Evaluation of microbial inoculants as biofertilizers for the improvement of growth and yield of soybean and maize crops in savanna soils

Open Access JournalCertain rhizobacteria exert considerable influence on plant growth and development, particularly under limiting conditions. The effects of some indigenous soil microbial isolates and commercially produced microbial inoculants, referred to as bio-inoculants, on the growth and dry matter yield (DMY) of maize (Zea mays) and soybean (Glycine max) crops were assessed under greenhouse conditions. In two sets of experiments, one set comprised of free-living nitrogen-fixing microorganisms (Azospirillum spp.), three soils from Ibadan, Mokwa and Shanono located in different agro-ecological zones, and maize as the test crop. The other set consisted of microbial inoculants that can act as biocontrol agents applied to sterilized and non-sterilized soils; soybean was the test crop. The bio-inoculants were applied separately and also in combination. The treatments included a reference termed ‘mineral N’ where macro- and micro-nutrients were supplied at optimal rates, a control where bio-inoculants were not applied, and four replicates. All treatments, excluding the reference, received only macro-nutrients at suboptimal rates. The crops were grown for eight weeks and growth parameters were measured. The shoot DMY of maize was relatively large (42 to 63 g plant-1) and differed significantly among the soils but the bio-inoculants did not improve the shoot DMY significantly (P > 0.05) in any of the soils when compared with the control. However, sole inoculation of Mazospiriflo-2 enhanced nitrogen uptake significantly in maize grown in Shanono soil. For soybean, the shoot DMY was also not improved by the inoculation or the addition of the microbial products compared with the control

Biological nitrogen fixation potential by soybeans at two lowP soils of southern Cameroon

Biological nitrogen fixation (BNF) potential of 12 soybean genotypes were evaluated in condition of low and sufficient supply in two acid soils of southern Cameroon. The P sources were Togolese phosphate rock (PR) and triple super phosphate (TSP). The experiment was carried out during two consecutive years (2001 and 2002) at two locations with different soil types. Shoot dry matter, nodule dry matter, N and P uptake were assessed at flowering and the grain yield at maturity. Shoot dry matter, nodule dry matter, N and P uptake, and grain yield significantly varied with site and genotypes (P < 0.05). On Typic Kandiudult soil, nodule dry matter ranged from 0.3 to 99.3 mg plant-1 increasing significantly with P application (P < 0.05). Total N uptake of soybean ranged from 38.3 to 60.1 kg N ha-1 on Typic Kandiudult and from 18 to 33 kg N ha-1 on Rhodic Kandiudult soil. Under P limiting conditions, BNF ranged from -5.8 - 16 kg N ha-1 significantly higher values for genotype TGm 1511 irrespective of soil type. Genotype TGm 1511 can be considered as an important companion crop for the development of smallholder agriculture in southern Cameroon

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

Article first published online: 24 FEB 2015Soil 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 in- cluded 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 condi- tions, foliar spraying of Agroleaf high-P significantly increased the shoot dry biomass of maize compared with the 0P 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 re- sources is a prerequisite for a sustainable maize intensification in the savanna agro-ecologies.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 in- cluded 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 condi- tions, foliar spraying of Agroleaf high-P significantly increased the shoot dry biomass of maize compared with the 0P 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 re- sources is a prerequisite for a sustainable maize intensification in the savanna agro-ecologies.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 in- cluded 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 condi- tions, foliar spraying of Agroleaf high-P significantly increased the shoot dry biomass of maize compared with the 0P 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 re- sources is a prerequisite for a sustainable maize intensification in the savanna agro-ecologies.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 in- cluded 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 condi- tions, foliar spraying of Agroleaf high-P significantly increased the shoot dry biomass of maize compared with the 0P 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 re- sources is a prerequisite for a sustainable maize intensification in the savanna agro-ecologies

Aluminum resistance of cowpea as affected by phosphorusdeficiency stress

Plants growing in acid soils suffer both phosphorus (P) deficiency and aluminum (Al) toxicity stresses. Selection of genotypes for adaptation to either P deficiency or Al toxicity has sometimes been unsuccessful because these two soil factors often interact. Two experiments were conducted to evaluate eight cowpea genotypes for Al resistance and to study the combined effect of P deficiency and Al toxicity stress on growth, P uptake, and organic acid anion exudation of two genotypes of contrasting Al resistance selected from the first experiment. Relative root inhibition by 30 microM Al ranged from 14% to 60% and differed significantly among the genotypes. Al significantly induced callose formation, particularly in Al-sensitive genotypes. P accumulation was significantly reduced (28% and 95%) by Al application for both the Al-resistant and the Al-sensitive genotypes. Al supply significantly enhanced malate release of root apices of both genotypes. However, the exudation rate was significantly higher in the Al-resistant genotype. P deprivation induced an enhanced malate exudation in the presence of Al only in the Al-resistant genotype IT89KD-391. Citrate exudation rate of the root apices was lower than malate exudation by a factor of about 10, and was primarily enhanced by P deficiency in both genotypes. Al treatment further enhanced citrate exudation in P-sufficient, but not in P-deficient plants. The level of citrate exudation was consistently higher in the Al-resistant genotype IT89KD-391 particularly in presence of Al. It is concluded that the Al-resistant genotype is better adapted to acid Al-toxic and P-deficient soils than the Al-sensitive genotype since both malate and citrate exudation were more enhanced by combined Al and P-deficiency stresses

Phosphorus benefits from grain-legume crops to subsequent maize grown on acid soils of southern Cameroon

We conducted field experiments over 2 years on two acid soils of southern Cameroon to test whether efficient uptake and use of phosphorus (P) from less available sources by grain legume genotypes could benefit subsequent rotational maize. We grew two crops each year. For the first crop we grew 4 genotypes of soybean and of cowpea, plus maize. For the second crop we grew maize. The first crops were fertilized with 0, 90 kg P ha?1 as phosphate rock (PR) or 30 kg P ha?1 as triple super phosphate (TSP). P application highly significantly increased shoot dry matter, P uptake, N2 fixation and grain yields of the grain legumes with TSP generally more effective than PR. Two of the soybean and two of the cowpea genotypes were more efficient at using P. Only the P-efficient soybean and cowpea genotypes increased subsequent maize yields. Yields of the subsequent maize grown in rotation were significantly correlated with shoot P uptake for which the quantity of P applied with the crop residues of the pre-crop appeared to be a major factor. We also grew the grain legumes in nutrient solutions and measured organic acid-anion exudation from roots, root-surface phosphatase-activity, and root morphological characteristics. Enhanced exudation of organic acid anions from roots of P-deprived plants might have contributed to the P acquisition efficiency under field conditions of the P-efficient cowpea genotypes and one of the P-efficient soybean genotypes. A higher activity of root-surface acid phosphatase might have been important for the other P-efficient soybean genotype. The results show, that the potential positive rotational effect of cowpea and soybean on the acid, highly P-sorbing soils of southern Cameroon depends on breeding and using P-efficient genotypes when sparingly soluble and suboptimal rates of soluble P fertilizers are used

Profitability analysis of commercial chemical and biological crop products among farm households in agroecological zones of West Africa

This paper evaluates the costs and returns incurred by the use of chemical and biological crop products among households in five selected Compro communities in the derived, Southern Guinea, Northern Guinea, Sudan and Sahel Savanna agro-ecological zones (AEZs) in West Africa. Sixty households were randomly selected in each of the communities to give a total of 300 households. Data were collected on the characteristics of the chemical products, households’ socio-economic variables such as age and education, as well as, on farm input and output quantities and prices in the 2009/2010 periods using a pre-tested questionnaire. Data were analyzed with descriptive statistics and budgetary techniques. The Results obtained show a male dominant, fairly literate farming household, with small landholdings (comprising mainly cereal and legume fields) that are predominantly inherited and located far away from the homestead. Inorganic fertilizers, organic manure, improved seeds and pesticides are known as commercial inputs/ products used on farmers’ fields, while agrolizer, apron plus and boost extra are the emerging products. The average quantity of inputs applied varied across the zones. The total quantity of inorganic fertilizer applied on the fields was highest in the NGS (924 kg) and lowest in the Sudan (676 kg). However, fertilizer application per hectare by respondents was below recommended dosages across the zones. The emerging chemical inputs (Agrolizer, Boost Extra and Apron Plus) were used only in Compro communities in the derived savanna (DS) and southern guinea savanna (SGS) by a small number of households. The results obtained from budgetary analysis show that gross margin per hectare was highest in the SGS ($254) where the emerging inputs were used by 41.7$ 76). Organic fertilizer was used only in small quantities in the AEZs.Total variable costs accounted for more than 30% of revenue generated, and labour and fertilizer accounted for the highest percentage of these costs. The study concludes that promoting the emerging chemical inputs through increased accessibility and farmers’ training on their appropriate agronomic use would increase farmers’ income generating potentials for sustainable crop production across the AEZs

Impact of inadequate regulatory frameworks on the adoption of bio-fertilizer (eg PGPR) technologies: a case study of sub-Saharan Africa

Recently, there has been a lot of interest to promote bio-fertilizers for eco-efficient intensification of agricultural systems in sub-Saharan Africa (SSA). Bio-fertilizers are considered cost-effective and environmentally-friendly. In SSA, bio-fertilizers have not been sufficiently evaluated for quality and efficacy because of weak or absence of regulatory frameworks. Consequently, a proliferation of low quality and inefficacious bio-fertilizer products has been reported. Based on a stepwise assessment of 66 bio-fertilizer products found in Ethiopia, Kenya, and Nigeria in 2009-2011, in more than 90% of cases, product composition didn’t match indications on the product labels or label claims related to product benefits were not supported by our research results. A few products were however found very promising; for instance, Legumefix (a rhizobial inoculant for soybean) showed a benefit cost analysis > 2.5. There was an obvious need of discriminating high quality products from poor ones. A five year study (i.e. 2012-2017) has started aiming at addressing that gap and scaling-up the best promising bio-fertilizer products. One of the key outcomes of the new project is therefore the institutionalization of quality control and efficacy testing of bio-fertilizer products to virtually eliminate the proliferation of poor-quality and inefficacious ones. That will increase the confidence of smallholder farmers, with high risk aversion, in the bio-fertilizer technologies. Adoption of bio-fertilizers by the resource-poor smallholder farmers in SSA, the majority of the population, will certainly result in improved crop yields, food security, and consequently better livelihood

Effects of commercial microbial inoculants and foliar fertilizers on soybean nodulation and yield in northern Guinea savannah of Nigeria

The use of microbial inoculants and less expensive sources of plant nutrients such as foliar fertilizers are ways to practice low-input agriculture, especially in sub-Saharan Africa where smallholder farmers’ soil nutrients are depleted. However, the application of microbial inoculants and foliar fertilizers are influenced by agroecological specific factors. Here we show the effects of microbial inoculants and foliar fertilizers application on soybean, under smallholder farmers’ conditions in northern Guinea savannah. Three microbial inoculants; Bradyrhizobium spp. (RACA 6), arbuscular mycorrhizal fungi (Rhizatech) and Trichoderma harzianum (Eco-T) and two foliar fertilizers; Agroleaf high P and Agrolyser were evaluated. The trial was carried out during 2011 cropping season in randomized complete block design with 12 treatments and 4 replicates. The shoot dry weight was increased separately by the Reference treatment with N, P chemical fertilizers, Rhizatech and RACA 6 + triple superphosphate (TSP) over 21% compared to the control. Significant effect existed among treatments for soybean nodulation and shoot phosphorus concentration. Grain yield was relatively increased by the application of RACA 6 + TSP, RACA 6 + Eco-T + Agrolyser and RACA 6 + Rhizatech + Agrolyser compared to the control. The experiment suggested that soybean co-inoculation with rhizobial and fungal inoculants and application of foliar fertilizers in northern Guinea savannah could lead to improved grain yield