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Authors: Shah, Syed Shahid Hussain
Keywords: Applied Sciences
Agriculture & related technologies
Field & plantation crops
Orchards,fruits & forestry
Garden crops(Horticulture)
Issue Date: 2013
Abstract: Soil physical degradation, specifically environmental degradation due to agriculture activity is a pressing issue in Pakistan causing reduction in agriculture performance. In this context, the study was conducted to assess water use efficiency, different components of water cycle, soil physical quality index, soil organic carbon pool and sequestration, and soil physical properties for sustainable wheat and maize production under different soil and water management regimes. Furthermore, an economic analysis was also carried out. Two Studies were conducted, Study-1 consisted of three irrigation levels and two sowing methods and Study-2 consisted of three mulching levels and two sowing methods. Irrigation levels were maintained fortnightly in wheat and weekly in maize on the basis of soil field capacity in combination with bed and flat sowing systems in Study-1. However, wheat straw and farm manure amendments were used as surface cover @ 8 Mg ha-1 in combination with bed and flat sowing systems in Study-2. In both studies, Randomized Complete Block Split Plot Design was used. Sowing methods, i.e. bed and flat sowing were kept in main plot, and amounts of irrigation and mulch levels were kept in sub plots. All the treatments showed maximum leaf area index (LAI) 75 and 60 days after sowing in wheat and maize crops, respectively, compared with earlier observation times (Study-2). However, Bed sowing + FC 100 (T 2 ) combination showed maximum LAI 4.55 (wheat) and 6.50 (maize) which was 6.4 and 6.9 %, 5.3 and 3.7 %, 16.3 and 14.2 %, 9.3 and 6.6 % and 14.8 and 10.4 % higher in wheat and maize, respectively, compared with Bed sowing + FC 125 (T 1 ), Bed sowing + FC 75 (T 3 ), Flat sowing + FC 125 (T 4 ), Flat sowing + FC 100 (T 5 ) and Flat sowing + FC 75 (T 6 ), respectively. Treatment T 2 also showed maximum 1000- grain weight, i.e. 50.5 (wheat) and 439.2 g (maize) and minimum was noted in treatment T 4 , i.e. 30.7 (wheat) and 263.1 g (maize). Interactive effect of mulch and sowing methods was also found significant on grain yield of wheat and maize. Wheat straw and farm manure mulching materials showed 26.3 and 20.3 % and 43.2 and 25.7 % increase in grain yield of wheat and maize, respectively on bed sowing system compared with Bed sowing + Mulch control (T 1 ) treatment. Furrow irrigated raised bed technique was found to be environmentally friendly in combination with farm manure compared to wheat straw having enhanced soil organic carbon contents. Wheat straw mulch depicted 14.4 and 6.8 % reduction in total amount of water applied; 8.6 and 2.2 % reduction in ET a ; 58.2 and 33.1 % increase in soil water storage in comparison with control (no mulch) and farm manure mulch, respectively, in wheat season. Wheat straw and farm manure mulching materials showed 47.0 and 35.5 %, and 57.7 and 32.9 % increase in irrigation WUE of wheat and maize, respectively, on bed sowing system compared with treatment T 1 . Amendments wheat straw and farm manure mulch alone resulted in 3.49 and 2.11 % less Bulk density (BD); 6.28 and 4.50 % less Soil penetration resistance (SPR); 8.70 and 22.53 % more Soil organic carbon pool (SOC); 33.53 and 17.37 % more Field saturated hydraulic conductivity (K fs ); 19.84 and 10.32 % more infiltration rate, respectively than control. Bed sowing alone provided good soil physical health compared to flood irrigated flat sowing. In respective two studies, there were noted higher BD (6.02 %, 5.10 %), SPR (12.29 %, 15.90 %), and less SOC contents (14.38 %, 22.98 %), K fs (31.39 %, 39.09 %) and infiltration rates (33.45 %, 14.19 %) in flat sowing compared to bed sowing. In Study-1, total amount of water applied under bed sowing system was 384.6 and 712.8 mm whichshowed 16.5 and 7.1 % reduction compared with flat sowing system in wheat and maize, respectively. Bed sowing showed 16.0 and 7.9 % lower ET a , i.e. 346.4 (wheat) and 533.8 mm (maize) in relation to flat sowing system. Soil water storage was higher, i.e. 22.2 and 30.1 % than that of flat sowing in wheat and maize, respectively. In Study-2, Bed sowing also revealed saving of water compared with flat sowing system. It was revealed that bed sowing system also made improvement in growth and yield components of wheat and maize compared with flat sowing system. Beds showed maximum 1000-grain weight, i.e. 43.1 (Study-1) and 46.5 g (Study-2), i.e. 27.1 and 30.6 % increase over flat sowing system in wheat crop. Beds also enhanced the grain yield of wheat (4311.9 kg ha -1 ) by 37.1 % and of maize (9.5 Mg ha -1 ) by 48.4 % in relation to flat sowing (Study-1). Enhanced harvest index on beds was noted 18.6 % over flat sowing system in wheat crop. Amounts of irrigation water levels based on soil water holding capacity were assessed for their effects on soil physical health indicators. Increases in BD, SPR and SOC, and decreases in K fs and infiltration rate were found as the amount of irrigation water increased. Positive but poor correlation (r = 0.32) was noted between SOC and K fs in Study-1. Higher amount of irrigation, i.e. 633.3 mm was observed at FC 1 irrigation level (125 % field capacity), followed by 403.9 and 230.7 mm at FC 2 (100 % field capacity) and FC 3 (75 % field capacity) irrigation levels, respectively, in wheat season. During the maize season FC 1 irrigation level showed 985.6 mm water, which was 33.8 and 98.1 % higher compared with FC 2 and FC 3 irrigation levels, respectively. Irrigation level equivalent to 100 % FC under bed sowing method yielded optimum soil physical environment that resulted in enhanced grain yield of wheat by 4.6 and 10.8 % and of maize by 13.8 and 25.9 % compared with T 1 and T 3 , respectively. The FC 2 and FC 3 irrigation levels showed 12.5 and 20.4 % decrease, respectively, in wheat grain yield, and 25.9 and 38.3 % decrease, respectively, in maize grain yield, compared with FC 1 irrigation level under flat sowing system. However, treatment T 2 showed maximum grain yield of wheat, i.e. 4526.0 kg ha -1 and of maize, i.e. 10.7 Mg ha -1 in Study-1. This treatment (T 2 ) also depicted maximum harvest index, i.e. 38 % and 1000-grain weight, i.e. 46.9 g compared with all other treatments in wheat crop. Similar results were depicted in maize crop. In case of 125 % FC, water use efficiency decreased in comparison with 100 % FC under both sowing methods. Irrigation level equivalent to 75 % FC could not fulfill the crop water requirement under both sowing methods, consequently the yield of wheat and maize decreased. When soil physical quality quantification was assessed in Study-1 using ā€˜Sā€™ Index, bed sowing yielded 15.9 and 7.2 % higher soil physical quality index than flat sowing at 0-15 and 15-30 cm soil depths, respectively, in April. During the November, bed sowing showed 18.2 % increase compared with flat sowing at 0-15 cm soil depth but at lower soil depths, it showed no effect. Irrigation levels also showed significant effect on soil physical quality index, S. There were 3.8 and 8.0 %, and 3.4 and 6.2 % high values of the index, S, noted in FC 2 and FC 3 , respectively in comparison to FC 1 irrigation level in April and November seasons, respectively. In 0-15 cm depth, wheat straw and farm manure mulches showed 9.8 and 3.4 % (April) and 9.1 and 3.6 % (November) more S value compared to no mulch plots, whereas in Study-2, bed sowing yielded 13.1 and 12.1 % high soil physical quality index in relation to flat sowing in April and November, respectively at 0-15 cm depth. As in case of mulching, bed sowing showed no difference compared with flat sowing system at lower soil depths.
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