Physicochemical and morphological properties of termite (Macrotermes bellicosus) mounds and surrounding pedons on a toposequence of an inland valley in the southern Guinea savanna zone of Nigeria

Abstract

Termites play a significant role in soil-forming processes of the tropics. The influence of termites on pedogenesis as affected by the toposequence, however, has rarely been explored. We investigated the soil physicochemical and morphological characteristics of epigeal mounds constructed by Macrotermes bellicosus (Smethman) compared with those of surrounding pedons along a toposequence (bottom, fringe and upland sites) of an inland valley in central Nigeria. The physicochemical and morphological properties of the mound soils varied according to structural units but were generally different from those of the adjacent pedons. The differences included finer texture, higher electrical conductivity, total N, exchangeable bases (Ca, Mg and K) and effective cation exchange capacity and lower C/N ratio and exchange acidity in the mound than the pedon at each toposequence position. This tendency to modify the soil properties was more prominent in the nest body where the termites actually live, that is, in the hives, royal cell and base-plate, than in the soils below the nest and the other mound parts, that is, the external wall, internal wall and pillars. We found this trend to a greater or lesser degree at all toposequence positions. Our findings suggest that: (1) M.?bellicosus can manipulate the mound soils according to functional applications of structure units or environmental requirements for its livelihood, regardless of local soils; (2) M.?bellicosus makes ecological patches (hot spots) at all toposequence positions in the same measure; (3) the influence of M.?bellicosus on the pedogenesis is reduced in the lowlands compared with the uplands because the number and volume of the mounds were substantially lower in the bottom and fringe sites compared with the upland site.     

Accumulation of free oxyhydroxides in termite (Macrotermes bellicosus (Smeathman)) mounds and the implications for their dynamics in an African savannah Ultisol

The present study aimed to assess the dynamics of oxyhydroxides via termite mounds in a tropical savannah of Central Nigeria, where the soils often contain oxyhydroxides as a major component of soil minerals. To this end, the quantities of oxyhydroxides stored in mounds built by Macrotermes bellicosus (Smeathman) were compared to those stored in surface (Ap1) soils, and their turnover rates were estimated. Both the mound wall and nest of M. bellicosus were enriched two- to 10-fold with acidified ammonium oxalate soluble iron (Fe_o) and aluminum (Al_o) and dithionite-citrate-bicarbonate (DCB) soluble iron (Fe_d) and aluminum (Al_d) relative to the adjacent surface soil horizon. These oxyhydroxide contents were positively correlated with the clay content (P < 0.05), suggesting that M. bellicosus preferentially used silicate clay-associated oxyhydroxides for mound construction. The Fe_d, Al_d and DCB-soluble manganese (Mn_d) preserved in the M. bellicosus mounds ran up to 112 ± 25.6, 5.72 ± 1.41 and 2.17 ± 0.68 kg ha^?1, accounting for 1.91 ± 0.23%, 1.00 ± 0.60% and 0.35 ± 0.09% of the total amount stored in the surface soil horizon, respectively. Furthermore, the estimated turnover rates of Fe_d, Al_d and Mn_d were 6.6, 0.33 and 0.14 kg ha^?1 year^?1, respectively. These findings suggest that the mound-building termites significantly impacted the dynamics of free oxyhydroxides in an African savannah soil.     

Nutrient storage in termite (Macrotermes bellicosus) mounds and the implications for nutrient dynamics in a tropical savanna Ultisol

The role of mounds of the fungus-growing termite Macrotermes bellicosus (Smeathman) in nutrient recycling in a highly weathered and nutrient-depleted tropical red earth (Ultisol) of the Nigerian savanna was examined by measuring stored amounts of selected nutrients and estimating their rates of turnover via the mounds. A study plot (4?ha) with a representative termite population density (1.5?mounds?ha^?1) and size (3.7?±?0.4?m in height, 2.4?±?0.2?m in basal diameter) of M. bellicosus mounds was selected. The mounds were found to contain soil mass of 9249?±?2371?kg?ha^?1, composed of 7502?±?1934?kg?ha^?1 of mound wall and 1747?±?440?kg?ha^?1 of nest body. Significant nutrient enrichment, compared to the neighboring topmost soil (Ap1 horizon: 0–16?cm), was observed in the nest body for total nitrogen (N) and exchangeable calcium (Ca), magnesium (Mg) and potassium (K), and in the mound wall for exchangeable K only. In contrast, available (Bray-1) phosphorus (P) content was found to be lower in both the mound wall and the nest body than in the adjacent topmost soil horizon. Consequently, the mounds formed by M. bellicosus contained 1.71?±?0.62?kg?ha^?1 of total N, 0.004?±?0.003?kg?ha^?1 of available P, 3.23?±?0.81?kg?ha^?1 of exchangeable Ca, 1.11?±?0.22?kg?ha^?1 of exchangeable Mg and 0.79?±?0.21?kg?ha^?1 of exchangeable K. However, with the exception of exchangeable K (1.2%), these nutrients amounted to less than 0.5% of those found in the topmost soil horizon. The soil nutrient turnover rate via M. bellicosus mounds was indeed limited, being estimated at 1.72?kg?ha^?1 for organic carbon (C), 0.15?kg?ha^?1 for total N, 0.0004?kg?ha^?1 for available P, 0.15?kg?ha^?1 for exchangeable Ca, 0.05?kg?ha^?1 for exchangeable Mg, and 0.06?kg?ha^?1 for exchangeable K per annum. These findings suggest that the mounds of M. bellicosus, while being enriched with some nutrients to create hot spots of soil nutrients in the vicinity of the mounds, are not a significant reservoir of soil nutrients and are therefore of minor importance for nutrient cycling at the ecosystem scale in the tropical savanna.     

Termite mounds in relation to the surrounding soils in the forest and derived savanna zones of southeastern Nigeria

Some physical and chemical properties of the two common termite mounds in southeastern Nigeria, Macrotermes (MM) and Cubitermes (CM) mounds, were compared and their relationships with the surrounding top and subsoils investigated. Percentage sand, silt, pH, calcium, magnesium, potassium, sodium, iron, and organic carbon were higher and clay and penetrometer resistance lower in the CM than the MM. Sand, silt, organic carbon, and calcium decreased and clay increased from the forest to the derived savanna in the CM, but no clear trend was shown with the other properties in both the CM and the MM. Most of the nutrients were higher in the CM than in the adjacent top or subsoil but the reverse was the case with the MM. More nutrients are associated with the inorganic fractions of the soil than with the organic carbon in the mounds and the soils surrounding them. The Ca:Mg ratio in the mounds and the top and subsoils adjacent to them was low for most crops but the K:Mg ratio was mostly adequate. Because of these differences in properties and sizes of the mounds, different management strategies are recommended for them and the soils around them.     

埃塞俄比亚罗毕高原含铬雏形土地区凋落物饲喂的白蚁(Macrotermes spp)的化学性质及其生化活动的研究

Termite(Macrotermes spp.) mounds are complex biological habitats originated by the termite activity and possessing peculiar physical, chemical and biochemical properties. In this study we examined the concentration of nutrients and the biochemical activity of abandoned soil and mounds colonized by termites of the genera Macrotermes located in the Borana District, Ethiopia. To elucidate the magnitude and persistence of the termite-induced effects, we also studied an abandoned mound, previously colonized by termites of the same genera formed on the same soil. Results confirmed that termite-colonized mounds are ‘hot spots' of nutrient concentration and microbial activity in tropical soils. This is due to the termite driven litter input and decomposition. The abandoned mounds showed higher microbial biomass and activity and displayed a nutrient redistribution and a greater microbial activity than the adjacent soils. These findings allowed us to hypothesize a model of nutrient cycling in colonized soils and a partition of the relative roles of termites and soil microorganisms in nutrient location and turnover in tropical soils. These results may be also useful for the optimal management of termite-colonized soils.     

Chemical,physical and micromorphological properties of termite mounds and adjacent soils along a toposequence in Zona da Mata,Minas Gerais State,Brazil

Little is known about the effects of neotropical mound-building termites in soil chemical and physical properties. The influence of soil termite activity on soil characteristics was studied by assessing chemical, physical and micromorphological properties of a toposequence of Latosols (Oxisols). Soil samples were collected from the walls and inner parts of termite mounds and also from adjacent soil. A high diversity of termite genera was found in the mounds along the toposequence, together with the inquiline termites and other soil-dwelling arthropods. Chemical analyses showed that pH and the contents of organic C and N, P, Ca and Mg were significantly higher in termite mounds compared with adjacent areas, with an inverse trend for Al content. Significant differences in pH and exchangeable Al were observed between soil and mound across the slopes. The mound density across the landscape was higher at the upper slope segment, followed by the hill top, middle slope and lower slope segments. Considering a lifespan of 30 years and dimensions of termite mounds found in the toposequence we conclude that the textural and chemical uniformity of Latosols may be increased, following the pedobiological turnover during mound building, with local rates varying from 2.1 to 7.5 m³ ha^− 1.     

Soil development and fertility characteristics of inland valleys in the rain forest zone of Nigeria: Physicochemical properties and morphological features

Abstract

Inland valleys are a widespread topography in West Africa and have significant potential for agricultural development, especially wet rice cultivation. This study investigated the physicochemical and morphological properties of the soils of two inland valleys in Abakaliki and Bende, Southeast Nigeria, where the soils are derived from shale materials, and discusses their agricultural potential as well as the soil-forming process. Particle size analysis suggested that the soils at both sites were fine-silty, fine-loamy or clayey and, thus, would be able to retain a high amount of water. In contrast, the higher content of clay and silt in the Abakaliki soils would enhance much more water retention than the Bende soils. The soils in Abakaliki, except for some subsoil horizons, generally had acidic reactions, low contents of exchangeable bases (Ca, Mg, K and Na) and high amounts of exchangeable acidity (Al and H) for which leaching effects under high precipitation in the area would be implicated. Bray-1 P values in these soils were generally low under such acidic conditions, while organic C and total N were recorded at relatively high levels, in particular at the surface horizons, reflecting large biomass production under a humid climate. The Bende soils showed similar chemical properties to Abakaliki except for relative accumulation of exchangeable bases throughout the profile on the downslope possibly because of the rolling topography. This result suggested that geological fertilization (i.e. afflux of nutrients released during the soil formation in the upland into the lowland) was more beneficial in Bende than Abakaliki. From the findings of the present study, we concluded that soils in both Abakaliki and Bende had good texture for sawah development (leveled and bounded rice field with an inlet and an outlet for irrigation and drainage), but their poor chemical properties would be constraints for agricultural production.     

High performance liquid chromatography studies on the polysaccharides in the walls of the mounds of two species of termite in Senegal,Cubitermes oculatus and Macrotermes subhyalinus: their origin and contribution to structural stability

 The origin, nature and quantity of polysaccharides in the walls of the epigeal mounds of a species of soil-feeding termite, Cubitermes oculatus, and a fungus-growing termite, Macrotermes subhyalinus, found in Senegal, and of soil not considered to be under the influence of termites, were studied to obtain a clearer picture of the structural stability of these materials. The compounds were extractedand analysed by high performance liquid chromatography. We found that the walls of mounds made by soil-feeding species were very rich in sugars soluble in aqueous acid or hot water. Most of the sugars originated from cellulose and hemicellulose, and only a small proportion from microorganisms. There were also significant amounts of stachyose in the mound walls and in the reference soil. This sugar was probably formed by the surrounding vegetation, which was mainly leguminous crops. Comparison of the mineral and organic-mineral particle sizes of samples confirmed that the walls of soil-feeding termite mounds where there is the greatest redistribution of clay have the best aggregating capacity. The results therefore show that the polysaccharides in mound walls of soil-feeding termites are mostly of plant origin. Their influence on the stability of these structure is discussed. The walls of fungus-growing termite mounds contain little organic matter and hence low levels of polysaccharides, which are mainly of plant origin. Received: 19 July 1999     

Response of maize (Zea mays) to the application of foliar fertilizers in the Sudan and Guinea savanna zone of Nigeria

Soil fertility problems resulting in low maize yields in smallholder farms are common in the West African moist savanna. The effectiveness of commercial foliar fertilizers in improving maize growth and yield was evaluated in three savanna agro‐ecological zones of Nigeria in two steps. In step one, eight commercial foliar fertilizers were assessed in a greenhouse study with two soil types using maize (Zea mays L. cv. 2004 TZE‐Y POPDT STR C4). The treatments included a control and a reference that received the optimum concentrations of nutrients. In step 2, three promising products from the greenhouse study (Turbotop, Agroleaf General, and Agroleaf high‐P) were evaluated under field conditions to validate the efficacy of products to enhance crop growth and yield. The foliar products were applied at the rate of 5 kg ha^?1. The treatments also included three rates of P application (0, 30, and 60 kg P ha^?1) as triple super phosphate (TSP) with or without foliar fertilizers. In the greenhouse study, differences in maize shoot dry matter yield and N and P concentrations, attributable to the spraying of the commercial foliar fertilizers, were observed for both soils. Spraying Turbotop, Agroleaf General, and Agroleaf high‐P gave the highest shoot dry biomass and N and P uptake compared to other products. Under field conditions, foliar spraying of Agroleaf high‐P significantly increased the shoot dry biomass of maize compared with the 0 P treatment in all locations. The grain yield of maize ranged from 1 to 4 t ha^?1 with significant differences across sites. Products with high concentrations of P and N in their formulation improved maize yield suggesting that appropriate management of P and N resources is a prerequisite for a sustainable maize intensification in the savanna agro‐ecologies.     

Artificial soil-like bodies of a river valley and their evolution in an urban environment (Based on the example of the Moscow River valley)

Technogenic soil-like bodies and raw soils on technogenic sediments in the valley of the Moscow River in the city territory were investigated. Soil destruction and the accumulation of techogenic sediments, as well as their remediation, result in the formation of soil-like bodies called replantozems. Spontaneous overgrowth and the formation of raw soils that gradually evolve into mature urban soils result in soils called urbanozems. It is shown that the best foundation for replantozems in river valleys is in situ alluvium with relatively favorable physical and physical-chemical properties.     

Tillage and plastic mulch effects on soil properties and growth and yield of cocoyam (Colocasia esculenta) on an ultisol in southeastern Nigeria

Protected cultivation, mainly represented by plastic-film mulching, has greatly improved crop production worldwide since the 1950s. However, despite its widespread use in tropical USA, Europe and China, its use in sub-Saharan Africa is not widespread. A field experiment was conducted using cocoyam (Colocasia esculenta L. Schott) to evaluate the effects of two tillage systems (tilled and no-till) and plastic-film mulch (black and clear plastic-film mulch) on soil properties and cocoyam growth and yield in 2003 and 2004 planting seasons on a Typic paleudult in southeastern Nigeria. The experiment comprised six treatments and was laid out in the field using randomized complete block design replicated three times. Results showed that 70–80% of the corms emerged 7–8 days (21 days after planting [DAP]) earlier in both tilled and no-till plastic-film mulched plots when compared to the unmulched plots. At later stages of crop development, the plants in the tilled black plastic-film mulched plots were taller by 61–67% than those in the unmulched no-till plots, which had the lowest plant height (27–30 cm). At 98 DAP, there were no significant treatment differences in leaf area index (LAI) between tilled and no-till mulched plots with LAI of 15.5–19.8. However, LAI was reduced in both unmulched plots by 35–54% when compared to the mulched plots. On the average soil temperature was higher in plastic-film mulched plots than that under plots without mulch by about 2 °C. Results show significantly lower soil bulk density (between 1.10 and 1.26 Mg m⁻³) in both tilled clear and black plastic-film mulched plots when compared to the corresponding no-till clear or black plastic-film mulched plots (1.40–1.45 Mg m⁻³). For the two seasons studied volumetric water content (VWC) in tilled black plastic-film mulched plots were significantly higher than VWC in other mulched plots by between 10 and 38% in 2003 and between 17 and 30% in 2004. At harvest (270 DAP) the highest corm yield was obtained in tilled black plastic mulched plots (29.1 Mg ha⁻¹). This was higher (P = 0.05) than yields obtained in no-till, no mulch plots by 72%. Yields were also higher in tilled black plastic mulched plots when compared to tilled clear plastic mulched plots, no-till black plastic mulched plots and no-till clear plastic mulched plots by 29, 47 and 59%, respectively. These findings suggest that plastic mulched plots provide a better soil environment for cocoyam than unmulched plots and that tilled mulched plots especially tilled black plastic mulched plots provide superior edaphic environment for cocoyam when compared to other treatments used.     

Impacts caused by the addition of wine vinasse on some chemical and mineralogical properties of a Luvisol and a Vertisol in La Mancha (Central Spain)

Background, aim, and scope  Using wastewaters from wine production that are often discharged directly into soil, with previous treatment, we carried out an experiment to identify the impact over time, specifically to identify the benefits and risks of its application. Materials and methods  Experiments were carried out using approximately 200 g of samples of agricultural soils which were amended with increased amounts of vinasse: 1–5–10–20–40–70 ml. The doses used were not arbitrary but similar to the usual one amended. Soil electric conductivity was determined in distilled water with a glass electrode (soil to H₂O ratio 1:5). Clay identification of soil samples are by X-ray diffraction. Results  The pH decreased slightly and salinity increased, possibly leading to changes in crop productivity. The increase in salinity reflects the concentration of dissolved salts in the vinasse. Significant changes were observed in the clay minerals after amendment with the vinasse. Conclusions  Our study indicates that, under experimental incubation, the application of increasing doses of wine vinasse for increasingly long periods can affect certain chemical properties. The results show that application of winery wastewaters to soil results in significant increases of electrical conductivity, reaching levels that can be detrimental to crop growth. The decrease in pH values is somehow beneficial, and finally there is a small increase in the chemical weathering of clay minerals