Brahima Kone
FELIX HOUPHOUET BOIGNY, Earth Science, Soil Sci. department, Faculty Member
- Soil Scientist with experience in ecology and agriculture over 30 years ago. Carbon sequestration in soil and agro-ec... moreSoil Scientist with experience in ecology and agriculture over 30 years ago. Carbon sequestration in soil and agro-ecology are the main concerns. Member of CFS-HLPE for food security and African network for Carbon sequestion as well belonging to IUSSS.edit
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The morphopedological characterization of the soils of Zépréguhé (Centre-West of Côte d'Ivoire) only exists on a small scale, whereas this support is essential for the arboriculture on which the region depends. This study aims to... more
The morphopedological characterization of the soils of Zépréguhé (Centre-West of Côte d'Ivoire) only exists on a small scale, whereas this support is essential for the arboriculture on which the region depends. This study aims to establish the morphopedological and typological characteristics of the soils of the Daloa area and particularly the soils of the locality of Zépréguhé located between longitude 6°22'18'' West, latitude 6°54'09'' North and 250 m above sea level. The soil pits were opened over a toposequence 551 meters long and the profiles were described following the approach of the Office de Recherche Scientifique et Technique d'Outre-Mer (ORSTOM). This study carried out in April 2022 showed that the soil types in the area are rejuvenated reworked ferrallitic soils (Plinthic Lixisols) on the summits, hardened reworked ferralitic soils (Plinthic Lixisols) on the mid-slope, depleted reworked ferrallitic soils ( Plinthic Arenosols) on the lower...
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Aims: To evaluate interaction of soil pH and acidity with weather on Rice Brown spot (BS) occurrence in rice lowlands. Study Design: Cross sectional study. Place and Duration of Study: Four distinct rice lowlands belonging to different... more
Aims: To evaluate interaction of soil pH and acidity with weather on Rice Brown spot (BS) occurrence in rice lowlands. Study Design: Cross sectional study. Place and Duration of Study: Four distinct rice lowlands belonging to different climatic zones (forest, transitional and savanna) of Côte d’Ivoire during cropping seasons of 2021. Methodology: BS characterization were done in different farmer fields where soil samples were also collected during dry and rainy seasons. Soil silicon and acidity were determined in those samples and rice grain yield at harvest time were recorded in different sites. Weather data related to sites and seasons were used to find out correlations. Results: Occurrence of BS was found in forest zones with scores of 4 and 3 compared to 1 and 2 in savanna and transitional zones, respectively, with seasonal variation. Both rice production and the occurrence of BS were explained by soil parameters in conjunction with climatic parameters. Rainfall (R=0.38) and rel...
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Les briques de terre stabilisées peuvent être une bonne alternative pour résoudre le problème de logement si les typologies de sol, les horizons de prélèvement de sol et les quantités de liants bon marché comme la paille de riz sont... more
Les briques de terre stabilisées peuvent être une bonne alternative pour résoudre le problème de logement si les typologies de sol, les horizons de prélèvement de sol et les quantités de liants bon marché comme la paille de riz sont identifiés. C’est pourquoi une étude a été réalisée sur les sols prélevés dans l’horizon B de Ferralsols et d’Acrisols ainsi qu’un échantillon de Kaolin ont été utilisés pour les fabrications d’adobe. Les briques de terre crue ont été fabriqué avec différentes proportion de paille de riz (0,2% ; 0,4% ; 0,6% ; 0,8% et 1%), et soumis à des tests de compressibilités et de flexions. Les résultats obtenus montrent que le dosage à 0,4% de paille a été optimal, avec une résistance à la compression de 1,04 - 1,2 N/mm2 pour les Ferrasols prélevés à une profondeur de (113 cm -30 m) et 0,21- 0,65N/mm2 pour les Acrisols (74 -122 cm). La proportion optimale en paille a été de 0,2% pour la flexion (0,01 - 0,06N/mm2) avec une plus forte valeur de 0,06 N/mm2 pour le kao...
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For improving knowledge on soil physical and chemical properties and management in cassava as food crop production areas of Côte d’Ivoire, field survey was conducted in localities of Dabou in the southwest and Bingerville in the south of... more
For improving knowledge on soil physical and chemical properties and management in cassava as food crop production areas of Côte d’Ivoire, field survey was conducted in localities of Dabou in the southwest and Bingerville in the south of Abidjan city targeting three sites in each of the locality. After defining a topographic position of the cassava fields encountered, the soil composite samples were taken in 0-40 cm depth. Pits were opened on the slope and the profiles were described therein. The subsoil is most frequently used for the production of cassava, the main crop in these two regions. The results of analysis showed that the soils are chemically poor. The pH was strongly acidic, causing the problem of solubilization of the aluminum ions in soil solution as well as phosphorus availability. In addition, organic matter levels were low overall threatening the increase of the productivity of crops unless applying fertilizers. Soils can be described as of poor quality and almost u...
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Ettien, D. J.B.*1, 2, Koné B1, 3, Kouadio K.K.H1, Kouadio N.E4, Yao-Kouamé A1, and Girardin O2., 1Université de Cocody, UFR des Sciences de la Terre et des Ressources Minières (STRM), Département des sciences du sol, 22 BP 582 Abidjan,... more
Ettien, D. J.B.*1, 2, Koné B1, 3, Kouadio K.K.H1, Kouadio N.E4, Yao-Kouamé A1, and Girardin O2., 1Université de Cocody, UFR des Sciences de la Terre et des Ressources Minières (STRM), Département des sciences du sol, 22 BP 582 Abidjan, Côte d’Ivoire ; 2Centre Suisse de Recherches Scientifiques en Côte d’Ivoire (CSRS), 01 BP1303 Abidjan 01 ; 3Centre du Riz pour l’Afrique, Cotonou. BP 2031 Cotonou 01. Bénin ; 4Centre National de Recherche Agronomique
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*Author for Correspondence Floristic sampling done in hundred plots around the sugar refinery complex of Ferke 1 and Ferke 2 located in Ferkessedougou in North Cote d’Ivoire during the cropping cycle of 2011-2012, revealed 30 species of... more
*Author for Correspondence Floristic sampling done in hundred plots around the sugar refinery complex of Ferke 1 and Ferke 2 located in Ferkessedougou in North Cote d’Ivoire during the cropping cycle of 2011-2012, revealed 30 species of weed including 6 of invasive Discoreas as D. bulbifera, D. dumetorum, D. hirtiflora, D. lecardi,. paraehensillis and D. preussii. Observations done on the biology, the phenology and the harmfulness showed that the occurrence of invasive Dioscorea in sugarcane fields was effective by bulbils and in certain level by tubers and bulbils generating new tubers, when produced during the vegetative growth stage between the second and seventh months of cultivation. D. bulbifera, D. dumetorum, D. hirtiflora and D. lecardi were producer of bulbils and occurred in highest potential densities. Excepted for D. lecardi, they were more harmful to sugarcane plant because of overlapping of vegetative cycle durations likewise for D. praehensilis. Hence, these weeds may have high competiveness ability with the crop for soil water and nutrient uptake as well as for sun light reception. Key Words: Weed, Dioscorea, Sugarcane, Biology, Phenology and Harmfulness
Pour améliorer la production du riz sur les sols acides en zone de forêt humide de l’Afrique de l’Ouest et approfondir la connaissance de la nutrition en phosphore (P) des variétés interspécifiques du riz de plateau, le potentiel de... more
Pour améliorer la production du riz sur les sols acides en zone de forêt humide de l’Afrique de l’Ouest et approfondir la connaissance de la nutrition en phosphore (P) des variétés interspécifiques du riz de plateau, le potentiel de production de certaines variétés a été évalué à l’application du phosphate sur un hyperdystric ferralsol à Ikwo au Nigeria. Cinq variétés de riz dont un sativa (V1 = WAB 56 - 104) et quatre interspécifiques (V2 = WAB450-1-B-P-38-HB, V3 = WAB450-11-1-P-40-HB, V4 = WAB450-11-1-P-P-40-1-H et V5 = WAB450-24-3-2-P-18-HB) ont été semées dans un dispositif de blocs complets randomisés à trois répétitions. Le phosphore a été appliqué annuellement à 50, 100 et 150 kg P ha-1 sous forme de triple super phosphate-TSP durant trois ans, ou en application unique du phosphate naturel du Mali (Ma) aux doses proportionnelles (150, 300 et 450 kg P ha-1) à la première année de l’étude. Les rendements en grain (1,6-3,7 t ha-1), les efficacités agronomiques (2-40 kg kg-1) et ...
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It is necessary to adopt high planting density of plantain (Musa sp.) for resorbing the seasonal deficit of the local market supplying while compulsory fertilizer recommendation only exist for low planting density (1667 plants ha-1 ) in... more
It is necessary to adopt high planting density of plantain (Musa sp.) for resorbing the seasonal deficit of the local market supplying while compulsory fertilizer recommendation only exist for low planting density (1667 plants ha-1 ) in Cote d’Ivoire. Five rates of each of the nitrogenN (200, 240, 260, 280 and 300 kgha-1 ) and potassium-K (548, 658, 712, 767 and 822 kgha-1 ) were partially combined adding 30 gP and 53 gCa per plant before applying during two (2012 – 2014) cropping seasons of plantain variety Corne 1 (2500 plants/ha). The girth of pseudo stem and the number of functional leaves were likely interfering with the bunch weight whichresponse was limited to the rates of 240 kgNha-1 and 658 kgKha-1 . Further improvement is expected when enhancing the efficiency of potassium nutrition by adjusting P-rate to 37.5 g/plant and the irrigation (> 20 mm) in order to induce greater response to N×K fertilizer.
Research Interests: Agronomy, Sustainable agriculture, Irrigation, Biology, Nitrogen, and 3 moreFertilizer, Potassium, and Sowing
Yam is being a strategic crop for food security in West Africa. However, there are many constraints that limit its productivity. Among the constraints, we have low quality of seeds and pest pressure. Therefore, there is a need to assess... more
Yam is being a strategic crop for food security in West Africa. However, there are many constraints that limit its productivity. Among the constraints, we have low quality of seeds and pest pressure. Therefore, there is a need to assess the tolerance of new cultivars released, especially for yam mosaic virus (YMV) wide spreader in yam agro-ecologies. During the cropping seasons of 2000 and 2001, a trial was conducted in augmented design including sixteen varieties of yam in four replications according to a density of 30000 plants per hectare. The checks were the local varieties named Bete bete and Florido. The severity effect of YMV was measured at 2, 4 and 6 months after planting. The results showed a significant effect of YMV on check cultivars and some improved varieties in 2000 and 2001 as well as significant correlation between canopy surface rate and yields. Highest yield (32 t/ha) was obtained in 2000 by the improved variety 98_01176 among eight tolerant cultivars while 14.9 ...
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A farmer-friendly method of determining the most suitable cultivation soils would help in transferring new integrated soil management technologies. The potential for using soil color (Munsell data) was tested by physico-chemical analysis... more
A farmer-friendly method of determining the most suitable cultivation soils would help in transferring new integrated soil management technologies. The potential for using soil color (Munsell data) was tested by physico-chemical analysis of 1028 ferrallitic soil samples from 289 profiles unequally allocated above 7 deg N in Côte d’Ivoire. Soil hue variations in depth and along the toposequence revealed the existence of vertical and lateral gradients of soil hue. The relative contribution of the different descriptors (clay, sand, carbon, total nitrogen, total phosphorus, potassium, magnesium and calcium) to the three functions extracted using a discriminant analysis to differentiate the four groups of soils with different hues was evaluated as well as the analysis of variance to determine the possible groups number for each one of the descriptors. Differences between physico-chemical components of red (2.5YR and 5YR) and yellow (7.5YR and 10YR) soils were determined, especially for P...
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Research Interests: Biology and Rice plant
ABSTRACT Soil nutrient deficiencies can affect rice yield and grain mineral content wherever they occur, but an understanding of their effect on upland rice production in humid forest zone of West Africa is still limited. Therefore, a... more
ABSTRACT Soil nutrient deficiencies can affect rice yield and grain mineral content wherever they occur, but an understanding of their effect on upland rice production in humid forest zone of West Africa is still limited. Therefore, a nutrient omission trial was conducted on foot slope soil in 2003, 2004 and 2005 in Côte d’Ivoire using rice variety WAB 56–104. The effect on rice grain yield (GY) and nutrient content of complete fertilizer (Fc with nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and zinc (Zn)) was compared with Fc from which a specific nutrient was excluded (Fc – N, Fc – P, Fc – K, Fc – Ca, Fc – Mg and Fc – Zn). Before the trial, soil K (0.10 cmol kg−1) and Mg (0.20 cmol kg−1) contents were suitable, but available P-Bray I (4.2 mg kg−1) was found to be deficient. In course of the study, K, Mg and P deficiencies were observed. An antagonistic effect was observed between rice GY and grain concentrations in P, Mg and Ca for treatments Fc – Mg, Fc – P and Fc – K, respectively. Therefore, the use of P, K and Mg fertilizers is recommended for successive cropping seasons in order to rich stable and high rice yield while decreasing of grain concentrations in P, Mg and Ca can be observed.
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For sustaining yield and extractable sugar production of sugarcane in Cote d'Ivoire in intensive cultivation, it is required an alternative organic source of nutrients vs. chemical fertilizer. Comparative trial was conducted at... more
For sustaining yield and extractable sugar production of sugarcane in Cote d'Ivoire in intensive cultivation, it is required an alternative organic source of nutrients vs. chemical fertilizer. Comparative trial was conducted at Zuenoula (Centre West of Cote d'Ivoire) from 2011 to 2013 including 4 rates of sugarcane foam (6, 12, 18 and 24 tha-1), 4 others (150, 300, 450 and 600 kgha-1) of chemical fertilizer [N (18.5%) P (9%) K (14%) + Mg (2%) S (2.5%)] and a control plot (no fertilizer) in a randomized complete block design with 3 replications. No significant difference was observed between leave concentrations of N, P and K while increased of soil contents of N and K occurred within two-year period under foam also showing a possibility to improve soil content of P according to the rates and years of cultivation for a specific target yield. Regularly, 600 kgha-1 of NPK induced significant difference of yield between both fertilizers but the rates of extractable sugar (9.6%) ...
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The quality of the plant production in periurban agriculture is subjected to question given the potential contamination of soils that can affect the crops. The levels of contamination of soils and vegetables by Metallic trace... more
The quality of the plant production in periurban agriculture is subjected to question given the potential contamination of soils that can affect the crops. The levels of contamination of soils and vegetables by Metallic trace elements (MTE) as copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in the district of Abidjan, have been evaluated. Multi-sites survey of cropping areas of sweet potato and Hibiscus was conducted in three municipalities in Abidjan (Port-BouA«t, Yopougon and Bingerville) in relation to the intensity of industrial and commercial activities. The site of Bingerville has been used as the reference site referring to the low activities. Soil samples (in 0-20 cm and 20 - 40 cm), combined with that of plants (leaf, stem, and root), and water were collected, transported in laboratory for analysis. The total amounts of MTE in soil, as well as the different fractions extracted were determined in addition to the respective concentration in plants (Hibiscus and Sweet potat...
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Declining yields in continuous cropping are a serious threat to rain-fed rice (Oryza spp.) production. Yields are affected by ecological stress, including soil nutrient deficiencies as well as plant mineral nutrition. However, there is a... more
Declining yields in continuous cropping are a serious threat to rain-fed rice (Oryza spp.) production. Yields are affected by ecological stress, including soil nutrient deficiencies as well as plant mineral nutrition. However, there is a limited diagnosis of soil nutrients and rice mineral nutrition in the humid forest zone of West Africa. Therefore, a nutrientomission trial was conducted in the humid forest in Côte D’Ivoire on a Ferralsol of foot slope during the cropping seasons in 2007, 2008, and 2009. The effect of the complete fertilizer (Fc: N, P, K, Ca, Mg, and Zn) and other treatments (Fc–N, Fc– P, Fc–K, Fc–Ca, Fc–Mg, Fc–Zn, and unfertilized plot) with the exclusion of a specific nutrient from Fc were evaluated on rice grain and straw yields coupled with mineral concentrations in rice leaves and grains. Significant decline of grain and straw yields was observed after the first cropping season. Effects of P and K deficiencies differed respectively between cropping seasons, wh...
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To improve yam production in West Africa and stabilize its cropping system on Dystric ferrallitisols, a varietal test was conducted at Bringakro (6°401’N, 5°091’O, alt. 150 m) in the savanna zone at the Centre of Cote d’Ivoire. Five... more
To improve yam production in West Africa and stabilize its cropping system on Dystric ferrallitisols, a varietal test was conducted at Bringakro (6°401’N, 5°091’O, alt. 150 m) in the savanna zone at the Centre of Cote d’Ivoire. Five improved cultivars of Dioscorea alata (TDa 95-079; TDa 95-226; TDa 95-387; TDa 98-1176; TDa 98-1177) and two local checks (Florido et Bete-Bete) were used in 2000 and 2001. Yields, multiplication factor and postharvest losses ratio were collected annually for each variety. Results of statistical analysis showed highest yields (20.31 t ha-1 – 15.73 t ha-1) for TDa98-1176 while lowest (9.37 and 10.50 t.ha-1) were obtained by local Bete-Bete. This improved variety has also the highest multiplication factor (5.62% - 7.25%) and its’ post-harvest loss ratio (19.23% – 41.58%) was among the lowest. The review of these results showed that the assession TDa98-1176 can insure equivalent yield of Bete bete if soil is well managed without any fertilization under ferr...
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Grain yield stabilization of lowland rice over cropping seasons was explored using different compositions of inorganic fertilizers (NPK, NPKCa, NPKMg, NPKZn, NPKCaMg, NPKCaZn and NPKCaMgZn) and straw incorporation (3, 6, 9, 12 and 15... more
Grain yield stabilization of lowland rice over cropping seasons was explored using different compositions of inorganic fertilizers (NPK, NPKCa, NPKMg, NPKZn, NPKCaMg, NPKCaZn and NPKCaMgZn) and straw incorporation (3, 6, 9, 12 and 15 tha-1 ). No fertilizer and no straw amended plot was the control in a split-plot design with three replications laid in a Fluvisol of Guinea savanna in Centre Cote d’Ivoire. Three weeks old nursery rice variety NERICA L19 was transplanted. No significant difference of grain yield was observed between the different treatments excluding the highest yields recorded for treatments NPKMg (5.09 tha-1 ), NPKZn (5.15 tha-1 ) and NPKCaéMg (5.31 tha-1 ) compared with 12 (3.95 tha1 ) and 15 tha-1 (4.14 tha-1 ) as straw rates respectively. Grain yield declining trend was more pronounced for mineral fertilizer treatments showing twice greater depressive effect of cropping cycle compared with the straw especially, for treatments characterized by highest grain yield i...
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Despite the beneficial effects of legumes on soil fertiliy, their adoption by farmers remains low due to the extra labour entailed. Lifting this constraint is of paramount importance in sustainable agriculture. This issue was dealt with... more
Despite the beneficial effects of legumes on soil fertiliy, their adoption by farmers remains low due to the extra labour entailed. Lifting this constraint is of paramount importance in sustainable agriculture. This issue was dealt with in the present study which was carried out in central Côte d’Ivoire through assessing the response of soil (chemical and biological parameters) and subsequent yam yield to two fallow systems: natural C. odorata fallow (control) vs. Combination of C. odorata and Cajanus cajan. The mixed plot was obtained by loosely introducing at the onset of fallow C. cajan which withstands competition by C. odorata. Soil chemical parameters, abundance and diversity of decomposer macrofauna, microbial parameters and subsequent yam tuber yield were measured. After a 30-month period of time, the P content in C. cajan leaf litter increased in the mixed plot. The density of diplopods in leaf litter was lower in the mixed fallow while the average order number in soil was ...
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The use of native soil nitrogen for crop production would be an ideal manner of producing food crop at low cost, in a sustainable way within a protected environment. Achieving this goal, requires the application of technical strategies... more
The use of native soil nitrogen for crop production would be an ideal manner of producing food crop at low cost, in a sustainable way within a protected environment. Achieving this goal, requires the application of technical strategies aiming at maximizing N mineralization and availability in soil and ensuring its efficient use by the food crops. In this paper, technical options to manage native soil N fluxes during the dry-to-wet season transition period (DWT) involved the use of improved fallow (pigeon pea) to retain native soil N on the upland slopes, and of nitrate catch crops (Brachiaria and Sesbania green manures) to temporarily immobilize incoming N from the slope in the lowland of the wide representative inland valleys. These types of slope management resulted in three extreme situations of interflow contribution from the slope to the lowland during the 3-months DWT. Data from 1997 indicate a flush of mineral soil N occurring during the first half of the dry-to-wet season transition period, with higher amounts of nitrate found in lowland than in upland ecologies (92 vs 78 kg N ha-1) of rice based systems of Cote d’Ivoire. In the present experiment, the presence of planted pigeon pea fallow on the upland slope conserved some 12 kg of soil nitrate-N ha-1 during the transition season. In the absence of pigeon pea (bare fallow), 47 kg N were translocated from the upland into the lowland. In the lowland about 20 kg nitrate-N ha-1 were absorbed by the growing biomass and thus saved from loss. Upon incorporation of this biomass in the course of land preparation, lowland rice yields increased significantly by up to 1.1 Mg ha-1 (p<0.04) compared to the bare fallow lowland plots. The use of improved fallow appears to be a suitable option to capture nutrients that would otherwise be lost. The effectiveness of such options and their adoption by farmers requires further studies.
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To evaluate and reinforce the level of tolerance of New Rice for Africa (NERICA) to midseason drought stress in tropical humid zone, nutrient-omission trials were conducted during two years on terre de barre soil at Niaouli, in southern... more
To evaluate and reinforce the level of tolerance of New Rice for Africa (NERICA) to midseason drought stress in tropical humid zone, nutrient-omission trials were conducted during two years on terre de barre soil at Niaouli, in southern Benin. A complete fertiliser treatment (Fc) comprising N, P, K, Ca, Mg and Zn and treatments with specifics nutrient-omission (Fc-N, Fc-P, Fc-K, Fc-Ca, Fc-Mg, Fc-Zn) were evaluated on the growth and yields of NERICA 4. Drought was expressed by mean annual rainfall of 0 – 40 mm with evaporation ranging from 2.39 to 4.20 mm during the period from July to August every year. There was a significant level of drought tolerance in treatments with omission of N, Mg, Zn and Ca. These treatments had higher grain yields with reduced number of tillers especially under severe drought condition Thus, it was recommended to use basal fertiliser containing P and K for NERICA rice production under bimodal rainfall pattern
Declining yield and yield gap reversibility of rainfed rice in continuous cropping was explored in a humid forest zone of Cot characterized by soil phosphorus (P) deficiency. S (Bu), Togo (To), Niger (Ni) and Senegal composed of that of... more
Declining yield and yield gap reversibility of rainfed rice in continuous cropping was explored in a humid forest zone of Cot characterized by soil phosphorus (P) deficiency. S (Bu), Togo (To), Niger (Ni) and Senegal composed of that of Taïba (Ta) and Thies (Pa) as well as the wa (TSP) were used in complete randomized block design with three replications. No P applied once in the first year (2003) at 200 and 400 kg P kg P2O5ha -1 before sowing rice variety WAB 56-104, as basal fertilizer likely for PR, combined with 30 kg N ha (KCl). There was negative effect of the number of cropping season which was also characterized by highest yield gap, especially for rates were observed indifferently to P-sources however. Enriched Mg rock phosphates with suitable ratios of MgO/P + Fe2O3)/P2O5 (<0.10) are recommended for rice production likely 200 kg P 1 is further required for maintaining high yield of about 3.5 tha recorded during the first half of year.
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Annual rice production in most the countries in West Africa is far below the local need and increasing is most depending to cultivated land extension while demographic growth is contrasting such agricultural system, hence intensification... more
Annual rice production in most the countries in West Africa is far below the local need and increasing is most depending to cultivated land extension while demographic growth is contrasting such agricultural system, hence intensification is required. Among the methods of intensification, rice ratooning ability was explored in 2012 and 2013 in relation with nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca) and zinc (Zn) fertilizer effects in a rainfed lowland of humid forest in South Cote d’Ivoire. Treatments were applied in a complete randomized block design with 3 replications at 100 N kgha-1, 55P2O5 kgha-1, 150 kg K ha-1, 33 kg Ca ha-1, 15 kg Mgha-1 and 10 Zn kgha-1 including no fertilized plot as control after the harvest of main crop of rice variety NERICA L14 previously fertilized with 200 kg ha-1 of NPK (10-18-18) in all the plots. There was significant (p< 0.05) effect of sequential cropping on the numbers of tiller and panicle every year likewise f...
Geochemical changes can occur in soils exposed to high annual rainfall, even in non cultivated soil of bush fallow as consequence of leaching. Missing data of leached N, P, K and Mg could have lead to erroneous fertilizer practice... more
Geochemical changes can occur in soils exposed to high annual rainfall, even in non cultivated soil of bush fallow as consequence of leaching. Missing data of leached N, P, K and Mg could have lead to erroneous fertilizer practice inducing declining of the crop yields. During the cropping seasons (June, July and August) of 2003 and 2004, 25 mi-piezometers were set (9600 m2) in soil systematically (20 × 30 m) for perched groundwater collection before laboratory analysis of N-NO3, N-NH4, P2O4, K, Mg and HCO3. Soil profiles of middle slope (MS), foot slope (FS) and fringe valley (FV) were also sampled by horizon for physic-chemical analysis (particle size, bulk density, C-organic, total-N, exchangeable K and Mg as well as the pHwater). Leached concentrations were in decreasing order as HCO3>N-NO3>K and Mg>N-NH4> P2O4 and the pH values were higher than 5.5. Although N-NO3 and P2O4 were found to be the main accompanying anions of leached N-NH4, K and Mg, there was specific an...