Nutrient deficiency in food crops is seriously affecting human health, especially those in the rural areas, and nanotechnology may become the most sustainable approach to alleviating this challenge. There are several ways of fortifying the nutrients in food such as dietary diversification, use of drugs and industrial fortification. However, the affordability and sustainability of these methods have not been completely achieved. Plants absorb nutrients from fertilizers, but most conventional fertilizers have low nutrient use and uptake efficiency. Nanofertilizers are, therefore, engineered to be target oriented and not easily lost. This review surveys the effects of the addition of macro- and nanonutrients to soil, the interaction, and the absorption capability of the plants, the environmental effect and food content of the nutrients. Most reports were obtained from recent works, and they show that plants nutrients could be enriched by applying nanoparticulate nutrients, which are easily absorbed by the plant. Although there are some toxicity issues associated with the use of nanoparticles in crop, biologically synthesized nanoparticles may be preferred for agricultural purposes. This would circumvent the concerns associated with toxicity, in addition to being pollution free. This report, therefore, offers more understanding on the application of nanotechnology in biofortification of plant nutrients and the future possibilities offered by this practice. It also highlights some of the ills associated with the introduction of nanomaterials into the soil for crop’s improvement.

Inclusion of legumes in cropping systems is essential for sustainable management of farming systems and reducing the nitrogen (N) fertilizer requirement for maize production. The study evaluated the effect of growing legumes (soybean, cowpea and velvet bean) and maize the same year in rotation, on maize yield and soil fertility indices. The agronomic practices implemented were residue management (residue added and residue removed) and fertilizer N application (0 kg N ha −1 and 60 kg N ha −1 ) under four rotation systems. The result showed that growing velvet bean the same year in rotation with maize was effective in increasing maize yield and improving some soil fertility indices over growing maize after maize the same year in the same location. Compared to maize monocropping, over 100% increase in maize yield was obtained with velvet bean-maize rotation even in absence of residue incorporation. In addition, velvet bean-maize rotation increased maize yield over cowpea- and soybean- maize rotations. The rotation effect occurred as a result of improvement in soil nitrogen, avail phosphorus (P), exchangeable magnesium (exch Mg) and effective cation exchange capacity (ECEC). Grain legumes-maize rotations equally increased maize yield over sole maize. Generally legume-maize rotations increased total N, avail P, exch K, Mg and effective cation exchange capacity over sole maize. Crop residue incorporation and N fertilizer application significantly improved soil N and maize grain yield (0.18%, 2.74 tha −1 in 2008; 0.22%, 1.16 tha −1 in 2009 and 0.19%, 2.72 tha −1 in 2008; 1.35 tha −1 in 2009 respectively) over non-residue incorporation (0.16% and 1.84 tha −1 in 2008, 0.66 tha −1 in 2009) and zero N application (0.16% and 1.83 tha −1 in 2008 and 0.17% and 0.85 tha −1 in 2009). Therefore, velvet bean could be planted the same season with subsequent maize in rotation cropping for intensive sustainable maize production in sandy-loam soils without fertilizer N. For grain legumes such as soybean and cowpea to be effective in rotation cropping with maize, the grain legumes have to be planted early before the full set of rain because excess rain would affect their growth and development.

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Purpose In soil-based nursery media, topsoil, poultry droppings and sawdust conventionally provide anchorage, nutrients and aeration, respectively. Considering poultry droppings' scarcity and sawdust's inertness nutrient-wise, more readily available organic wastes should be explored as substitutes. Here, we evaluated the effect of such substitution on media fertility, aimed at seeking alternatives to the conventional practice. Methods In a topsoil-manure-aerator volume ratio of 3:2:1, poultry droppings was substituted with pig slurry (slurry) or cattle dung (dung) as manure and sawdust with rice-husk dust (huskdust) as aerator, giving seven soil-based media including reference medium (topsoil+droppings+sawdust) and the control (topsoil+topsoil+topsoil). They were watered regularly and analysed for fertility parameters 4 months later. Results Reference had the highest pH (8.60) and topsoil + dung + huskdust/control the lowest (6.83). Substituting sawdust with huskdust enhanced pH, organic matter and Mg 2+ in droppings/dung-amended media (topsoil+droppings+huskdust/ topsoil+dung+huskdust) unlike slurry-amended ones where it too reduced total nitrogen (0.19 vs 0.11%). The substitution also enhanced available phosphorus in topsoil+droppings+huskdust (117.50 mg kg −1) and topsoil+dung+huskdust (71.50 mg kg −1) but reduced K + in the latter where it too had moderating effects on Na +. Reference surpassed topsoil+slurry+huskdust for Ca 2+ , but was surpassed by topsoil+droppings+huskdust for Mg 2+. Reference/topsoil+droppings+huskdust and topsoil+slurry+huskdust/control showed highest and lowest CEC, respectively. Excluding pH, topsoil+dung+huskdust and topsoil+slurry+sawdust were, notably, consistently similar. Overall, droppings-amended > dung-amended > slurry-amended media and, for available phosphorus only, sawdust-aerated < huskdust-aerated media. Conclusion Based on fertility status 4 months after blending, topsoil+droppings+huskdust could serve as alternative to the conventional nursery medium, or topsoil+dung+huskdust where near-neutral pH is preferred to increased phosphorus/ cations release.

Fluted pumpkin (Telfairia occidentalis) has high agronomic and food relevance in the tropics. Production of this vegetable in the dry season with irrigation is increasingly popular and is mostly on droughty soils, thus requiring research on appropriate combination of soil moisture conservation/management practices. This study evaluated the interactions among seedbed configuration (flat and raised), surface mulching (grass‐mulched and no‐mulch) and plant spacing (1002, 502 and 252 cm2, designated wide, intermediate and close spacing, respectively) on fluted pumpkin performance in a sandy‐loam soil in southeastern Nigeria during 2014/2015 dry season. Seedling emergence (ratio of emerged to expected seedlings) was highest and lowest in flat/mulched/wide and flat/no‐mulch/close combinations, respectively. Main effects showed higher seedling emergence in mulched (67.9%) than no‐mulch plots (53.1%) and in wide (70.8%) and intermediate spacing (64.6%) compared to close spacing (46.0%). Fresh leaf yield assessed biweekly during 6–14 weeks after sowing was generally highest and lowest in flat/mulched/close and flat/no‐mulch/wide combinations, respectively. Seedbed configuration had no distinct effect on leaf yield; hence, flat/mulched/close option was similar to raised/mulched/close option. Yields from mulched/wide and no‐mulch/close options were similar with a mean (2735 kg/ha) approximating the overall mean (2868 kg/ha). Flat/mulched/close combination is the best management practice to grow fluted pumpkin with irrigation on droughty soils during the dry season of the tropics. Where this best practice is compromised due to mulch or seed scarcity, the ensuing no‐mulch/close and mulched/wide, respectively can support dry‐season production of pumpkin in droughty tropical soils at average levels.

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Agricultural sustainability ensues when cultivation of field crops and associated techniques improve not just crop yields but also management-responsive soil properties. Bambara groundnut as an underutilized crop lacks research-based information on its agronomic requirements. This paper reports the key fertility indices of a loamy-sand soil in southeastern Nigeria as influenced by soil and agronomic management practices involving factorial combinations of two bambara groundnut varieties (Caro and Olokoro), two plant spacings (30 cm × 75 cm and 45 cm × 75 cm) and four organic/inorganic fertilizer options. These fertilizer options were NPK 15-15-15 (NPK), single super phosphate (SSP), poultry manure (PM) and Control. The plots under Caro variety spaced 30 cm × 75 cm and grown with NPK or SSP fertilizer showed the highest CEC (8.40 cmol kg–1) and exchangeable K (0.15 cmol kg–1), respectively. Olokoro variety spaced 45 cm × 75 cm and grown with PM or SSP gave the highest total nitrogen (0.14%), soil pHwater (6.35), available phosphorus (107.60 mg kg-1) and exchangeable Ca (3.70 cmol kg-1). The interactions plant spacing × fertilizer type and crop variety × fertilizer type affected all the soil fertility indices studied, while crop variety × plant spacing affected soil pHwater, available phosphorus, CEC and exchangeable Ca and Mg. Generally, as main factors, Olokoro variety, NPK and 45 cm × 75 cm improved soil properties better than their counterparts.