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The partial replacement of chemical fertilizer with straw return is considered an effective method for improving the accumulation of organic matter and soil fertility, but the characteristics of soil nitrogen fixation and mineralization in a double-cropped rice paddy system are unclear. Based on a 12-year field experiment, we conducted a waterlogged incubation experiment for 49 days to determine the effect of long-term straw return combined with reducing chemical fertilizer application on the dynamic changes of mineralized soil nitrogen (N) content and mineralized N rate under the treatments, including NPK (chemical fertilizers application with straw removal), SBR (straw burned return), and SR (straw return). Results showed that, compared with SBR and NPK, SR significantly increased available nitrogen by 7.4% and 16.5%, respectively, due to the higher ammonium nitrogen and nitrate nitrogen, as well as the total carbon, available phosphorus, and slowly available potassium, suggesting that it could stock a sufficient nitrogen source. During the incubation period, the amount of N mineralization was relatively higher under SR than under SBR and NPK treatments, especially during the later mineralization time, whereas there was no difference in the N mineralization rate. In addition, SR significantly increased soil cumulative N mineralization and N mineralization potential. However, SBR significantly decreased the soil mineralizable N ratio compared with SR and NPK, which may result in a worsening of the N mineralization potential. The results indicated that long-term straw return combined with reducing chemical fertilizer application could significantly improve the N supply capacity of paddy rice field soil to better coordinate the soil N supply and immobilization. [ABSTRACT FROM AUTHOR]

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]

In order to enhance utilization of millet straw and reduce fertilizer loss, a novel multifunctional fertilizer (MS-g-PAA/PDMUA) was developed using straw cellulose and linear polymer (PDMUA) by semi-interpenetrating technology. The structure and morphology characterization of MS-g-PAA/PDMUA were measured by fourier-transform infrared, x-ray diffraction, x-photoelectron spectroscopy and scanning electron microscopy techniques, to provide evidence of semi-IPNs networks and component interactions, and the results show that the product exhibited excellent water absorbency (562.3 g/g) and enhanced the soil infiltration. Cumulative release of N, P was 49.2% and 55.1%, respectively, after 40 days, coming up to the Committee of European Normalization (CEN) standard. The agricultural application of MS-g-PAA/PDMUA showed that it could promote growth indexes of wheat, which could improve wheat yields. Therefore, desirable water retention, slow-release properties, and wheat growth effects highlight the product's potential for agriculture application. [Display omitted] ● MS-g-PAA/PDMUA is derived from millet straw, can enhance waste straw utilization. ● The MS-g-PAA/PDMUA is rich in nitrogen and phosphorus, which promote wheat growth. ● The product has excellent water retention and slow fertilizer-release properties. ● Preparing by waste straw can reduce cost, is beneficial to industrial production. [ABSTRACT FROM AUTHOR]