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This work presents the advantages and risks of selected soil quality criteria using data from the monitoring of agricultural soils in the Czech Republic. Soil samples were taken from 71 sites covering various soil types. Basic soil parameters and mid-infrared spectra were measured. Indicators describing the quality of soil organic matter (SOM), and soil were calculated. The results show that soil types differ significantly in the qualitative indicators of soil organic matter. More acidic soils with lower clay content contain lower proportions of aromatic and higher proportions of aliphatic organic compounds than neutral soils with higher clay particles content. These soils differ little in total carbon content and C/N ratio but considerably in C/clay ratio. Cambisols are the least degraded soils in the Czech Republic in terms of C/clay ratio, which is controversial in many respects. The results indicate that more aliphatic organic matter is important for the SOM content in the upper part of the agricultural soil, and more aromatic organic matter is mainly bound to the clay fraction. The results raise questions about the suitability of uniform C/clay target values proposed in European legislation as a criterion for assessing soil degradation due to carbon loss. [ABSTRACT FROM AUTHOR]

Agriculture is the main economic activity of Mozambique and there is a lack of information about the quality of agricultural soils. In this paper, five soils from the Manica and Sussundenga districts (Manica province) sampled in the years 2021/2022 and 2022/2023 (before and after the rainy seasons) were subjected to an agronomical and environmental chemical analysis to assess their quality, from the fertility and environmental contamination points of view. Standard analytical methodologies from external certified laboratories and local X-ray fluorescence measurements were used. All the studied soils were acidic (pH ranging from 4.5 to 5.4), had no salinity problems (conductivity ranging from 4.2 to 11.8 mS/m), and had a low amount of soil organic matter (0.90% to 1.81%). Soils from the Sussundenga district had a very low cation exchange capacity (CEC) (average of 3.33 cmolc/kg), while that of those from the Manica district ranged from very low to average CEC (3.59 to 13.11 cmolc/kg). Sussundenga soils also had a phosphorous deficiency (values ranging from <20 to 38.5 mg/kg) and there were deficiencies and/or excesses of some macro and micronutrients in all soil samples. Manica soils were contaminated, apparently from geogenic origin, with Cr (280 to 1400 mg/kg), Co (80 mg/kg), Ni (78 to 680 mg/kg) and V (86 mg/kg). Agricultural soil monitoring must be fostered in Mozambique in order to improve food quality and quantity to ensure economic and environmental sustainability. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) emissions occur as a consequence of the turnover of soil nitrogen (N), but gross N transformations and N2O production are often not studied in combination, so the relationships are poorly understood. Here, we quantified gross N transformations and the N2O production pathway of alkaline fluvo-aquic soils under different fertilization regimes collected from a long-term field experiment in the North China Plain and compared them with six acidic UK soils (one was alkaline for reference) with high soil organic carbon (SOC). We found that nitrification was the dominant N2O production pathway in the alkaline Chinese soil with a contribution of nitrification to N2O emissions (N2Onit) of 81%. By contrast, denitrification was the main N2O production pathway for the acidic UK soils with the contribution of denitrification to N2O emissions (N2Oden) of 66%. Long-term manure applications significantly increased N2Oden, compared to the synthetic N and no N treatments (25% vs. 18%). The N2Onit was positively correlated with gross autotrophic nitrification rates and pH but negatively correlated with gross N mineralization, SOC, soil total N content, and C:N ratios. Our findings highlight the importance of soil pH in controlling the N2O production in cropland soils, and suggest that the increased contribution of denitrification to N2O emissions should be considered, when increasing SOC through long-term manure and straw management for carbon sequestration and soil fertility improvement. [ABSTRACT FROM AUTHOR]

The main purpose of the present study, conducted in the Piedemonte Llanero of Colombia, was to identify the role of covariates that influence soil properties under different land uses by analyzing the dynamics of selected soil properties in natural and agricultural areas. Soil samples were collected from 90 different sites throughout the region, 45 from areas with agricultural activities and 45 natural areas or areas with low anthropic intervention. The studied soils were strongly acidic (pH < 5.5), had low organic matter contents (1.73% and 2.34% on average in agricultural soils and natural areas, respectively) and, in general, represented poor conditions for agricultural production. The use of multivariate analysis showed that altitude was an important influence on soil properties. Moreover, it was found that land use influenced soil properties, which may limit productive capacity. The results presented here help to clarify the relationships between soils, climate, and landforms in an equatorial climate. [ABSTRACT FROM AUTHOR]

Background: In search for more sustainable crop production, the subsoil has recently come into focus as considerable reservoir of nutrients and water. Aims: Dimensions of subsoil phosphorus (P) reserves are yet largely unknown but crucial for identifying regions suitable to include subsoil into sustainable management strategies. Methods: We analyzed stocks of total and plant‐available (calcium acetate lactate‐extractable) P in 96 representative soil profiles of German arable land down to 1 m depth. Results: We found that the German arable soils stored, on average, 8 t ha−1 of total P, of which nearly 500 kg ha−1 were readily plant‐available. Notably, one third of plant‐available P was located below the plow layer and one fifth even at depths below 0.5 m. The depth gradients of plant‐available P stocks were affected more by major reference soil group than by texture. Generally, Chernozem but also Anthrosol, Gleysol and Fluvisol exhibited the largest P stocks in German cropland. The contribution of plant‐available P to total P stocks was larger in sandy and extremely acidic (pH < 4.5) soils compared with more fine‐grained and slightly acidic to alkaline soils, possibly because fertilization compensated for overall lower total P stocks at these sites. Generally, the more P was stored in topsoils, the more P was stored also in subsoils. Conclusions: A hypothetical crop utilization of 10% from plant‐available P stocks and 0.1% from total P stocks from shallow subsoil could compensate for P fertilization by ca. 8 kg ha−1, but the rate of plant‐available P replenishment in subsoil likely remains the crucial factor for the role of subsoil P stocks in crop nutrition. Generally, the large P reserves found in subsoil could act as an 'insurance' system for crops. [ABSTRACT FROM AUTHOR]

Summary: Accurate evaluation of metal bioavailability to hyperaccumulators is necessary for prediction of metal uptake and estimation of phytoextraction potential. Sedum plumbizincicola X.H. Guo et S.B. Zhou ex L.H. Wu (Crassulaceae), a hyperaccumulator of cadmium (Cd) and zinc (Zn), was grown in a pot experiment in 108 agricultural soils representing a wide range of typical Chinese soil types. The contribution of soil properties to Zn uptake was assessed quantitatively. Soil total Zn, soluble Zn, CaCl2‐extractable Zn and (DGT)‐extractable Zn concentrations (Zntotal, Znsoln, ZnCaCl2 and ZnDGT, respectively) were compared to predict shoot Zn concentration (Znshoot) using a piecewise equation. This showed a logarithmic increase with increasing Zntotal from 100–1000 mg kg−1 but plateaued outside this range. The optimum soil pH for Zn removal was ~ 5.5 and further acidification was unnecessary because Znshoot increased significantly with a decrease in pH from 7.5 to 5.5 and rarely changed at pH < 5.5. Sedum plumbizincicola grown in loamy or clay loam soils had larger Znshoot than in sandy or clay soils. The ZnCaCl2 was superior to other methods in estimating Zn bioavailability across all the data. At pH < 5.5, ZnCaCl2 showed much stronger correlation with Znshoot than Zntotal, Znsoln or ZnDGT. Piecewise equations (single linear regression equations at different intervals of soil properties) versus Zntotal and ZnCaCl2 at different pH ranges considerably increased the accuracy of prediction of Znshoot compared with the global equations derived from all data. Estimation of the potential of S. plumbizincicola for Zn phytoextraction in the field indicated that it is feasible to decontaminate acid‐polluted soils with Zntotal ≤ 500 mg kg−1 with S. plumbizincicola. Highlights: Zn bioavailability to hyperaccumulators needs to be estimated over a wide range of soil types.Piecewise equations considerably improved the prediction of shoot Zn concentration.CaCl2 extraction was more suitable than DGT for the estimation of Zn bioavailability.Decontamination with S. plumbizincicola is feasible for acid soils with Zntotal ≤ 500 mg kg−1. [ABSTRACT FROM AUTHOR]

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Microbially mediated soil nitrification process was largely limited by ammonia-oxidizing archaea (AOA) and bacteria (AOB), which further affect nitrogen (N) loss and retention with concomitant impacts on both crop productivity and environment. However, the spatial distribution of ammonia-oxidizers and their varying contributions to soil nitrification activity at provincial scale are poorly explored. 135 agricultural soils across different soil types and fertility conditions were collected from Henan province in North China Plain to draw the map of soil AOA and AOB abundance with quantitative PCR analysis. Soil nitrification potential (NP) and the relative contribution of AOA and AOB to NP that recovers after acetylene inactivation were essentially determined among the five major soil types. The abundance of ammonia-oxidizers, which was positively and significantly related with pH, was obviously predominated by AOA with AOA/AOB ranging 1.96–9.79 at provincial scale. AOA contributed more (at 60%–79%) to soil nitrification in acidic and neutral soils (Lime concretion black soil, Yellow-cinnamon soil, Paddy soil and Cinnamon soil) with significant relationships with its higher abundance, pH, soil organic carbon and ammonium nitrogen. On the contrary, the even contribution of AOB compared with AOA in alkaline Fulvo-aquic soil showed poor relationship with its abundance but was strongly affected by soil N availability. In summary, AOA even with lower abundance showed stronger function in acidic and ammonia-limited soil environments, but AOB with higher abundance tends to be the leader of soil nitrification in alkaline and substrate-rich soils of Henan province. • AOA dominated the ammonia-oxidizing populations with wide adaptation. • The contribution of AOA to soil nitrification decreased with increasing pH. • Strong contribution of AOA to nitrification significantly related to its abundance. • Contribution of AOB to nitrification in alkaline soils was related with substrate. [ABSTRACT FROM AUTHOR]

• This study tests the effects of acid rain on soil greenhouse gas emissions. • High-intensity acid rain reduces the soil cumulative CH 4 flux. • Acid rain promotes microbial and arbuscular mycorrhizal fungal abundance. • CO 2 and CH 4 fluxes were negatively correlated with soil microbial biomass. • Soil NO 3 −-N content controls N 2 O emission. Since the advent of industrialization and urbanization, acid rain has emerged as one of the quintessential global environmental issues. However, the effects of acid rain on carbon (C) and nitrogen (N) cycles of terrestrial ecosystems are still far from fully understood, though some studies have reported the sensitivity of living organisms and soil physicochemical properties to acidic conditions. Herein, we conducted intact soil core experiments to understand the effects of artificial acid rains of pH 5.0, 4.0 and 3.0 on soil CO 2 , CH 4 , and N 2 O fluxes and microbial communities in an agricultural soil of southern China. We did not detect any effect of acid rain on CO 2 and N 2 O fluxes as compared to the control; however, acid rain of pH 3.0 significantly reduced the cumulative CH 4 flux from the soil. Most noticeably, both acid rains of pH 4.0 and pH 3.0 significantly increased the total amount of soil microbial phospholipid fatty acids (PLFAs) by increasing the PLFA contents of gram-positive bacteria, actinomycetes, fungi, and arbuscular mycorrhizal fungi, though all the acid rain treatments did not change the relative abundance of microbial groups. In addition, both CO 2 and CH 4 fluxes negatively correlated with the total amount of soil microbial PLFAs; however, the N 2 O flux positively correlated to soil NO 3 −-N contents (p < 0.05). These results confirm the recent theoretical predictions that N-addition (e.g., by acid rain) may alter microbial C utilization pattern by allocating more C to the microbial biomass than to respiration. Overall, our results demonstrated that acid rain substantially altered the soil microbial biomass, and reduced the cumulative CH 4 flux from the agricultural soil during the experimental period. Given these findings, we suggest further research to investigate the responses of soil greenhouse gas emissions and microbial communities to long-term acid rain exposures in the context of climate change. [ABSTRACT FROM AUTHOR]