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Coating of nonwovens with potassium nitrate containing carboxymethyl cellulose for efficient water and fertilizer management

Özen, İlhan, Okyay, Gamze, Ulaş, Abdullah
Cellulose 2018 v.25 no.2 pp. 1527-1538
carboxymethylcellulose, citric acid, coatings, crosslinking, fertilizers, gels, irrigation, nitrate nitrogen, nonwoven fabrics, polyvinyl alcohol, potassium nitrate, spectrophotometers, sustainable agriculture, water holding capacity, water uptake
This paper presents the generation of an innovative agrotextile material possessing a controlled fertilizer release with an improved water absorption/retention property. To this end, nonwoven fabrics were coated with carboxymethyl cellulose/potassium nitrate solutions. Coatings were carried out on polyvinyl alcohol pre-coated and non-pre-coated structures. Citric acid was used as the cross-linker for carboxymethyl cellulose. Fertilizer release from the coated nonwoven structures was calculated as cumulative percentages from nitrate nitrogen amounts measured by a UV/Vis spectrophotometer. In addition to morphological and structural analyses, the gel fraction (degree of cross-linking), water absorbency and water retention capacity of the generated materials were investigated. Usage of citric acid cross-linked the carboxymethyl cellulose polymer chains. The best results were obtained with the pre-coated structure together with 10 wt% citric acid. Pre-coating with polyvinyl alcohol acted as a supporting layer for carboxymethyl cellulose to form a quite compact layer on the nonwoven fabric and thus enabling increased water absorption (up to 4000%) and water retention capacity (up to 46 h). Also, the fertilizer release profile was improved markedly (starting with a release value of 28% and reaching a value of 75% after the 19th irrigation). These property enhancements would result in decreased amount of water and fertilizer and thus contribute to sustainable agriculture.