Effect Of Landuse On Soil Bulk Density In Owerri, Imo State, Nigeria

ABSTRACT

A study on how landuse affects the soil bulk density was carried out at Owerri in Imo State Nigeria. The land use types considered were Fallow (FS), Pear plantation (PP), Continuous Cultivated (CC), Municipal Waste (MW) and Automatic Workshop (AW) soils. A total of 30 undisturbed soil samples and 30 composite soil samples were collected from 0 -15cm and 15-30cm depth across these landuse types. The bulk density value was highest in AW, (1.70g/cm³) at 0 -15cm and at 15-30cm depth it is 1.81g/cm³, followed by CC (1.50g/cm³) at 0 – 15cm and (1.63g/cm³) at 15 – 30cm depth. FS has the lowest bulk density, (0.95g/cm³) at 0 – 15cm and (1.12g/cm³) at 15 –30cm depth. The soil with the highest porosity is FS (29.63%) at 0-15cm and (25.00) at 15-30cm while the soil with the lowest porosity is AW (4.50%) at 0-15cm and (4.23%) at 15 – 30cm depth. The soil pH was highest in MW (6.29) in pH (H₂O) and (5.42) in pH (Kcl) while it is lower in CC (4.45) in pH (H₂O) and (3.91) in pH (Kcl) at 0-15cm and at 15-30cm depth, MW has the value of (6.42) in pH (H₂O) and (5.02) in pH (Kcl) while AW has the lowest pH with (4.00) in pH (H₂O) and (3.40) in pH (Kcl),%OM was highest in MW (3.78) and the lowest is CC (1.07) at 0-15cm and at 15-30cm, MW (2.22) while the lowest was AW (0.93) . Result also showed that there is a significant positive correlation between Bulk density (BD) and Sand (r = 0.68^*) at 0 -15cm and at 15-30cm the correlation is strongly significant positively (r = 0.88^**). There is also a strong negative correlation between BD and Porosity at the depth of 0-15cm (r = 0.97^**) and (r = 0.96^**) at 15 – 30cm. Negative correlation also showed in BD vs OC (r = -0.45), BD vs OM (r = -0.45), BD vs TN (r = -0.44)in 0-15cm and in 15-30cm, BD vs OC (r = -0.71^*), BD vs OM (r = -0.71^*)and BD vs TN (r = -0.79^**). It is observed that different landuse types affect bulk density of the soil as it is seen that AW and CC have the highest BD and the lowest porosity indicating difficulties in root penetration and inhibition of water, air and nutrient movement in the soil therefore adding organic material to the soil will increase the soil quality both plant and animal debris or waste.

 Keywords: Landuse, bulk density, fallow soil, pear plantation, continuous cultivated soil, municipal waste and Automatic workshop.

CHAPTER ONE

 1.1     EFFECT OF LANDUSE ON SOIL BULK DENSITY

Bulk density of the soil is the ratio of soil mass to that of bulk volume of the soil. Bulk density is affected by factors such as water, aeration status, root penetration, clay content, texture, land use and management (Ramasamy et al., 2019). It controls the porosity of the soil and bulk density is an important property that can be used to predict the concentration and flow of nutrients in the soil (Bernoux et al., 1998).

Soil organic matter is an important component of soil solid. It constitutes 5% of solid space as it has been the composed of plant and animal debris in various stages of decomposition to humus (Oades, 1998). It is used as one of the important indices to evaluate soil quality (Gregorich et al., 1994). Organic matter reduces surface crusting facilitating seed germination, reduces the stickiness of clay soils making them easier to till. Organic matter improves water-holding capacity, aggregate stability, soil aeration and reduces bulk density (Cornell, 2008). Soil organic matter is mainly seen as the main indicator of soil fertility (Reeves, 1997).

Bulk density varies inversely with respect to soil organic matter content i.e., higher the organic matter content lower will be the bulk density (Leifeld et al., 2005).

Angela and Nina (2007) in their investigation showed that the addition of organic materials (at least 33% for sandy loam and 50% for clay loam) to a compacted soil reduced bulk density to below root restricting thresholds and increased macroporosity significantly more than 100% in some cases.

Generally, loose, well-aggregated soils and those rich in organic matter have lower bulk density and high porosity (NRCS, 2008). Loosely packed soils, which have a lower bulk density, will usually have better aeration, better drainage, and have a longer growing season (SAIN, 1996). Soil compaction caused by heavy machinery is known to result in increased soil bulk density (Rafiq 1990; Hassan and Gregory 1996); reduced porosity limits root growth and inhibits germination of seed which affects crop production negatively (Soane et al., 1981).

Different landuses cause lost and increase of organic matter in the soil. For instance it has been suggested that the conversion of forest into grassland and of forest or grassland into agriculture can significantly affect the dynamics of soil organic matter, soil C and N cycles, and soil biological and physical properties, thus altering soil quality and function (Chen et al, 2000; Zeng et al, 2009). Theobald et al., (2018) in their results showed that changing land use from forest to cultivated land reduced the organic matter, available nitrogen, soil moisture and porosity as well as soil bulk density and pH were significantly increasing. In mechanic workshops oil reduces amount of air and water in the soil which may lead to anaerobic condition (Atlas, 1977). In Mechanic workshop area, spilled oil seal or block the soil pores which may decrease  water holding capacity, aeration and increases soil  bulk density (Kayode et al., 2009), in this area weight of stationary vehicles cause compaction in the soil.

It is likely to have low bulk density in Fallow soil because there is an increase of Soil Organic Carbon and Soil nutrients (NPK) due to the decay of above ground and root biomass of fallow vegetation (Sameke et al., 2005). Bulk density could be lower in Municipal waste because of high compost particles or organic material (Haynes and Naidu, 1998).

There are some practices that can cause organic matter buildup in the soil. Organic matter in the soil can be maintained through agroforestry, intercropping with legumes and the use of mulches and other organic inputs (Shelam, 1993), rotating crops to include cover crops, perennial grasses, legumes and crops/plant that produce greater biomass, incorporate straw/crop residues, reduce tillage and apply manure plant material (NIANR, 2017).

Soil organic matter can be estimated by Loss on Ignition Method (LOI) (Sarah, 2011 and Ball, 1964), and also Soil organic matter can be calculated by multiplying Organic Carbon by Van Bemmelen factor of 1.724 (Udo et al. 2009). Bulk density will be determined by the core method (Grossman and Reinsch, 2002).

However, low soil fertility is the major problem of tropical soils, it has been attributed to influence of landuse which changes soil function and quality.

 1.2     OBJECTIVES OF THE STUDY

The major objectives of the study is to

• Determine how different landuses affect bulk density of the soil.
• Determine how organic matter build up in the soil is affected by land use.
• Determine the relationship between bulk density and soil organic matter content with other soil properties.

Pages:  71

Category: Project

Format:  Word & PDF         

Chapters: 1-5                                 

Material contains Table of Content, Abstract and References.