A binderless board was produced from mechanically dissociated compost straw via suction filtration. The binderless board was applied to replace the topsoil that is currently used predominantly as the substrate for rice seedlings in China. The binderless board showed the highest tensile strength when the rice straw had been composted for 20 days. The bulk density, aeration, and total porosity of the binderless board showed an increasing trend with composting time, due to the increased decomposition of rice straw. The examination of the growth parameters and root morphology of the rice seedlings showed that electrical conductivity (EC), pH, and nutrient content of the binderless board made from rice straw composted for 10 days were conducive to the growth of seedlings. Polyphenols inhibited rice seedling height and shoot weight and promoted the rice seedling stem diameter and root weight. Considering the quality loss, growth index, and the strength of the binderless board, 10 days of composting is the optimal condition. These results indicate that binderless board can replace top soil and peat when used as the substrate for rice seedling.

Manganese dioxide (MnO2) is a very promising catalyst material due to its unique physicochemical properties and synergistic effects with other metals or metal oxides. Especially, MnO2 was widely used to remove organic pollutants. In this paper, we summarize the phase and morphology structures of MnO2. The effects of doping and composite on the structures and catalytic properties of MnO2 materials are also compared and described. The catalytic properties of MnO2-based materials on organic pollutants (phenolic compounds, antibiotics, dyes, and pesticides) are also analyzed. In addition, we summarize the degradation mechanisms, degradation pathways, and degradation efficiency of different MnO2-based materials on organic pollutants. The development status and shortcomings of MnO2 are discussed. Its development trend of catalytic degradation of organic pollutants by manganese oxides is provided.

Crop residues are mainly post-harvest remains of agriculture. The organic matters, nutrients, and hollow structures of crop residues enable them to be applied in agriculture. In this review, we summarize the impacts of crop residues on soil health. Crop residue returning is beneficial to soil physicochemical properties. Soil water content, total porosity, aggregate stability, cation exchange capability (CEC), organic carbon, phosphorus, and potassium all increased after being amended with crop residues. The negative effects of allelochemicals from crop residues on crop growth can be adjusted by crop residue returning management. The rice straw has positive impacts on soil microbial properties. Besides, crop residue play a crucial part in soil remediation. Crop residues as soil amendments have inhibitory effects on some heavy metals, organic pollutants, and pathogens. They can also alleviate the pressure of saline-alkali soil. Finally, we provide some suggestions for improving soil health with crop residues.