Variability in the Physical Properties of an Eroded Cultivated Steep Land Under Farmers’ Practice and Vetiver Technology (Bio-Engineering Structure)

Variability in soil properties is evident in the variability in crop performance in a field and failure of engineering structures. During erosion particles are detached, transported and deposited at different locations down the slope. An experiment was conducted on a 20 and 30% slopes within the Cross River University of Technology to assess variability in soil physical properties as induced by water erosion on erosion plots constructed and planted to maize/cassava mixture. No vetiver [farmer’s practice] and vetiver grass strips at 5m, 15m and 25m [bioengineering structure] constituted the treatments. Core samples (0 - 15cm) were collected at 5m intervals down the slope in all the treatments for determination of some soil physical properties. Infiltration was measured using double ring infiltrometer. Coefficient of variability (CV%) values ranged from 2 - 4% [bulk density], 2 - 4% [porosity], 16 - 33% [gravimetric moisture], 3 - 8% [void ratio], 16 - 33% [volume wetness], 15 - 32% [degree of saturation], 16 - 37% [water volume ratio], 2 - 7% [air-filled porosity], 16 - 33% [available moisture holding capacity] for the two slopes. Initial infiltration ranged between 1.87 - 2.90cm per minute and 82.63 - 127.80cm after 260 minutes for cumulative infiltration. Coefficient of variability were 19.5% [initial infiltration] 6.18% [cumulative infiltration] for 20 and 30% slopes respectively. CV% values of <15%, 15 - 35% and >35% are considered low, moderate and high respectively. Understanding field variability of soil properties could be a veritable tool for precision soil management to optimize and increase profitability. Keywords: Erosion, Vetiver, Bioengineering structure and Soil Variability