Use of organic manures to meet the nutrient requirement of crop would be an inevitable practice in the years to come for sustainable agriculture since organic manures generally improve the soil physical, chemical and biological properties. Hence, field experiments were carried out in 2017 and 2018 to compare the impact of different organic manures and NPK fertilizer on soil properties, growth, yield, proximate and mineral contents of okra (Abelmoschus esculentus L.). The treatments each year 2017 and 2018 consisted of: rabbit manure, cow dung, poultry manure, green manure [Mexican sunflower (Tithonia diversifolia Asteraceae)], pig manure, NPK 15-15-15 fertilizer applied at 120 kg N ha−1 and a control (no manure/inorganic fertilizer). The seven treatments were laid out in a randomized complete block design with three replication. Organic manures and NPK fertilizer increased the soil organic matter (OM), N, P, K, Ca and Mg (NPK fertilizer did not increase OM, Ca and Mg significantly), growth, yield, minerals, protein, ash, carbohydrate and mucilage contents of okra fruit as compared with control. Organic manures improved okra yield compared with NPK fertilizer. Okra growth and yield parameters were significantly higher in 2018 compared with 2017. Control, rabbit manure, cow dung, poultry manure, green manure, pig manure and NPK fertilizer in 2018 increased the pod yield of okra by 9.7%, 35.3%, 57.9%, 36.2%, 39.2%, 45.5% and 3.2%, respectively compare with the same treatment in 2017. Amongst various organic manures, poultry manure produced significantly higher plant growth, yield, mineral and proximate composition of okra because of its high soil chemical properties which could be related to its lowest C: N ratio, lignin and lignin: N ratio. Results also showed that okra grown during high intensity rainfall has higher yield but with reduced quality except its mucilage content. Therefore, planting of okra with poultry manure under moderate rainfall will enhance the health benefit from the fruit, however, those that desire its mucilage content planting during high rainfall is recommended.

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AbstractBiochar has a low chemical composition and is recalcitrant to degradation. For good soil fertility and nutrient use efficiency of crops it becomes imperative that addition of a fast releasing nutrient source to biochar be sought. Therefore, studies were conducted in 2017 and 2018 to evaluate the effects of biochar with poultry manure (PM) and NPK fertilizer on soil properties, growth and yield of ginger. Treatments evaluated were: biochar applied alone at 15 t ha-1 , PM applied alone at 15 t ha-1, NPK fertilizer applied alone at 200 kg ha-1, biochar applied at 15 t ha-1 with poultry manure applied at 15 t ha-1 (B+PM), biochar applied at 15 t ha-1 with NPK fertilizer applied at 200 kg ha-1 (B+NPK) and a control with no amendment whatsoever. The experimental design was a randomized complete block design with three replications. Biochar, PM, NPK fertilizer alone or B+PM and B+NPK improved soil physical and chemical properties, growth and yield of ginger compared to no amendment (control). NPK fertilizer did not improve soil physical properties nor increased pH, OM, Ca and Mg significantly. B+PM and B+NPK improved soil physical and chemical properties, growth and ginger yield compared to their sole forms. Although B+PM had better soil physical properties, B+NPK increased yield and growth of ginger compared to B+PM. B+NPK increased the yield of ginger by 12.2% and 10.6% in 2017 and 2018, respectively compared with B+PM. B+NPK also increased the yield of ginger by 49.2% and 50.3% in 2017 and 2018, respectively compared to biochar alone. This was related to high presence of nutrients in B+NPK especially N and K which are important for ginger rhizome formation.

Field experiments were conducted during 2016 and 2017 cropping seasons in the derived agro-ecological zone of Nigeria to study the combined and sole effect of zinc and boron fertilizers on the growth, seed yield, and quality of groundnut (Arachis hypogaea L).e experiment was laid out in randomized complete block design (RCBD), replicated four times. ree levels of zinc (0, 4, and 8 kg·ha − 1 ) and four levels of boron (0, 300, 600, and 900 ml·ha − 1 ) were combined and evaluated. Groundnut seeds were analyzed at the end of the experiments to determine nutrient elements and some heavy metal contents. Data collected were subjected to Statistical Analysis of Variance using SAS 2000. Treatment means were compared using the Duncan multiple range test at 0.05 level of probability. e effect of zinc was not significant on the vegetative parameters, while application 8 kg Zn·ha − 1 significantly increased number of seeds, weight of seeds, seed yield per hectare, and seed quality though the values were similar to the application of 4 kg Zn·ha − 1 only on the seed yield and its parameters. Application of 600 and 900 ml B·ha − 1 gave higher and statistically similar values for vegetative parameters, yield, and yield parameters, while 600 ml B·ha − 1 significantly improved the seed quality. It can therefore be recommended that for optimum yield and seed quality, application of 8 kg Zn·ha − 1 combined 600 ml B·ha − 1 is sufficient in the study area without increasing the heavy metal concentration of groundnut seed.Means in a column under any given treatment followed by the same letters do not differ significantly at 0.05 level of probability using the Duncan multiple range test (DMRT). * Significant at 0.05 level of probability.

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Two field experiments were conducted concurrently in 2019. The study investigated the effects of single and combined application of wood biochar (WB) and cow dung biochar (CDB) with green manure (GM) on soil properties, performance, and tuber qualities of tiger nut. The treatments consisted of: CDB at 10 t ha−1, WB at 10 t ha−1, GM—Tithonia diversifolia at 10 t ha−1, CDB + GM, WB + GM, control. The six treatments were arranged in RCBD with three replications. CDB, WB, and GM either sole or combined increased moisture content, SOC, nutrient contents, culturable microorganisms, performance, moisture, ash, fiber, and protein contents of the tiger nut compared with the control. CDB has a higher N, C: N ratio, P, K, Ca, Mg, CEC, and pH relative to. CDB alone and CDB + GM increased growth and yield compared with WB alone and WB + GM. CDB + GM has the highest value of growth and yield of tiger nut. GM alone improved growth and yield of tiger nut compared with the two sole biochar treatments. CDB + GM and WB + GM increased growth and yield of tiger nut compared with their sole forms. This was adduced to biochar allowing the retention of nutrients from rapidly decomposing Tithonia within the rooting zone, thereby promoting better effectiveness of nutrient uptake and increase in yield. Therefore, for good soil fertility and tiger nut yield, it is important that the addition of a fast releasing nutrient source to biochar be sought.

For soil fertility maintenance, secondary nutrient such as Magnesium (Mg) is always being neglected. However, its role is critical in the growth, yield, and quality of crops. Therefore, two field experiments were initiated in 2017 and 2018 to evaluate the response of soil chemical properties, performance, and qualities of turmeric (Curcuma longa L.) to Mg fertilizer alone and in combination with poultry manure (PM) and NPK 15-15-15 fertilizer (NPK). The treatments applied were the following: (i) PM alone at 8 t ha−1, (ii) NPK alone at 200 kg ha−1, (iii) Mg fertilizer alone (in form of MgO) at 20 kg ha−1, (iv) PM at 8 t ha−1 with MgO at 20 kg ha−1 (PM + Mg), (v) NPK at 200 kg ha−1 with MgO at 20kgha−1 (NPK + Mg), and (vi) control (no amendment of any kind). PM, NPK, and Mg fertilizers alone or NPK + Mg and PM + Mg increased soil chemical properties, performance (plant height, number of leaves, number of tillers, number of rhizomes, and fresh rhizome weight), and minerals and vitamins C and A contents of turmeric rhizome compared with the control. By averaging 2017 and 2018, Mg fertilizer alone increased the yield of turmeric by 10.8% compared with the control. For this experiment, NPK + Mg increased growth and yield of turmeric compared with other treatments. Also, averaging 2017 and 2018, NPK + Mg increased rhizome yield of turmeric by 13.6% and 10.6% compared with PM + Mg and NPK alone, respectively. Similarly, PM + Mg significantly improved mineral and vitamins contents compared with other treatments. Therefore, for those that desire turmeric rhizome for its nutritive value, PM + Mg is recommended. For those that want quantity, NPK + Mg is recommended.

PurposeThe study examined policy improvement and cassava attractiveness. The purpose was to determine the optimum rewards using three strategies: selling of farm produce to harvesters, making wholesale of harvested outputs and retailing harvested outputs.Design/methodology/approachThree hundred and sixty (360) cassava farmers were surveyed in three local government areas in Edo South senatorial district of Nigeria. From their responses, probabilities were assigned to rewards for each strategy from each of the locations. Subsequently, dynamic programming was employed in data analysis. Specifically, Howard policy improvement technique was used to forecast expected rewards to cassava farmers in the three local government areas using the three strategies.FindingsCassava farmers in Edo South senatorial district of Edo state, Nigeria, can maximize their earnings from cassava by retailing at the local markets in Oredo and Egor local government areas and by making wholesales at Ikpoba Okha local government area. Using this policy, they will realize approximately N2360 per basin and approximately N33040 per plot of 100 × 100 ft. This will translate to N143724 per acre (4.35 plots of 100 ft2).Research limitations/implicationsAvailability of storage facilities as well as technical constraints to cassava production.Social implicationsProvision of jobs to the unemployed, thereby reducing the level of unemployment in the country.Originality/valueSuggestion of the sales strategy that will yield optimum returns to cassava farmers, using policy iteration technique, and the projected estimates of the likely turnover when the strategy is adopted. This is a point of departure from previous studies. Thus, the study used operations research methodology to model solutions, through involvement in agriculture, to Nigeria's economic/financial problems, thus making it unique. In broad terms the study demonstrates that investment in agriculture will help to reduce unemployment and enhance the country's national income.