Abstract
This study was carried out in Abeokuta, South-western Nigeria in 2008 and 2009 to assess the impact of tillage and poultry manure (PM) on soil infiltration rate and maize root growth. The experiment was a split-plot design with three replications. The main plot consisted of three tillage treatments: zero tillage (ZT), minimum tillage (MT) and conventional tillage (CT) while the sub-plot comprised three PM treatments (0, 10 and 20 Mg ha-1). Soil infiltration characteristics were determined on the field using disc permeameter while root mass was evaluated by excavation method. In 2008, the soil infiltration rate (IR) was significantly higher under MT than other tillage systems while the IR was higher by about11% under CT than ZT. Though, there was no significant difference in IR among the three tillage systems in 2009, IR was lower under CT by about 9% and 3% compared with MT and ZT, respectively. The IR of 10.87 cm hr-1 observed in 2008 under the plots treated with 20 Mg ha-1 of PM decreased to 6.19 cm hr-1 in 2009 possibly due to reduction in the large pores of the sandy soil by repeated application of 20 Mg ha-1 of PM. The implication of this is that nutrients are likely to be held against leaching when 20 Mg ha-1 PM is applied in a sandy soil. Root mass was insignificantly higher under MT than CT in both years of the study while root mass was lower under ZT than CT by about 26% in 2009. Plots treated with poultry manure gave significantly higher root mass than the control. Therefore, fast draining pores dominating sandy soil may be modified by application of large quantity (20 Mg ha-1) of PM to improve the soil water and nutrient holding capacities and maize root growth.Keywords: Disc permeameter; fast draining pores; infiltration rate; maize root
Highlights
Several research activities have shown that the state of soil surface influence to a great extent its water infiltration and redistribution characteristics
Cumulative infiltration (CI) and sorptivity were significantly higher under conventional tillage (CT) than zero tillage (ZT) while steady state flow (SSF), unsaturated hydraulic conductivity (Ko) and the infiltration rate (IR) were about 11% higher under CT compared with ZT
The fast draining macro-pores created by CT could have facilitated infiltration momentarily after tillage, but these pores reduced as a result of repackaging of soil aggregates (Martinez et al, 2008) resulting in higher IR and other unsaturated water flow (UWF) parameters under ZT than CT at the end of the second year after tilage
Summary
Several research activities have shown that the state of soil surface influence to a great extent its water infiltration and redistribution characteristics. One of the major farmer’s practices that affect directly the state of soil surface and its properties is tillage operation. It has been reported that tillage can increase the prevalence of infiltration-limiting layers by exposing surface soil to raindrop impacts and contributing to structural degradation by creating smeared and compacted layers under the tilled layer (Silburn and Glanville, 2002) or on the surface (Li et al, 2001). According to Martinez et al (2008) the increase in topsoil compaction under zero tillage (ZT) systems may decrease water infiltration and soil may become waterlogged under intense rainfall. Research reports are yet to agree on the appropriateness of one tillage system or the other on soil infiltration rate. Other studies (e.g. Pikul and Aase, 1995; Shukla et al, 2003) have found higher infiltration rates under ZT than conventional tillage (CT) because of the protection of the soil surface and the effect of soil organic
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