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Variation in SOC affects the global carbon cycle and climate change and it also determines differences in soil fertility and consequently the plant communities growing in different habitats. The overall goal of this study is to determine variation in SOC in the soils associated with two trees that dominate forests in the highlands of southwestern Saudi Arabia. Juniperus procera dominates forests at higher elevation sites and Acacia gerrardi dominate forests at lower elevations in these highlands. Soils of the J. procera study site had significantly higher mean values for SOC content and SOC density, compared to the mean values of the A . gerrardii study site. The mean value of SOC stock at the J . procera study site was higher than that of the A . gerrardii site, but these differences were not significant. Conversely, the value of soil bulk density (SBD) at the A . gerrardii was significantly higher compared to the J . procera study site. Values of SOC content and SBD were inversely related, and this relationship appeared stronger for the J . procera site. The higher SOC values of the J . procera study site appear to be influence by the significantly larger values of DBH, tree radius, and basal area of these trees, compared to the A . gerrardii trees. Values for five of six soil parameters did not differ significantly between the two study sites, but the clay content of the J . procera study site was significantly higher than the A. gerrardii site. SOC variation at the two study sites appears to be influenced by differences in elevation, climate, species identity, soil bulk density, and clay content. However, the relative importance of these factors on SOC variation was not assessed. Additionally, the roles of litterfall and understory vegetation in contributing to the SOC variation of these two forest ecosystems are yet to be determined. Juniperus procera and A . gerrardi , and the communities they occur in, should be the focus of effective management actions because these species and communities play an important role in carbon sequestration and are also important for biodiversity conservation and the maintenance of ecosystem function.

While cover crop residue (CR) incorporation offsets soil organic C (SOC) losses caused by plastic-film mulching (PFM), the microbial modulators and mechanisms of SOC accumulation remain poorly understood. Using functional gene microarray, soil enzyme activities, and soil density fractionation approaches, we investigated the mechanism, by incorporating CR (13.0 and 9 Mg ha−1 on a dry weight basis) under PFM in organic maize cropping systems, spanning 2 consecutive years. Compared to no-mulching, PFM without CR amendment significantly decreased SOC stock by 23%, corresponding to an increase in CO2 efflux by 74%, a decrease in light fraction C (LFOC) and heavy fraction C (HFOC) by 13 and 11%, respectively, and an increase in relative abundances of labile as well as recalcitrant C-degrading genes and related soil enzyme activities. However, PFM with CR amendment reduced the SOC stock loss to 11%, corresponding to 36% increase in CO2 efflux, 22% decrease in LFOC but 12% increase in HFOC, and an increase in relative abundances of labile C-degrading genes and related soil enzyme activities but a decrease in relative abundances of recalcitrant C-degrading genes and related soil enzyme activities. Our results, based on microbial functional genes, suggest that reduced degradation of recalcitrant C was responsible for increased mineral-associated C and thus SOC accumulation under PFM in organically cultivated maize.

Exploring the impact of different tillage practices on soil moisture retention and crop yield in dryland winter wheat- spring maize rotation on the Loess Plateau is crucial for enhancing rainfall utilization and advancing tillage systems in arid agricultural regions. A long-term field experiment was conducted from 2019 to 2021 in the Weibei dryland area of the Loess Plateau to investigate the effects of conservation tillage. Continuous tillage (CC) was used as the control, with three alternative methods: no-tillage (NN), subsoiling (SS), and a combination of no-tillage and subsoiling (NS). The study assessed the impact of these tillage practices on soil water retention, bulk density, relative chlorophyll content, crop yield, and water use efficiency during both the fallow period and the growing seasons of winter wheat and spring maize. The results revealed the following: (1) All treatments effectively reduced soil bulk density in the 0–60 cm soil layer relative to pre-experiment levels and increased soil porosity. Among the treatments, NS was the most effective, reducing the average bulk density in the 0–60 cm layer by 0.1–0.2 g cm⁻³ and increasing porosity by 2.0-5.5% compared to the other treatments. (2) During the fallow period, tillage treatments significantly enhanced soil water content and storage compared to CC, with NN and NS treatments showing superior water retention effects. (3) In the winter wheat growing season, the average soil water content in the 0–200 cm layer for the NN, SS, and NS treatments was 4.8%, 5.4%, and 3.5% higher than that of CC, respectively. During the spring maize growing season, the increases were 49.3 mm, 17.7 mm, and 36.3 mm, respectively. All tillage treatments resulted in higher soil water storage in the 0–200 cm layer compared to CC, with NN being the most effective during the winter wheat season and SS during the spring maize season. (4) Compared to CC, all tillage treatments improved SPAD values, with NS showing the most significant effect. (5) All treatments increased the yields of both winter wheat and spring maize compared to the control, with increases of 5.4-10.0% for winter wheat and 7.3-18.7% for spring maize. Notably, NS significantly boosted crop yields. Water use efficiency improved by 1.2-6.0% for winter wheat and 5.5-31.3% for spring maize, with SS improving water use efficiency for winter wheat and NS for spring maize. In conclusion, the combination of no-tillage and subsoiling significantly improves soil quality, crop yield, and water use efficiency in the drylands of the Loess Plateau. This makes it a promising tillage practice for the sustainable development of dryland agriculture.

Two field experiments were conducted at Kafr El Sheikh Gov., Egypt, during two winter growing seasons (2020/2021 and 2021/2022). The objective of this study was to improve some chemical and physical properties of soil and the yield and water productivity of faba beans (Viciafaba L.), Cv. Sakha-4 by application of gypsum, compost, and some nanoparticles in salt-affected soils. The experimental treatments were arranged in a split-plot design with three replications. The main plots had the following soil amendments: T1: control treatment, T2: 10 tons compost/hectare, T3: soil gypsum requirement (GR) of 8.59 ton ha−1, and T4: GR + 10 tons compost/hectare. The subplots were treated with foliar application as follows: no treatment, manganese nanoparticles (Mn-NPs), selenium nanoparticles (Se-NPs), and Mn-NPs + Se-NPs. According to the findings, the application of compost + GR significantly decreased soil salinity (EC), exchangeable sodium percentage (ESP), and soil bulk density (BD). However soil porosity, soil penetration resistance (SPRa), and basic soil infiltration (IR) were significantly increased. On the other hand, the results revealed significant positive effects onthe 100-grain weight as well as proline, chlorophyll, superoxide dismutase, and catalase contents due to the interaction between gypsum + compost and Mn-NPs + Se-NPs, which enhanced the productivity of both the seed and straw yields of faba beans compared to the alternative treatments. In addition, the seed yield and irrigation water productivity (PIW, kg m3) of faba beans were significantly increased with addition of gypsum and compost and foliar application of nanoparticles. The highest values of these parameters were achieved due to the interaction between gypsum + compost and Mn-NPs + Se-NPs. It can be concluded that application of GR of 8.59 ton ha−1 and 10 ton ha−1 compost as well as foliar application of Mn-NPs and Se-NPs may be a key strategy for improving some chemical and physical properties of soil and the yield and water productivity of faba beans in salt-affected soil under these experimental conditions.

PurposeSuperabsorbent polymers, new water-saving materials and soil conditioners, are used widely in dry-farming agriculture. However, little is known about their effects on the soil physical properties under dry-farming conditions. To elucidate the effects of two SAPs (Wote and microbe) at different doses on the soil bulk density, water status, potato growth, yield, and economic benefit in a dry-farming region, we conducted a 2-year fixed field position experiment in the semiarid drought-prone area of Ningxia, China.Materials and methodsThe two SAPs were diluted 1:10 (product:soil) and applied at different rates before planting, i.e., Wote SAP 30 kg ha−1, Wote SAP 60 kg ha−1, Wote SAP 90 kg ha−1, microbe SAP 30 kg ha−1, microbe SAP 60 kg ha−1, and microbe SAP 90 kg ha−1. The treatment without SAP was used as the control.Results and discussionThe tilth soil bulk density decreased under different SAP doses compared with the control, and the soil total porosity improved greatly, where the Wote SAP treatments had the greatest effects. The soil bulk density (0–60 cm) under Wote SAP 90 kg ha−1 was significantly decreased by 6.4% compared with the control. The Wote SAP treatments had the greatest effects on water conservation during the critical potato growth stage, where the soil water storage (0–100 cm) was significantly higher than the control. The Wote SAP treatments promoted potato growth in the later period, where the plant height and stem diameter were higher than the control. Higher yield and commodity rate improvements were achieved by the application of Wote and microbe SAP compared with the control, where the optimum dose was 60–90 kg ha−1 for Wote SAP. The application of Wote SAP 90 kg ha−1 significantly increased crop water use efficiency compared with no SAP, and the commodity rate was highest with Wote SAP 60 kg ha−1. The mean potato yield, commodity rate, and net income increased significantly using Wote SAP at 60 and 90 kg ha−1, i.e., by 38.2 and 50.5%, 18.5 and 14.1%, and 28.5 and 35.0%, respectively, compared with no SAP.ConclusionsThe application of SAPs can decrease soil bulk density and significantly improve soil porosity and soil water conservation capacity, thereby promoting potato growth. The application of Wote SAP 60–90 kg ha−1 significantly increased potato yield and net income in a dry-farming region of Ningxia, China.

Compared with long-term and continuous application of large amounts of chemical fertilizers, fertilizers with microbial organic nutrient sources can improve soil environment, increase soil fertility and increase crop yield. In view of the current low soil fertility and poor soil environment leading to low crop yield and instability in the arid regions of northwest China, the effects of organic fertilizer with microbial nutrient sources on soil nutrients and pumpkin yield were studied in 2022 and 2023 in this region. The fertilizer application level was used as control factor, with four treatments of low level (L), medium level (M), high level (H), and a conventional fertilizer control (CK). The results showed that the high application level of organic fertilizer was more beneficial to the growth of pumpkin, and the stem diameter, vine length, and leaf area of pumpkin under H treatment were the highest from 2022 to 2023. Compared to CK, the average soil bulk density was significantly decreased by 8.27–18.51% (P< 0.05); the soil organic carbon, available phosphorus, available potassium, and nitrate nitrogen under H treatment were increased by an average of 32.37%, 21.85%, 18.70%, and 36.97%, respectively. Under different organic fertilizer treatments, the pumpkin yield under M treatment was the highest, reaching 30926.18 kg·ha -1 , followed by H treatment. compared to CK, M and H treatments increased the yield by 25.26% and 7.01%, respectively, and improved water use efficiency by 14.18% and 2.21%, respectively. Redundancy analysis (RDA) of soil nutrients, pumpkin growth dynamics and yield in 2022 and 2023 showed that soil organic carbon, available phosphorus, available potassium, nitrate nitrogen, and water use efficiency were significantly positively correlated with pumpkin yield (P<0.01). In conclusion, H and M treatments can improve soil fertility promote pumpkin growth and development, and ultimately increase pumpkin yield. In summary, medium organic fertilizer level (M=5700 kg·ha -1 ) is recommended as the fertilization scheme for local pumpkin cultivation.

Large sample sizes are crucial for accurately capturing spatial changes in soil properties by spatial interpolation methods. However, soil bulk density (BD) data in historical datasets is often incomplete, and it’s uncertain if filled values enhance spatial interpolation accuracy. Using 2,883 cropland soil BD samples from the Sichuan Basin in China, we developed the best prediction models from traditional pedotransfer function (PTF), multiple linear regression (MLR), random forest (RF), and radial basis function neural network (RBFNN) to fill missing BD values for 1,336 samples. We then applied ordinary kriging (OK) and inverse distance weighting (IDW) to map soil BD, incorporating the filled BD as modeling points. The RBFNN model, tailored for each sub-watershed, yielded the highest accuracy in filling missing BD, with an increase in coefficient of determination ( R 2 ) by 19.54–37.36% and reductions in mean absolute error (MAE), mean relative error (MRE) and root mean square error (RMSE) by 8.91–14.81%, 9.02–16.22% and 7.71–13.61%, respectively. Incorporating filled BD data reduced the MAE, MRE, and RMSE of OK and IDW by 4.17%, 4.36%, 4.96%, and 6.54%, 6.92%, 8.15%, respectively, significantly lowering spatial interpolation uncertainty. This methodology improves the accuracy of soil property mapping in regions with incomplete historical data.

Aims Soil compaction is a major yield-reducing factor worldwide and imposes physico-chemical constraints to plant growth and development. Facing limitations, roots can adapt and compensate for loss of functioning through their plasticity. Being primarily a belowground challenge, tolerance to soil compaction needs to be associated with root phenotype and plasticity. It is therefore of importance to distinguish between size-related apparent and size-independent adaptive plasticity. We determined the above- and belowground plasticity of sorghum genotypes varying in overall plant size. Methods We quantified plasticity as the degree response (adaptive and apparent plasticity) to soil compaction and conducted two experiments with sorghum and two soil density levels (1.4 and 1.8 Mg m −3 ). First, we quantified the shoot biomass plasticity of 28 sorghum genotypes. Second, we studied the root plasticity of six genotypes varying in shoot size and tolerance to soil compaction. Results Plasticity was correlated with plant biomass with larger genotypes responding earlier and more intensely. Soil compaction affected roots more than shoots and plasticity was expressed foremost in nodal root number and fine root length. Impeded plants produced 35 and 47% less root mass and length, respectively. Conclusions Plasticity to soil compaction varies among genotypes, but less-sensitive lines are in general smaller-sized genotypes. The association between tolerance and plant biomass may pose challenges to crop production; however, vigorous genotypes with unresponsive shoots to soil compaction do exist. Maintaining shoot growth relatively stable while the root modifies its structure can be an important adaptation mechanism to soil compaction.

Large-scale land reclamation has become common in northwestern China; however, low soil fertility and poor soil water-holding capacity limit agricultural production on these reclaimed lands, requiring increased fertilizer and irrigation inputs. Biochar, produced from agricultural waste, has shown potential in improving soil quality and water-holding capacity. In this two-year field study (2021 and 2022), we investigated the effects of biochar produced from maize straw on soil properties and grain yield of foxtail millet grown on newly reclaimed land. Three biochar treatments (3000, 4500, and 6000 kg ha−1) were compared to a control (CK) with no biochar application. Biochar application resulted in increased soil organic matter, total phosphorus, total nitrogen, soil enzyme activity, and soil organic acid content. It also significantly decreased soil pH and bulk density. Compared with the CK, biochar increased available nitrogen from 29.7% to 108% in 2021 and 37.0% to 88.4% in 2022. Similarly, biochar increased available phosphorus from 64.7% to 143% in 2021 and 41.9% to 96.5% in 2022. Grain yields ranged from 3092 to 4753 kg ha−1. Biochar treatments increased grain yield compared to the CK, ranging from 12.2% to 24.6% in 2021 and 27.1% to 53.7% in 2022. Correlation analysis revealed that soil pH was negatively related to soil oxalic acid content, phosphorus content, and sucrase activity. Available nitrogen and phosphorus contents were negatively related to soil bulk density and positively related to catalase activity. Soil water content was negatively correlated with soil bulk density and positively correlated with organic matter. In conclusion, biochar improved the rhizosphere soil pH and the effectiveness of soil fertility in the newly reclaimed soil, resulting in an enhanced grain yield of foxtail millet.

Graphene waste has had enormous growth due to many industrial applications. Agriculture exploits waste through the circular economy, and graphene waste is thereby investigated in this study as a soil conditioner for improving the physical–hydraulic properties of soil. Experiments were performed on three differently textured soils amended with traditional soil conditioners (compost, biochar, and zeolites) and graphene. The conditioners were applied at two different doses of 10% and 5% dry weight (d.w.) for compost, biochar, and zeolites, and 1.0% and 0.5% d.w. for graphene. We compared (i) the major porosity classes related to water-retention characteristics (drainage, storage, and residual porosity), (ii) bulk density, and (iii) van Genuchten water-retention curve (WRC) characteristics. Graphene application caused the largest decrease in dry bulk density (ρb), lowering the soil bulk density by about 25%. In fact, graphene had ρb of 0.01 g/cm3. The effects of graphene were more intense in the finer soil. Compost and biochar showed similar effects, but of lower magnitude compared to those of graphene, with ρb of 0.7 and 0.28 g/cm3, respectively. Although zeolites had ρb of 0.62 g/cm3, they showed quite different behavior in increasing the mixtures’ ρb. Graphene and biochar showed the most pronounced effects in the clayey soil, where storage porosity showed a reduction of >30% compared to the control. For storage porosity, the graphene treatments did not show statistically significant differences compared to the control. The results show that, when the conditioner increased drainage porosity, there was a high probability of a concomitant reduction in storage porosity. This finding indicates that graphene use for improving soil aeration and drainage conditions is viable, especially in fine soils.