Aggregate stability, crust formation, steady state infiltration and mode of seedling emergence in soils with various texture and mineralogy
- Authors: Nciizah, Adornis Dakarai
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Crop Science)
- Identifier: vital:11871 , http://hdl.handle.net/10353/d1015539
- Description: The general objective of this study was to quantify the interactive effects of soil texture and mineralogy on soil crusting, infiltration and erosion and the subsequent effects on maize seedling emergence and early development using soils collected from 14 ecotopes in the Eastern Cape Province. The specific objectives were to determine; i) particulate organic matter, soil texture and mineralogy relations, ii) aggregate stability and breakdown mechanisms as affected by soil texture and organic matter, iii) crust formation and steady state infiltration, iv) rainfall pattern effects on crusting, infiltration and erodibility and v) rainfall intensity effects on crusting and mode of seedling emergence. Particulate organic matter (POM) was fractionated into litter POM, coarse POM and fine POM. Both total soil organic matter (SOM) and the POM in each fraction were determined using the weight loss on ignition procedure. Most ecotopes were either sandy loam or sandy clay loam and primary minerals especially quartz dominated the soil mineralogy. The clay content was significantly related to the total SOM (r = 0.78), hematite (r = 0.83) and quartz (r = -0.74). Aggregate stability was determined following methods described by Le Bissonnais (1996) i.e. fast wetting (FW), slow wetting (SW) and wet stirring (WSt). Aggregate breakdown followed the order; slaking < mechanical breakdown < micro-cracking for most ecotopes except Lujiko Leeufontein and Amatola Jozini where SW and WSt resulted in the least MWD respectively. Aggregate stability was significantly correlated to POM only for FW and SW and only positive but not significant for WSt. To study crust formation, aggregate sizes <2, 2 to 3, 3 to 5 mm were exposed to 60 mm hr-1 simulated rainfall. Sieving structural crusts, ~0.2 to ~0.8 mm thick with a surface layer of loose grains overlying a thin plasmic layer, formed in all ecotopes. Crusts with strengths between 0.25 and 3.42 10-4 kg m-2 developed on the <2 mm compared to <2.23 10-4 kg m-2 in the >2 mm aggregates. The reverse occurred in Alice Jozini, which had relatively low clay content of 120 g kg-1. Two significantly different groups of the SSIR were observed. The SSIR was between 1.24 and 3.60 mm hr-1 in the group of ecotopes dominated by primary minerals and relatively lower clay content. In the second group, consisting one ecotope dominated by kaolinite and relatively higher clay content, the SSIR was 15.23 mm hr-1. Rainfall pattern i.e. rainfall applied either as an eight minute single rainstorm (SR) or four-two minute intermittent rainstorms (IR) separated by a 48 h drying period significantly (p < 0.05) affected crust strength, SSIR and erosion. The IR resulted in higher crust strength and SSIR than SR. The effect of rainfall pattern on SSIR was mostly influenced by the primary minerals namely, quartz. Three maize seeds of equal size were planted in plastic pots, pre-wetted by capillary action and then subjected to simulated rainfall at three intensities for 5 min. Rainfall intensity (30, 45 and 60 mm h-1) significantly (P < 0.05) affected crust strength and mean emergence day (MED) but not emergence percentage (EMP) and shoot length (P > 0.05). The 60 mm h-1 rainfall intensity resulted in the highest crust strength and MED.
- Full Text:
- Date Issued: 2014
- Authors: Nciizah, Adornis Dakarai
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Crop Science)
- Identifier: vital:11871 , http://hdl.handle.net/10353/d1015539
- Description: The general objective of this study was to quantify the interactive effects of soil texture and mineralogy on soil crusting, infiltration and erosion and the subsequent effects on maize seedling emergence and early development using soils collected from 14 ecotopes in the Eastern Cape Province. The specific objectives were to determine; i) particulate organic matter, soil texture and mineralogy relations, ii) aggregate stability and breakdown mechanisms as affected by soil texture and organic matter, iii) crust formation and steady state infiltration, iv) rainfall pattern effects on crusting, infiltration and erodibility and v) rainfall intensity effects on crusting and mode of seedling emergence. Particulate organic matter (POM) was fractionated into litter POM, coarse POM and fine POM. Both total soil organic matter (SOM) and the POM in each fraction were determined using the weight loss on ignition procedure. Most ecotopes were either sandy loam or sandy clay loam and primary minerals especially quartz dominated the soil mineralogy. The clay content was significantly related to the total SOM (r = 0.78), hematite (r = 0.83) and quartz (r = -0.74). Aggregate stability was determined following methods described by Le Bissonnais (1996) i.e. fast wetting (FW), slow wetting (SW) and wet stirring (WSt). Aggregate breakdown followed the order; slaking < mechanical breakdown < micro-cracking for most ecotopes except Lujiko Leeufontein and Amatola Jozini where SW and WSt resulted in the least MWD respectively. Aggregate stability was significantly correlated to POM only for FW and SW and only positive but not significant for WSt. To study crust formation, aggregate sizes <2, 2 to 3, 3 to 5 mm were exposed to 60 mm hr-1 simulated rainfall. Sieving structural crusts, ~0.2 to ~0.8 mm thick with a surface layer of loose grains overlying a thin plasmic layer, formed in all ecotopes. Crusts with strengths between 0.25 and 3.42 10-4 kg m-2 developed on the <2 mm compared to <2.23 10-4 kg m-2 in the >2 mm aggregates. The reverse occurred in Alice Jozini, which had relatively low clay content of 120 g kg-1. Two significantly different groups of the SSIR were observed. The SSIR was between 1.24 and 3.60 mm hr-1 in the group of ecotopes dominated by primary minerals and relatively lower clay content. In the second group, consisting one ecotope dominated by kaolinite and relatively higher clay content, the SSIR was 15.23 mm hr-1. Rainfall pattern i.e. rainfall applied either as an eight minute single rainstorm (SR) or four-two minute intermittent rainstorms (IR) separated by a 48 h drying period significantly (p < 0.05) affected crust strength, SSIR and erosion. The IR resulted in higher crust strength and SSIR than SR. The effect of rainfall pattern on SSIR was mostly influenced by the primary minerals namely, quartz. Three maize seeds of equal size were planted in plastic pots, pre-wetted by capillary action and then subjected to simulated rainfall at three intensities for 5 min. Rainfall intensity (30, 45 and 60 mm h-1) significantly (P < 0.05) affected crust strength and mean emergence day (MED) but not emergence percentage (EMP) and shoot length (P > 0.05). The 60 mm h-1 rainfall intensity resulted in the highest crust strength and MED.
- Full Text:
- Date Issued: 2014
Cattle manure, scalping and soil wetness effects on some physical properties of a hardsetting soil and associated early maize growth
- Authors: Nciizah, Adornis Dakarai
- Date: 2011
- Subjects: Soil formation , Crops and soils , Manures , Soil mechanics , Soil moisture , Soil stabilization , Soil penetration test
- Language: English
- Type: Thesis , Masters , MSc Agric (Crop Science)
- Identifier: vital:11861 , http://hdl.handle.net/10353/349 , Soil formation , Crops and soils , Manures , Soil mechanics , Soil moisture , Soil stabilization , Soil penetration test
- Description: Most soils in the Eastern Cape Province, South Africa are shallow and are low in organic matter. Therefore these soils are structurally fragile and highly susceptible to inherent degradative processes like hardsetting. The objective of this study was to determine the effect of cattle manure, scalping and soil wetness on aggregate stability, penetration resistance and early maize growth in hardsetting soils. Glasshouse and field studies were conducted to determine the effect of cattle manure on aggregate stability and penetration resistance of freshly exposed topsoils by scalping at 0, 10 and 20 cm depths. In the glasshouse cattle manure was applied at 0 and 20 Mg/ha and matric suction was kept at ~ 30 and ~ 400 kPa; contrasting high and low soil wetness. Three soils were put in pots and arranged in a randomized complete block 3 2 2 factorial design. The field study was done at the University of Fort Hare research farm and the treatments were arranged in a split-plot complete randomized design with three replications. Scalping treatment was the main plot whilst the quantity of the cattle manure applied was the sub plot. Cattle manure increased mean weight diameter (MWD) by between 48% and 71% under glasshouse and between 18% and 33% under field conditions, depending on the soil wetting rate. Cattle manure reduced MWD when the soil under field condition was subjected to mechanical shaking. Soil penetration resistance decreased linearly, with increasing soil wetness but it rapidly increased with increase in matric suction up to ~200 kPa and thereafter the rate of increase reduced. In the glasshouse, all treatments had no significant effects on shoot dry weight but low matric suction increased root dry weight by 133%. Interaction of cattle manure and low matric suction reduced shoot length by 6%, shoot fresh weight by 25%, root surface area by 36%, root length by 5% and root fresh weight by 29% compared to the control. In contrast, application of cattle manure and high matric suction increased shoot length by 37%, shoot fresh weight by 136%, root surface area by 159%, root length by 94% and root fresh weight by 119%. In the field, cattle manure application increased root length density and shoot dry matter by 26% and 30% respectively. Cattle manure improved the stability of aggregates of the hardsetting soil under rapid or slow water intake conditions experienced during rainfall or irrigation. However, under field conditions cattle manure acted as a deflocculant and decreased the stability of aggregates when mechanical stress was applied. The effectiveness of cattle manure in improving maize growth in hardsetting soils was determined by matric suction.
- Full Text:
- Date Issued: 2011
- Authors: Nciizah, Adornis Dakarai
- Date: 2011
- Subjects: Soil formation , Crops and soils , Manures , Soil mechanics , Soil moisture , Soil stabilization , Soil penetration test
- Language: English
- Type: Thesis , Masters , MSc Agric (Crop Science)
- Identifier: vital:11861 , http://hdl.handle.net/10353/349 , Soil formation , Crops and soils , Manures , Soil mechanics , Soil moisture , Soil stabilization , Soil penetration test
- Description: Most soils in the Eastern Cape Province, South Africa are shallow and are low in organic matter. Therefore these soils are structurally fragile and highly susceptible to inherent degradative processes like hardsetting. The objective of this study was to determine the effect of cattle manure, scalping and soil wetness on aggregate stability, penetration resistance and early maize growth in hardsetting soils. Glasshouse and field studies were conducted to determine the effect of cattle manure on aggregate stability and penetration resistance of freshly exposed topsoils by scalping at 0, 10 and 20 cm depths. In the glasshouse cattle manure was applied at 0 and 20 Mg/ha and matric suction was kept at ~ 30 and ~ 400 kPa; contrasting high and low soil wetness. Three soils were put in pots and arranged in a randomized complete block 3 2 2 factorial design. The field study was done at the University of Fort Hare research farm and the treatments were arranged in a split-plot complete randomized design with three replications. Scalping treatment was the main plot whilst the quantity of the cattle manure applied was the sub plot. Cattle manure increased mean weight diameter (MWD) by between 48% and 71% under glasshouse and between 18% and 33% under field conditions, depending on the soil wetting rate. Cattle manure reduced MWD when the soil under field condition was subjected to mechanical shaking. Soil penetration resistance decreased linearly, with increasing soil wetness but it rapidly increased with increase in matric suction up to ~200 kPa and thereafter the rate of increase reduced. In the glasshouse, all treatments had no significant effects on shoot dry weight but low matric suction increased root dry weight by 133%. Interaction of cattle manure and low matric suction reduced shoot length by 6%, shoot fresh weight by 25%, root surface area by 36%, root length by 5% and root fresh weight by 29% compared to the control. In contrast, application of cattle manure and high matric suction increased shoot length by 37%, shoot fresh weight by 136%, root surface area by 159%, root length by 94% and root fresh weight by 119%. In the field, cattle manure application increased root length density and shoot dry matter by 26% and 30% respectively. Cattle manure improved the stability of aggregates of the hardsetting soil under rapid or slow water intake conditions experienced during rainfall or irrigation. However, under field conditions cattle manure acted as a deflocculant and decreased the stability of aggregates when mechanical stress was applied. The effectiveness of cattle manure in improving maize growth in hardsetting soils was determined by matric suction.
- Full Text:
- Date Issued: 2011
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