Reclaimed water (RW) is an alternative water resource that has been utilized all over the world, but its environmental effects are not fully understood. Soil biodiversity is an important indicator of soil tolerance and resilience. In the present study, the impact of RW irrigation on the microbial community diversity and chemical properties of topsoil was investigated by monitoring nitrogen (N) rates. Tomato plants were grown on plots which had been irrigated with reclaimed water for 5 years with varying levels of N fertilization (N270, 270 kg ha⁻¹; N216, 216 kg ha⁻¹; N189, 189 kg ha⁻¹; and N135, 135 kg ha⁻¹). Soil bacterial community composition was analyzed by PCR amplification of the 16S rDNA gene and Illumina MiSeq high-throughput sequencing technology of a total of 770,066 quality sequences. The results showed that long-term RW irrigation altered the bacterial composition of soil in an N-dependent manner. RW irrigation increased the abundances of Gemmatimonadetes, Actinobacteria, Firmicutes, and Nitrospirae in soils. The Chao, ACE, and H indices revealed no significant difference under RW irrigation with varying levels of N fertilization. The tomato yield and partial factor productivity from applied N for RN216 increased significantly under RW irrigation with reducing N fertilization. RW irrigation increased the yield of tomato and the abundance of functional microorganisms, which eventually improved the practice of irrigating with reclaimed municipal wastewater. Meanwhile, the potential environmental and health risks of long-term RW irrigation warrant further investigation.

The interest in reusing wastewater for irrigation is being popularized in most countries. The objective of this study was to evaluate the effects of different wastewater and nitrogen fertilizer on soil fertility and plant quality, as well as to identify the optimal irrigation mode in the North China Plain. A total of nine treatments, including control (groundwater, no fertilizer), piggery wastewater, reclaimed water, and saline water, combined with nitrogen fertilizer (300 kg/ha and 200 kg/ha), were conducted in a greenhouse in 2019 (Xinxiang, Henan Province). Soil pH, electrical conductivity, organic matter, heavy metals contents, and cucumber yield and quality were analyzed. The results showed that: (1) compared with the underground water (control), soil pH value with a decrement of 0.21 units in piggery wastewater (PW), and 0.24 units in saline water treatments (SW). Soil electrical conductivity (EC) value significantly increased by 5.8~20.9% in PW and SW treatments, while there was no significant difference in EC in reclaimed water. The highest EC (770 µS/cm) was recorded in SW treatment. (2) No dramatic difference on the concentrations of soil lead (Pb) and cadmium (Cd) in the PW, RW, and SW treatments, compared with the control, but soil organic matter, copper (Cu), and zinc (Zn) concentrations in wastewater treatments were increased by 2.1~43.4%, 24.4~27.0%, and 14.9~21.9%, respectively. (3) There were no significant differences in cucumber yield and quality in RW treatment, while there was a slight decrease by 1.4% in yield in the SW treatment. The highest cucumber yield was observed in PWH treatment, with an increment of 17.5%. In addition, the contents of Vitamin C, soluble sugar, and protein were also improved by PW treatment. In this study, PW treatment showed the strongest ability to promote cucumber yield and quality, thus indicating that piggery wastewater irrigation with 300 kg/ha nitrogen would be the optimal practice in this region. Long-term study is necessary to monitor potential risk of heavy metals on the quality of soil and plant.

In order to reveal the effects of microplastics (MPs) on the growth and rhizosphere soil environmental effects of wheat (Triticum aestivum L.), three microplastic types (polypropylene MPs (PP-MPs), high-density polyethylene MPs (HDPE-MPs), and polylactic acid MPs (PLA-MPs)), particle sizes (150, 1000, and 4000 μm), and concentrations (0.1, 0.5, and 1 g·kg⁻¹) were selected for a pot experiment under natural environment conditions. The differences in germination rate (GR), germination inhibition rate (GIR), growth characteristics, physicochemical properties, and enzymatic activities of wheat in rhizosphere soil were analyzed using statistical analysis and variance analysis. The results show that the germination rate of wheat seeds decreased under different MPs, and the HDPE-MPs, medium particle size (1000 μm), and medium concentration (0.5 g·kg⁻¹) had the greatest inhibitory effect on wheat seed germination. The effects of MPs on wheat seed growth characteristics were inconsistent; the germination potential (GP), germination index (GI), and vitality index (VI) showed a significant decreasing trend under the PLA-MPs and medium-concentration (0.5 g·kg⁻¹) treatment, while the mean germination time (MGT) showed a significant increasing trend; the GP and MGT showed a significant decreasing and increasing trend under the high-particle-size (4000 μm) treatment, respectively, while the GI and VI showed a significant decreasing trend under the medium-particle-size (1000 μm) treatment. The growth characteristics of wheat plants showed a significant decreasing trend under different MPs, with the SPAD, nitrogen concentration of the leaves, and plant height decreasing the most under PLA-MP treatment, the SPAD and nitrogen concentration of leaves decreasing the most under low-particle-size (150 μm) and low-concentration (0.1 g·kg⁻¹) treatments, and the decreases in plant height under the high-particle-size (4000 μm) and high-concentration (1 g·kg⁻¹) treatments being the largest. There were significant increasing trends for ammonium nitrogen (NH₄⁺), total phosphorus (TP), soil urease (S-UE), soil acid phosphatase (S-ACP), and soil sucrase (S-SC) under different microplastics, while the PLA-MPs had a significant increasing trend for nitrate nitrogen (NO₃⁻) and a significant decreasing trend for pH; there was a significant decreasing trend for total nitrogen (TN) under the HDPE-MPs and PLA-MPs, and for each particle size and concentration, the PLA-MPs and low-concentration (0.1 g·kg⁻¹) treatments showed a significant decreasing trend for soil catalase (S-CAT). The research results could provide certain data and theoretical bases for evaluating the effects of MPs on crop growth and soil ecological environments.

To reveal the relationship between agricultural water resource consumption and grain production in the Yellow River Basin, the irrigation water productivity (WPI), crop water productivity (WPC), total inflow water productivity (WPT), and eleven influencing factors were selected. The spatial and temporal distribution characteristics and driving factors of water productivity of the main crops in the Yellow River Basin were analyzed with the spatial autocorrelation analysis, grey correlation analysis, sensitivity analysis, and relative contribution rate. The results showed that the minimum mean values of WPI, WPC, and WPT were 0.22, 0.35, and 0.18 kg/m³ in Qinghai, respectively, the maximum mean value of WPI was 2.11 kg/m³ in Henan, and the maximum mean values of WPC and WPT were 0.71 and 0.61 kg/m³ in Shandong, respectively. The changing trends in WPI and WPT in Qinghai and in WPC in Shandong were insignificant, whereas the WPI, WPC, and WPT in other provinces showed a significant increasing trend. Water productivity displayed a certain spatial clustering feature in the Yellow River Basin in different years, such as a high-high (H-H) aggregation in Henan in 2005, and an H-H aggregation in Shanxi in 2015 for WPI. The water productivity had a significant positive correlation with the consumption of chemical fertilizer with a 100% effective component (CFCEC), effective irrigated area (EIA), plastic film used for agriculture (PFUA), and total power of agricultural machinery (AMTP), while it had a significant negative correlation with the persons engaged in rural areas (PERA). There was a large grey correlation degree between the water productivity and the average annual precipitation (AAP), CFCEC, PFUA, consumption of chemical pesticides (CFC), and AMTP in the Yellow River Basin, but their sensitivity was relatively small. The main driving factors were EIA (8.98%), agricultural water (AW, 15.55%), AMTP (12.64%), CFCEC (12.06%), and CPC (9.77%) for WPI; AMTP (16.46%), CFCEC (13.25%), average annual evaporation (AAE, 12.94%), EIA (10.49%), and PERA (10.19%) for WPC; and EIA (14.26%), AMTP (13.38%), AAP (12.30%), CFCEC (10.49%), and PFUA (9.69%) for WPT in the Yellow River Basin. The results can provide support for improving the utilization efficiency of agricultural water resources, optimizing the allocation of water resources, and implementing high-quality agricultural developments in the Yellow River Basin.