (2.6%) while lowest for 24 hrs inundation periods (1.6%). ST gave higher grain yield of rice compared to ZT and CT in both seasons under clay loam, loam and sandy loam soils except CLS during Boro 2012-13 seasons where ZT gave higher yield. Averaged over two seasons and three soil types, 24 hrs inundation periods gave higher yield followed by 18 hrs inundation periods. However, ST, ZT and CT gave higher yield for 18 (6.1 t/ha), 24 (6.0 t/ha) and 24 hrs (5.9 t/ha) inundation periods followed by 24 (5.9 t/ha), 18 (5.6 t/ha) and 18 hrs (5.7 t/ha), respectively. Finally, it can be stated that unpuddled minimum tillage is a resource saving technique of rice production while 18 hrs inundation prior to transplanting for strip and 24 hrs inundation for zero and conventional tillage showed more benefited for rice production.