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The goal of this study was to enhance the utilization of millet straw and endow it with the fertilizer function through modifying the carboxymethylcellulose (CMC-NH 4), based on wheat straw, by acidification and ammonification to improve water and fertilizer efficiency. Amine group was introduced through the electrophilic substitution to supply nutrients to crops. The order of influential factors on the water absorption property was determined by an orthogonal experiment and showed that the highest water absorbency of 224.7 g/g, which was achieved for the conditions of 3:1 carboxymethylcellulose to nitric acid solution (mass percentage concentration of 50%), 3:1 carboxymethylcellulose to ammonia solution with the mass percentage concentration is 30%. The CMC-NH 4 was characterized by scanning electron microscopy, fourier-transform infrared, x-ray diffraction, and X-ray photoelectron spectroscopy techniques, and the results indicated that application of CMC-NH 4 promoted the growth indexes of wheat, improved wheat yields. Therefore, the waste straw was modified into the soil conditioner with specific function by the group targeted modification strategy. In addition, the fertilizer efficiency and water-retention behavior of CMC-NH 4 encouraged its use as a safe water- and fertilizer-retaining agent in agricultural applications. [Display omitted] • The product prepared by straw can reduces cost, is easy for agricultural extension. • The CMC-NH 4 is rich in ammonium, could provide fertilizer for crop growth. • The product shows excellent water retention and could prevent water percolation. [ABSTRACT FROM AUTHOR]

• Few studies have analyzed the utilization of millet straw as raw materials in the preparation of superabsorbent resin. • The product had excellent water absorbency and slow-release property. • The product prepared by millet straw not only reduces production cost, but also promote plant growth. • Application of the fertilizer could achieve the goal of straw return to soil. To enhance utilization of waste straw and improve fertilizer efficiency, a novel semi-interpenetrating polymer network fertilizer (MSP-g-AA/PVA-APP) synthesized from straw cellulose and linear polymer was prepared by solution polymerization. The ammonium polyphosphate (APP) was introduced to supply nitrogen and phosphorus nutrients. The prepared materials were characterized with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). The water absorbency and slow-release behavior of MSP-g-AA/PVA-APP were also studied. The results indicated that MSP-g-AA/PVA-APP exhibited excellent water absorbency of 681.3 g/g in distilled water and enhanced the water retention capacity of soil. The cumulative N and P release rates of MSP-g-AA/PVA-APP were 55.1 % and 47.3 % after 30 days in soil, respectively. The effect of MSP-g-AA/PVA-APP on growth of wheat was studied, and the results show that the application products could facilitate the growth of wheat. It could be concluded that the product with water retention and slow-release property, being low costs and friendly to environment, had great potential for application in agricultural. [ABSTRACT FROM AUTHOR]