Evaluating the Effectiveness of Four Selected Methods of Investigating Soil Erosion Effect on Soil Productivity in Nsukka, Enugu State, Nigeria

Evaluating the Effectiveness of Four Selected Methods of Investigating Soil Erosion Effect on Soil Productivity in Nsukka, Enugu State, Nigeria.

ABSTRACT

This study was conducted in 2012 at the University of Nigeria,  Nsukka  Teaching  and Research Farm (UNN), and Ekwegbe, both in Nsukka agricultural zone; to evaluate the effectiveness of four selected methods of quantifying erosion effect on soil productivity at Nsukka, southeastern Nigeria.

The four methods were (1) desurfacing technique (DT), (2) Neill’s (1983) productivity index, (3) modified productivity index (MPI) and (4) Riquier’s productivity index (RI).

Soils were sampled at 0-30, 30-60, and 60-90 cm depth zones at each location prior to planting and after harvest. Incremental depths (0, 2, and 4 cm)  of  topsoil layers were manually removed to simulate erosion at the two sites. Poultry manure (10 t ha^-1) was applied two weeks before planting as a soil amendment.

Correlation and regression analyses revealed that RI was significantly (p < 0.05) correlated (positively) with plant  height at 10 WAP (r = 0.75*), LAI at 14 WAP (r = 0.76*) and  pod  yield (r = 0.72*) at UNN,  and  was ranked first in effectiveness, followed by DT, which had a significant (p < 0.05) negative correlation with plant height at 6 WAP (r = -0.45*), while PI and MPI were less effective.

At Ekwegbe, DT showed significant (p < 0.05; p  < 0.01) negative  correlations with plant  height at 10 (r = -0.42*) and 14 WAP (r = -0.66**), and LAI at 14 WAP (r = -0.52**), and was validated as the most effective index, whereas RI, PI and MPI were less useful.

INTRODUCTION

The value of a soil has traditionally been measured in terms of its productivity, defined as the capacity of the soil to produce a plant or sequence of plants under a physically defined set of management practices (Soil Survey Staff, 1951).

Maintenance of soil productivity depends on management practices as well as on soil and site characteristics, the major ones being soil rooting depth, topsoil thickness, available water capacity, plant nutrient  storage,  surface  runoff, soil tilth, and soil organic matter content (McCormack et al., 1982). Soil quality has historically been equated with agricultural  productivity.

Soil  quality,  of which soil productivity is a vital integral component, is defined by Larson and  Pierce  (1991) as “the capacity of a soil to function, both within its ecosystem boundaries (such as soil map unit boundaries) and within the  environment external to  that ecosystem  (particularly relative to air and water quality)”.

In other words, it is the capacity of a specific kind of  soil  to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation.

Soil productivity includes two aspects: the inherent productivity of soil and its response to management. Crop yield has been considered the best indicator of soil productivity as it integrates the inherent and managed components of soil productivity (Pierce, 1994).

This is precisely why land evaluation procedures or indices relate to the potential of land to produce food and fibre, and hence must correlate to crop yield (Pierce, 1994). Crop yields are an expression of historical production, whereas productivity is a measure of potential yield (Tengberg and Stocking, 1997).

REFERENCES 

Agber, P.I. and Ali, A. (2012). Evaluation of the productivity of soils in Makurdi, Southern Guinea Savanna, Nigeria, using Riquier’s index. J. Environ. Sci. Water Resource. 1(5): 100-104.

Agber, P.I. and Anjembe. (2012). Testing the effectiveness of soil productivity  index (PI) model for selected soils in Makurdi, Nigeria.ARPN Journal of Agricultural and Biological Science 7 (11): 927-932.

Aina, P.O. and Egolum, E. (1980). The effect of cattle feed lot  manure  and  inorganic  fertilizer on the improvement of subsoil productivity. Soil Sci. 129, 212-217.

Aina, P.O., Lal, R. and Taylor, G.S. (1977). Soil and crop management in relation to soil erosion in the rainforest region of Western Nigeria. Soil Conserv. Soc. America Spec. Publ. no. 21, 75-82.

Akamigbo, F.O.R. (1984). The accuracy of field textures in a humid tropical environment. Soil Survey and Land Evaluation 4 (3): 63-70.

Allison, F.E. (1982). Organic Carbon. In: Black, C.A. (ed.), Method of Soil Analysis. Part 2. American Soc. Agron. 9:1367-1378.

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