Organic Soil Fertility Research Articles

Bioaccessibility Characterization of Organic Matter, Nitrogen, and Phosphorus from Microalgae-Bacteria Aggregates

The quality of microalgae-bacteria biomass as an organic soil fertilizer may depend on the biomass’s microbial composition, morphology, and growth history. This study aims to characterize the molecular complexity and bioaccessibility of organic matter, nitrogen, and phosphorus from microalgae-bacteria aggregates with different morphologies (flocs and granules) grown under nutrient-abundant and starvation conditions. A biochemical fractionation method was used based on sequential chemical extraction and fluorescence spectroscopy. Microalgae-bacteria aggregates were cultured and collected from photobioreactors using contrasting growth conditions to generate (i) loose flocs, (ii) consolidated flocs, (iii) smooth granules, and (iv) filamentous granules. The organic matter, nitrogen, and phosphorus from consolidated flocs were mostly extractable, accounting for up to 94% of their total content. In contrast, the organic matter from loose flocs was up to 50% non-extractable. The extractability of loose flocs was improved under starvation conditions. All microalgae-bacteria aggregates showed a low structural complexity, corresponding to an abundance of simple microbial-related constituents like tyrosine and tryptophane. Differences between the gradients of bioaccessibility for each microalgae-bacteria structure were related to the abundance of microorganisms and their metabolic products. The findings of this study have implications for the development of sustainable and environment-friendly organic fertilizers.Graphical

Understanding the Perspectives of Small-Scale Arable Crop Farmers on Soil Management Practices in Uhen L.G.A, Edo State

This study provides insights into the perceptions of small-scale arable crop farmers in Uhen L.G.A regarding soil management practices. A total of 50 questionnaires were administered to randomly selected farmers and the questionnaires covered various aspects, including demographics, farming and soil fertility management practices, awareness of organic agriculture, soil health, and soil fertility, as well as acceptance, viability, and sustainability of organic inputs. The findings revealed that the majority of the respondents were male, with a range of ages and educational backgrounds, mostly attaining secondary education with varying levels of farming and agricultural experience. Regarding farming and soil fertility management practices, respondents reported adopting practices such as tillage, mound/heaps/ridges, bush burning, mulching, and mixed cropping. Organic fertilization was more commonly used than inorganic fertilization, with reasons cited including availability, low cost, crop response, and long-term effects. Farmers recognized the importance of organic residue and soil organisms for soil health. However, there was limited awareness of organic agriculture among the respondents, and their knowledge of soil organisms and their contributions to soil health was moderate. The findings highlight the need for increased awareness and knowledge of organic agriculture and the potential benefits of organic inputs for soil health and fertility.

The effect of anaerobic digestate as an organic soil fertilizer on the diversity and structure of the indigenous soil microbial and nematode communities.

Anaerobic digestate is a popular soil additive which can promote sustainability and transition toward a circular economy. This study addresses how anaerobic digestate modifies soil health when combined with a common chemical fertilizer. Attention was given to soil microbes and, a neglected but of paramount importance soil taxonomic group, soil nematodes. A mesocosm experiment was set up in order to assess the soil's microbial and nematode community. The results demonstrated that the microbial diversity was not affected by the different fertilization regimes, although species richness increased after digestate and mixed fertilization. The composition and abundance of nematode community did not respond to any treatment. Mixed fertilization notably increased potassium (K) and boron (B) levels, while nitrate (NO3-) levels were uniformly elevated across fertilized soils, despite variations in nitrogen input. Network analysis revealed that chemical fertilization led to a densely interconnected network with mainly mutualistic relationships which could cause ecosystem disruption, while digestate application formed a more complex community based on bacterial interactions. However, the combination of both orchestrated a more balanced and less complex community structure, which is more resilient to random disturbances, but on the downside, it is more likely to collapse under targeted perturbations.

Enhancing soil health and strawberry disease resistance: the impact of calcium cyanamide treatment on soil microbiota and physicochemical properties.

Continuous strawberry cropping often causes soil-borne diseases, with 20 calcium cyanamide being an effective soil fumigant, pig manure can often be used as soil organic fertilizer. Its impact on soil microorganisms structure, however, remains unclear. This study investigated the effectiveness of calcium cyanamide and pig manure in treating strawberry soil, specifically against strawberry anthracnose. We examined the physical and chemical properties of the soil and the rhizosphere microbiome and performed a network analysis. Results showed that calcium cyanamide treatment significantly reduces the mortality rate of strawberry in seedling stage by reducing pathogen abundance, while increasing actinomycetes and Alphaproteobacteria during the harvest period. This treatment also enhanced bacterial network connectivity, measured by the average connectivity of each Operational Taxonomic Unit (OTU), surpassing other treatments. Moreover, calcium cyanamide notably raised the levels of organic matter, available potassium, and phosphorus in the soil-key factors for strawberry disease resistance and yield. Overall, applying calcium cyanamide to soil used for continuous strawberry cultivation can effectively decrease anthracnose incidence. It may be by changing soil physical and chemical properties and enhancing bacterial network stability, thereby reducing the copy of anthracnose. This study highlights the dual benefit of calcium cyanamide in both disease control and soil nutrient enhancement, suggesting its potential as a valuable tool in sustainable strawberry farming.

Improving organic grape production: the effects of soil management and organic fertilizers on biogenic amine levels in Vitis vinifera cv., 'Royal' grapes

BackgroundThe integration of organic viticulture practices in grape cultivation represents a pivotal advancement towards sustainable agriculture, emphasizing the importance of environmentally friendly methods that enhance soil health, grape quality, and overall ecosystem biodiversity, thereby contributing significantly to the resilience and long-term sustainability of viticultural ecosystems. This study explored the effects of soil management practices, including chisel, disc harrow, and no tillage, as well as the impact of utilizing Antep radish, broccoli, and olive blackwater as fertilizer applications, on the biochemical composition, specifically biogenic amines (BAs), in the clusters of the 'Royal' grape cultivar within a vineyard setting.ResultsThroughout the three-year study, no tillage soil management consistently emerged as the most influential soil treatment for enhancing BAs in 'Royal' grape berries, especially in combination with Antep radish and olive blackwater fertilizer applications. Among fertilizer applications, the nontreated control vines consistently had the highest concentrations of critical BAs, such as putrescine, cadaverine, histamine, and dopamine, across different soil management practices. Among the soil management practices and fertilizer applications evaluated, the disc harrow soil management and olive blackwater fertilizer application generally yielded the lowest concentrations of BAs across several metrics.The PCA biplots indicated that experimental years have a similar effect on BA content in grape berries, with specific amines such as serotonin and dopamine being more affected in 2020, while cadaverine, histamine, spermidine, trimethylamine, and norepinephrine were more influenced in 2021, and putrescine, spermine, agmatine, and tryptamine in 2022.ConclusionThese findings hold significant implications for organic agriculture, emphasizing the nuanced influence of soil management practices and organic fertilizers on the BA composition of grape berries. Our results indicate the potential of tailored agricultural strategies to enhance plant health and quality, aligning with the principles of sustainability and environmental stewardship inherent to organic farming.Graphical

Environmental viability and economic sustainability of tillage for wheat: Evidence from Croatia

A multidisciplinary field experiment was performed during three seasons for winter wheat in Croatia. The intention of this study was to examine and diagnose the effect of Tillage Systems (TS) on soil chemical properties (soil acidity, phosphorus, potassium, and organic matter content) as well as the outcome of economic indicators such as Gross Margin (GM), Rate of Profitability (ROP), cost-effectiveness (E) and productivity (P). TS were CT - plowing up to 30 cm depth; DT - disking up to 8-12 cm depth; LT - loosening up to 35 cm depth; NT - no-tillage. The experimental design was a randomised block design in four repetitions, where the basic TS plot was 540 m2. Soil sampling for 0-30 cm soil layer was done prior to setting up the experiment and after three seasons, a total of 320 soil samples and chemical analyses were performed according to standard pedological procedures. Economic indicators are calculated using economic equations and standards and statistical analysis was performed with SAS 9.3 and Microsoft Excel 2016. Generated results point that on systems with shallower tillage or no- tillage expressed accumulation of phosphorus and potassium appeared with distinct vertical stratification. At the same time, these TS ensured soil organic matter and soil fertility preservation. From the aspect of economic calculations, LT assigned the prime economic results. The ROP was in order CT (32.67%) < DT (37.39%) < LT (40.31%) < NT (42.29%). The same order was established for E, namely, CT (1.33) < DT (1.37%) < LT (1.40%) < NT (1.42%). NT established the best P because of the lowest costs of production, but due to significantly lower yield, NT has limited adoption in practice. The conservable and viable agricultural production by intermediation of reduced soil tillage systems has its capabilities and potency, firstly ecological, through providing soil degradation, and then economical by potentiating economic sustainability and financial efficiency of agricultural production.

Utilization of dried dairy cow feces as biogas substrate and biogas sludge as organic soil conditioner

Utilization of farm waste as an alternative energy source is a form of farm waste management, but field applications are not optimal. The purpose of this study is to find out to what extent the dried dairy cow feces can function as a biogas substrate for an overview of the number of anaerobic bacteria, the volume of bio-gas, and the use of organic carbon-containing biodiesel mud so that it can be used as an organic soil fertilizer. This study uses an experimental research method and looks at the results of an independent T test with two treatments: sundry and dry oven. The tests were done on days 0 (after 4 hours), 7, 14, 21, and 28. The water level, number of bacteria, volume of gas, and pH and organic C content of the biogas sludge were all recorded. The study's findings showed that the number of anaerobic bacteria on days 0 (after 4 hours), 7, 14, 21, and 28 and the amount of biogas on days 14 and 21 did not change whether the samples were dried in the sun or in a furnace. However, on days 7 and 28, the amounts of biogas changed depending on whether the samples were dried in the sun or in a furnace.

Soil organic carbon stocks and fertility in smallholder indigenous agroforestry systems of the North-Eastern mountains, Tanzania

Soil organic carbon and soil fertility are critical components of soil health and play a significant role in sustaining agricultural productivity. Indigenous agroforestry practices have been identified as an interesting avenue to sequester carbon and enhance soil fertility in tropical smallholder farms. However, that potential remains poorly quantified. To better understand the dynamics of soil organic carbon stocks and fertility, this study evaluated and compared 4 different smallholder indigenous agroforestry systems (i.e., Kihamba, Ginger, Miraba, and Mixed spices) in the northeastern volcanic and block mountains of Tanzania. Specifically, we compared old and young agroforestry systems in terms of soil organic carbon stocks and soil fertility (proxied by effective cation exchange capacity (eCEC)). In each agroforestry system, a network of old and young tree farm plots were selected for soil sampling at different depths and physico-chemical parameters were analyzed (soil organic carbon, texture, bulk density, pH-H2O, and eCEC). Our findings showed that there was no significant difference between young and old agroforestry systems in terms of soil organic carbon stocks, except in the Kihamba system on the slopes of Kilimanjaro. The highest soil carbon sequestering potential was found in the old Kihamba (located on Nitisols) compared to other systems on Acrisols. Young agroforestry in Ginger and Miraba appeared to have a higher capacity to sequester soil carbon than Mixed spices. Regarding eCEC levels, there was a significant difference between old and young agroforestry systems in both the Kihamba and Miraba system. At the 0–10 cm depth, the highest eCEC levels were found in young agroforestry for Kihamba, Miraba, and Mixed spices. Our results implied that specific management and restoration strategies should focus on optimizing soil fertility and carbon sequestration potential of agroforestry systems in the South Pare and Usambara Mountains characterized by low-fertility Acrisols.

Cassava growth and yield on ultisol of different soil organic carbon content and NPK fertilizer levels

The demand for cassava tuber in Indonesia is high, however, domestic production is still limited therefore increasing production is important. Ultisol soils have the potential for cassava production, but low soil fertility in such soils needs to be improved. The research aimed to evaluate the effect of soil organic carbon (SOC) and NPK fertilizer on the growth and yield of cassava tuber in an ultisol. The experiment was conducted at the Jonggol Experimental Farm, IPB Bogor, West Java from September 2022 to January 2023. The experiment used a split-plot design with three replications. The main plot was SOC level of 1.93 (control), 2, 3, and 4%, and the subplot was NPK 15-15-15 level of 150, 300, 450, and 600 kg ha-1. SOC level was increased through the application of cow manure 0, 3.59, 54.93, and 106.27 tons ha-1 corresponding to SOC levels of 1.93 (control), 2, 3, and 4%, respectively. Results showed that enhancing SOC up to 3% and NPK 300 kg ha-1 were enough to support cassava growth as shown by plant height, stem diameter, and leaf number. The leaf number was the highest in the 3% SOC+150 kg NPK, 2% SOC+300 kg NPK or+450 kg NPK, and control+600 kg ha-1 NPK treatment. Leaf greenness was only affected by adding NPK fertilizer; a high greenness value was obtained at NPK level of > 150 kg ha-1 and 300 to 600 kg ha-1 resulting in non-significantly leaf greenness. The status of N and K in the leaves increased by SOC and NPK treatments, while the P status was unaffected. SOC at a level of 3% and NPK at a level of 150 kg ha-1 stimulated cassava to produce the highest fresh tuber weight (1.85 kg per plant) at 4 months after planting. Cassava productivity in ultisol soil can be increased by applying cow manure of 54.93 tons ha-1 to enhance SOC up to 3% combined with NPK of 150 kg ha-1.
 Keywords: Extensification; food security; intensification; tuber production; nutrient uptake

Nitrate Source and Transformation in Groundwater under Urban and Agricultural Arid Environment in the Southeastern Nile Delta, Egypt

With the intensification of human activities, nitrate pollutants in groundwater are receiving increasing attention worldwide. Especially in the arid Nile Delta of Egypt, groundwater is one of the most valuable water resources in the region. Identifying the source of nitrate in groundwater with strong human disturbances is important to effective water resource management. This paper examined the stable isotopes (δ15N/δ18O-NO3 and δ2H/δ18O-H2O) and the hydrogeochemical parameters of the shallow groundwaters in the arid southeast of the Nile Delta to assess the potential sources and transformation processes of nitrate under severe urban and agricultural activities. The results revealed that the groundwaters were recharged by the Nile River. Meanwhile, the infiltration of irrigation water occurred in the west, while the mixing with the deep groundwater occurred in the east regions of the study area. The TDS, SO42−, NO3−, and Mn2+ concentrations of groundwaters (n = 55) exceeded the WHO permissible limit with 34.6%, 23.6%, 23.6%, and 65.5%, respectively. The NO3− concentrations in the shallow groundwaters ranged from 0.42 mg/L to 652 mg/L, and the higher levels were observed in the middle region of the study area where the unconfined condition prevailed. It extended to the deep groundwater and eastward of the study area in the groundwater flow direction. The δ15N-NO3 and δ18O-NO3 values suggested that the groundwater NO3− in the west and east regions of semi-confined condition were largely from the nitrification of soil organic nitrogen (SON) and chemical fertilizer (CF). In contrast, wastewater input (e.g., domestic sewage and unlined drains) and prevalent denitrification were identified in the middle region. The denitrification might be tightly coupled with the biogeochemical cycling of manganese. This study provides the first report on the groundwater NO3− dynamics in the Nile Delta, which generated valuable clues for effective water resource management in the arid region.

Unlike chemical fertilizer reduction, organic fertilizer substitution increases soil organic carbon stock and soil fertility in wheat fields.

Improvements in farmland soil organic carbon (SOC) stock enhance crop yield and soil fertility while mitigating climate change. Rational fertilization in agricultural production is crucial for safeguarding SOC stock. In this study, field experiments were conducted with different ratios of chemical fertilizer reduction and organic fertilizer substitution for three consecutive years (2018-2020) to explore their effects and interlinkages on SOC fractions, soil properties and SOC stock. The results showed that organic fertilizer substitution increased SOC and its fractions content, SOC stock (by 3.98-12.98% and 7.15-18.13%) and soil fertility index (by 11.76-49.26% and 33.33-91.47%) compared to conventional fertilization in 2019 and 2020, while chemical fertilizer reduction had the opposite effect. Moreover, soil properties (except total nitrogen to total phosphorus ratio, N/P) and SOC fractions significantly affected SOC stock, with SOC fractions contributing more than soil properties. The high sensitivity of microbial biomass carbon (MBC) and dissolved organic carbon (DOC) can indicate changes in soil carbon pool. Structural equation modeling (SEM) revealed that organic fertilizer substitution increased SOC content and stock by increasing SOC fractions [recalcitrant organic carbon (ROC) and labile organic carbon (LOC) fractions] content and soil fertility. Our study revealed the corresponding mechanisms of the two fertilization modes affecting SOC stock changes. The use of organic fertilizer substitution is recommended to increase SOC stocks and soil fertility in wheat fields. © 2023 Society of Chemical Industry.

Dynamics of Organic Carbon Fractions, Soil Fertility, and Aggregates Affected by Diverse Land-Use Cultivation Systems in Semiarid Degraded Land

Dynamics of Organic Carbon Fractions, Soil Fertility, and Aggregates Affected by Diverse Land-Use Cultivation Systems in Semiarid Degraded Land

Management Practices Affect Soil Organic Carbon Stocks and Soil Fertility in Cactus Orchards

Management practices might alter soil chemical properties. This study evaluated soil chemical properties in a forage cactus Opuntia stricta (Haw.) Haw. (‘Orelha de Elefante Mexicana’) (OEM) production system in the Brazilian semiarid region. The experiment was established in June 2011, and the design was a split-split-plot in randomized complete blocks, in which the main plots were formed by distinct levels of organic fertilizer (cattle manure) (0, 10, 20, and 30 Mg ha−1 year−1), the subplots were formed by different levels of N inorganic fertilizer applied as urea (0, 120, 240, and 360 kg N ha−1 year−1), and the sub-subplots were distinguished by the distinct OEM harvesting frequency (annual or biennial). Soil samples were collected for chemical analysis, C and N contents analysis, and stocks analysis at 0 to 10 and 10 to 20 cm depths in August 2019. Organic fertilizer contributed to a linear increase in soil pH, Ca2+, Na+, sum of bases (SB), cation exchange capacity (CEC), and base saturation (V) at both depths (p < 0.05). With the application of 30 Mg ha−1 year−1 of cattle manure, there was storage of approximately 126 Mg C ha−1 and 13 Mg N ha−1 at 0 to 20 cm depths. Managing OEM with organic fertilizer and a biennial frequency of harvesting affects the soil’s chemical characteristics in cactus orchards, and it is a sustainable alternative for semiarid regions.

Isotopic Signatures of Nitrogen in Selected Soils from Croatia

The mobility of nitrogen (N) in the environment is conditioned by its cycling between atmospheric, terrestrial, and marine ecosystems. It is a key element for global biogeochemistry, and although isotope analysis has been an integral part of many studies over the past eighty years, the complexity of the nitrogen cycle hinders a correct and detailed understanding of the mechanisms behind its processes. It could be argued that the interpretation of the isotopic signatures of nitrogen in soils is still in its infancy. In Croatia, such research has recently begun and is driven by a need for the comprehensive study of nitrogen isotopes in terrestrial ecosystems. The aim of this study was to compare the abundance of the 15N isotope in soils from continental and coastal parts of Croatia with different types of land use (arable land/crop production, meadows, forests, orchards, ski slopes, urban soil/city roads) and to authenticate the nitrogen origin in soils in relation to different soil management practices. This research was based on 27 soil samples collected at 11 locations in Croatia. The samples differed according to soil type, land use, applied mineral and organic nitrogen fertilization, and climatic condition at each specific location. The determination of δ15NT (T—total nitrogen) values in bulk samples was performed in duplicate with the IRMS (Isotope Ratio Mass Spectrometry) method using an IsoPrime100-Vario PYRO Cube (OH/CHN Pyrolyser/Elemental Analyzer). The results reveal that the mean δ15N abundance in soils according to different land use declines in the following order: crop production (+5.66 ± 1.06‰) > apple orchard (+5.60 ± 0.10‰) > city road (+4.33 ± 0.38‰) > meadow (+3.71 ± 0.85‰) > ski slope (+2.20 ± 0.10‰) > forest (+2.15 ± 1.86‰). The individual values were in the range from 0.00 ± 0.10‰ in the forest soil in continental Croatia to +7.19 ± 0.07‰ in the vegetable garden (crop production) soil in coastal Croatia. Among the investigated soil properties and weather conditions, PCA analysis identified close correlations between P2O5 content and δ115N abundance in arable soils, as well as between soil reaction (pH) and mean annual temperatures, while high C/N ratio values explained the isotopic distribution in non-arable soils (city roads and forests). Despite the long-term application of mineral nitrogen fertilizers, the results represent nitrogen of organic origin in the arable soils (crop production), which partly confirms the sustainable management of those agroecosystems.

From Soil to Spectrum: Decoding the Impact of Nutrient Management Practices and Herbicides using FTIR

Background: FTIR spectroscopy is the instrumental technique used in science for studying soil constituents and their variations rapidly. Being a non-extraction technique, FTIR could also be used to study the interaction of soil composition with the applied external inputs like fertilizer nutrients through organic and inorganic sources and herbicides by assessing the variations in spectral patterns. This will also reveal the type of interaction and changes taking place in soil swiftly. Hence, the current study was carried out to investigate the interaction of herbicides with soil components under various fertilizer nutrient management practices. Methods: Three herbicides (glyphosate, pendimethalin, metribuzin) were applied to the sandy loam soil treated with soil inorganic fertilizer (NPK+MN) and organic fertilizer (NPK+FYM). Treated soils along with control, were collected, processed and subjected to FTIR analysis. Based on the intensity of absorption changes, the type of interactions and changes that occurred in the soil were assessed. Result: Results of the study reveal that the application of herbicides (glyphosate, pendimethalin and metribuzin) to soil and NPK + micronutrients and NPK + FYM resulted in complex interactions and changes in FTIR absorption intensities, notably in fingerprint regions (1200-400 cm-1). Shift in the peaks at different wave numbers occurred due to the interaction of soil constituents with the herbicides and organic matter as FYM. The study highlights that a deeper understanding of these complex interactions is crucial for optimizing the use and time of application of fertilizer nutrients and herbicides, minimising environmental impacts and promoting sustainable agricultural practices that preserve soil health and productivity.

Utilization of Sludge from the Communal Wastewater Treatment Plant (WWTP) in the Asrama Dinas Lingkungan Hidup (DLH) Jagakarsa of South Jakarta City as Basic Material for Organic Fertilizer

Asrama DLH Jagakarsa has a communal wastewater treatment plant (WWTP) that produces sludge that has not been treated. Asrama DLH residents directly apply the sludge from the communal WWTP as fertilizer for plants. Fecal sludge contains organic substances that provide nutrients to plants. However, there is a possibility that it still contains pathogenic bacteria and metals that can be harmful to plants. This research aims to utilize the fecal sludge from Asrama DLH Jagakarsa WWTP as organic fertilizer with additional ingredients in the form of humic acid. During fertilizer manufacturing, the bacteria and metals are removed. The analysis used includes the composting process conditions analysis, characteristics tests to determine the content of feces and fertilizers, and analysis of the application to plants. Analysis of the conditions in the composting process is the analysis of the pH value of organic fertilizers. Characteristic tests include soil variation (V1), WWTP sludge (V2), and organic fertilizer (V3). Analysis of the application of plant growth was carried out by testing the variation of soil 100% (P1), soil 80% + 20% fecal sludge (P2), and soil 80% + 20% organic fertilizer (P3). The laboratory analysis includes the analysis of nitrogen, phosphorus, potassium (NPP), and water content which will be compared with the quality standard of the Decree of the Minister of Agriculture Number 261 of 2019. The plant that is used as an indicator of the success of organic fertilizer in plant growth is the kale plant. The best value was obtained in the variation of organic fertilizer (V3), namely the NPP content and water content, respectively, which were 4.52%, 2.57%, 0.05%, and 19.84%. This shows that organic fertilizer increases NPP elements and plant growth.

Thermochemical degradation of agricultural mulch films for potential organic fertilizer precursors: Low-temperature pyrolysis in nitric acid

Polyethylene mulch films (PEMFs) are widely used in agriculture to boost crop yields but pose significant environmental challenges due to their non-degradable nature. This study investigated the pyrolysis of PEMFs in nitric acid (HNO3) using micro-glass reactors under mild conditions for the production of thermochemical degradation products (TDP) as potential organic fertilizer precursors. The effects of HNO3 concentration (10–60 %), HNO3:PEMF ratio (0.5–2), pyrolysis temperature (150–250 °C), and reaction time (1 – 45 min) on the yield of TDP, tetrahydrofuran-soluble fraction (THF-S), tetrahydrofuran-insoluble fraction (THF-IS), and HNO3 consumption were studied. SEM, elemental analysis, GPC, and FTIR were employed to assess product characteristics and degradability potential. Optimal conditions were HNO3 concentration of 36 %, HNO3:PEMF ratio of 0.5, pyrolysis temperature of 200 °C, and reaction time of 10 min. Higher temperatures or longer time would lead to TDP condensation to carbonaceous residues. The introduction of N and O-containing functional groups in TDP suggested its potential as an organic soil fertilizer. This study presents a novel, eco-friendly, and cost-effective solution to address the waste PEMF disposal problem.

Does a decade of soil organic fertilization promote copper and zinc phytoavailability? Evidence from a laboratory biotest with field-collected soil samples

Despite chronic contamination, long-term organic fertilization tends to decrease copper (Cu) and zinc (Zn) availability in agricultural soils. Root activities of crop plants can also induce substantial changes in rhizosphere chemistry and consequently in the Cu and Zn availability in the rhizosphere. The balance between these two drivers and the overall effect of organic fertilization on Cu and Zn bioavailability to plants (i.e., phytoavailability) remains a matter of debate. We assessed the effect of a decade of agronomically realistic organic fertilization on Cu and Zn availability in the rhizosphere and their phytoavailability. Using a laboratory biotest, Festuca arundinacea was exposed to 34 soil samples collected from three agricultural field trials that had received no, mineral, or organic fertilization for a decade. Dissolved organic matter (DOM) properties (i.e., concentration, aromaticity, and binding properties toward Cu), pH, and Cu and Zn availability (i.e., total dissolved concentration and free ionic activity) were determined in the rhizosphere solutions. Cu and Zn phytoavailability was measured as the plant uptake flux. Contrary to bulk soils, organic fertilization induced very few changes in the chemistry and Cu and Zn availability in the rhizosphere solutions compared to no and mineral fertilization. Consistently, Cu and Zn phytoavailability did not increase with organic fertilization, but it was mostly driven by soil properties rather than by fertilization. Despite increasing soil Cu and Zn contamination, a decade of soil organic fertilization did not increase Cu and Zn phytoavailability, presumably due to the root-mediated levelling of Cu and Zn availability in the rhizosphere.

Manure application decreases soil organic carbon priming by increasing mineral protection and nitrogen availability

Rational chemical fertilizer application, especially combined with manure or straw amendment, serves as a key strategy for facilitating soil organic carbon (SOC) sequestration and soil fertility improvement. However, the effects of fertilization managements on the SOC priming induced by straw return remains unclear. Here, a microcosm was conducted to clarify the mechanisms of 13C-labeled maize straw addition effects on priming effect (PE) in two 29-year fertilized soils (Urumqi, UQ; Gongzhuling, GZL) subjected to four fertilization regimes (no fertilizer, CK; chemical fertilizers, NPK; combined application of NPK with straw, NPKS; combined application of NPK with manure, NPKM). Results showed that straw addition strongly increased native SOC decomposition by 15–44%, inducing positive PEs across sites and fertilization treatments. Compared to CK treatment, the NPK and NPKS treatments significantly increased PE by 26% and 98%, respectively, in the UQ soil, but had little effect on the PE in the GZL soil. The NPKM treatment strongly decreased PE by 51–55%, mainly due to the increased proportion of mineral-associated organic carbon (MAOC) and N availability, and decreased fungal abundances, as compared to the CK treatment in UQ and GZL soils. The PE intensities were significantly lower in GZL soil (5.1–11.7 mg CO2-C/g SOC) relative to UQ soil (13.7–54.8 mg CO2-C/g SOC), primarily due to the higher MAOC/SOC ratio and N availability in the former across fertilization regimes. Overall, manure application has the potential to mitigate soil C loss via priming, mainly resulting from enhanced SOC stabilization via mineral protection and increased N availability, thus facilitating SOC sequestration in agroecosystems.

The effect of organic and inorganic soil fertility management technologies on smallholder farmers’ net revenue and nutrition security: Evidence from southwest region of Ethiopia

Technologies are better evaluated as packages, i.e., bundles of adoption decisions, rather than a segregate adoption, given the preeminent effect of the combinations on food and nutrition security, productivity, and other welfare outcomes. This study therefore assessed the effect of organic and inorganic soil fertility management technologies on net revenue and Nutrition security of smallholder farmers in Southwest Ethiopia. A multinomial endogenous switching regression (MESR) model, which captures both self-selection bias and the interactions between choices of alternative packages, was applied for this study since farmers’ adoption decisions are likely influenced by unobservable characteristics that may be correlated with the outcomes of interest. The investigation result revealed that, from the three adoption combinations of organic and inorganic soil fertility management technologies, joint adoption of the two technology groups was found to have a significant effect on both net revenue and Nutrition security simultaneously. Unlikely, the isolated adoption of the two soil fertility management technologies may not result in an intended nutrition security outcome. Thus, for the simultaneous improvement in net revenue and nutrition security, the study recommends concentrating on the joint practice of the two organic and inorganic soil fertility management technologies.