Influence of N:P:K Ratios in Soils on Growth, Nutrient Availability and Yield of Maize (Zea mays L.)

This study was undertaken in two distinct ecological zones of Edo state of Nigeria to determine the effects of N:P:K ratios applied to the soils on the availability of N, P, K and on yield of maize. The sites used were Rubber Research Institute of Nigeria (RRIN) Iyanomo (Rain forest) and the Teaching and Research Farms of Ambrose Alli University, Emaudo, Ekpoma (derived savanna). Soils from both sites were analyzed for both physical and chemical properties before the commencement of the experiments. The experiments were carried out as: Pot and Field experiments. Each of the experiments had ten treatments (adjusted ratios) that were fitted into randomized complete block design and replicated three times, with maize as the test crop. Results from pot experiment in the screen house revealed that N:P:K ratio 4:1:1 had the highest dry matter yield for both locations, (RRIN; 7.10 g/pot and Emaudo; 6.33 g/pot) but these values were not significantly different (P < 0.05) from what were obtained from N:P:K ratio 3:1:1 and 2:1:1, respectively. The N:P:K ratio in soil had influence on the availability of N,P and K. Under field conditions, N:P:K ratio 3:1:1 had the highest grain yield for both locations (RRIN; 5.54 ton/ha and Emaudo; 5.25 ton/ha). The N:P:K ratio 3:1:1 was the best ratio with the highest yield for both locations and is therefore suggested for these soils.

Residual activity of sulfentrazone and its impacts on microbial activity and biomass of Brazilian Savanna soils

ABSTRACT Soil attributes may affect the residual activity and impacts of herbicides on non-target organisms. This study aimed to evaluate the residual activity of the sulfentrazone herbicide and its impacts on microbiological parameters of Brazilian Savanna soils, as well as to identify soil attributes that can be used to predict the residual activity of the herbicide in these soils. The experimental design was completely randomized, in a 6 x 5 factorial scheme, with 4 replications, being 5 soil types (Rhodic Acrustox; Typic Quartzpsamment; Rhodic Haplustox; Typic Humaquepts; Fluventic Dystrustepts) and 6 periods (0, 15, 30, 45, 60 and 90 days after herbicide application - DAA). The residual activity of the sulfentrazone herbicide is dependent of the soil type, and the time that the herbicide can control at least 80 % of Urochloa decumbens plants ranges from 0 (Typic Humaquepts) to 38 days (Rhodic Haplustox). The bases saturation is the only soil attribute correlated with the herbicide efficacy over time, in the Brazilian Savanna soils, showing a moderate correlation up to 90 DAA. The pH, organic matter and clay content are not correlated with the herbicide efficacy over time in these soils. Sulfentrazone reduces the microorganisms activity from 45 to 90 DAA in all the studied soils. However, it does not affect the microbial biomass carbon.

Organic fertilization for the beginning of sweet potato (Ipomoea batatas L.) cultivation in savanna soils

Due to limited information on sweet potato (Ipomoea batatas L.) cultivation in uncultivated savanna areas, the objective of this research was to determine the ideal dose and type of organic fertilizer for sweet potato cultivation in savanna soils with no history of use. In four experiments, the following fertilizer doses were tested: cattle manure (0, 10, 20, 30, and 40 t∙ha-1), poultry manure (0, 5, 10, 15, and 20 t∙ha-1), compost A (0, 0.75, 1.5, 2.25, and 3.0 t∙ha-1), and compost B (0, 0.75, 1.5, 2.25, and 3.0 t∙ha-1). The fifth experiment consisted of an organic fertilizer efficiency test using applications already recommended for sweet potato crops, which resulted in six treatments: control (without organic fertilization), cattle manure (20 t∙ha-1), poultry manure (10 t∙ha-1), compost A (1.5 t∙ha-1), compost B (1.5 t∙ha-1), and compost C (0.375 t∙ha-1). In the first four experiments, the products and their recommended doses were defined in order of production efficiency, as follows: poultry manure (doses between 13 and 20 t∙ha-1) > cattle manure (doses between 30 and 40 t∙ha-1) > compost B (doses between 0.75 and 2.25 t∙ha-1) = compost A (doses between 2.25 and 3.00 t∙ha-1). The fifth experiment concluded that: 1) poultry manure was the most suitable starting point for sweet potato cultivation in savanna soils and 2) sweet potato yield was directly linked to the commercial root mass, number of commercial roots, and branch productivity, which, in turn, were maximized by an increase in organic matter and satisfactory amounts of phosphorus in the soil.

Combined Application of Inoculant, Phosphorus and Potassium Enhances Cowpea Yield in Savanna Soils

Low soil phosphorus levels in savanna soils of Ghana limit cowpea response to inoculation. A two-year experiment was carried out on 2 soil types of the Guinea and Sudan savanna zones of Ghana based on the hypothesis that Bradyrhizobia inoculant (BR3267) in combination with phosphorus and potassium fertilizer will significantly increase cowpea root nodulation, growth and yield. The study aimed to determine the effect of phosphorus and potassium fertilizer on cowpea response to Bradyrhizobia inoculant. The treatments were laid out in Randomized Complete Block Design, replicated four times. The plot size was 8 × 3 m, with the sowing distance of 60 × 20 cm. The treatment comprises of commercial Bradyrhizobia inoculant, phosphorus (0, 30, 40 kg P2O5 ha−1) and potassium (0, 10, 20, 30 K2O ha−1). Application of Bradyrhizobia inoculant with 30 kg P2O5 ha−1 and 20 kg K2O ha−1 gave the highest grain yield (1.68 and 1.86 tons ha−1) at both soils which did not differ from the yield obtained from BR-40-30 kg ha−1 P2O5 and K2O ha−1 on the Ferric Lixisol and BR-40-20 kg ha−1 P2O5 and K2O on the Ferric Luvisol. The same treatment also gave the highest nodule number and nodule dry weight. The results of this study have shown that the application of Bradyrhizobia inoculant followed by P and K fertilizer was effective for cowpea growth in field conditions.

Effects of Maize (Zea Mays L.) Hybrids and Nitrogen Application on Striga Infection and Grain Yield under Natural Infestation with the Parasitic Weed Striga Hermonthica

Low soil nitrogen status of savanna soils in Nigeria contributes to the persistent Striga hermonthica (Del.) Benth. infestation that limits maize production. The application of nitrogen fertilizer to Striga-resistant hybrids may reduce Striga infection and increase grain yields. This study assessed the performance of maize hybrids at low (30 kg ha-1) and high (120 kg ha-1) nitrogen application under natural infestation with Striga at Kafin Madaki and Tudun Wada in 2014 and 2015. Results showed that the application of nitrogen at 120 kg ha-1 reduced number of Striga plants by 59% compared to application at 30 kg N ha-1 in Kafin Madaki and by 21% in Tudun Wada. Compared to 30 kg N ha-1, the 120 kg N ha-1 rate also reduced Striga damage rating by 22% in Kafin Madaki and by 33% in Tudun Wada across the hybrids. Hybrids 8338-1 (5.3) and OBASUPER 1 (4.3) were the only entries with Striga damage rating greater than 4.5 (SDR &gt; 4.5) when averaged across the nitrogen levels at both locations. Grain yield was 86 and 98% higher in Kafin Madaki and Tudun Wada, respectively when N was applied at 120 kg N ha-1 than at 30 kg N ha-1. The hybrids M1124-3 and M1227-14 produced grain yields that were significantly higher than those of the other hybrids in all locations. The hybrid 8338-1 produced the lowest grain yield across locations. Our results showed that, the application of 120 kg N ha-1 to Striga resistant maize hybrids will reduce Striga infection and increase grain yield.

Multiple soil element and pH interactions constrain plant performance on tropical soils with a long history of fire

Agriculture and forestry in savanna soils worldwide are often constrained by multiple soil limitations. We measured the effect of fertilisation on growth of Pinus caribaea var. hondurensis in order to improve savanna soil productivity in the Northern Territory, Australia. Growth responses to nitrogen, potassium, sulfur and a combined trace element treatment (abbreviated to N × K × S × T) with basal phosphorus (P) application on three soils, and N × P × K × S × T on another three soils, were examined in glasshouse factorial experiments. Without P, there was little response to N, S or T. Growth was usually greatest on N + P + S treatments. The P applications increased soil pH and growth, while N and S applications decreased pH. Growth was consistently poor at soil pH &lt; ~5.2; a pH where exchangeable cations can be leached from the soil and aluminium can become more mobile. Responses to P, N, S and K, and likely also to zinc, were consistent with savanna soils with a long history of nutrient losses due to fire and weathering. Establishing productive plantations or agriculture will require detailed knowledge of soil properties, careful attention to soil pH and balanced fertiliser applications so as not to produce perverse outcomes. Long-term protection from fires could improve soil conditions, to be balanced against the risks of crop loss through unplanned fire.

Diversity of Streptomyces spp. in desert and savanna soils in Sudan

Objective The purpose of this study was to investigate streptomycete populations in desert and savanna ecozones in Sudan and to identify species diversity on the basis of 16S rRNA gene sequence analysis. Results A total of 49 different Streptomyces phenotypes (23 from sites representing the desert and semi-desert zone; 26 representing the Savanna zone) have been included in the study. The isolates were characterized phenotypically and confirmed using 16S rRNA analysis. The two zones showed similarities and uniqueness in the types of isolates. Shared species were: Streptomyces werraensis , S. enissocaesilis, S. leeuwenhoekii –like, but desert zone revealed unique species such as S. griseostramineus, S. chromofuscus –like and S. prasinosporus . Whereas, the savanna zone revealed unique species such as S. albogriseolus, S. djakartensis, S. chilikensis and S. variabilis . Streptomycetes are widely distributed in both desert and the savannah ecozones and most of them require full descriptions. Extending knowledge on Streptomyces communities and their dynamics in different ecological zones for health and production benefits is needed.