Shellac-based Capsule for Long-Term Controlled Releasing Urea with a Broad Soil Ph Tolerance

Environmentally friendly slow-release fertilizers are highly desired in sustainable agriculture. Encapsulating fertilizers can routinely achieve controlled releasing performances but suffers from short-term effectiveness or environmental unfriendliness. In this work, a bio-derived shellac incorporated with poly-dodecyl trimethoxysilane (SL-PDTMS) capsule was developed for long-term controlled releasing urea. Due to enhanced hydrophobicity and thus water resistance, the SL-PDTMS encapsulated urea fertilizer (SPEU) demonstrated a long-term effectiveness of 60 d, compared with SL encapsulated urea fertilizer (SEU, 30 d) and pure urea fertilizer (U, 5 min). In addition, SPEU showed a broad pH tolerance from 5.0 to 9.0, covering most various soil pH conditions. In the pot experiments, promoted growth of maize seedlings was observed after applying SPEU, rendering it promising as a high-performance controlled-released fertilizer.