Propiedades químicas del suelo y producción de maíz tras la aplicación de enmiendas orgánicas e inorgánicas a un suelo ácido en el suroeste de Nigeria

A factorial experiment with a randomised complete block design (three replicates) was performed to determine the effects of poultry manure (PM), lime (L) and NPK 15-15-15 fertilizer on soil chemical properties, and to determine the effects of their combinations on soil productivity and maize yield. The factors were PM (0, 5 and 10 Mg/ha), L as CaCO3 (0 and 250 kg/ha) and NPK 15-15-15 (0 and 100 kg/ha). The soil had a loamy sand texture. The application of L and PM increased the surface soil pH in a similar fashion. In both years of the experiment, the effective cation exchange capacity (ECEC) of the soil after the combined application of 10 Mg/ha PM, L and NPK was significantly higher than after the individual application of L or NPK or their combination (5.75-7.65 cmol/kg compared to 3.36-4.57 cmol/kg). The application of 10 Mg/ha PM with L and/or NPK reduced the possibility of Mn toxicity, with soil levels ranging from 108 to 136 mg/kg. The combined use of the three amendments gave the highest leaf nutrient concentrations. The highest maize grain yield (4.62 Mg/ha) was obtained with L + 10 Mg/ha PM; with no amendment the grain yield was 1.9 Mg/ha. The application of PM enhanced the effects of L and NPK in improving soil productivity. However, separate applications of 5 and 10 Mg ha-1 PM similarly affected soil productivity; the sandy nature of the soil at depths of 0-20 cm seems to have prevented differences between the two rates from becoming manifested.Para determinar los efectos del abono de residuos de aves (PM), de cal (L) y de fertilizante NPK 15-15-15 sobre las propiedades químicas del suelo, y determinar los efectos de sus combinaciones sobre la productividad del suelo y producción del maíz, se llevó a cabo un experimento factorial con un diseño en bloques al azar (tres réplicas). Los factores fueron PM (0, 5 y 10 Mg/ha), L como CaCO3 (0 y 250 kg/ha) y NPK 15-15-15 (0 y 100 kg/ha). El suelo tenía una textura franco arenosa. La aplicación de L y PM aumentó el pH de la superficie del suelo de forma parecida. En los dos años del experimento, la capacidad de cambio de cationes efectiva (ECEC) del suelo tras la aplicación combinada de 10 Mg/ha PM, L y NPK fue significativamente superior que la de la aplicación individual de L ó NPK o una combinación de ambos (5,75-7,65 cmol/kg vs. 3,36-4,57 cmol/kg). La aplicación de 10 Mg/ha PM con L y/o NPK redujo la posibilidad de toxicidad con Mn, con niveles de suelo de 108-136 mg/kg. El uso combinado de las tres enmiendas produjo las concentraciones de nutrientes en hoja más altas. La producción de grano más alta en maíz (4,62 Mg/ha) se obtuvo con L + 10 Mg/ha PM; sin enmiendas se obtuvo 1,9 Mg/ha. La aplicación de PM aumentó los efectos de L y NPK en la mejora de la productividad del suelo. Sin embargo, aplicaciones separadas de 5 y 10 Mg/ha de PM afectaron de forma similar a la productividad del suelo; la naturaleza arenosa del suelo a profundidades de 0-20 cm parece disminuir las diferencias entre las dos dosis

Soil water depletion under various leguminous cover crops in the derived savanna of west africa

Leguminous cover crops have the potential of making cropping systems in the tropics sustainable if they would not deplete resources such as soil water and nutrients to the detriment of companion crops. Therefore, a study was carried out at Alabata, Ibadan, southwestern Nigeria, to evaluate the effects of leguminous cover crops on soil water suctions in 1993 and 1994 in order to assess the possibility of integrating them into the farming systems of the savanna zone of West Africa. In 1993, 13 leguminous cover crops (Aeschynomene histrix, Centrosema brasilianum, Centrosema pascuorum, Chamaecrista rotundifolia, Cajanus cajan, Crotalaria verrucosa, Crotalaria ochroleuca, Lablab purpureus, Mucuna pruriens, Psophocarpus palustris, Pseudovigna argentea, Pueraria phaseoloides and Stylosanthes hamata) were planted in a randomized complete block design with four replications. Maize and natural fallow (mainly Chromolaena odorata and Imperata cylindrica) were included as comparisons. Only six of the legumes (A. histrix, C. pascuorum, C. cajan, C. ochroleuca, M. pruriens, and P. phaseoloides) were included in the measurements in the 1994 new plots. Soil water suctions at various stages of legume growth were measured at daily or weekly intervals (depending on the frequency of rainfall events) using tensiometers installed at 0–15 and 15–30 cm soil depths. Soil water suctions exceeding 10 kPa (theoretical field capacity) were observed mainly between 6 and 12 weeks after planting (WAP), and by 20 WAP when cover crops had matured and rainfall frequency was very low. Soil water suctions were significantly related (r2>0.80) to dry matter between 8 and 10 WAP. The studied cover crops were classified in three groups which can be used as a guide for choosing the legumes in tropical farming systems. Soil water depletion was markedly influenced by growth characteristics of legumes and distribution of rainfall during the rainy season. Leguminous cover crops conserved soil water after their growth needs were satisfied

Litter and biomass production from planted and natural fallows on a degraded soil in southwestern Nigeria

To rehabilitate a degraded Alfisol at Ibadan, southwestern Nigeria, Senna siamea (non-N-fixing legume tree), Leucaena leucocephala, and Acacia leptocarpa (N-fixing legume trees) were planted in 1989, and Acacia auriculiformis (N-fixing legume tree) in 1990. Pueraria phaseoloides (a cover crop) and natural fallow were included as treatments. Litterfall and climatic variables were measured in 1992/1993 and 1996/1997 while biomass production and nutrient concentrations were measured in 1993 and 1995. Total litter production from the natural and planted fallows was similar, with means ranging from 10.0 (L. leucocephala) to 13.6 t ha−1 y−1 (natural fallow) during the 1996/1997 collection. Leaves constituted 73% (L. leucocephala) to 96% (A. auriculiformis) of total litterfall. Acacia auriculiformis grew most quickly but S. siamea produced the highest aboveground biomass which was 127 t ha−1 accumulated over four years, and 156 t ha−1 accumulated over six years of establishment. The aboveground biomass of P. phaseoloides and natural fallow was only 6 to 9 t ha−1 at six years after planting. Nitrogen concentration in the leaves/twigs of was 2.5% for L. leucocephala, and 2% for other planted species and natural fallow. Pueraria phaseoloides had concentrations of P, K, Ca and Mg comparable to levels in the leaves/twigs of the tree species. Through PATH analysis, it was found that maximum temperature and minimum relative humidity had pronounced direct and indirect effects on litterfall. The effects of these climatic variables in triggering litterfall were enhanced by other variables, such as evaporation, wind, radiation, and minimum temperature. Improvement in chemical properties by fallows was observed in the degraded soil

Intercropping oil palm (Elaeis guneensis) with cocoyam (Xanthosoma sagittifolium) on windows and nonwindows in southern Nigeria

Yields of intercropped oil palm (Elaeis guineensis) and cocoyam (Xanthosoma sagittifolium) were assessed at Okomu (6°25'N, 5°12'E), near Benin City, southern Nigeria. Yields were assessed during the fifth and sixth year after the establishment of oil palm. The annual yield of fresh fruit bunches (FFB) was 12.9 Mg/ha on windrows, and 8.5 Mg/ha on non-windrows. For Xanthosoma, the average annual yield of cormel was 11.3 Mg/ha on windrows, and 7.5 Mg/ha on non-windrows. The performance of Xanthosoma under the canopy shade was good and this suggests that it would tolerate oil palm shade at the early stages of palm establishment. Also, the oil palm yield was comparable with the expected average yield in the area. Owners of small-scale oil palm plantations in the region are encouraged to maximize land use and profit by intercropping oil palm with Xanthosoma during the first five years of palm establishment or when a shade-tolerant crop is required as an intercrop within the five years

Comparative assessment of several rainfall erosivity indices in southern Nigeria: short communication

Soil erosion, measured in field runoff plots, was correlated with several rainfall erosivity indices. Erosion was measured on field plots established on a Typic Paleudult in southeastern Nigeria. Several erosivity indices were computed from a daily recording rain gauge sited in vicinity of the runoff plots. Erosivity indices computed included EI30 (WISCHMEIER & SMITH 1978), KE>1 (HUDSON 1971) and AIm (LAL 1976). In addition, several new indices were computed including EkIm and EkI30, where, the new kinetic energy (Ek) factor was computed using an empirical relation developed by KOWAL & KASSAM (1976) in northern Nigeria. Two new indices were slightly better correlated with soil erosion than the conventionally used indices

An improved cover cropfallow system for sustainable management of low activity clay soils of the tropics

The potential of planted leguminous cover crop fallow as an alternative to the natural regrowth fallow for sustaining the productivity of low activity clay (LAC) soils in the tropics as the fallow period shortens was tested at Ibadan in the forest-savanna zone of southwestern Nigeria. The study, initiated in 1990, compared an improved system (cover crop-fallow) and a traditional system (natural fallow), with the aim of developing an improved cover crop-fallow system for sustainable management of LAC soils of the tropics. Pueraria phaseoloides, an herbaceous, N-fixing, perennial legume with a slow initial growth habit, was selected as a test cover crop. Pueraria was sown with a maize-cassava intercrop at the same season. In a 2-year cycle, 1 year of cropping was followed by 1 year fallow with pueraria for the cover crop-fallow system or with natural regrowth (mainly Chromolaena odorata) for the natural fallow system. Maize-cassava intercropping without a fallow period (continuous cropping) was included as a control. No fertilizer was applied throughout the experimental period. Pueraria produced 253 kg N ha−1 after the fallow period, compared with 109 kg N ha−1 for chromolaena; pueraria was also better in recycling P (11 kg P ha−1) than was chromolaena (9 kg P ha−1). Natural fallow for 1 year increased the maize yield from 75 to 350% from 1992 to 1996, and the cassava yield from 9 to 130% compared with continuous cropping. Cover crop-fallow resulted in a 22 to 72% higher maize yield than the natural fallow from 1992 to 1996. Although in 1992 and 1994 cassava tuber yield was lower with the cover crop-fallow than with the natural fallow, with better pueraria husbandry in 1996, cover crop-fallow increased the cassava tuber yield by 41%. With residue burning, the N balance was 27 kg N ha−1 yr−1 for the pueraria cover crop-fallow system and −15 kg N ha−1 yr−1 for the chromolaena natural fallow system. Cover crop-fallow maintained soil organic carbon status better than the natural fallow. Integration of a pueraria legume cover crop did not affect soil pH. Results indicate cover crop-fallow with pueraria could be a better alternative to traditional natural fallow under shortened fallow periods for raising or maintaining productivity of LAC soils of the humid tropics

Soil macroaggregate stability under different fallow management systems and cropping intensities in southwestern Nigeria

Evaluation of soil aggregate stability under managed fallow systems is very relevant in the assessment of their agricultural sustainability. It is also important to identify the parameters that are most responsive to the effects of these fallow systems on aggregate stability. This study was carried out in southwestern Nigeria to quantify the effects of various fallow management systems on the macroaggregate stability of surface soil (0–15-cm depth) using a long-term fallow management trial established in 1989 on an Alfisol toposequence. Data were collected between 1994 and 1995. Three fallow systems (bush fallow, Pueraria phaseoloides, and Leucaena leucocephala) and three fallow periods (1–3 years after 1-year cropping) were evaluated. Cropping consisted of maize+cassava intercropping. A split-plot design with fallow systems as main plot and cropping intensities as subplot in four replications was used in the trial. Soil aggregate samples were wet-sieved to evaluate their mean-weight diameter (MWD) and fractal dimension (D). The means of MWD for the fallow systems and cropping intensities ranged from 2.4 to 6.4 mm. The mean D values ranged from 2.29 to 2.72 while the mean intercepts (log k) of the regression ranged from 2.01 to 2.28. Low D values (cohesive and stable aggregates) were associated with fallowing whereas high D values (fragmented aggregates) were associated with cultivation. Fallowing enhanced soil aggregate stability. The Pueraria system also enhanced soil aggregate stability more than the bush fallow and Leucaena systems when continuous cropping was practised. The subplots, which were fallowed for 2 or 3 years after 1 year of cropping, were usually similar in aggregate stability to the secondary forest soil. Fractal analysis showed further that soil aggregates in the dry season and on the upper slope of the toposequence were more cohesive than in the wet season and on the lower slope. Observed D and log k values were also significantly influenced by laboratory method