Effects of different agricultural land use types on physical properties under rainforest agroecology

Abstract

The study was conducted at the Teaching and Research Farm, Obafemi Awolowo University Ile-Ife which approximately lies on latitude 7 degrees 28'N and longitude 4 degrees 33'E with an altitude of about 244 m above the sea level. Different agricultural land uses examined were: Secondary forest, planted fallow with legumes, Bush fallow ( Cromolaena odoratum), Continuous cassava/cowpea plot ( Manihot esculenta-Vigna unguiculata (L) Walp), Continuous maize/soybean plot ( Zea mays-Glycine max), and Tree crop ( Theobroma cacao). Selected soil physical properties assessed were: Aggregate stability, Bulk density, Porosity, and Gravel content. Composite soil samples were taken from each of the investigated plot. The samples were sub-sampled for aggregate stability test while the other samples were air dried, crushed and passed through 2 mm sieve for other laboratory analysis. The mean bulk density of Cassava/Cowpea plot, Maize/Soybean plot, Bush fallow plot and Secondary forest were higher and significantly different from Planted legume and Tree crop. Soil compaction and low level of organic matter were the major causes of soil degradation in continuous arable crop production that practices conventional tillage system going by history. It is suggested that a rotational system involving one year of conventional tillage following every three years of no-tillage under continuous Cassava/cowpea and Maize/soybean plots might cause less soil deterioration, hence higher grain yield.