OJSSOpen Journal of Soil Science2162-5360Scientific Research Publishing10.4236/ojss.2013.33019OJSS-33800ArticlesEarth&Environmental Sciences Effects of Tillage Practices on Soil Properties under Maize Cultivation on Oxic Paleustalf in South Western Nigeria olaA. Senjobi1*OlufunmilayoT. Ande2A.E. Okulaja3Federal University of Agriculture, Abeokuta, NigeriaInstitute of Agric Research and Training, Obafemi Awolowo University, Apata, IbadanDepartment of Crop Production, Olabisi Onabanjo University, Ago-Iwoye, Nigeria* E-mail:bolasenjobi@gmail.com(OAS);210620130303163168September 12th, 2012May 18th, 2013 May 27th, 2013© Copyright 2014 by authors and Scientific Research Publishing Inc. 2014This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/

A study was conducted to determine the effect of tillage practices on soil properties under maize cultivation in savanna ecosystem of South Western Nigeria. The tillage systems evaluated were zero, convectional and traditional tillage systems. The results showed that there is a significant difference in soil parameters and crop morphologies at p < 0.05 among the tillage systems. The traditional tillage system resulted to the most favorable soil environment, for crop growth and best performance of crop followed by conventional and no-tillage system in the area are studied respectively. The significant difference in yields adduced to lower bulk density, higher water holding capacity and porosity which increased plant root proliferation and optimal utilization of soil nutrients under tilled methods. Hence tillage methods have the capability to increase production while no-tillage is better under long term production for sustainable land use.

Tillage Practices; Soil Properties; Maize; Sustainable Production1. Introduction

The ever-increasing population scenario of Nigeria, makes it a necessity for more land to be opened up and efficiently managed for increased food production. The Nigerian traditional tillage method involves the use of hoes to make mounds size of which depends on the crop to be grown on. This method is gradually being replaced by conventional method of plough and harrow. Considering the fragile nature of Nigeria savannah soils, this method has further impoverished the soils due to erosion, increased loss of soil moisture by evaporation and compaction. Tillage, according to [1], is a terminology that is applied to the creation of enabling environment for the germination and growth of crops. Technically according to [2], tillage refers to the mechanical stirring of soil to provide a suitable soil environment for growth of crops. Ashaye [3] affirmed that the productivity of any soil depends on the way and how it is managed through cultivation practices imposed on it. Appropriate tillage practices are those that avoid the degradation of soil properties but maintain crop yields as well as ecosystem stability [4], [5,6]. In recent years, the interest in conservation tillage systems has increased in response to the need to limit erosion and promote water conservation [7,8]. This has been considered to provide the best opportunity for halting degradation and for restoring and improving soil productivity [9]. Conservation tillage is being adopted by local farmers in order to protect the soils from adverse effects of climate. However, the effects of this method need to be examined further in savanna soils of Nigeria characterized with limited rainfall, high temperature and fragile soils prone to erosion.

The major stable crop grown widely in south western savanna is maize which cultivation and utilization have increased due to greater demands for consumption and for industrial purposes. Hence more land is being opened up yearly to sustain increase demands. An understanding of the climate and soil environment is necessary in order to select appropriate management practices such as tillage practices, fertilization, irrigation etc., as well as modification of the soil nutrients to optimize maize yield. This has necessitated the use of modern implements for tillage practices to facilitate farming operations. However, poor choice of implements and soil management practices, inappropriate tillage systems, seed bed types have often been identified as major constraints to cereal crop production in the savannah agro-ecological zones of South-Western, Nigeria [6]. Lal [6], therefore advocated that in tropical countries, soil tillage practices that have significant effects compared to zero tillage should be encouraged since mechanized tillage appeared to be indispensable in large scale farming. This is necessary, since a granular structure does not only encourage rapid infiltration and good retention of rainfall but also provides adequate moisture, air exchange capacity within the soil and minimizes resistance to root penetration.

This study was carried out to examine the influence of tillage practices on properties of soils under a maize cultivation and to determine the effective and appropriate tillage practice(s) for sustainable maize production.

2. Materials and Methods2.1. Field Work

Composite surface samples (0 - 15 cm) and sub-surface samples (15 - 30 cm) were taken at the lower slope of the toposequence selected for the research. In addition to the above, a representative profile pit was dug and samples were taken from it. These were later air-dried, crushed and sieved before taken to the laboratory for physical and chemical analyses of the soils.

Three tillage operations were imposed on the soil. These were traditional, conventional and zero tillage operations. The experiments were laid out in a randomized complete block design with three replicates. Maize was used as test crop and morphological properties such as stem girth, number of internodes, number of cob/plant, fresh weight of cobs with bract. Fresh weight of grains cob, fresh weight of 10 grains and grain yield/ha were taken.

2.2. Laboratory Analyses

Soil analysis were carried out later to observe the variations in soil properties due to applied different tillage operations. The soil particle size analysis was done mechanically by using the hydrometer method of Bouyoucos [10] with sodium hexa-metaphosphate as the dispersing agent. Soil pH was determined potentiometrically in both water and 0.01 M Potassium Chloride solution (1.1). Exchangeable bases were extracted with neutral ammonium acetate solution; Ca and Mg were determined by atomic absorption spectrophotometer, and K and Na by flame photometer. Exchangeable acidity was determined by the KCL extraction method [11]. Total nitrogen was determined by the macro-kjeldah method [12]. Available Phosphorus was determined by the Bray and Kurtz [13], method and organic carbon by the method of Walkley and Black [14]. ECEC was determined as the sum of exchangeable bases and exchangeable acidity.

All the parameters collected were subjected to analysis of variance and the means were compared using Duncan Multiple Range Test.

3. Results and Discussion

Table 1 shows the result of the physical and chemical properties of the profile pit dug on the experimental site. The soil textures ranged from clay loam to sandy clay. The bulk density ranged from 1.24 to 1.59 g/cm3. Gravel concentration and total porosity around the rooting zone were 28.7% to 66.8% and 40.0% to 53.3% respectively.

Hydraulic conductivity, permeability and water holding capacity (WHC) fluctuated with depth down the profile. This may probably be due to variation in soil texture down the profile pit. The organic carbon, pH and exchangeable bases with exception of potassium and sodium decreases with depth down the pit. The soil was classified as Oxic Paleustalf because of its Ustic moisture regime, percent CEC greater than 35% in the sub soil and Oxic diagnostic horizon.

Table 2 shows the soil properties of the studied site before tillage at 0 - 15 cm and 15 - 30 cm depths. It was observed that the bulk density and porosity decreased with depth while the pH varied between 4.82 and 4.85. The organic carbon and exchangeable bases with the exception of phosphorus were low. The low nutrient status of the soil might be due to continuous cultivation without corresponding return of organic materials to the soil. The clay content range from 28.8% to 30.4% while

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