Influence of long term irrigation with pulp and paper mill effluent on the bacterial community structure and catabolic function in soil

Effects of Grass Inter-Planting on Soil Nutrients, Enzyme Activity, and Bacterial Community Diversity in an Apple Orchard

The orchard inter-planting pattern is being widely used in many countries of the world, but it is relatively new in China. This study evaluated the interrow mono- and mixed-planting of Lolium perenne (Lp) and Medicago sativa (Ms) in orchards on soil nutrient, enzyme activity, and bacterial community diversity in 0-10, 10-20, and 20-40 cm soil layers. The clean tillage orchard was used as control (CK) treatment. Compared with CK, Lp and Lp + Ms. significantly increased the contents of soil organic matter (OM), total nitrogen (TN), and alkali-hydrolyzable nitrogen (AN) in 0-20-cm soil layer, and up-regulated the activities of urease (URE) and alkaline phosphatase (ALP). The Lp treatment significantly increased the relative abundance of Gemmatimonadetes and Planctomycetes in the 0-10-cm soil layer. Besides, cover crops significantly increased the abundance of Actinobacteria, Gemmatimonadetes, and Chloroflexi in the 10-20-cm soil layer and that of Gemmatimonadetes and Chloroflexi in the 20-40 cm soil layer. The redundancy analysis (RDA) showed significant positive correlations of Actinobacteria with ALP, OM and TN and that of Bacteroidetes with available potassium (AK), and Proteobacteria with available phosphorus (AP). Overall, the grass inter-planting improved the soil nutrients, enzymes activities, and bacterial community composition of the soil. Based on these results, inter-planting perennial ryegrass in the apple orchards is a suitable grass-orchard inter-planting strategy in Weibei, Shaanxi Province of China.

Response of grass interplanting on bacterial and fungal communities in a jujube orchard in Ningxia, northwest China

Orchard grass is an important soil management method that improves pest resistance in fruit trees and it reduces the usage of chemical fertilizer to protect the environment. In this study, we investigated the bacterial and fungi communities in the rhizosphere of Ziziphus jujuba Mill cv. 'lingwuchangzao' by high-throughput sequencing to test the effects of different sward types. The soil organic matter, available phosphorus, available potassium, and total nitrogen contents were higher with cleared tillage compared with the other planting grass treatments. Ascomycota, Basidiomycota, and Mortierellomycota were the dominant fungal groups. Most of the soil nutrient levels were lower in the treatments with grass (except for planting with ryegrass and pea grass) than cleared tillage, but there were no significant differences in the bacterial and fungi diversity. pH and total phosphorus were the main contributors to variations in the bacterial communities. The variations in the fungal communities were mainly attributed to the soil nutrient levels. The changes in the titratable acids and vitamin C contents were clearly correlated with the dynamics of the bacterial and fungi communities. Network analysis showed that 60% of the bacteria had close connections with fungi, including the dominant bacteria comprising Proteobacteria, Actinobacteria, and Bacteroidetes. Our findings demonstrated that different types of grass treatments affected the abundances of microbes rather than their composition.