Journal of Agriculture and Environment for International Development - JAEID 2015, 109 (2): 179-187
DOI: 10.12895/jaeid.20152.330
Assessment of the microbial biomass carbon, nitrogen and phosphorus in relation to physico-chemical properties of Acric Luvisols in Ibadan South West, Nigeria ADEDAYO OMOWUMI OYEDELE1*, ADENIKE ANIKE OLAYUNGBO2, OLUBUNMI ADERONKE DENTON1, OLUBOLA MORONKE OGUNREWO3, FOLUKE OLORUNFEMI MOMODU4 1
Institute of Agricultural Research and Training, Obafemi Awolowo University, Ibadan, Nigeria. Natural History museum, Obafemi Awolowo University, Ile-Ife, Nigeria. 3 Department of Agricultural Sciences, Wesley University of Science and Technology, Ondo, Nigeria. 4 Department of Botany, University of Ibadan, Nigeria. 2
*
Corresponding author:
[email protected]
Submitted on 2014, 30 January; accepted on 2015, 29 October. Section: Research Paper Abstract: Maintenance of soil quality is a key component of agriculture sustainability and there is an increase in the use of soil microbial parameters as sensitive indicators. This study aimed to determine the impact of different agricultural land uses on soil microbial biomass and to study the interrelationships between microbial biomass carbon (MBC, μgCg-1), Nitrogen (MBN, μgN g-1) and Phosphorus (MBP, μgC g-1) with the physicochemical characteristics of the soil. A total of 100 soil samples were taken from four different agricultural land uses: cocoa plantation, grazed land, arable land and fallow land. Average MBC was 200.04 μgCg-1, 189.24 μgCg-1, 180.04 μgCg-1 and 129.18 μgCg-1; average MBN was 19.84 μgNg-1, 18.16 μgNg-1, 17.60 μgNg-1 and 12.74 μgNg-1 while the average MBP was 7.62 μgPg-1, 7.26 μgPg-1, 7.22 μgPg-1 and 6.40 μgPg-1 for cocoa plantation, grazed land, arable land and fallow land respectively. One-Way ANOVA showed a significant difference in microbial biomass C, N and P among the study areas. MBC, MBN and MBP were significantly correlated to the physico-chemical properties of the soil (P≤0.05) under the same ecological conditions. The significant relationship between soil nutrients and microbial biomass facilitates the use of microbial biomass as an important soil quality indicator in relation to land use types. Key words: microbial biomass, land use, soil quality, soil physico-chemical properties.
Introduction Measuring microbial biomass is a valuable tool for understanding and predicting long-term effects on changes in land use and associated soil conditions (Sharma et
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A. O. Oyedele et al.: Assessment of the microbial biomass carbon,........ of Acric Luvisols in Ibadan South West, Nigeria
al., 2004). Maintenance of soil quality is a key component of sustainability wherein soil microbial biomass was used as indicators (Kara and Bolat, 2007; Tóth et al., 2007 and Kaschuk et al., 2011). Dry and rainy seasons are two extrema in tropical ecosystems which have a major influence on productivity, nutrient cycling and microbial biomass. Several studies reported seasonal variability of microbial biomass, with more contents of soil microbial biomass in both, dry (Maithani et al., 1996 and Montaño et al., 2007) and wet seasons (Devi and Yadava, 2006). The agricultural productivity in the East African region varies enormously during the year and is strongly affected by climatic change (Thornton et al., 2009). Due to the slow plant growth and nutrient uptake during dry seasons, it has been reported that high amounts of microbial biomass retain nutrients (Singh et al., 1989). In the rainy seasons, fast plant growth and root activity as well as drastic changes in soil moisture stimulate fast turnover of microbes (Fierer and Schimel, 2003). This leads to lower microbial biomass contents and increasing CO2 efflux rates (Otieno et al., 2010; Singh et al., 1989 and Sugihara et al., 2010). Hence, it is assumed that in tropical ecosystems with a bimodal climatic pattern soil microbes represent both a sink and source of nutrients (Srivastava, 1992). The tropical ecosystems are in special focus due to increasing anthropogenic disturbances and decreasing C budgets (decrease in C stocks of 25 - 30%, Don et al., 2011). Land use due to human perturbations strongly alters natural tropical ecosystems in terms of C turnover and sequestration (Katovai et al., 2012). Soil and crop management research over the years has helped in understanding the impact of various natural factors and agricultural practices on the population and diversity of microorganisms in the soil (Venkateswarlu and Srinnivasa Rao, 2014). The soil biomass work with respect to land use in Nigeria is scanty. Hence, in the present study, an attempt is made to analyze the soil microbial biomass nitrogen, carbon and phosphorus under four dominant land use systems in South Western, Nigeria (cocoa plantation, grazed land, arable land with mixed cropping (vegetables and maize) and fallow land) and studied their relationships between MBC, MBN and MBP with the physico-chemical characteristics of some Acric Luvisols of Institute of Agricultural Research and Training, Ibadan. Materials and Methods Study area
The study area is located in the vicinity of the Institute of Agricultural Research and Training, Moor Plantation, Ibadan, Oyo State, South West, Nigeria (7° 23’ N; 3° 51’E and 160 m above mean sea level). The tropical climate is marked with wet and dry seasons having a bimodal rainfall pattern with rainfall peaks mostly in June to September and annual temperature of 21.3°C to 31.2°C. The soils in the study area Journal of Agriculture and Environment for International Development - JAEID - 2015, 109 (2)
A. O. Oyedele et al.: Assessment of the microbial biomass carbon,........ of Acric Luvisols in Ibadan South West, Nigeria
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are mostly sandy loam at the top, to brown loamy sand sub-soil well drained, and formed on a plain level ground with the slope of 2-6%. The dominant soil is the Iwo series, also known as Acric Luvisol (Smyth and Montgomery, 1962), it is also classified under the world reference base (WRB) as KanhaplicHaplustalf. The soils are mostly sandy loam at the top, to brown loamy sand sub soil and they are well drained. Four different representative locations having similar ecological conditions under the land use types of cocoa plantation, grazed land, arable land with mixed cropping (vegetables and maize) and a fallow land were chosen for this study. Soil sampling
The sampling of surface soils (0 - 5cm) was done in a completely randomized design using stainless steel rings (10 cm diameter, 5 cm height) from 25 different points of each land use types, and mixed to form five composite samples at each site. Each land use type covers an area of approximately 1.2 ha and soil samples were collected during May, 2012. Stones, plant and root debris were removed and stored at 4°C before microbial analysis whereas subset of fine earth fraction (
