Regeneration of Earthworm Populations in a Degraded Soil by Natural and Planted Fallows under Humid Tropical Conditions

Abstract

Earthworm populations (predominantly Hyperiodrilus africanus and Eudrilus eugeniae) were sampled monthly for 1 yr during 1994 and 1995 in natural regrowth vegetation fallow (dominated by the natural fallow shrub Chromolaena odorata L.), planted fallow (the woody species Senna siamea Lam., Leucaena leucocephala Lam., and Acacia leptocarpa), and intercropped maize (Zea mays L.)–cassava (Manihot esculenta Crantz) established in 1989 in a degraded Alfisol (Oxic paleustalf) in southwestern Nigeria. Compared to leaves of Chromolaena (3.3% N), N concentrations were lower in those of Senna and Acacia, and higher in Leucaena Acacia and Leucaena had higher polyphenol relative to the natural fallow (2%). The lignin was lower in Leucaena than the natural fallow leaves (14%). For 65% of the sampling dates, earthworm numbers under all fallows were significantly higher than under continuous maize–cassava. The mean earthworm numbers (no. m−2) during the rainy season (April–October) decreased in the following order: Chromolaena (147), Senna (131), Leucaena (92), Acacia (80), and maize–cassava (14). Earthworm fresh weights in fallow plots were higher than in the maize–cassava plot, though this was significant for only 4 out of 11 sampling dates. Higher earthworm numbers and biomass in fallow plots were attributed to higher litterfall, lower soil temperature, and higher soil moisture. The mean earthworm numbers were directly correlated with the mean soil moistures (, P < 0.05) in fallow plots and N/polyphenol ratios of fallow litterfall (, P < 0.05). Increase in earthworm population by fallows led to an increase in leaf‐litter decomposition, soil organic matter, available P, and extractable cations and pH; and a decrease in soil bulk density and penetrometer resistance in the fallow plots.

Upland Rice and Allelopathy

“…[61] During the fallow period, plant nutrients are taken up from various soil depths and stored in the fallow vegetation. The nutrients depleted during cropping are replenished with those from fallow vegetation.…”

“…Replenishment of soil organic matter and regeneration of biological activity led to an increase in soil porosity and reduction in soil compaction. [61] This practice is only possible where land is available for such management and on such lands forage species can be grown for livestock feeding.…”

“…[66] Earthworms are known to accelerate plant residue decomposition in the tropics and elsewhere [67] and play a role in converting plant residue into soil organic matter. [68 -70] Tian et al [61] reported that an increase in earthworm population on fallow land led to an increase in leaf litter decomposition, soil organic matter, available P, and extractable cations and pH; and a decrease in soil bulk density and penetrometer resistance in the fallow plots. Lal [71] also reported that eliminating earthworms led to high soil bulk density and unfavorable soil structure.…”

Earthworm biomass and abundance, soil chemical and physical properties under different poplar plantations in the north of Iran

“…Also, native tree plantations can benefit from the establishment of populations of native earthworm species (Zou, Gonzalez 2002). According to Tian et al (2000), tree plantations may influence earthworm abundance by altering the physicochemical properties of soils viz. temperature, moisture regime, pH, soil organic content, litter inputs.…”

Evaluación del efecto del follaje de árboles forrajeros y oligoquetos en el crecimiento del sorgo en condiciones de invernadero.

“…Estudios realizados por Tian et al (2000) sugieren que las especies como Chromolena odorata que producen hojarasca con contenidos bajos de polifenoles y altas concentraciones de nitrógeno favorecen las poblaciones de lombrices debido a que los recursos con un mejor grado de palatabilidad hacen que su descomposición sea mas rápida. En este estudio el follaje de los árboles forrajeros con altos contenidos de compuestos solubles y bajas concentraciones de fibras lignificadas como R y C favoreció la población de lombrices pero no al crecimiento de los cultivos.…”