Abstract
The performance of maize on tilled and untilled sandy loam soil, under different levels of compaction of 0, 2, 4 and 6 tractor-wheel passes in a humid tropical environment was investigated with a Massey Ferguson (MF) 90-disc plough, mounted on an MF 260 tractor. The experimentation had different aspects, respectively conducted in the field and laboratory, at the Rivers State University, Port Harcourt, Nigeria. The experimental field was a 72 m2 plot of land, which was left fallow for two years before the investigation. The plot was sub-divided into five experimental subplots of 9 m2 each, numbered 1 to 5, with a furrow spacing of 0.5 m. Soil samples were taken randomly at a depth of 0.3 m for the determination of the soil physical properties. After the compaction treatments, maize seeds were manually planted at a depth of 0.05 m and the growth and yield of the maize monitored over a period of fourteen weeks after planting. The investigation showed that the maize crop performed optimally on subplot (2), which was tilled and un-compacted, with a dry matter content of 2,859 kg ha-1, while the least performance was on subplot (1) that was untilled and un-compacted, with a dry matter content of 1,192 kg ha-1. Therefore, this research establishes that, with the agricultural practice of shifting cultivation, sandy loam soil in a humid tropical region requires a minimum level of tillage to achieve optimal yield of maize crop. Key words: Maize, compaction, growth and yield, tilled soil, untilled soil, sandy loam.
Highlights
In agricultural production, the type and condition of soil are critical for the overall performance of the cultivated crops
The results indicate that the bulk density of the soil on the plots varies directly with the number of tractor wheel passes on the plots; especially, while the untilled sub-plot (1) had a bulk density of 1.20 g cm-3, the tilled and un-compacted sub-plot (2) had 1.17 g cm-3
Further analysis on the results showed that a significant relationship exists between the bulk densities of the soil and the level of the soil compaction using the 95% confidence interval and the reasonable overlap observed in the Figure 2
Summary
The type and condition of soil are critical for the overall performance of the cultivated crops. Soil is one of the three major natural resources, alongside air and water; and is described as a natural body of loosed, unconsolidated materials several meters below, which are formed on the earth surface (Smith et al, 1999). Soils are formed from the weathering of rocks and are composed of four major components: minerals, organic matter, water and air (Patricia, 2003). Soils have pores and void volume between their aggregates. The amount of voids in any soil partly determines the behaviour of the soil and its support for plant growth. Its pores are filled with water and constitute a bulk solution. The top layers of soil form the basis for plant growth and are referred to as agricultural soil, while the layer below the agricultural soil
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