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.

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.

28Use of organic manures to meet the nutrient requirement of crop would be an inevitable practice 29 in the years to come for sustainable agriculture since organic manures generally improve the soil 30 physical, chemical and biological properties. Hence, field experiments were carried out in 2017 31 and 2018 to compare the impact of different organic manures and NPK fertilizer on soil properties, 32 growth, yield, proximate and mineral contents of okra (Abelmoschus esculentus L.). The 33 treatments each year 2017 and 2018 consisted of: rabbit manure, cow dung, poultry manure, green 34 manure [Mexican sunflower (Tithonia diversifolia Asteraceae)], pig manure, NPK 15-15-15 35 fertilizer applied at 120 kg N ha -1 and a control (no manure/ inorganic fertilizer). The seven 36 treatments were laid out in a randomized complete block design with three replication. Organic 37 manures and NPK fertilizer increased the soil organic matter (OM), N, P, K, Ca and Mg (NPK 38 fertilizer did not increase OM, Ca and Mg significantly), growth, yield, minerals, protein, ash, 39 carbohydrate and mucilage contents of okra fruit as compared with control. Organic manures 40 improved okra yield compared with NPK fertilizer. Okra growth and yield parameters were 41 significantly higher in 2018 compared with 2017. Control, rabbit manure, cow dung, poultry 42 manure, green manure, pig manure and NPK fertilizer in 2018 increased the pod yield of okra by 43 9.7%, 35.3%, 57.9%, 36.2%, 39.2%, 45.5% and 3.2%, respectively compare with the same 44 treatment in 2017. Amongst various organic manures, poultry manure produced significantly 45 higher plant growth, yield, mineral and proximate composition of okra because of its high soil 46chemical properties which could be related to its lowest C: N ratio, lignin and lignin: N ratio. 47Results also showed that okra grown during high intensity rainfall has higher yield but with 48 reduced quality except its mucilage content. Therefore, planting of okra with poultry manure under 49 moderate rainfall will enhance the health benefit from the fruit, however, those that desire its 50 mucilage content planting during high rainfall is recommended. 51

Background:Soil properties are anisotropic in nature, hence the need to study soil associations and regional landscapes for sustainable nutrient management and soil profile is an important tool which can be utilized for this purpose.Objective:The objectives of the study are to describe the morphology of the soils of the toposequence, determine their physical and chemical properties, classify them and make an appraisal of their agricultural potentials.Methods:Three slope classes were considered and a total of three profile pits, one on each slope were studied and described in the field morphologically at Eleyin Farms Omu-Aran, Kwara State, Nigeria, which was a newly opened up plantation.Samples of soil were collected from the horizons of the profile pits. The soil samples were analyzed for their physical and chemical properties.Results:All the three pedons showed appreciable differences in physical, chemical, and morphological characteristics of the soils and their classifications were determined as guided by their characteristics. The textural classes were defined mainly by the sand compositions which decreased from the upper and middle slopes down to the bottom slope, and the clay compositions which increased progressively from the uppermost slope through the middle slope to the bottom slope. Silt compositions did not exhibit any particular pattern.Conclusion:Thus, sand and clay compositions were more significant and relevant to the textural classification of the soils of the area than silt. The low nutrient status of the soils can be ameliorated by incorporation of organic or farm residues to increase the organic matter content of the soil, and also improve management practices and guided chemical fertilizer use. The soils of the area were classified as Typic Haplustalf (USDA), and Ferric Luvisol (FAO).

Farmers have not tested their soils for nutrient status and therefore are unaware of the fertility status of their soils. Therefore, a baseline fertility survey of 50 hectares of land of a gravelly Alfisol in the Teaching and Research Farm of Landmark University, Omu-Aran, Kwara State, Nigeria was carried out with a view to identifying soil health constraints and site-specific sustainable land management practices for optimizing crop production. Standard field protocols and laboratory analytical procedures were employed for all sample parameters measured. Results show that the soil textural classes vary from sand to loamy sand, exchangeable acidity, Ca, Mg, K, and Na and the effective cation exchange capacity has the surface and subsurface soil values of 0.0–0.92 and 0.00–0.89 cmol kg−1, 1.6–7.7 and 2.0–5.8 cmol kg−1, 1.2–11.5 and 0.7–8.0 cmol kg−1, 0.09–0.33 and 0.09–0.43 cmol kg−1, 0.0–0.16 and 0.04–0.16 cmol kg−1, 7.2–12.10 and 0.9–12.5 cmol kg−1, respectively. P values lie in the ranges of 2.5–68.9 mg kg−1 and 2.0–37.7 mg kg−1 in the surface and subsurface soils, respectively, organic C values were 0.86–2.81% and 0.68–3.49%, respectively, in the surface and subsurface soils while the values of N were 0.12–0.61% in the surface and 0.11–0.56% subsurface soils. Land evaluation shows that the soils of the project site are very fragile and poor in native fertility. Compound fertilizers low in nitrogen contents but high in phosphorus and potassium are recommended for gravelly Alfisol in a derived savannah ecological zone of the Kwara State, Nigeria to avoid a nutrient imbalance that may create artificial deficiencies of otherwise adequate nutrient elements.