Impacts of poultry manure and biochar amendments on the nutrients in sweet potato leaves and the minerals in the storage roots.

Poultry manure (PM) has demonstrated its potential to enhance crop nutritional quality. Nevertheless, there remains a dearth of knowledge regarding its synergistic effects when combined with wood biochar (B) on the nutrient concentrations in sweet potato leaves (Ipomoea batatas L.) and the mineral content stored in sweet potato storage roots. Hence, a two-year field trial was undertaken during the 2019 and 2020 cropping seasons in southwestern Nigeria, spanning two locations (Owo-site A and Obasooto-site B), to jointly apply poultry manure and wood biochar as soil amendments aimed at enhancing the nutritional quality of sweet potato crop. Each year, the experiment involved different combinations of poultry manure at rates of 0, 5.0, and 10.0 t ha-1 and biochar at rates of 0, 10.0, 20.0, and 30.0 t ha-1, organized in a 3 × 4 factorial layout. The results of the present study demonstrated that the individual application of poultry manure (PM), biochar (B), or their combination had a significant positive impact on the nutrient composition of sweet potato leaves and minerals stored in the sweet potato storage roots, with notable synergistic effects between poultry manure and biochar (PM × B) in enhancing these parameters. This highlights the potential of biochar to enhance the efficiency of poultry manure utilization and improve nutrient utilization from poultry manure. The highest application rate of poultry manure at 10.0 t ha-1 and biochar at 30.0 t ha-1 (PM10 + B30), resulted in the highest leaf nutrient concentrations and mineral composition compared to other treatments at both sites. Averaged over two years, the highest application rate of poultry manure at 10.0 t ha-1 and biochar at 30.0 t ha-1 (PM10 + B30) significantly increased sweet potato leaf nutrient concentrations: nitrogen by 88.2%, phosphorus by 416.7%, potassium by 123.8%, calcium by 927.3%, and magnesium by 333.3%, compared to those in the control (PM0 + B0). The same treatment increased the concentration of sweet potato root storage minerals: phosphorus by 152.5%, potassium by 77.4%, calcium by 205.5%, magnesium by 294.6%, iron by 268.4%, zinc by 228.6%, and sodium by 433.3%, compared to the control. The highest application rate of poultry manure at 10.0 t ha-1 and biochar at 30.0 t ha-1 yielded the highest economic profitability in terms of gross margin (44,034 US$ ha-1), net return (30,038 US$ ha-1) and return rate or value-to-cost ratio (VCR) (263). The results suggested that the application of poultry manure at 10 t ha-1 and biochar at 30 t ha-1 is economically profitable in the study areas and under similar agroecological zones and soil conditions.

Mineralogical compositions of soils under three geological formations in some parts of Ogun state, Nigeria and their agricultural potentials.

Investigating the mineralogical compositions of soils under different geological formations becomes imperative for maximizing agricultural productivity and ensuring the long-term viability of agricultural practices. Therefore, studies were carried out on mineral compositions and diversities of soils developed over the Basement complex rock, Coastal plain sands and Ewekoro formations in Ogun state Nigeria. A total of nine profile pits (three per location) of 2 m × 1 m × 2 m size were dug in all the three locations. Soil samples were collected from the pedogenic horizons of each profile pits in replicates into a well labeled polyethylene bag. Using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) the mineral contents and their relative abundance, elemental compositions and morphologies of the fine sand, coarse silt and clay fractions of the soils at different topographic positions were identified, described and compared. Results obtained from XRD and SEM analyses exhibited similarities. The most abundant elements in the basement complex and Ewekoro pedon were oxygen, carbon and silicon whereas in the coastal plain sand pedon, oxygen, carbon and aluminum were the most abundant element. The presence of mixed-layer illite, mica, kaolinite, quartz, hematite, anatase, goethite, and chlorite at varying degrees was observed in the pedons developed on these geological formations, although kaolinite and quartz dominated the soil matrix. The mineralogical complexity of the pedons followed the order of basement complex > coastal plain sand > Ewekoro formation. Profiles developed on the Ewekoro formation exhibited the highest degree of weathering, as evidenced by their chemical properties and mineralogical compositions. The petrographic evaluation of the three geological formations revealed that all pedons were rich in quartz and exhibited varying degrees of mineral complexity and maturation. The overlapping and distinct characteristics among the geologies indicated different stages of weathering. By using the mineral maturity index, profiles developed over the basement complex rock and the coastal plain sand could be regarded as sub-matured and this could have contributed significantly to the native fertility of these soils and profiles from the Ewekoro formation were the most weathered. The use of Ewekoro formation for agriculture would necessitate significant investments in agro-inputs and sound principles of soil management through integrated soil fertility management.

Sole and Combined Application of Biodigestate, N, P, and K Fertilizers: Impacts on Soil Chemical Properties and Maize Performance.

The fertilizing effects of biodigestate produced from biogas plants on crop and soil productivity are very scarce. Hence, a field study was conducted in 2022 at the Teaching and Research Farm of Bowen University, Iwo, Osun State, Nigeria. The study evaluated the effects of biodigestate fertilizer, applied alone or in combination with urea, single superphosphate, or muriate of potash fertilizers at low (N1, K1, and P1) and high (N2, P2, and K2) rates on soil chemical properties, growth, and yield of maize (Zea mays (L.)). The treatments were biodigestate alone (D), D + N fertilizer (urea) at 60 kg·ha-1 (DN1), D + N at 120 kg·ha-1 (DN2), D + P fertilizer (single superphosphate) at 30 kg·ha-1 (DP1), D + P at 60 kg·ha-1 (DP2), D + K fertilizer (muriate of potash) at 30 kg·ha-1 (DK1), D + K 60 kg·ha-1 (DK2), D + N1 + P1 + K1 (DN1P1K1), D + N2 + P2 + K2 (DN2P2K2) (10), and control. The 10 treatments were arranged in a randomized complete block design and replicated three times. Results showed that both low and high rates of fertilizer application improved soil chemical properties, growth parameters, and yield of maize compared with the control. High fertilizer rates (N2, P2, and K2) significantly enhanced soil chemical properties and growth parameters, but lower rates (N1, P1, and K1) resulted in higher maize yield. DN1 fertilizer significantly increased maize yield compared with DN2, DP1, DP2, DK1, and DK2. Overall, the treatment of DN1P1K1 demonstrated the highest grain yield, likely due to optimal nutrient supply from N, P, and K fertilizers, along with an improved soil environment facilitated by the biodigestate. The study recommends a balanced and sustainable fertilizer application strategy of 60 kg·N·ha-1, 30 kg·P2O5·ha-1, and 30 kg·K·ha-1 with 2500 L·ha-1 of biodigestate to enhance maize production while minimizing cost and environmental impact. However, for those aiming for maize fodder production, a higher fertilizer rate of 120 kg·N·ha-1, 60 kg·P2O5·ha-1, and 60 kg·K·ha-1 with 2500 L·ha-1 of biodigestate is advised.

Combined lime and biochar application enhances cowpea growth and yield in tropical Alfisol.

It is essential to increase the pH of tropical soils in order to reduce acidity and promote soil and crop productivity. Therefore, experiments were carried out in 2020 and 2021 to assess the impacts of biochar and lime on the chemical properties, growth, nodulation, and yield of cowpea (Vigna unguiculata). The study involved various levels of lime (CaCO3) and wood biochar (ranging from 0 to 10 t ha-1), organized in a factorial combination. The treatments were arranged in a randomized complete block design and replicated three times. The application of lime and biochar, either separately or in combination, led to improvements in soil chemical properties such as pH, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), and cation exchange capacity (CEC), as well as enhancements in the growth, nodulation, and yield of cowpea when compared to the control. Lime and biochar alone and combined reduced exchangeable acidity (Al + H) relative to the control. Cowpea yield increased with lime rate up to a point, but then decreases. The highest cowpea yield is achieved at a lime rate of 2.5 t ha-1, whereas cowpea yield increased as the Biochar rate increased from 0 up to 10 t ha-1. There was a significant correlation between pH and cowpea pod weight in both years (2020 and 2021). The R values were - 0.615 and - 0.444 for years 2020 and year 2021 respectively at P < 0.05. At higher lime levels combined with biochar, there were considerable reductions in cowpea yield, and this decrease can be attributed to unfavorable soil pH conditions. Relative to 2.5 t ha-1 lime + 5 t ha-1 biochar, 10 t ha-1 lime + 10 t ha-1 biochar, reduced cowpea grain yield by 853% in 2020 and 845% in 2021. Since there were no significant differences between the effects of 2.5 t ha-1 lime + 5 t ha-1 biochar, 2.5 t ha-1 lime + 7.5 t ha-1 biochar, and 2.5 t ha-1 lime + 10 t ha-1 biochar applications on cowpea yield, therefore to prevent waste of Biochar, 2.5 t ha-1 lime + 5 t ha-1 biochar is recommended for production of cowpea.