Search Results (6)

Soil acidification is a significant form of agricultural soil degradation, which is accelerated by irrational fertilizer application. Sweetpotato and wheat rotation has emerged as an important rotation system and an effective strategy to optimize nutrient cycling and enhance soil fertility in hilly areas, which is also a good option to improve soil acidification and raise soil quality. Studying the effects of different fertilization regimes on soil acidification provides crucial data for managing it effectively. An eight-year field experiment explored seven fertilizer treatments: without fertilization (CK), phosphorus (P) and potassium (K) fertilization (PK), nitrogen (N) and K fertilization (NK), NP fertilization (NP), NP with K chloride fertilization (NPK1), NP with K sulfate fertilization (NPK2), and NPK combined with organic fertilization (NPKM). This study focused on the soil acidity, buffering capacity, and related indicators. After eight years of continuous fertilization in the sweetpotato–wheat rotation, all the treatments accelerated the soil acidification. Notably, N fertilization reduced the soil pH by 1.30–1.84, whereas N-deficient soil showed minimal change. Organic fertilizer addition resulted in the slowest pH reduction among the N treatments. Both N-deficient (PK) and organic fertilizer addition (NPKM) significantly increased the soil cation exchange capacity (CEC) by 8.83% and 6.55%, respectively, compared to CK. Similar trends were observed for the soil-buffering capacity (pHBC). NPK2 increased the soil K⁺ content more effectively than NPK1. NPKM reduced the sodium and magnesium content compared to CK, with the highest magnesium content among the treatments at 1.60 cmol·kg⁻¹. Regression tree analysis identified the N input and soil magnesium and calcium content as the primary factors influencing the pHBC changes. Structural equation modeling showed that the soil pH is mainly influenced by the soil ammonium N content and pHBC, with coefficients of −0.28 and 0.29, respectively. Changes in the soil pH in the sweetpotato–wheat rotation were primarily associated with the pHBC and N input, where the CEC content emerged as the main factor, modulated by magnesium and calcium. Long-term organic fertilization enhances the soil pHBC and CEC, slowing the magnesium reduction and mitigating soil acidification in agricultural settings. Full article

The accumulation of nitrite is frequently overlooked, despite the fact that nitrification is the most essential phase of the entire nitrogen (N) cycle and that nitrifying bacteria play a significant role in nitrification. At present, the effects of different N application rates on soil nitrite-oxidizing bacteria (NOB) abundance, community composition, diversity, and its main influencing factors are still unclear. In this study, five N fertilizer application rates under film mulching and a drip irrigation system were studied in the semi-arid area of Northeast China. The treatments were 0 kg ha⁻¹ (N0), 90 kg ha⁻¹ (N1), 150 kg ha⁻¹ (N2), 210 kg ha⁻¹ (N3), and 270 kg ha⁻¹ (N4). Fluorescent quantitative PCR and Illumina Miseq sequencing were used to analyze the abundance and community structure of NOB under different amounts of N application. The results showed that the increase in amounts of N application was strongly accompanied by an increase in the content of soil organic matter (SOM), total nitrogen (TN), nitrate nitrogen (NO₃⁻-N), and ammonium nitrogen (NH₄⁺-N), while the pH significantly reduced with an increase in N fertilization. N fertilization significantly increased soil nitrite oxidoreductase (NXR) activity, soil nitrification potential (PNR), and soil nitrite oxidation potential (PNO). A high N application rate significantly heightened the abundance of Nitrospira- and Nitrobacter-like NOB. N fertilizer considerably raised the Shannon index of Nitrospira-like NOB. The N application amount was the key factor affecting the community structure of Nitrospira-like NOB, and available nitrogen (AN) had the dominant influence on the community structure of Nitrospira-like NOB. N fertilizer can cause soil acidification, which affects NOB abundance and diversity. Nitrospira-like NOB may promote nitrite oxidation in different N application rates under a mulched fertigation system. The findings offered a crucial scientific foundation for further investigation into how nitrite-oxidizing bacteria respond to N fertilizer management strategies in farmland soil under film mulching drip irrigation in Northeast China. Full article

Conventional farming practices can provide higher agricultural yields through the extensive use of fertilizers, pesticides, and other inputs. These practices have been associated with severe environmental effects, such as eutrophication, acidification, etc. Laser technology, among many other techniques, could be a viable option for environmental reduction if incorporated into agricultural production systems. However, the environmental performance of using lasers in agriculture practices needs to be investigated in order to provide sustainable management of the agriculture sector. Therefore, in this study, the life cycle assessment (LCA) of laser-induced maize production in bio-stimulated seeds was compared to conventional farming practices using the software SimaPro ver. 9.0. The study emphasized human toxicity, freshwater ecotoxicity, and marine ecotoxicity due to their significant contributions. The results demonstrated that laser technology was an environmentally friendly system for treating maize seeds before sowing. The study further identified the mineral fertilization process as the most critical threat to the environment. Based on normalization, maize production process-related toxicity accounts for the highest environmental impacts of 8.2 and 7.3 kg 1,4-DCB/ton of grain produced by conventional practices and laser maize production, respectively, on the general environmental profile. At the endpoint level, the irradiated maize seeds performed better than their non-irradiated counterpart impacting human health at 5.46 × 10⁻³ DALY, ecosystems at 1.86 × 10⁻⁵ species⋅year, and resources at 60.74 USD 2013. Soil management was also identified as the conventional maize production process with the most significant environmental impacts. The greatest observed impacts were on marine ecotoxicity (19.23 kg 1,4-DCB) and freshwater ecotoxicity (12.94 kg 1,4-DCB) per ton of grain produced. The evaluation of potential human toxicity concluded that zinc contributed more than 90% in ReCiPe 2016 Midpoint (H) and benzene contributed approximately 22% in CML 2000. The study concluded that improved environmental performance was obtained for laser-induced maize production compared to conventional farming practices. The LCA can provide information to policymakers and government agencies about shifting to more sustainable agricultural practices in arid regions, such as Iraq, prone to drought linked to water availability and soil salinity. Full article

The long-term overuse of fertilizers negatively affects soil chemical properties and health, causing unsustainable agricultural development. Although many studies have focused on the effects of long-term fertilization on soil properties, few comparative and comprehensive studies have been conducted on fertilization management over the past 35 years in China. This meta-analysis (2058 data) evaluated the effects of the fertilizer, climate, crop types, cultivation duration and soil texture on the soil chemical properties of Chinese croplands. NPKM (NPK fertilizers + manure) led to the highest increase in pH (−0.1), soil organic carbon (SOC) (+67%), total nitrogen (TN) (+63%), alkali-hydrolysable nitrogen (AN) (+70%), total phosphorus (TP) (+149%) and available potassium (AK) (+281%) compared to the unfertilized control, while the sole nitrogen fertilizer (N) led to the lowest increase. The SOC (+115%) and TN (+84%) showed the highest increase under the influence of NPKM in an arid region. The increase in the chemical properties was higher in unflooded crops, with the maximum increase in the wheat–maize rotation, compared to rice, under NPKM. The SOC and TN increased faster under the influence of organic fertilizers (manure or straw) compared to mineral fertilization. Fertilizers produced faster effects on the change in the SOC and TN in sandy loam compared to the control. Fertilizers showed the highest and lowest effects on change in pH, organic C to total N ratio (C/N), TP and TK in clay loam with the cultivation duration. NPKM greatly increased the C/N compared to NPK in an arid region by 1.74 times and in wheat by 1.86 times. Reaching the same SOC increase, the lowest TN increase was observed in wheat, and the lowest increase in TP and AK was observed in rice, compared to the other crops. These results suggest that organic fertilizers (manure or straw) play important roles in improving soil fertility and in acidification. NPKM greatly increased the potential for soil C sequestration in wheat and in the arid region. The small increases in TP and TK can increase the SOC in rice and in the humid region. Therefore, considering the crop types and climatic conditions, reduced fertilization and the combination of mineral fertilizers with manure may be the best ways to avoid agricultural soil deterioration and increase soil carbon sequestration. Full article

Soil acidification is a global issue that often results in increased aluminum (Al) toxicity. While no-till (NT) management has many benefits regarding sustainability, a discrete zone of acidification often occurs when ammoniacal fertilizers are banded below the seed. The full agroecological consequences of NT stratification and impacts on bacterial communities are largely unknown. Using next-generation sequencing (NGS) and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt), we characterized the influence of liming amendment and soil stratification on bacterial community composition and predicted function in 2-cm depth increments. Soil depth, pH, DTPA extractable aluminum (DTPA-Al), and KCl extractable Al (KCl-Al) were all significantly correlated with bacterial community structure and function. In soils with the lowest pH and greatest extractable Al, bacterial community was distinct, with highest relative abundance of the Koribacteraceae family, an indicator of soil degradation. Additionally, aspects of bacterial metabolism and nutrient turnover were impacted in the lowest pH zones, including secondary metabolite, carbohydrate, and energy metabolism. These results suggest that soil stratification (Al and pH) in NT systems has direct impacts on microbial community structure and function, potentially influencing ecosystem services at a highly resolved spatial scale within surface depths relevant to seed germination and emergence. Full article

Form and function of mycorrhizas as well as tracing the presence of the mycorrhizal fungi through the geological time scale are herein first addressed. Then mycorrhizas and plant fitness, succession, mycorrhizas and ecosystem function, and mycorrhizal resiliency are introduced. From this, four hypotheses are drawn: (1) mycorrhizal diversity evolved in response to changes in Global Climate Change (GCC) environmental drivers, (2) mycorrhizal diversity will be modified by present changes in GCC environmental drivers, (3) mycorrhizal changes in response to ecological drivers of GCC will in turn modify plant, community, and ecosystem responses to the same, and (4) Mycorrhizas will continue to evolve in response to present and future changes in GCC factors. The drivers of climate change examined here are: CO₂ enrichment, temperature rise, altered precipitation, increased N-deposition, habitat fragmentation, and biotic invasion increase. These impact the soil-rhizosphere, plant and fungal physiology and/or ecosystem(s) directly and indirectly. Direct effects include changes in resource availability and change in distribution of mycorrhizas. Indirect effects include changes in below ground allocation of C to roots and changes in plant species distribution. GCC ecological drivers have been partitioned into four putative time frames: (1) Immediate (1–2 years) impacts, associated with ecosystem fragmentation and habitat loss realized through loss of plant-hosts and disturbance of the soil; (2) Short-term (3–10 year) impacts, resultant of biotic invasions of exotic mycorrhizal fungi, plants and pests, diseases and other abiotic perturbations; (3) Intermediate-term (11–20 year) impacts, of cumulative and additive effects of increased N (and S) deposition, soil acidification and other pollutants; and (4) Long-term (21–50+ year) impacts, where increased temperatures and CO₂ will destabilize global rainfall patterns, soil properties and plant ecosystem resilience. Due to dependence on their host for C-supply, orchid mycorrhizas and all heterotrophic mycorrhizal groups will be immediately impacted through loss of habitat and plant-hosts. Ectomycorrhizal (ECM) associations will be the principal group subject to short-term impacts, along with Ericoid mycorrhizas occurring in high altitude or high latitude ecosystems. This is due to susceptibility (low buffer capacity of soils) of many of the ECM systems and that GCC is accentuated at high latitudes and altitudes. Vulnerable mycorrhizal types subject to intermediate-term GCC changes include highly specialized ECM species associated with forest ecosystems and finally arbuscular mycorrhizas (AM) associated with grassland ecosystems. Although the soils of grasslands are generally well buffered, the soils of arid lands are highly buffered and will resist even fairly long term GCC impacts, and thus these arid, largely AM systems will be the least affect by GCC. Once there are major perturbations to the global hydrological cycle that change rainfall patterns and seasonal distributions, no aspect of the global mycorrhizal diversity will remain unaffected. Full article