Effects of Tractorization and Organic Manure on Physical Properties of Sandy Loam Soil in Abeokuta, Nigeria

Soil compaction has effect on soil physical properties which could affect crop growth and yield. This study was conducted to determine the influence of incorporating organic materials and load application (tractorization) on the physical properties of sandy loamy soil in Abeokuta, Ogun State, Nigeria. Organic materials were cow dung, poultry and swine manure. Application rates of organic manures were 0 (control), 5 and 10 tonnes per hectare. Forty-five plots measuring 5 by 3 m were established in a complete randomized block experimental design with three replications making a total of 135 plots. Load application was done using an MF 435 tractor coupled with a 20-disc harrow at 0 (control), 5, 10, 15 and 20 passes. Penetration resistance, bulk density, gravimetric moisture content andporosity were determined using standard procedures. Penetrometer resistance at these passes were 392.2, 293.3, 285.0, 302.0 and 224.9 kPa respectively with significant differences between treatments (P≤0.05). Mean bulk density for the passes were 1.21, 1.26, 1.31, 1.27 and 1.29 g/cm3 respectively and bulk density increased with tractor passes. The effect of tractor passes, and manure incorporation rate did not have any significant effect on gravimetric moisture content. Poultry manure increased bulk density and penetrometer resistance on plots than swine manure and cow dung hence poultry manure at 10 t/ha can be incorporated on a sandy loam soil to enhance soil fertility and sustainability. Keywords: Tractorization, organic manure, sandy loam, penetration resistance, bulk densit

The Influence of Organic Matter on Soil Compactibility and Air Permeability of some Soils in Borno State

A laboratory experiment was conducted to determine the influence of an organic material (groundnut haulms) on the compactibility and air permeability of three most common agricultural soils (clay, sandy clay and sandy loam) in Borno state. The organic material was incorporated into the soils at three levels (2, 4 and 6% by mass of dry soil) and the soil-organic matter mixtures were compacted at three levels (5, 15 and 25 hammer blows). Incorporation of the organic material into the soils reduced their bulk densities and increased their air permeabilities. The bulk density for Ngala town clay, Nguma sandy clay and University sandy loam soils when incorporated with 2% organic matter and compacted using 25 hammer blows at 10% moisture content were 1.50, 1.59 and 1.74 Mgm-3 respectively. When the organic matter level was increased to 6% and compacted at 10% moisture content using 25 hammer blows, the bulk densities of the soils reduced to 1.41, 1.49 and 1.63 Mgm-3 for Ngala town clay, Nguma sandy clay and University sandy loam respectively. The air permeability for Ngala town clay, Nguma sandy clay and University sandy loam soils when incorporated with 2% organic matter and compacted using 25 hammer blows at 25% moisture content were 17, 23 and 37 μm² respectively. When the organic matter level was increased to 6% and compacted at 25% moisture content using 25 hammer blows, the air permeability of the soils increased to 28, 32 and 48 μm² for Ngala town clay, Nguma sandy clay and University sandy loam, respectively. For each level of organic material, air permeability of each soil decreased with increase in the number of hammer blows. Incorporation of the organic material into the clay soil increased its susceptibility to compaction and this resulted in much lower values of air permeability than in the sandy loam soil. Statistical models were generated to predict the air permeability of the soils in terms of silt and clay contents, moisture content, compaction and organic material levels. The implications of the results obtained in determining severity of compaction on these agricultural soils were discussed

Atributos físicos nos tempos de adoção de manejos em Latossolo cultivado com soja

A condução das operações de preparo de forma inadequada ocasiona sérios problemas de conservação do solo, destacando-se a compactação, que acarreta a redução do espaço poroso, principalmente dos macroporos, e altera os atributos físico-hídricos. Este trabalho teve como objetivo verificar a influência dos diferentes sistemas e tempos de adoção de manejos em Latossolo Vermelho de Jaboticabal, Estado de São Paulo, por meio da densidade máxima, e correlacioná-la com a produtividade da soja, a densidade relativa e a umidade crítica de compactação. O delineamento experimental foi o inteiramente casualizado com parcelas subdivididas (cinco sistemas de uso e três camadas), com quatro repetições. Os cinco sistemas de uso foram: plantio direto por cino anos (SPD5), plantio direto por sete anos (SPD7), plantio direto por nove anos (SPD9), preparo convencional (SPC) e uma área adjacente de mata nativa (MN). As camadas do solo avaliadas foram as de 0-0,10, 0,10-0,20 e 0,20-0,30 m, nas quais foram determinados a densidade máxima do solo (Ds máx), a umidade crítica de compactação (Ugc), a densidade relativa do solo (Dsr), a composição granulométrica, a porosidade e o teor de matéria orgânica do solo. Os resultados mostraram que o comportamento das curvas de compactação do solo foi o mesmo em todas as camadas dos diferentes manejos e que os teores de matéria orgânica não justificaram as pequenas alterações da Ds máx. Para o Latossolo Vermelho, as operações mecanizadas nos sistemas de manejo podem ser executadas na faixa de 0,13 a 0,19 kg kg-1 de umidade sem causar degradação física. Verificou-se que a Dsr ótima e a umidade crítica de compactação foram de 0,86 e 0,15 kg kg-1, respectivamente, embora os diferentes sistemas e tempos de adoção de manejo tenham apresentado comportamento semelhante quanto à produtividade da soja