Biochar and biogas slurry have been proved to improve the quality of some soil types, but the long-term effects on fluvo-aquic soil are not fully understood. This study aimed to compare the continuity effects of peanut-shell biochar and biogas slurry on the physicochemical properties, microbial population size, and enzyme activities of fluvo-aquic soil. We conducted a four-year field experiment of winter wheat-summer maize rotation in the North China Plain. Along with equal nitrogen inputs, three treatments were applied—conventional fertilizers, peanut-shell biochar, and hoggery biogas slurry—after which various soil quality indicators were compared. Compared with those of control, both biochar and biogas slurry increased the soil total nitrogen and organic matter content, and improved soil aggregation, microbial biomass, and actinomycetes. Biogas slurry decreased soil pH and improved urease and protease activities. With biochar and biogas slurry treatments, wheat yield increased by 8.46% and 23.47%, and maize yield by 18% and 15.46%, respectively. Biogas slurry increased the content of crude protein and starch in the grains. Both biogas slurry and peanut-shell biochar improved fluvo-aquic soil nutrient content, water-stable macroaggregates, and microbial population, which might be related to their high nutrient content, large specific surface area, adsorption capacity, and functional groups. Biogas slurry generally exhibited stronger effects than biochar probably because of its richness in nutrients and bioactive substances.

Due to climate change, 2/3 of the world’s population will face water shortage problems by 2025, while a 50% increase in food production is required in 2050 to feed nine billion people. In addition, the intensified anthropogenic activities have significantly increased water resource pollution. In this condition, wastewater reuse for crop irrigation to reduce water scarcity is currently becoming global, while it often causes soil pollution and heavy metal accumulation in agricultural areas. This situation has increased public concern over its environmental impact. Thus, an integrated framework was conducted to discuss the status of water availability in China, wastewater treatment and reuse in irrigation systems, and the potential health risks. Avenues for new research toward sustainable agriculture were discussed. We emphasize that wastewater reuse reduces the freshwater deficit and increases food productivity. However, adequate treatment should be applied before use to reduce its adverse impacts on human health risks and environmental pollution. Facilities and policies should support more accessible access to reclaimed water used in industries and urban facilities from secondary municipal wastewater treatment plants. This could be a long-term solution to eradicate water scarcity and inefficient water resources in agricultural systems.