Water-Preserving and Salt-Resistant Slow-Release Fertilizers of Polyacrylic Acid-Potassium Humate Coated Ammonium Dihydrogen Phosphate

Abstract

Polyacrylic acid (PAA) has high water absorbency but poor salt resistance. Humic acid (HA) extracted from lignite was introduced into the cross-linked copolymer systems of AA to improve the water absorbency and salt-tolerance. A polyacrylic acid-potassium humate (PAA-KHA) coated ammonium dihydrogen phosphate (ADP) fertilizer with water-preserving, salt-resistant and slow-release properties was prepared. The main properties of HA extracted from lignite oxidized by H2O2 were studied. Furthermore, the synthesis process, water absorbency of PAA-KHA in deionized water and in NaCl solution, morphologies of PAA-KHA, and the slow-release performance of the fertilizer (ADP@PAA-KHA) were investigated. The results showed PAA-KHA had a layered interpenetrating network, which can provide sufficient storage space for water and nutrients. The salty water absorbency of PAA-KHA increased by about 3 times compared to PAA. Both the PO43− and NH4+ cumulative release of ADP@PAA-KHA with a coating rate of 10% in deionized water, were less than 20% within 24 h, and were 55.71% and 28.04% after the 15th day, respectively. The weight change of ADP@PAA-KHA before and after absorbing water was about 53 times in deionized water and about 4 times in 1 wt% of NaCl salty water. The results show that ADP@PAA-KHA has excellent properties of water retention, salt resistance and slow-release. This will efficiently improve the utilization of fertilizer and reduce the irrigation water consumption at the same time.

Rational Design of a Multifunctional Hydrogel Trap for Water and Fertilizer Capture: A Review

“…21 However, the water absorption and salt tolerance of hydrogels are generally constrained in practical soil applications. 85,86 The enhancement of water absorption and salt tolerance of hydrogels is therefore crucial.…”

“…The capture of water by hydrogels enhances soil’s water retention performance, reduces the evaporation of soil interstitial water, and improves the efficient utilization of water resources . However, the water absorption and salt tolerance of hydrogels are generally constrained in practical soil applications. , The enhancement of water absorption and salt tolerance of hydrogels is therefore crucial.…”

Equilibrium Solubility Behavior and Thermodynamic Properties of Potassium and Ammonium Di-Hydrogenophosphate Aqueous Solutions at T = 298.15 K

“…Phosphoric acid salts are of great commercial and scientific importance. They are broadly employed in several industries, such as agrifood and pharmaceuticals. , Potassium and ammonium orthophosphates can be used as food additives, stabilizers, antioxidants, and water retention agents. – Ammonium and potassium dihydrogenphosphate are important in fertilizers and industrial materials. The physicochemical properties of electrolyte solutions are very useful for understanding their behavior.…”

Preparation of Novel Biodegradable Polymer Slow-Release Fertilizers to Improve Nutrient Release Performance and Soil Phosphorus Availability

“…Up to now, many preparation methods for slow-release P fertilizers have been widely reported, among which coated slow-release P fertilizers are the most widely used [ 7 , 8 ]. Garcia et al reported the use of pine lignin as a coating material for fast available P fertilizer to produce coated P fertilizer [ 9 ].…”