Carbon-Based Slow-Release Fertilizers for Efficient Nutrient Management: Synthesis, Applications, and Future Research Needs

Nutrient Dynamics in Sandy Soil and Leaf Lettuce Following the Application of Urea and Urea-Hydrogen Peroxide Impregnated Co-Pyrolyzed Animal Manure and Bone Meal

“…Despite the enormous benefits that can accrue from the usage of such fertilizers, their utilization is still tremendously low, accounting for just less than 1% of the total quantity of Agronomy 2021, 11, 1664 2 of 17 fertilizers consumed globally every year [3]. This low level of utilization mainly stems from the fact that they are expensive and their production involves sophisticated technology [4]. Lammel et al [5] for example, indicated that most common polymer-coated fertilizers are about 8-12 fold more expensive than the conventional mineral fertilizers.…”

“…Lammel et al [5] for example, indicated that most common polymer-coated fertilizers are about 8-12 fold more expensive than the conventional mineral fertilizers. Additionally, some of the coating materials used in the formulation of the slow release fertilizers are non-biodegradable, while others are mutagenic and/or carcinogenic [4,6,7]. Because of the issues mentioned above, a lot of research effort has been geared towards exploring environmentally friendly and cost-effective carriers and coating materials for the plant nutrients [4].…”

“…However, lignocellulose and compost are subject to rapid decomposition once incorporated into soil [11]. For that matter, carbon-based materials such as, biochar and lignite, have lately gained copious interest with several studies conducted to assess their potential as coating agents and fertilizer nutrient carriers [4]. The growing interest in using carbonbased materials to prepare the slow release fertilizers is premised on their biodegradability and additional benefits they render when applied to the soil, including improving soil physical, chemical, and biological properties as well as sequestering carbon from the atmosphere [4].…”

“…For that matter, carbon-based materials such as, biochar and lignite, have lately gained copious interest with several studies conducted to assess their potential as coating agents and fertilizer nutrient carriers [4]. The growing interest in using carbonbased materials to prepare the slow release fertilizers is premised on their biodegradability and additional benefits they render when applied to the soil, including improving soil physical, chemical, and biological properties as well as sequestering carbon from the atmosphere [4]. Of all the carbon-based materials, biochar has attracted the most interest for usage in the formulation of slow release fertilizers and several biochar-based slow release fertilizers have been formulated and studied for their agronomic efficiencies.…”

“…Apart from increasing the amount of carbon (C) retained in the biochar, co-pyrolysis of biomass with P also slows down the rate of discharge of P and it is thus an effective way of formulating a slow release P fertilizer as confirmed by Zhao et al [13] and Luyima et al [7]. It is worthy to note, however, that adsorption is a crucial mechanism in the preparation of slow release fertilizers [4], which may explain why the vast majority of the biocharbased fertilizers have been formulated with salts containing charged elements such as ammonium, nitrate, phosphates, K, etc. However, since urea is the most widely used nitrogen fertilizer in the world [15,16], its efficient management (checking its inordinate release into the environment) is of utmost importance for both agricultural productivity and environmental quality [17].…”