Although extensive manipulative experiments have been conducted to study the effects of altered precipitation intensity and duration on soil greenhouse gas (GHG; carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O)) fluxes, the general patterns of GHGs to altered precipitation have not been globally described across biomes. Thus, we performed a meta-analysis of 84 published studies to examine the general responses of CO₂, CH₄, and N₂O fluxes to altered precipitation. Our results indicated that increased precipitation significantly increased N₂O emissions ( 154.0%) and CO₂ fluxes ( 112.2%) and significantly decreased CH₄ uptake (-41.4%); decreased precipitation significantly decreased N₂O emissions (-64.7%) and CO₂ fluxes (-8.6%) and significantly increased CH₄ uptake ( 32.4%). Moreover, increased precipitation significantly increased litter biomass and microbial biomass and decreased root biomass and the root:shoot ratio. However, decreased precipitation significantly decreased litter biomass and root biomass and significantly increased root:shoot ratio. These results suggest that precipitation changes could alter the carbon distribution patterns in plants. In addition, the CO₂, CH₄, and N₂O fluxes exhibited diverse responses to different ecosystems, durations of precipitation changes, and changes in precipitation intensity. These results demonstrate that there are many factors that regulate the responses of GHG to precipitation changes.

A better understanding of preferential water flow is important because water-related crises, i.e., water scarcity and security, are strongly associated with water retention rates in different landscapes. This review aims to evaluate significant advances in the main themes of preferential water flow to establish the inconsistent roles of preferential water flow in eco-hydrology and suggest promising areas for future work. Results showed that preferential water flow studies have made significant advances in our understanding of certain parameters functioning at multiple scales but that most studies focus on preferential water flow in the vadose zone, whereas few studies on the soil surface. Preferential water flow can have a positive effect on averting water crises, such as when it affects surface runoff soil erosion, soil formation as ecosystem services, nutrient cycling in root zone, and overall water regulation of the water cycle. Conversely, preferential water flow can have a negative effect on eco-hydrological issues via slope stability, gully erosion, geological disaster, waste treatment, water supply in root zone, and food production. Our review concludes that more information is required on preferential water flow before we can assess its role in mitigating water-related crisis events.

Soil management practices have the potential to modify the diversity and function of microbes in agricultural fields. The aim of this study was to investigate bacterial and fungal diversity in a 15 yr wheat–pea rotation tillage experiment. The treatments included conventional tillage with stubble removed, no-till with stubble removed, no-till with stubble retained (NTS), and conventional tillage with stubble incorporated. Illumina high-throughput sequencing platform was employed to sequence bacteria 16S rRNA (V3V4) and fungi internal transcribed spacer (ITS2) region genes in 0–10 cm and 10–30 cm of soil sampled. The dominant bacterial and fungal phyla identified at 97% similarity cutoff across both depths of treatments were Proteobacteria (26.3%), Actinobacteria (25.1%), Acidobacteria (15.0%), Gemmatimonadetes (8.8%), Ascomycota (85.8%), and Basidiomycota (8.0%). NTS had significantly (p < 0.05) higher microbial diversity indices, total organic carbon, soil microbial biomass carbon and nitrogen, NO₃-N, and NH₄-N at 0–10 cm depth. Tillage and stubble effects had a significant correlation with some phyla such as Proteobacteria, Actinobacteria, Gemmatimonadetes, JL-ETNP-Z39, Nitrospirae, Chloroflexi, Firmicutes, and other identified and unidentified minor microbial phyla. No-till and residue retention practices influenced fungal and bacterial species diversity through improved soil chemical properties, which have potential to affect the habitat and activity of soil microbes. Therefore, no-till and stubble retention could improve soil quality and promote sustainable agriculture in the rainfed Loess Plateau.

Well-planned crop rotations and targeted use of organic amendments are critical to success in organic wheat production. The impact of green manure (GMr) type, GMr termination timing, and “Acti-Sol” [pelletized dehydrated poultry manure (DPM); 5-2-3] on organic wheat productivity and quality was evaluated from 2014 to 2016 in Truro, NS, and Saint-Mathieu-de-Beloeil, QC. Crops prior to wheat were soybean or GMr of hairy vetch/oat (HVO), common vetch/oat (CVO), and red clover (RC) (NS site), and HVO, red clover/oat (RCO), and oat (QC site). Trials were split-split-plot designs with treatments of precrops, GMr termination (fall vs. spring), and DPM at 0, 40, 80, and 120 kg total N ha^-1. Wheat yields ranged from 1500 to 1800 kg ha^-1 if unfertilized with DPM and following soybean or oat precrops. All legume GMrs (HVO, CVO, and RC/RCO) and DPM applications increased grain yield (2000–4200 kg ha^-1) and protein content (13%–16%), wheat total N uptake [49–60 kg N ha^-1 (QC); 87–125 kg N ha^-1 (NS)] and soil mineral N content mid-season and postharvest, and responses were consistently greatest following HVO. Timing of GMr incorporation largely had no impact. Applying DPM at 80 kg N ha^-1 was an effective substitute for a GMr precrop.

This study investigates changes in soil phosphorus (P) in different fertilization treatments applied since 1902 on Chernozem soil at a “Static Fertilization Experiment” in Germany. Total and plant-available soil P, and soil P balances were assessed at 0–30, 30–60, and 60–90 cm depth layers in unfertilized “Zero”, mineral “NK” and “NPK”, and combined mineral and organic “FYM NK” (farmyard manure NK) and “FYM NPK” fertilization treatments. P-use efficiencies were determined for each crop in rotation (sugar beet, spring barley, potato, and winter wheat). The 110 yr of P fertilization at rates between 22 and 55 t ha^-1 yr^-1 resulted in a significant increase of available P contents. P stocks increased up to 60 cm depth. Total P accumulation comprised 1.4 t ha^-1 for NPK, 1.3 t ha^-1 for FYM NK, and 3.1 t ha^-1 for FYM NPK. Crops cultivation without P fertilization in Zero and NK treatments resulted in negative P balances and reduction of available P below recommended levels. Reduction of mineral P application rates after 1981, along with crop variety-dependent yield increases, resulted in an improved P-use efficiency. An organic fertilization combined with mineral N and K fertilizers (FYM NK) was found to be the most P-efficient treatment for Chernozem soils.

Erosion leads to substantial loss of soil productivity. To abate such decline, amendments such as manure or fertilizer have been successfully employed. However, the longevities of erosion and soil amendment legacy effects are not well quantified. In 1957, a Dark Brown Chernozem soil at Lethbridge, AB, was land-levelled, creating three degrees of topsoil removal or erosion: noneroded, moderate erosion, or severe erosion. Two amendment studies (1980–1985 and 1987–1991) were superimposed on the erosion treatments. Both studies were cropped to spring wheat (Triticum aestivum L.) from 1993–2010 to examine legacy effects of erosion and soil amendments on wheat yield and soil properties. Without amendment, mean wheat yield under moderate erosion was 40% of the noneroded treatment, whereas severe erosion was 34% of the noneroded treatment, 36–42 yr (1993–1999) after erosion. Under moderate or severe erosion, the restorative power of manure diminished substantially in the first 10–15 yr following cessation of addition, but then levelled off resulting in wheat yields up to 35% higher than equivalent nonamended treatments. Legacy effects of erosion (54 yr) and amendment (27–31 yr) on soil organic carbon and total nitrogen were also observed.

A 5 yr (2011–2015) field study was conducted to test the hypothesis that streambank fencing had a significant effect on selected vegetation and soil properties of the Mixed prairie component of a complex corridor pasture. The grazing treatments [ungrazed (UG) – periodic grazing (PG)] inside the corridor pasture were 11 yr (2001–2012) of cattle exclusion (UG), followed by 3 yr (2013–2015) of periodic grazing (PG) when the riparian soil was dry. A control treatment outside the fencing was continuous grazing (CG). Selected vegetation and soil properties were measured over the growing season at 10 paired locations in each treatment (nonreplicated) pasture over 5 yr (2011–2015), and rangeland health was measured in 2011. The UG–PG treatment significantly (P ≤ 0.10) increased the total biomass by 2- to 5-fold in all 5 yr compared with CG treatment and improved the rangeland health score of the UG phase of the UG–PG (63%) treatment compared with the CG treatment (50%) in 2011. It also significantly reduced surface soil temperature by 2.2–5.2 °C, significantly increased volumetric water content of the surface soil by 7%–10% in 3 of 5 yr, and significantly increased surface soil CO₂ efflux (instantaneous) by 17%–60% in all 5 yr. Overall, the UG–PG treatment improved rangeland health, increased total biomass, soil water, and soil CO₂ efflux of the Mixed prairie, but decreased soil temperature compared with the CG treatment. Excessive dead biomass, greater fire risk, and an increase in noxious weeds caused by cattle exclusion suggested that periodic grazing may be the preferred option.

Biosolids have been shown to improve forage production and soil quality on semiarid rangelands in the short term, but less is known about longer-term impacts of one-time biosolids applications. The objective of this study was to determine the effects of a single, surface biosolids application (at 20 dry Mg ha^-1) on stability of soil aggregates, bulk density, total carbon (C) and nitrogen (N), permanganate-oxidizable carbon (POXC), polysaccharides, pH, nutrient availability, and soil water content (all at 0–7.5 cm depth) 14 yr following application to ungrazed rangelands in the Central interior of British Columbia. Fourteen years following the biosolids application, aboveground plant biomass was almost two times greater with biosolids application than on control, while exposed mineral soil and microbiotic crust significantly decreased in biosolids plots. Despite differences in aboveground biomass, there was no difference in total soil C and N, POXC, and polysaccharides between biosolids and control plots. Biosolids-amended soil did exhibit significantly greater mean weight diameter of water-stable aggregates, lower pH, increased spring soil water content, and increased availability of Fe³ , Zn² , Cu² , and phosphate ions. These findings indicate that the long-term improvements to soil on ungrazed rangeland are possible even from a single biosolids application.

Placement of Plant Root Simulator (PRS^®) probes (ion-exchange membranes in a plastic support) may strongly influence nutrient supply measurements and their relationship to nutrient loss to overlying water due to gradients in ion activity and redox potential with depth. A laboratory study was conducted with two soils contrasting in potential nutrient loss (manured vs. unamended control) to determine the impact of probe placement (vertical, horizontal, and flat on the soil surface) on nutrient supply rate. The supply rates of the redox-sensitive nutrients Mn and Fe were generally 1–2 orders of magnitude lower for PRS probes placed on the soil surface than buried vertically. In contrast, the supply rate of P and K varied by 1–2 orders of magnitude between soils, but placement impacts were modest or absent. The ratio between manured and control soils in water P concentration was identical to that of soil P supply rate determined with PRS probes placed flat on the soil surface. All placements were effective in demonstrating the increased potential for loss of P and K from the manured soil, but only measurements from PRS probes placed on the soil surface were closely related to loss of the redox-sensitive nutrients Mn and Fe.

Soil microbial diversity is expected to be altered by the establishment of invasive plant species, such as dog-strangling vine (DSV) [Vincetoxicum rossicum (Apocynaceae)]. However, in urban ecosystems where DSV invasion is high, there is little research evaluating the impacts of DSV and other anthropogenic disturbances on microbial diversity. Our study was based in Rouge National Urban Park, Canada, where we used terminal restriction fragment length polymorphism data to evaluate (i) if DSV has a detectable impact on soil bacterial community composition and (ii) if these impacts occur independently of other anthropogenic change or soil characteristics. Variation in soil bacterial communities was greatly reduced in DSV-invaded sites vs. less-invaded sites. The degree of DSV invasion independently explained 23.8% of variation in bacterial community composition: a value similar to the explanatory power of proximity to roadways (which explained 22.6% of the variation in community composition), and considerably greater than soil parameters (pH, moisture, carbon, and nitrogen concentrations) which explained only between 6.0% and 10.0% of variation in bacterial community composition. Our findings indicate that DSV influences soil bacterial community composition independent of other anthropogenic disturbances and soil parameters, with potential impacts on multiple facets of plant–soil interactions and plant invasion dynamics.

Stagnating potato (Solanum tuberosum L.) yields in eastern Canada have resulted in loss of competitive advantage in global potato markets. Therefore, there is a need to investigate the potential to increase yield by adopting precision agriculture technology. This study evaluated the efficiency of an apparent soil electrical conductivity (EC_a) sensor to delineate management zones (MZs) in two commercial potato fields in New Brunswick, Canada, using an unsupervised fuzzy k-means clustering algorithm. Georeferenced soil samples from 0 to 15 cm depth were analyzed for physicochemical properties. Tuber yields were recorded using a yield monitor. The two MZs delineated using soil EC_a differed significantly in soil physicochemical properties for both fields; however, tuber yield differed significantly between MZs only in Field 1. The yield difference (7.1 Mg ha^-1) in Field 1 was attributed to a difference in soil moisture (23.5% vs 28.5%) resulting from a difference in clay content (141 vs 189 g kg^-1). The lack of a yield difference between MZs in Field 2 may reflect relatively low within-field spatial variability. The soil EC_a sensor showed promise for use in commercial potato production in New Brunswick, especially in fields with high spatial variability.

Automated wet-sieving is preferred for this clay loam soil due to better sensitivity and savings (time and disposables) despite a larger capital investment. Rotations with greater frequency of winter wheat and no-till compared with conventional plow system had greater wet aggregate stability values, indicating better surface soil quality.