Thursday, 13 July 2006
75-4

Studies on the Effect of Insitu Soil Moisture Conservation Practices on the Productivity of Spanish Bunch Groundnut under Rainfed Farming Situations.

L okanath H. Malligawad, Univ of Agricultural Sciences, Krishinagar, Dharwad, 580 005, India

                Two field experiments to study the productivity of Spanish bunch groundnut as influenced by in situ soil moisture/rainwater conservation practices (planting methods, planting geometry and mulching) were conducted on medium Vertisols during rainy seasons of 2001-2003 under rain fed farming situations at the Main Agricultural Research Station, University of Agricultural Sciences, Dharwad (Karnataka), India. The initial soil tests values were 0.45 % organic carbon, 40 kg available P2O5/ha and 295 kg available K2O/ha with 7.35 pH. The amount of rainfall received during the crop growth period of 2001-2003 was 134.7 mm (in 14 rainy days), 71.5 mm (in 8 rainy days) and, 59.6 mm (in 6 rainy days), respectively. First experiment (rainy season 2001/2002) consisted of five planting methods with common recommended plant population stand of 3,33,333 plants/ha {P1-Flat bed method of planting with row to row 30 cm and plant to plant 10 cm, P2-4:1 skip row with row to row 30 cm and plant to plant 7.75 cm, P3-2:1 skip row with row to row 30 cm and plant to plant 6.65 cm, P4-broad bed and furrow method of planting with 2 rows in each bed (60 cm bed with row to row 30 cm and plant to plant 6.65 cm) and P5-broad bed and furrow method of planting with 3 rows in each bed (60 cm bed with row to row 20 cm and plant to plant 10 cm)} and three mulching treatments (M1-No mulching, M2-mulching of inter-row space with groundnut shell applied @ 5 t/ha and M3-mulching of inter row space with thin polythene sheet of 7. Second experiment (rainy season of 2003) consisted of two plant densities (D1-3,33,333 and D2-2,96,296 plants/ha) and three planting methods (MP1-Flat bed method of planting with row to row spacing of either 30 or 22.5 cm and plant to plant spacing of either 10 cm to 15 cm, MP2-2:1 skip row and MP3-2:1 skip row + opening of furrow in skipped row with wooden plough at 20 days after sowing. Treatments in both the experiments were replicated four times and recommended production/cultivation practices were followed. The results of the first experiment indicated that the productivity of groundnut under rain fed situations did not differ even though there was difference in the amount of rainfall received during the crop growth period in the respective years of experimentation. The mean of two years data indicated that the higher productivity of groundnut was observed in flat bed with 2:1 skip row method of planting. Flat bed with 2:1 skip row (with a plant density of 3,33,333 plants/ha) produced 15.78 and 17.85 % higher dry pod and kernel yield, respectively over flat bed with regular row method of planting (with a plant density of 3,33,333/ha (2725 and 1993 kg dry pod and kernel yield/ha, respectively) and other methods of groundnut planting. The yield components such as total number of pods/plant and dry pod weight/plant were favourably influenced in flat bed with 2:1 skip row (with a plant density of 3,33,333 plants/ha) due to better moisture conservation and border effect. The mean of the two years data indicated that mulching of inter-row space with polythene sheet produced higher dry pod and kernel yield (3056 and 2224 kg/ha, respectively) compared to mulching of inter-row space with groundnut shell applied @ 5 t /ha (2773 and 2282 kg/ha, respectively) and groundnut crop without any mulching (2609 and 1888 kg/ha, respectively). The yield components were favourably influenced due mulching either with polythene sheet or with groundnut shell. The highest dry pod (3604 kg/ha) and kernel (2720 kg/ha) yields were obtained in flat bed with 2:1 skip row method of planting in addition to mulching of inter-row space with polythene sheet. The productivity of groundnut was not affected by low amount rainfall during 2003. This was mainly because of frequent rains occurred in trace amounts for 64 days in addition to total rain of 59.6 mm received during the crop growth period of groundnut. Among the different methods of planting in the second experiment, flat bed method of groundnut planting produced higher dry pod and kernel yield (2551 and 1859 kg/ha, respectively) over 2:1 skip row (1789 and 1300 kg/ha, respectively) and 2:1 skip row + opening of furrow in skipped row at 20 days after planting (1387 and 969 kg/ha, respectively). Yield components were better with flat bed method of planting compared to 2:1 skip row and 2:1 skip row + opening of furrow in skipped row method of plantings. In situ soil moisture conservation practices through land configuration either with 2:1 skip row or with 2:1 skip row + opening of furrow in skipped row method of planting failed to produce higher yield of groundnut over flat bed method of planting due to insufficient rainfall during crop growth season of 2003. The groundnut crop in 2:1 skip row or 2:1 skip row + opening of furrow in skipped row planting showed greater moisture stress symptoms during 40, 55 and 85 days after sowing (DAS) than in flat bed method of planting. Failure of groundnut to produce higher yields in 2:1 skip row and 2:1 skip row + opening furrow was ascribed to 1. Insufficient rainfall (59.6 mm) without runoff /saturating rains 2. Greater evaporation through the exposure of land surface in skipped rows and further aggravated with opening of furrow in skipped rows. On the contrary, crop in flat bed method of planting did not show greater moisture stress during 40, 55 and 85 DAS due to coverage of land surface by crop canopy. Full coverage of land surface by crop canopy in flat bed method of planting resulted in reduced moisture evaporation. The studies indicated that 2:1 skip row and 2:1 skip row + opening of furrow in skipped row for in situ moisture conservation assumes greater importance with respect to groundnut productivity only when crop receives one or two soil saturating/runoff rains during its growth period.


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