Morchella importuna is a highly priced edible and medicinal mushroom. Crop rotation is an important management technique to improve soil health. In this study, the morphological characteristics, chemical composition, and nutritional quality of the M. importuna fruitbody under five different rotation systems (named RSA to RSE) were investigated. The results showed that the fruitbodies of M. importuna in rotation system C (RSC, Rice–Pea–M. importuna rotation) grew best (with the highest yield of 6804.90 kg/hm²) and were of higher quality, which showed significant increases in crude protein (37.32 g/100 g) and decreases in crude fat (4.04 g/100 g), crude fiber (10.06 g/100 g), and total ash (9.32 g/100 g). The heavy metal contents (Pb, Cd, and Hg) in the fruitbodies from all rotation systems were rare or none, which meets the standards of the Chinese Green Food Standard and the maximum limit in foodstuffs of the European Union Standard. In addition, the free amino acid compositions of morel under different rotation systems were analyzed. The ratio of essential amino acids to total amino acids (EAA/TAA) was highest in RSC (37.11%). The tested morels were abundant in umami, sweet, aromatic, and medicinal amino acids (UAA, SAA, AAA and MAA). Combining amino acid score, chemical score, and other nutrition indexes, RSC had the best impact on the yield and quality of morel. Our results demonstrate the feasibility and effectiveness of the cultivation model of rotating “Rice–Vegetables–Fungi” for the production of M. importuna in a way that develops high-quality agriculture.

Long-term plant residue retention can effectively replenish soil quality and fertility. In this study, we collected rhizosphere soil from the residual roots of annual Cenchrus fungigraminus in the Ulan Buh Desert over the past 10 years. The area, depth, and length of these roots decreased over time. The cellulose content of the residual roots was significantly higher in the later 5 years (2018–2022) than the former 5 years (2013–2017), reaching its highest value in 2021. The lignin content of the residual roots did not differ across samples except in 2015 and reached its highest level in 2021. The total sugar of the residual roots in 2022 was 227.88 ± 30.69 mg·g⁻¹, which was significantly higher than that in other years. Compared to the original sandy soil, the soil organic matter and soil microbial biomass carbon (SMBC) contents were 2.17–2.41 times and 31.52–35.58% higher in the later 3 years (2020–2022) and reached the highest values in 2020. The residual roots also significantly enhanced the soil carbon stocks from 2018–2022. Soil dehydrogenase, nitrogenase, and N-acetyl-β-D-glucosidase (S-NAG) were significantly affected from 2019–2022. The rhizosphere soil community richness and diversity of the bacterial and fungal communities significantly decreased with the duration of the residual roots in the sandy soil, and there was a significant difference for 10 years. Streptomyces, Bacillus, and Sphigomonas were the representative bacteria in the residual root rhizosphere soil, while Agaricales and Panaeolus were the enriched fungal genera. The distance-based redundancy analysis and partial least square path model results showed that the duration of residual roots in the sandy soil, S-NAG, and SMBC were the primary environmental characteristics that shaped the microbial community. These insights provide new ideas on how to foster the exploration of the use of annual herbaceous plants for sandy soil improvement in the future.