Granular urea‐formaldehyde slow‐release fertilizer with superabsorbent and moisture preservation

Abstract

ABSTRACT:To improve the utilization of fertilizer and water resource at the same time, a new type of slow-release fertilizer with superabsorbent and moisture preservation was developed, with the combination of slow-release technique and superabsorbent polymers. The coatings were formed by the inverse phase polymerization technique. The element analysis results showed that the product contained 22.58% nitrogen element, and the water absorbency of the product was 94 times its own weight if it was allowed to swell in tap water at room temperature for 2 h. The results of the slow-release behavior of N and the water absorbency and retention properties in soil showed that the product not only had good slow-release property but also had excellent water absorbency and water retention capacity, which was a significant advantage over the normal slow-release or controlled-release fertilizers. The effects of the amount of initiator, crosslinker, reaction time, and the degree of neutralization of acrylic acid on water absorbency were investigated and optimized. At the same, a rather new and simple method was used to make homogeneous urea-formaldehyde granules.

Mineral-Based Slow Release Fertilizers: A Review

“…In other way kaolin was used as one of the constituents to prepare a superabsorbent polymer which can slowly release nutrients. Liang et al (2006) prepared controlled release nitrogen, phosphorus and potassium compound fertilizer consisting of the core/shell structure with the function of water retention. Its core was formaldehyde and polyphosphate potassium fertilizer, and the shell was P(acrylic acid-co-acrylamide)/kaolin superabsorbent composite.…”

“…Its core was formaldehyde and polyphosphate potassium fertilizer, and the shell was P(acrylic acid-co-acrylamide)/kaolin superabsorbent composite. Various inorganic clays including kaolin were added to this type of fertilizers in order to improve swelling property, hydrogel strengths, and production costs (Wu et al, 2003;Zhang et al, 2006;Lee et al, 2005;Liang et al, 2006). The fertilizers not only showed good slow release of nutrients but also high water retention capacity.…”

“…There are many advantages for use of slow release fertilizers compared to normal fertilizers. They: (1) reduce damage to seeds or seedlings of crops by high local concentration of salts; (2) prevent rapid nitrification and nitrogen loss; (3) supply nutrients sustainably; (4) decrease chemical and biological immobilization in soils which blocks uptake of nutrients by plant roots; (5) lower a fertilizer application frequency consequently reducing a detrimental effect on environment (Govind, 1979;Ni et al, 2010;Guo et al, 2006;Shaviv and Mikkelsen, 1993).…”

Polymer in Agriculture: a Review

“…The authors described the preparation of urea granules (core) coated by an inner layer based on urea-formaldehyde (UF) and by a cross-linked poly(acrylic acid)/ organ-attapulgite (O-APT) as outer layer (Figure 8). Urea-formaldehyde granules coated by a crosslinked calcium alginate (inner layer) and by a superabsorbent polymer based on ammonium acrylate (outsider layer) were developed as fertilizer with slow release, superabsorbent and moisture preservation properties (USFSMP) [35] . Du et al studied the differential release rate and patterns of nitrate, ammonium, potassium and phosphate from two polyurethane-coated controlled release fertilizer (CRFs) and the effect of the temperature, the water content and type of release medium on it [36] .…”

Development of a Biochar-Plant-Extract-Based Nitrification Inhibitor and Its Application in Field Conditions

“…In this regard, nitrification control could be a strategy to improve N use efficiency (NUE) [4] while also decreasing N2O emissions. To improve NUE and to reduce the associated environmental impacts, three methods have been studied in recent years: (a) the use of urease inhibitors that regulate the transformation of organic-N (amide and urine) to ammonia [10]; (b) the use of controlled release fertilizers (CRFs) which have demonstrated many advantages over conventional fertilizers [11,12]; and (c) the use of biological nitrification inhibitors.…”