Salinity and sodicity problems are ubiquitous in dryland and irrigated systems, and research into possible amendments to remediate soils in these systems is needed. This study was conducted to investigate the effects of organic and inorganic amendments on spring wheat (Triticum aestivum UG99) yield and salts redistribution within the profile of a repacked saline-sodic silt loam soil (EC e = 12.9 dS m −1 , exchangeable sodium percent (ESP) = 17.6% for control). The experimental design for greenhouse study was completely random with two factors (amendment and leaching fraction, LF). The amendments included biochar (2%) [B], biochar + manure (2%) [BM], zeolite modified with CaCl 2 (2%) [ZC], super absorbent (1%) [SA], and a control (no amendment) considering two levels of LF (15 and 30%). All amendments, except ZC, decreased soil bulk density and electrical conductivity, and increased soil pH and water content at field capacity after 2 pore volumes leaching. There was positive effect (p < .001) of B, BM and SA on wheat ground cover and grain yield; ZC amendment had no effect on wheat growth or yield. The LF levels did not affect wheat growth or yield. The amendments (B, BM and SA) decreased Na + and Mg 2+ concentration in straw, while K + concentration increased; resulting in reductions in the Na + /K + ratio. In general, the study showed that B, BM and SA are suitable amendments for increasing yield by improving soil conditions and reducing salts and Na + accumulation in plants.

One of the approaches for recycling and reusing agricultural and animal wastes is to pyrolyse the residues and subsequently use them as soil amendments. The prevalence of several feedstocks suggests that it is necessary to investigate the optimal combinations of feedstocks and pyrolysis temperature for use as soil amendments. This study was done to evaluate five combinations of raw materials (sugarcane bagasse, rice husk, cow manure and pine wood) and their biochars produced by slow pyrolysis at 300°C and 500°C for soil amendment. Several physicochemical properties (electrical conductivity (EC), pH, cation exchange capacity (CEC), total organic matter content (C) total porosity (TP), total nitrogen (N), particle density (PD) and bulk density (BD)) were investigated. Comparison among feedstocks showed that the highest PD, BD and CEC were observed in WM (cow manure-pine wood). The pyrolysis process increased the PD, TP, N and monovalent cations and decreased EC, CEC and BD. Compared to the feedstock, pyrolysis increased the N content, but higher temperatures lowered the N content. Pyrolysis at 500°C reduced the EC, N, CEC and biochar yield by 18%, 13%, 21% and 24% respectively, compared to 300°C. Pyrolysis at 500°C increased the pH, Na+ and K+ by 17%, 12% and 22%, respectively, compared to 300°C. Considering the physicochemical properties of biochar and the costs, the bagasse-wood-rice (BWR) combination and temperature of 300°C are suggested for biochar production for soil amendment.

The increasing salinization and sodification of soils in drylands and irrigated systems present a great challenge to agricultural production and threaten soil quality. There is an urgent need to investigate potential strategies to remediate soils that are threatened by these processes. To address this challenge, the current study investigated the effects of organic and inorganic amendments and leaching fraction (LF) on physical and hydraulic properties including the soil water characteristic curve (SWCC), Dexter's index of soil physical quality (SDexter), bulk density (BD), saturated hydraulic conductivity (Ks), and water repellency index (RI) in a saline‐sodic soil. A greenhouse experiment was carried out in a completely randomized design with two factors (amendment and LF). The amendments included superabsorbent (1%) (SA), zeolite modified with CaCl2 (2%) (ZC), biochar (2%) (B), biochar + manure (2%) (BM), and a control (no amendment) (CT), and combined with two levels of LF (15% and 30%). Spring wheat (Triticum aestivum, ‘UG99’) was planted in the soil columns. After harvest, undisturbed samples were collected from each column for the determination of soil properties. The results demonstrated the effectiveness of the SA and organic amendments to enhance Ks and decrease BD. There was a significant (p < 0.01) positive effect of the amendments, particularly biochar and superabsorbent on the soil pore size distribution. The SA amendment significantly increased soil water retention, especially at high matric potentials (i.e., 0 to −80 hPa). The effect of organic amendments on the SWCC was in between those of the ZC and SA amendments. The SA and BM treatments were sub‐critically water repellent, while the ZC treatment increased soil water repellency. The SA, B, and BM15 treatments exhibited very good physical quality (SDexter > 0.05). The relative air and moisture capacities were optimal in the B‐amended soil at field capacity (matric potential –330 hPa). We conclude that B, BM, and SA are suitable amendments for reducing the adverse effects of salinity and sodicity via an improvement in soil physical quality.

&lt;p&gt;Conservation tillage practices, such as reduced tillage, are often considered beneficial regarding soil fertility and sustainability. However, a risk of developing a shallow compact hardpan is associated with these practices that can hinder optimal water and gas transport within the root zone and thus impact soil health and productivity. To explore this risk, we compared conventional mouldboard ploughing (to 30 cm depth; MP) and reduced tillage (5-7 cm; RT) in a long-term experiment (approximately 15 years) on sandy loam soil. The field was uniformly tilled to a depth of 15-20 cm depth after the termination of the experiment. We evaluated the soil water and gas flow variables (saturated hydraulic conductivity, gas diffusion, and effective air-filled porosity), and biological soil properties for the 20-30 cm layer for the MP and RT treatments.&lt;/p&gt;&lt;p&gt;Soil was more compact in the reduced tillage treatment compared to conventional tillage, especially in the 20-30 cm soil layer. Soil bulk densities in the 20-30 cm soil layer were 1.62 and 1.80 g cm&lt;sup&gt;-3&lt;/sup&gt; in MP and RT treatments, respectively. There was no difference between the conventional and reduced tillage for effective air-filled porosity or gas diffusivity measured at -100 hPa water potential. Similarly, saturated hydraulic conductivity measured in the field was not different under the two tillage practices. The conventional tillage had 61% more earthworm abundance than the reduced tillage. The results indicated that despite the formation of a compact hardpan at 20-30 cm soil layer, as characterized by a higher bulk density, there were little to no effects of tillage on the soil functions related to water and gas transport. Moreover, the linkages between the soil physical quality indicators and microbial indicators (enzyme activity, microbial biomass carbon and nitrogen) were also explored.&lt;/p&gt;

&lt;p&gt;Soil compaction of agricultural systems due to the passage of heavy machinery persistently impairs the soil physical, hydrological, and biogeochemical functioning. Despite the existence of numerous studies on the influence of compaction on soil and plant characteristics, we lack studies translating such impacts into soil-related ecosystem services. Therefore, we aimed to develop five indices of compaction impacts on ecosystem services related to soil, including fresh water supply, food, feed, and fiber production, microbial habitat provision, climate regulation, and water purification. First, we selected the most appropriate soil quality indicators for each ecosystem service based on literature data and expert knowledge. Second, we scored each indicator using the fuzzy logic method and standardized scoring functions. Third, we summed the indicators and divided them by the number of the indicators to achieve a total index for each ecosystem service. Finally, we combined the five individual indices to attain a composite index for the soil-related ecosystem services. We validated the developed ecosystem services indices using experimental data of soil compaction impacts. The results showed that the five indices and the composite index were able to detect the impacts of soil compaction on the investigated ecosystem services. We advocate the use of such indices or composite index to assess how soil compaction interferes with the delivery of soil-related ecosystem services in agricultural systems.&lt;/p&gt;