Land application of biochar as a soil amendment can be an effective strategy for reducing nutrient leaching while providing simultaneous benefits to soil health. However, biochar effects on soil nitrogen (N) and phosphorus (P) dynamics in biochar‐amended soils are poorly understood, particularly in Florida sandy soils receiving fertilizers. This study evaluated the effects of different biochar materials (particle size of 0.1 mm produced from pine (Pinus spp.) wood vs. ∼0.5–2 mm produced from fescue (Festuca arundinaceaSchreb.) grass, herein referred as “powder” and “coarse” biochar, respectively) and their application methods (surface vs. incorporated) on N and P leaching from soils amended with inorganic fertilizer or biosolids. Biochar materials were either mixed throughout columns of soil or surface applied at a 1% (w/w) rate. Columns were periodically leached over 6 mo to attain 138 ml (equivalent to ∼1 pore volume) of drainage in each event (total of ∼16 pore volume of leachate). Biochar materials exhibited modest affinity to retain ammonium (NH₄⁺) but showed no ability to sorb nitrate (NO₃^–). Powder biochar incorporated throughout the soil reduced cumulative NH₄–N, NO₃–N, and total N mass leached (average of 25% reduction) relative to control (no biochar) treatments. Biochar materials acted as P sources and were ineffective in reducing leachate P. Biosolids generally resulted in significant lower risk of N and P leaching than inorganic fertilizer. Results suggested biochar ability to retain N and P in soils varies with biochar source, application method, and nutrient source. Biochar type and application method affected N and P dynamics in biosolids or inorganic fertilizer‐amended soils, but understanding the mechanisms requires additional study.

Conventional spherical nucleic acid enzymes (SNAzymes), made with gold nanoparticle (AuNPs) cores and DNA shells, are widely applied in bioanalysis owing to their excellent physicochemical properties. Albeit important, the crowded catalytic units (such as G-quadruplex, G4) on the limited AuNPs surface inevitably influence their catalytic activities. Herin, a hybridization chain reaction (HCR) is employed as a means to expand the quantity and spaces of G4 enzymes for their catalytic ability enhancement. Through systematic investigations, we found that when an incomplete G4 sequence was linked at the sticky ends of the hairpins with split modes (3:1 and 2:2), this would significantly decrease the HCR hybridization capability due to increased steric hindrance. In contrast, the HCR hybridization capability was remarkably enhanced after the complete G4 sequence was directly modified at the non-sticky end of the hairpins, ascribed to the steric hindrance avoided. Accordingly, the improved SNAzymes using HCR were applied for the determination of AFB1 in food samples as a proof-of-concept, which exhibited outstanding performance (detection limit, 0.08 ng/mL). Importantly, our strategy provided a new insight for the catalytic activity improvement in SNAzymes using G4 as a signaling molecule.