ガーナニオケルイナサクノタメノユウヨウビセイブツノタヨウセイオヨビトクセイカイセキ

博士（農学）東京農工大

Influence of organic inputs with mineral fertilizer on maize yield and soil microbial biomass dynamics in different seasons in a tropical acrisol

Introduction The practice of co-applying chemical fertilizers (CF) with organic inputs (OIs) as a soil amendment is still low in Ghana, although it has the potential to improve crop yield and soil productivity. Objectives In a two-year study, we evaluated the effects of co-applying contrasting OIs with and without CF on maize yield and soil chemical and microbial composition. Methods Aboveground biomasses of Centrosema pubescens (CEN), Pueraria phaseoloides (PUE), and Zea mays (MZE) were amended to an acrisol at 4 t ha−1 season−1. The combined treatments (CEN+, PUE+, and MZE+) were fertilized with basal NPK 15:15:15 at 40 kg N ha−1, followed by topdressing with [(NH4)2SO4] at 50 kg N ha−1. Sole OI inputs (CEN, PUE, and MZE) did not receive any CF inputs. The controls (CON− and CON+) received 0 and 90 kg N ha−1 season−1. Results The results showed that either sole OIs except for MZE or its combination with CF improved grain yield compared to the CON. Grain yield ranged from 2.1 t ha−1 to 2.6 t ha−1 in the first season versus 0.8 t ha−1 to 1.7 t ha−1 in the second. The MZE+ and CEN+ treatments showed the highest mean grain yields and were similar to CON+. Although CF addition to OIs improved grain yield in all treatments, negative interaction was observed for CEN and PUE as opposed to a positive interaction in the MZE treatment. Co-application of CF with OIs on dissolved organic carbon and nitrogen (DOC) and (EON) dynamics depended on seasonal soil moisture and sampling time. Moreover, co-application of CF with OIs enhanced microbial biomass in CEN but showed minimal and suppressive effects on MZE and PUE amendments, respectively. Conclusion Overall, the increased grain yield in MZE+, CEN+ and CON+ was attributable primarily to the CF addition. Thus, long term evaluations are recommended for sustainable utilization of MZE and CEN given their minimal responses in the short term in the presence of CFs.Peer Reviewe

Exploring Farmers’ Indigenous Knowledge of Soil Quality and Fertility Management Practices in Selected Farming Communities of the Guinea Savannah Agro-Ecological Zone of Ghana

Efforts to improve soil productive capacity aimed at boosting crop production in the Northern Ghana has primarily focused on field-based experiments with little documentation on farmer practice and local indigenous knowledge of soil management. A sample group of 114 farmers from five farming communities in the Guinea Savannah was interviewed to evaluate their indigenous knowledge of crop production practices in the context of soil health, fertilization management, and crop yield. Data were collected using semi-structured interviews and responses for each category were calculated using simple proportions. Farmers’ fertilization practice was primarily influenced by fertilization resource availability and crop yield response. The results showed that inorganic fertilization was the commonest fertilization type among farmers. Farmer local indicators of soil health were predominantly limited to visually observable signs such as presence or absence of indicator plants, growth vigor of plants, soil color, and tilth, texture, and compaction. Non-tactile and visible indicators, notably soil chemical composition and presence of soil microorganisms, was rarely used. The listed indicators were congruent with scientific reports, although some knowledge gaps, particularly on the use of indicator plants, were identified. The use of indicator plants as determinants of healthy or non-healthy soils appeared to be influenced by the ease of control of weeds, its utilitarian benefits, benefits to the soil, and threats on cultivated crops. Famers were well informed about the decreasing crop yield. Fertilization practices and limitations in soil management practices with proposed capacity building approaches aimed at enhancing productive capacities of cultivated farmlands are discussed.Japan Society for the Promotion of SciencePeer Reviewe

Nitrogen Mineralization and Microbial Biomass Dynamics in Different Tropical Soils Amended with Contrasting Organic Resources

The use of location-specific and underutilized organic residues (OR) as soil amendments in small-holder agro-ecosystems is promising. Six ORs (Leucaena leucocephala, Centrosema pubescens, Gliricidia sepium, Pueraria phaseoloides, Azadirachta indica, and Theobroma cacao) were amended to three tropical soils each at 24 mg g−1 dry soil in 120-day incubation study to estimate their nitrogen (N) mineralization and microbial biomass carbon (C) dynamics. Inorganic N contents varied among ORs, soil type and incubation days. Regardless of soil type, Gliricidia had the highest inorganic N among the studied ORs. Mineralization rate of 1.4 to 1.5 mg N kg−1 soil day−1 was observed for Lego and Tec soils, respectively, and was twice higher than Nya soil. However, Nya soil released higher inorganic N than Tec and Lego soils, implying high N mineralization efficiency in the former. Consistent soil pH increase was respectively observed for Theobroma and Pueraria treatments in all soils. Moreover, Theobroma and Pueraria amendments showed the highest soil microbial biomass C (MBC) at the end of the incubation. The assessed soil properties likely affected by the dominant edaphic factors and management influenced differences in MBC and dissolved organic carbon (DOC) while OR quality indices controlled N mineralization. Thus, we conclude that soil properties and OR type are important factors for optimal utilization of organic resources.Japan Society for the Promotion of SciencePeer Reviewe

Impacts of Fertilization Type on Soil Microbial Biomass and Nutrient Availability in Two Agroecological Zones of Ghana

The decline in soil productivity amidst efforts to increase crop yield in Sub Saharan Africa (SSA) has made it imperative to assess the current fertilization management approaches. This study was conducted in two agroecological zones (i.e., Guinea Savannah (GS) and Deciduous forest (DF)) of Ghana to evaluate how different fertilization schemes in the long term (>5 years) impacted the soil biochemical properties. Soil samples under four fertilization schemes (inorganic fertilizer only, low-to-medium organic residues only, inorganic fertilizers plus low-to-medium organic residues, and no fertilization) from 20 farmers’ field were sampled from March to April 2015. Soil biochemical quality indicators were determined using standard procedures. Overall, the average chemical and microbial biomass contents for most indicators were significantly higher in DF compared to GS. Relative to the reference sites, soil quality improvement were observed under inorganic fertilization in both agroecologies in contrast to significant soil deterioration (26.5%) under sole organic residue application in GS. Furthermore, the results showed that increased inorganic fertilization rate alone or combination with organic residues improved soil quality relative to the reference. The present results suggest the need to raise the current fertilizer application rates, especially in GS in order to enhance optimum soil productivity

Exploring Farmers’ Indigenous Knowledge of Soil Quality and Fertility Management Practices in Selected Farming Communities of the Guinea Savannah Agro-Ecological Zone of Ghana

Efforts to improve soil productive capacity aimed at boosting crop production in the Northern Ghana has primarily focused on field-based experiments with little documentation on farmer practice and local indigenous knowledge of soil management. A sample group of 114 farmers from five farming communities in the Guinea Savannah was interviewed to evaluate their indigenous knowledge of crop production practices in the context of soil health, fertilization management, and crop yield. Data were collected using semi-structured interviews and responses for each category were calculated using simple proportions. Farmers’ fertilization practice was primarily influenced by fertilization resource availability and crop yield response. The results showed that inorganic fertilization was the commonest fertilization type among farmers. Farmer local indicators of soil health were predominantly limited to visually observable signs such as presence or absence of indicator plants, growth vigor of plants, soil color, and tilth, texture, and compaction. Non-tactile and visible indicators, notably soil chemical composition and presence of soil microorganisms, was rarely used. The listed indicators were congruent with scientific reports, although some knowledge gaps, particularly on the use of indicator plants, were identified. The use of indicator plants as determinants of healthy or non-healthy soils appeared to be influenced by the ease of control of weeds, its utilitarian benefits, benefits to the soil, and threats on cultivated crops. Famers were well informed about the decreasing crop yield. Fertilization practices and limitations in soil management practices with proposed capacity building approaches aimed at enhancing productive capacities of cultivated farmlands are discussed

Exploring Farmers’ Indigenous Knowledge of Soil Quality and Fertility Management Practices in Selected Farming Communities of the Guinea Savannah Agro-Ecological Zone of Ghana

Efforts to improve soil productive capacity aimed at boosting crop production in the Northern Ghana has primarily focused on field-based experiments with little documentation on farmer practice and local indigenous knowledge of soil management. A sample group of 114 farmers from five farming communities in the Guinea Savannah was interviewed to evaluate their indigenous knowledge of crop production practices in the context of soil health, fertilization management, and crop yield. Data were collected using semi-structured interviews and responses for each category were calculated using simple proportions. Farmers’ fertilization practice was primarily influenced by fertilization resource availability and crop yield response. The results showed that inorganic fertilization was the commonest fertilization type among farmers. Farmer local indicators of soil health were predominantly limited to visually observable signs such as presence or absence of indicator plants, growth vigor of plants, soil color, and tilth, texture, and compaction. Non-tactile and visible indicators, notably soil chemical composition and presence of soil microorganisms, was rarely used. The listed indicators were congruent with scientific reports, although some knowledge gaps, particularly on the use of indicator plants, were identified. The use of indicator plants as determinants of healthy or non-healthy soils appeared to be influenced by the ease of control of weeds, its utilitarian benefits, benefits to the soil, and threats on cultivated crops. Famers were well informed about the decreasing crop yield. Fertilization practices and limitations in soil management practices with proposed capacity building approaches aimed at enhancing productive capacities of cultivated farmlands are discussed

Impact of Azospirillum sp. B510 on the Rhizosphere Microbiome of Rice under Field Conditions

There has been increasing attention toward the influence of biofertilizers on the composition of microbial communities associated with crop plants. We investigated the impact of Azospirillum sp. B510, a bacterial strain with nitrogen-fixing ability, on the structure of bacterial and fungal communities within rice plant rhizospheres by amplicon sequencing at two sampling stages (the vegetative and harvest stages of rice). Principal coordinate analysis (PCoA) demonstrated a significant community shift in the bacterial microbiome when the plants were inoculated with B510 at the vegetative stage, which was very similar to the effect of chemical N-fertilizer application. This result suggested that the inoculation with B510 strongly influenced nitrogen uptake by the host plants under low nitrogen conditions. Least discriminant analysis (LDA) showed that the B510 inoculation significantly increased the N2-fixing Clostridium, Aeromonas and Bacillus populations. In contrast, there was no apparent influence of B510 on the fungal community structure. The putative functional properties of bacteria were identified through PICRUSt2, and this hinted that amino acid, sugar and vitamin production might be related to B510 inoculation. Our results indicate that B510 inoculation influenced the bacterial community structure by recruiting other N2-fixing bacteria in the absence of nitrogen fertilizer

Impact of <i>Azospirillum</i> sp. B510 on the Rhizosphere Microbiome of Rice under Field Conditions

There has been increasing attention toward the influence of biofertilizers on the composition of microbial communities associated with crop plants. We investigated the impact of Azospirillum sp. B510, a bacterial strain with nitrogen-fixing ability, on the structure of bacterial and fungal communities within rice plant rhizospheres by amplicon sequencing at two sampling stages (the vegetative and harvest stages of rice). Principal coordinate analysis (PCoA) demonstrated a significant community shift in the bacterial microbiome when the plants were inoculated with B510 at the vegetative stage, which was very similar to the effect of chemical N-fertilizer application. This result suggested that the inoculation with B510 strongly influenced nitrogen uptake by the host plants under low nitrogen conditions. Least discriminant analysis (LDA) showed that the B510 inoculation significantly increased the N2-fixing Clostridium, Aeromonas and Bacillus populations. In contrast, there was no apparent influence of B510 on the fungal community structure. The putative functional properties of bacteria were identified through PICRUSt2, and this hinted that amino acid, sugar and vitamin production might be related to B510 inoculation. Our results indicate that B510 inoculation influenced the bacterial community structure by recruiting other N2-fixing bacteria in the absence of nitrogen fertilizer

Evaluation of the Effectiveness of Loose and Compressed Wood Chip Mulch in Field-Grown Blueberries—A Preliminary Study

Blueberry production in the field faces several challenges, including competition from weeds and soil suitability. Different mulch types are widely used in blueberry cultivation to control weeds, conserve moisture, and mitigate soil erosion. However, the comparative effects of loose and compressed wood chips on fruit quality and weed control in blueberry production systems have not been studied. Many farmers use expensive imported peat moss as soil covers, while others apply organic mulches such as chips or chaff, which can be easily washed away by runoff. This study aimed to evaluate the effects of compressed mulching boards (MB) fabricated without the use of chemical adhesives using pressurized steam and compression technologies in blueberry cultivation. During the two growing seasons, the effectiveness of compressed MB on soil moisture retention, fruit quality, and weed biomass was compared to that of wood chip (WC) and control treatments in a blueberry field. Although a significant difference was observed in the fruit fresh weight, no significant differences were observed in the other fruit growth parameters for all the treatments. Generally, the compressed MB significantly improved soil moisture retention capacity compared to WC and control during the two-year study. The compressed MB showed effective weed suppression ability by significantly reducing the weed biomass at all sampling times.Research on Agriculture and Food ScienceJST CRESTPeer Reviewe