No abstract

Soil degradation and desertification pose a major threat to agricultural production in sub-Saharan Africa. The influence of cropping systems which had been established on selected physical and chemical properties of soil were investigated in Akinyode-Okinni community in Egbedore Local Government Area (LGA) of Osun State, Nigeria. The cropping systems included agri-silviculture (SCM), silvi-pasture (SPC), agri-horti-silviculture (PAH) and agroforestry (AFT) selected from existing farms in the community. The selected plots had cocoa (Theobroma cacao), oil palm (Elais guineensis) and kolanut (Kola nitida) as permanent crops; coco-yam (Coco nucifera), guinea grass (Panicum maximum), plantain (Musa spp), maize (Zea mays), and cassava (Manihot utilissima) were the annual crops. The experiment was carried out for two cropping seasons. Results showed that in the AFT system, bulk density (BD) decreased slightly from 1.22 to 1.16 g/cm 3 in the top soil and from 1.18 to 1.09 g/cm 3 in the subsoil after two cropping seasons. The pH varied between 6.40 and 7.05 in the first season and between 7.05 and 7.29 after two seasons. On average, the topsoil contained more organic carbon (OC) in SPC (38 g kg -1 ) and SCM (36 g kg -1 ) systems than in the PAH and AFT systems. Similarly, the total phosphorus content was higher in the topsoil of SPC and SCM systems than in the other systems. There was a slight reduction in soil acidity and no significant changes occurred in the concentrations of exchangeable bases after two cropping seasons. Conclusively, these cropping systems have the potential to reduce soil deterioration and thus; further studies to develop appropriate management strategies are necessary.

Lateritic soils are found in many farms even though they have not been known to be encouragingly productive to farmers because of their non-supportive of agricultural products. This experiment was to help farmers whose lands are lateritic to produce more crops/ha when buffered with organic manure. There were six treatments namely: laterite soil, laterite soil buffered with organic manure, laterite soil buffered with NPK 15-15-15, sandy loam soil, sandy loam soil buffered with organic manure (OM) and sandy loam soil buffered with NPK 15-15-15. There were three replicates for each treatments, the arrangement was 2 × 6 × 3 factorial design of 36 pots, parameters measured during the experiment were days to emergency, days to flowering, days to fruiting, number of branches, number of fruits per plant, nodes and internodes, stem girth length, leaf length of plant, plant height (from the surface of the soil to the apex (tip) of the plant) at twice a week and number of leaves per plant counted and recorded each week. The whole arrangements were subjected to the same environmental and climatic conditions. Chemical and physical characteristics of the soil in different treatments were done in the laboratory before and after. The data collected were subjected to two-way ANOVA. The results revealed that seed germination percentage was higher in sandy-loam buffered soil, 92.5%, followed by lateritic buffered soil 87.5%. Statistical analysis showed statistical differences among the yield and yield parameters for types of soil. However, the growth parameters taken as height, number of leaves, fresh and dry weight were found to be higher in sandy-loam soil followed by laterite soil and finally alluvium soil. Statistical analysis of these also showed significant differences between the types of soil used. Laterite buffered soil could yield as high as sandy loam soil in the production of tomatoes.

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.

No abstract