Organic Soil Amendments Research Articles

Invertebrate communities (Collembola and Acari) in soil cover treatments for mine tailings in a long‐term field experiment

AbstractAssessment of mine rehabilitation strategies including soil cover treatments rely mainly on soil physico‐chemical properties or plant performance indices, while much less is known about the response of biological soil properties. This field study evaluated the response of soil mesofauna (Collembola and Acari) in soil cover treatments (mainly subsoil and subsoil) on mine tailings, with or without organic amendments. The field experiment was conducted in large (1 m3) units rehabilitated in 2014, and mesofauna in soil cores was assessed 7 years later. The richness of Collembola and Acari as well as the density of Acari increased with organic amendments. Collembola community composition changed with the addition of soil cover and organic amendments. The density and community composition of Acari were strongly positively associated with organic carbon. The density of Euedaphic Collembola decreased, whereas Hemiedaphic and Epedaphic forms increased with soil cover. The contribution of generalist and metal‐tolerant species explained the high density of Euedaphic life forms in tailings. Species‐specific traits for Collembola and Acari could play an essential role in explaining the response of populations to treatments, such as affinity for C‐enriched habitats, food preferences, and sensitivity to heavy metals. Overall, it is recommended to use a multiple diversity indices approach, to collect data on the density and assemblage of mesofauna species to investigate the response of mesofauna communities to soil cover treatments. Mine tailings rehabilitation strategies should focus on improving the nutrient content of soil covers, since it benefits diversity and density of soil fauna.

Microbial Degradation of Plant Residues Rapidly Causes Long-Lasting Hypoxia in Soil upon Irrigation and Affects Leaching of Nitrogen and Metals

With this study, we aim to relate the substrate quality of different organic materials derived from plant residues to the respiratory activity of soil microorganisms after amendment, the formation of oxygen gradients upon irrigation, and the leaching of macronutrients and metals in soil. Elemental analyses were performed to determine the chemical composition of wheat straw, green compost, and a biochar product, showing that carbon availability, C/N ratio, and metal contents varied markedly. Consequently, after application to well-aerated sandy loam soil at 1% w/w, only straw increased microbial activity substantially, and nitrate was depleted within one week. Upon intense irrigation of soil columns packed with differently amended soils, strong hypoxia formed only in straw–soil, where microbial oxygen demand for straw degradation was high. This was enhanced after the application of mineral fertilizers, and nitrate leaching was mitigated. With the decreasing redox potential in straw–soil, the leaching of Fe, Mn, Al, Ni, Co, and As was increased. However, nitrate from mineral fertilizer mitigated the reduction of redox potential and, thus, the leaching of these metals. Measuring oxygen at different depths revealed near anoxic conditions at −15 cm of straw–soil with NP-fertilizer applied within 12 h after the start of irrigation and remained for at least 60 h, while oxygen showed extensive fluctuations in the upper few centimeters. This study showed that organic soil amendments with high carbon availability induce microbial respiration to the extent that causes strong and long-lasting hypoxia upon irrigation, even in sandy soil, which leads to substantial effects on the mobility of nutrients and toxic metals. In contrast, organic soil amendments with low carbon availability did not cause such effects.

Bioinoculants and organic soil amendments affect nematode diversity in apple orchards

Nematodes with their versatile lifestyles provide a suitable lens to decipher the conditions of agroecosystems, but less is known about how they are affected by bioinoculants and organic soil amendments. To test if treatments modify the nematode community, we studied nematode communities in two different apple orchards under organic and integrated farming. Soil was treated with products containing arbuscular mycorrhizal fungi, bioeffectors, and organic amendments. The comparison between baseline and control samples indicated an overall higher nematode richness in organic than the integrated orchard. Sampling time more than treatment had a significant effect, and higher community richness was observed during spring as compared to autumn. The variation in nematode community composition was mainly explained by sampling time followed by treatment, and orchard type. Although all treatments reduced nematode richness, their effect generally varied across treatments. In both orchards, season-dependent effects of treatment on nematode families and trophic guilds were observed, with a higher percentage of bacterivorous and lower percentage of herbivorous nematodes during spring. The effect was driven by a few families, i.e. Rhabditidae and Tylenchidae. Our study provides insights about the effect of soil treatment on nematodes with implications for the development and modification of bioinoculants.

Fertigation and Carboxymethyl Cellulose Applications Enhance Water-Use Efficiency, Improving Soil Available Nutrients and Maize Yield in Salt-Affected Soil

Conventional organic soil amendments and drip irrigation are insufficient for mitigating soil salinization. The development of a more potent soil amendment with higher water retention capability is critical. Carboxymethyl cellulose (CMC) has excellent water retention and adsorption properties and is suitable for soil water retention and amendment; however, its effects on water and salt distribution, soil nutrients, and maize yield have not been clearly investigated. We set up five treatments with flood irrigation (CK), drip irrigation (W), drip irrigation combined with 100 kg CMC ha−1 (WC1), drip irrigation combined with 200 kg CMC ha−1 (WC2), and drip irrigation combined with 300 kg CMC ha−1 (WC3). Our findings demonstrate that the application of CMC in conjunction with drip irrigation led to a significant surge in soil water content within the 0–40 cm layer, ranging from 3.73% to 16.46%, while simultaneously inducing a reduction in salt content of 4.08% to 16.61%. Consequently, this resulted in a desalination rate spanning from 10.32% to 12.93%. The salt was gradually washed down and formed a desalination area with the drip emitter as the center, and the salt distribution characteristics shifted from a surface accumulation type to a bottom deposition type. The drip irrigation and CMC application also increased the content of available nutrients, reduced surface evaporation, underground water loss, and maize evapotranspiration, and improved water-use efficiency, thus increasing the aboveground biomass and grain yield. In summary, CMC had a significant effect on water retention, desalination, and yield increases. It can serve as a novel soil amendment for salt-affected soil.

EFFECT OF PLANT BASED NEMATICIDE ON POPULATION OF PARASITIC NEMATODES AND BACTERIA ASSOCIATED WITH OKRA (ABELMOSCHUS ESCULENTUS L. MOENCH)

Rapid declines in nematode populations has been observed by the use of organic amendments in soil when decomposing plant based material release toxic compounds, while long term effects include increase in the yield and have no toxic effect on soil bacteria unlike the chemicals. In the present experiment Turtob-F was used to control population of three plant nematodes and to observe its effect on yield and population of Klebsiella sp. in soil. The population of all three nematode namely Meloidogyne incognita, Helicotylenchus pseudorobustus and Tylenchorhynchus indicus were remarkably decreased (P<0.001) by Turtob-F. The yield of okra was significantly increased (P<0.01) by the application of Turtob-F, whereas the population of bacterial sp. Klebsiella remains unchanged during the experiment.

Mulching vs. organic soil amendment: Effects on adsorption-desorption of herbicides

Mulching and organic soil amendment are two agricultural practices that are being increasingly used to preserve soil from degradation, although they may modify the fate of herbicides when applied in soils subjected to these practices. This study has set out to compare the impact of both agricultural practices on the adsorption-desorption behaviour of the herbicides S-metolachlor (SMOC), foramsulfuron (FORAM), and thiencarbazone-methyl (TCM) involving winter wheat mulch residues at different stages of decomposition and particle size, and unamended soils or those amended with mulch. The Freundlich Kf adsorption constants of the three herbicides by mulches, and unamended and amended soils ranged between 1.34 and 65.8 (SMOC), 0–34.3 (FORAM), and 0.01–1.10 (TCM). The adsorption of the three compounds was significantly higher in mulches than in soils (unamended and amended). The adsorption of SMOC and FORAM increased significantly with mulch decomposition, with this positive impact also being observed on the adsorption of FORAM and TCM after mulch milling. Simple and multiple correlations between mulches, soils, and herbicide properties, and adsorption-desorption constants (Kf, Kd, Kfd) reflected the organic carbon (OC) content and/or dissolved organic carbon (DOC) content of the adsorbents as main variables controlling the adsorption and/or desorption of each herbicide. The statistic R2 revealed that >61 % of the variability in the adsorption-desorption constants could be explained by jointly considering the OC of mulches and soils and the hydrophobicity (for Kf) or water solubility of herbicides (for Kd or Kfd). The same trend observed for Kfd desorption constants as for Kf adsorption ones resulted in higher percentages of herbicide remaining adsorbed after desorption in amended soils (33 %–41 % of SMOC, 0 %–15 % of FORAM, and 2 %–17 % of TCM) than in mulches (< 10 %). The results reveal a higher efficiency of organic soil amendment than mulching as an agricultural practice for immobilising the herbicides studied when winter wheat mulch residues are used as a common adsorbent, and as a better strategy for avoiding groundwater contamination.

Contrasting effects of biochar application rate in an alkaline desert cropland soil

Improving water and nutrient retention in desert croplands using soil organic amendments can be a major challenge because organic matter decomposes quickly under irrigated conditions in a hot climate. Biochar—a long-lasting carbon-rich soil organic amendment—has been proposed to improve soil water and nutrient retention, but only by carefully selecting an appropriate application rate. To better understand effects of biochar application rate on soil water and nutrient retention in desert croplands, we set up a mesocosm-scale experiment with biochar added at rates of 0, 19.8, 39.7, 79.4, 119.0, and 158.7 t ha−1 to an alkaline, sandy loam soil. After initial water retention measurements, we added fertilizer and then measured gaseous nitrogen losses as well as soil nitrate (NO3−) and phosphate (PO₄³⁻) leaching. Then, we measured biochar's effect on the soil's capacity to hold plant-available water (i.e., available water capacity, or AWC) using Tempe cells and a dewpoint potentiometer. We found contrasting effects of low and high biochar application rates. First, we found that applying a minimum of 79.4 t ha−1 biochar was necessary to improve soil water and PO₄³⁻ retention; application rates below 79.4 t ha−1 exacerbated PO₄³⁻ leaching whereas treatments above 79.4 t ha−1 improved AWC by up to 34% compared to the control treatment. While biochar application rate did not affect soil nitric oxide or ammonia emissions, we did find that low biochar application rates increased soil nitrous oxide emission while higher application rates reduced emission compared to soil with no biochar. Overall, we found that lower and higher rates of biochar application can have contrasting effects on soil water and nutrient retention in an alkaline, desert cropland soil. Therefore, farmers and other land managers must consider potential drawbacks of lower application rates and threshold responses of higher application rates prior to large-scale biochar use in arid agroecosystems.

Sweetpotato storage root formation as affected by soil organic amendment applications

Organic amendments have been utilised as a source of nutrients to improve the growth and yield of many crops, including sweetpotato. However, none of the studies examined the relationship between organic amendments and the initiation of sweetpotato storage roots (SRs). A study was conducted in sweetpotato Orleans cultivar to investigate anatomical changes to roots during storage root formation aiming to elicit if organic amendment affects SR formation by changing soil available nitrogen (N) concentration. Two locally available organic amendments including poultry manure (PM) and sugarcane trash (SCT), were used in this experiment at different rates. Six treatments were included in the study: unamended soil (control), unamended soil with chemical fertiliser, PM 22 Mg/ha, PM 66 Mg/ha, SCT 10 Mg/ha and SCT 30 Mg/ha. Compared with unamended control, SCT application at both rates, 10 or 30 Mg ha−1, significantly promoted the formation of SRs and reduced root lignification, while PM amendment from 22 to 66 Mg ha−1 significantly inhibited SR initiation and enhanced the formation of lignified roots, which appear to be associated to high soil available N caused by PM addition. During the SR initiation, all amended treatments increased N accumulation in plants compared to the control. These results indicated that excessive soil available N introduced by PM amendment could inhibit the formation of SR of sweetpotato. Thus, when applying a lower rate of PM to sweetpotato, and planting should be delayed from 2 to 3 weeks after amending to avoid the detrimental effect on SR initiation. Excessively high rates of PM soil amendment (66 Mg ha−1) should be avoided. A suitable rate of SCT may be applied (~ 10 Mg ha−1 in this study) to promote SR formation of sweetpotato in soil with adequate available N level, but high rates could lead to immobilisation of N and suppress crop growth.

CONTROL OF BURROWING NEMATODE INFECTION OF MUSA SPP AS AFFECTED BY PLANTING DEPTH AND POULTRY MANURE RATES IN MGBAKWU, ANAMBRA STATE.

Yield and control of burrowing nematode disease of Musa spp as affected by planting depth and poultry manure rates as soil organic amendment were studied in a 3x3x2 factorial experiment in a randomized complete block design with six replicates. The organic amendments were applied in two Musa spp. The poultry manure was apllied at the rate of 0 t/ha, 5 t/ha and 10 t/ha while the planting depth were 30cm, 45cm, and 60cm respectively. The 0 t/ha of poultry manure served as the control. The result of the analysis showed that burrowing nematode population density and its infection on Musa spp varied among the organic amendment applied. The same was true for yield and other yield components. Planting depth of 60cm and 10 t/ha poultry manure efficiently controlled the activities of burrowing nematode and therefore improved yield.

Post-Tin-Mining Agricultural Soil Regeneration Using Local Organic Amendments Improve Nitrogen Fixation and Uptake in a Legume–Cassava Intercropping System

The low nitrogen content of Bangka Island’s post-tin-mining soil may limit its suitability for agricultural production. In this study, we investigated the effect of locally available organic soil amendments on nitrogen fixation (N2–fixation) and crop nitrogen (N) uptake in a cassava–legume intercrop system. Cassava was intercropped with centrosema in post-tin-mining soils with six treatments, including a control and different soil amendments, such as dolomite, compost, charcoal, a combined treatment of charcoal and compost, and a combined treatment of compost and sawdust. The percentages of N derived from N2-fixation (%Ndfa) with the different seasons and treatments were comparable. Nonetheless, due to the higher shoot biomass accumulation, the mass of N2–fixation in soil amended with compost and when combined with charcoal was significantly higher than the control (50 to 73 kg ha−1). Treatments with compost and its combination with charcoal exhibited higher N uptake from the cassava–centrosema intercropped system (82 and 137 kg ha−1) and higher inorganic ammonium (NH4+) concentrations in the soil at harvest time (5.5 and 6.7 µg g−1). When combined with organic soil amendments, N2–fixation from centrosema produces not only higher biomass, but also higher N contribution to the system. Overall, locally available organic amendments, particularly the combined application of charcoal and compost, showed promise for improving N2–fixation of intercrop centrosema as well as for increasing N availability in the soil, which is of critical importance for crop growth in post-mining soils that have lost fertility.

Analysis of Water Infiltration Characteristics and Hydraulic Parameters of Sierozem Soil under Humic Acid Addition

The farmland in Yinchuan is composed of sierozem soil, which is characterized by high sand content and low organic matter content, resulting in poor water-holding capacity and weak soil structure. Humic acid is a natural organic polymer soil amendment. It is critical to study how humic acid affects soil water infiltration in sierozem soil at the microlevel. A one-dimensional vertical infiltration experiment was conducted to explore how adding different amounts of humic acid (0, 1%, 2%, 3% and 4%) affected the infiltration characteristics and hydraulic parameters of the sierozem soil. The results revealed that the wetting front and cumulative infiltration decreased with the increase in humic acid addition. When the infiltration time was 90 min, the wetting front of the 1%, 2%, 3% and 4% treatments was 6.50%, 10.00%, 15.00% and 21.00% lower than CK (0 for CK), and the cumulative infiltration volume was 4.50%, 11.14%, 18.42% and 23.60% lower than CK, respectively. Among the three infiltration models created by Philip, Horton and Kostiakov, the Kostiakov model (R2 &gt; 0.95) could more accurately describe the soil water infiltration process in the study area. After infiltration, the moisture content of each soil layer increased with the increase in humic acid, which improved the water-holding capacity of the sierozem soil. Using Hydrus-1D to calculate soil hydraulic parameters, we found that the humic acid addition affected the hydraulic parameters. With the increase in the amount of humic acid addition, the retention water content θr and saturated water θs were positively correlated with the humic acid addition amount and negatively correlated with the saturated water conductivity Ks and the reciprocal of air-entry α. The results showed that humic acid could increase the water-holding capacity of soil and improve the rapid water loss and poor water-holding capacity of sierozem soil.

Agro-morphological and biochemical responses of quinoa (Chenopodium quinoa Willd. var: ICBA-Q5) to organic amendments under various salinity conditions.

In the Sahara Desert, due to drought and salinity and poor soil fertility, very limited crop choice is available for the farmers to grow crops. Quinoa (Chenopodium quinoa Willd.) has shown promising under such conditions in the South of Morocco, a true representative site of Sahara Desert. Soil organic amendments have the potential to minimize negative effects of soil salinity and improve crop production. Thus, this study aimed to elucidate the impact of nine organic amendments on quinoa (var. ICBA-Q5) growth, productivity, and biochemical parameters under saline irrigation water application (4, 12, and 20 dS·m-1). Results of the experiment indicate a significant effect of organic amendments on major agro-morphological and productivity parameters. Biomass and seed yield tends to decrease with the rise of salinity level, and organic amendments have improved productivity compared to the non-treated control. However, salinity stress alleviation was assessed by determining pigments concentration, proline content, phenolic compounds, and antioxidant activity. Therefore, the action of organic amendments varies from one level of salinity to another. Furthermore, a remarkably significant decrease in total saponin content was reached due to the application of amendments even at high saline conditions (20 dS·m-1). The results demonstrate the possibility of enhancing the productivity of quinoa as an alternative food crop under salinity conditions by using organic amendments and improving the quality of grains (saponin reduction) during the pre-industrialization process.

Increasing growth and productivity of several rice varieties in new opening rice fields by using soil organic amendment

The purpose of this research was to determine the effect of soil amendment on the growth and productivity of several varieties of rice in newly opened rice fields. This research was conducted in Montasik District, Aceh Besar District, Aceh Province from June to September 2021. A factorial randomized block design consisting of three rice varieties Inpari 42, TG/IRBB27, and Koshihikari was set up as the first factor. Whereas the second factors consist of two levels of organic amendment by using manure 20 tons ha−1 and biochar 20 tons ha−1. The results showed that the TG/IRBB27 was the best variety by producing plant height at harvest reaching 120.81 cm, the number of tillers 16.03 tillers, panicle length of 28.74 cm, grain weight per hill of 98.86 g, with yield potential reached 12.70 tons ha−1. The best soil amendment was found with Biochar 20-ton ha−1 amendment that caused an increase in the number of tillers to 14.37 tillers and yield potential reached 9.82 tons’ ha−1.

Gross nitrogen transformations and ammonia oxidizers affected by nitrification inhibitors and/or organic amendments in a calcareous soil: A 15N tracing study

Nitrification inhibitors (NIs) combined with organic amendments are considered effective strategies for improving soil nitrogen availability and reducing nitrogen loss. However, these effects might depend on the types of organic amendments and nitrification inhibitors, and whether their combined application could generate a synergistic effect on nitrogen transformation rate has not been well investigated. In this study, a 15N aerobic incubation experiment was conducted to investigate the effects of nitrification inhibitors (3,4-dimethylpyrazole phosphate [DMPP, 1 % of applied NH4+-N] or methyl 3-(4-hydroxyphenyl) propionate [MHPP, 5 % of applied NH4+-N]) and/or organic amendments (straw [1 %, w/w] or straw-derived biochar [1 %, w/w]) on the gross nitrification rates of mineralization, nitrification, and immobilization in calcareous soil. Our findings revealed that compared with the control treatment, biochar, straw, and MHPP_straw boosted gross mineralization rates by 1.19–2.69 times. The addition of nitrification inhibitors and/or organic amendments inhibited the gross nitrification rates by 15.8 %–89.7 %, which ranged from 0.85 mg N kg−1 day−1 to 8.28 mg N kg−1 day−1 across treatments. DMPP_straw showed the greatest inhibiting effect, whereas 5 % MHPP treatment had the least effect. Gross NH4+ immobilization rates increased by 4.12–18.18 times, where NO3− immobilization rates were only stimulated with the treatments of straw, DMPP_straw, and MHPP_straw. DMPP was more efficient in inhibiting nitrification than MHPP, but it also significantly enhanced ammonia (NH3) volatilization, which rose by 2.77 times over that in MHPP. The high C/N ratio and inorganic-N adsorption of straw and biochar might play prominent roles in affecting NH4+ content by stimulating mineralization and inorganic immobilization. The decrease in the abundances of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) can be partially explained by the inhibitory effects of DMPP and MHPP. Changes in the community of AOB were more sensitive to management measures than those of AOA. In conclusion, our study demonstrates that treatments with DMPP_straw and MHPP_straw efficiently promote inorganic nitrogen immobilization, mitigate NH3 volatilization, inhibit nitrification to the greatest extent, and thus yield the most positive synergistic effects on soil nitrogen retention.

Technological Breakthrough for Large Scale Bioconversion of Coir Pith towards Sustainable Soil Health Management and Development of Source Point Methane Abatement Model

Coir pith, a byproduct of coir industry, continues to be dumped as a waste in India, because despite its utility being claimed in different applications, an efficient and adoptable technology for its safe utilization is yet unavailable. Due to high lignin content and high C:N ratio, coir pith when left untreated can take decades to decompose, which not only leads to environmental pollution but most importantly methane emission, thereby contributing to climate change. However, once composted, coir pith can transform into an effective soil rejuvenator, considering its utility towards amelioration of especially marginal/ agriculturally degraded soil and improvement of soil productivity. But so far, there is no available composting technology in this respect which is practically feasible, economically viable and socially acceptable.&#x0D; Under IBM-IORF Sustainability project (2022-23) at Mandya, Karnataka, an effort was initiated utilizing Novcom Composting Technology, towards bioconversion of coir pith into safe, mature and qualitative compost for sustainable soil management, especially looking at the stony red soils of the area which are erosion prone, and have a poor productive potential.&#x0D; Periodical study of Novcom coir pith compost samples on 0, 10, 20 and 30 days confirmed effective degradation as demonstrated by the rapid decline of C:N ratio from 1:100 to &lt; 1:25, appreciation of total nitrogen by 98 percent and 60 % degradation of lignin within a 30 days’ time period. The facts are corroborated by the respective very high (in the order of 1016 c.f.u. per gm or one Trillion Billion microflora per ton compost) population of bacteria, fungi and actinomycetes. Phytotoxicity Bioassay test values confirmed not only the absence of phytotoxic elements in compost, but also indicated that this compost can actually accelerate seed germination and root growth process. Estimation of methane mitigation potential under this technology utilizing the carbon assessment tool - Agriculture Carbon Footprint Assessor (ACFA, version: 1.0) indicated that untreated coir pith can potentially emit methane in the range of 5897 – 6025 kg CO2 equivalent (taking GWP24 years of methane: 75).&#x0D; GHG emission during biodegradation of coir pith utilizing Novcom Composting Technology, was found to be about 31 times lower (6.47 kg CO2 equivalent/ ton treated waste) than the reference values recorded in respect of any other standard biodegradation process. Especially in terms of methane the negligible emission under this composting technology is the highlight, as corroborated by the documented value of 0.61 kg CO2 equivalent/ ton treated waste. The evaluation confirmed that bioconversion of coir pith utilizing Novcom Composting Technology can enable methane mitigation of about 6000 ton CO2 equivalent per 1000 ton waste, directly from the source point.&#x0D; The study indicated that Novcom Composting Technology can transform not only a potential pollutant to a quality organic soil amendment, the process also etches out and effective pathway for methane abatement directly from the source point that has crucial impact not only in respect of Sustainable Development Goal (SDG) 13, but also SDG 15, SDG-3 and most importantly SDG-2. Hence, bioconversion of coir- pith utilizing this technology can also facilitate an effective model towards the Net Zero commitment with significant social and environmental impacts.

Suppression of Meloidogyne incognita by co-application of chitin and Streptomyces nigrescens (AMV1033)

ABSTRACT Root-knot nematodes, Meloidogyne spp., are among the most polyphagous and ubiquitous plant-parasitic nematodes. Among other management strategies, organic soil amendments and biological control agents are proposed. In this study, potential synergistic benefits of co-application of chitin and Streptomyces nigrescens (AMV1033) against M. incognita were determined. Hypothetically, chitinolytic activity of these microbes deteriorates nematode eggshells reducing nematode numbers. Additional chitin could enhance actinobacteria activity for nematode suppression. In in vitro and greenhouse bioassays, suppressive capacities of M. incognita by chitin amendment at 50 mg/g of soil (chitin-low) and at 500 mg/g of soil (chitin-high; only tested in the greenhouse), Streptomyces nigrescens (AMV1033) and the co-application of AMV1033 with the two chitin rates were tested. After four weeks of in vitro egg incubation, the number of extractable second-stage juveniles (J2s) was significantly reduced after co-application of chitin-low plus AMV1033, and less so after sole application of AMV1033. In a similar 2-week in vitro assay with M. incognita egg masses, the numbers of J2s were similarly reduced after the same treatments. In a watermelon greenhouse bioassay with M. incognita, root infection was decreased after co-application of AMV1033 plus chitin-high or chitin-low compared to the non-treated control. After these treatments, plants grew similarly as in the control, whereas sole chitin-high addition led to severe plant damage. Some amelioration of phytotoxicity of chitin-high by the co-application of AMV1033 was found. The results of the study demonstrated the potential to enhance suppression of M. incognita by S. nigrescens by co-application of chitin.

Integrating multiple soil management practices: A system‐wide approach for restoring degraded soil and improvingBrachiariaproductivity

AbstractLand degradation has severely affected soil health and agricultural productivity in the Sasiga district of western Oromiya, Ethiopia, demanding urgent and extensive solutions. Integrated soil management in particular is a comprehensive approach that could mitigate the multifaceted effects of land degradation. Hence, a field experiment was conducted on degraded farmers’ land to assess the potential of lime, organic amendments, tillage, and soil–water conservation (SWC) in improving the productivity of soil andBrachiaria(Mulato II). The experiment employed 15 treatments, which were systematically formulated from lime, organic amendments (compost and cattle manure), the SWC method (constructed soil bunds and no soil bunds), and tillage practices (ploughing and no‐ploughing). The study showed that applying lime with tillage or both tillage and SWC and organic amendments alone improved soil pH from very strongly acidic to moderately acidic. The combined application of lime, SWC, and tillage also enhanced the organic carbon, organic matter, total nitrogen, and moisture contents of the soil. Besides, the integrated use of cattle manure, SWC, and tillage practices boosted plant cover, tillering, plant height (PH), and dry biomass ofBrachiaria(Mulato II). Consequently, the physicochemical properties of the degraded soil and the agronomic performance ofBrachiariacan be improved by amending with combinations of lime or cattle manure with SWC and tillage. In general, integrating multiple soil management practices, including lime, organic amendments, SWC, and tillage, offers a whole‐system approach to rehabilitating degraded soil and improving its physicochemical properties and productivity ofBrachiariagrass.

Reuse of Sludge as Organic Soil Amendment: Insights into the Current Situation and Potential Challenges

Sludge generation as an organic by-product of wastewater treatment has seen a consistent increase worldwide due to population growth and industrial activities. This poses a chronic challenge regarding management options and environmental concerns. The agricultural valorization of unconventional organic materials has become inevitable, especially in semi-arid and arid countries that suffer from depleted soils and shortages in farm manure supply. High-income countries have also been interested in this recycling practice to mitigate landfilling or incineration issues. Sewage and some industrial sludges contain a complex mixture of beneficial and harmful substances, which varies with the origin of effluents. Therefore, sludge land application should be well managed in order to achieve sustainable agro-environmental goals. This review paper focuses on different aspects related to sludge reuse in agriculture, starting by investigating the diversity of sludge types and composition. In addition to the preponderant urban sewage sludge, the less-studied industrial sludges, such as those generated from pulp and paper mills or gas-to-liquid industries, are hereby addressed as well. Then, post-land application effects are discussed in relation to sludge quality, dose, and reuse conditions. The present paper also examines the disparities between guidelines that determine sludge conformity for land application in various countries or regions. Accordingly, special attention is given to increasing risks related to emerging pollutants in sludge such as pharmaceuticals, which have been overused since the outbreak of COVID-19 pandemic. This exhaustive investigation will assist the establishment of sustainable strategies for the safe agricultural reuse of biosolids.

Aquaculture sediments amended with biochar improved soil health and plant growth in a degraded soil

Sustainable and safe management of aquaculture sediments is of great concern. Biochar (BC) and fishpond sediments (FPS) are rich in organic carbon and nutrients and thus can be used as soil amendments; however, it is not fully explored how the biochar amended fishpond sediments can affect soil properties/fertility and modulate plant physiological and biochemical changes, particularly under contamination stress. Therefore, a comprehensive investigation was carried out to explore the effects of FPS and BC-treated FPS (BFPS) on soil and on spinach (Spinacia oleracea L.) grown in chromium (Cr) contaminated soils. Addition of FPS and BFPS to soil caused an increase in nutrients content and reduced Cr levels in soil, which consequently resulted in a significant increase in plant biomass, chlorophyll pigments, and photosynthesis, over the control treatment. The most beneficial effect was observed with the BFPS applied at 35 %, which further increased the antioxidant enzymes (by 2.75-fold, at minimum), soluble sugars by 24.9 %, and upregulated the gene expression activities. However, the same treatment significantly decreased proline content by 74.9 %, Malondialdehyde by 65.6 %, H2O2 by 65.1 %, and Cr concentration in spinach root and shoot tissues. Moreover, the average daily intake analysis showed that BFPS (at 35 %) could effectively reduce human health risks associated with Cr consumption of leafy vegetables. In conclusion, these findings are necessary to provide guidelines for the reutilization of aquaculture sediments as an organic fertilizer and a soil amendment for polluted soils. However, more future field studies are necessary to provide guidelines and codes on aquaculture sediments reutilization as organic fertilizer and soil amendment for polluted soils, aiming for a more sustainable food system in China and globally, with extended benefits to the ecosystem and human.

Regenerative agriculture v. conservation agriculture: potential effects on soil quality, crop productivity and whole-farm economics in Mediterranean-climate regions

AbstractSmall-grain farming systems in Mediterranean climatic regions are characterized by poor quality soils, high climate variability, and resulting heavy agrochemical reliance. The adoption of Conservation Agriculture, based on minimum tillage, permanent soil cover, and crop rotations, has improved soil quality, enhanced crop productivity, and help mitigate financial risk. However, emerging issues that threaten sustainability, such as herbicide resistance, inputs costs rising disproportionately to product prices, and increasing climate variability and unpredictability, drive the need for innovation in small-grain Mediterranean-based CA systems. The aim of the review was to evaluate a set of agroecological practices which constitute a Regenerative Agriculture (RA) concept, for their potential to address these challenges from a soil quality, crop productivity and whole-farm economics perspective. Organic soil amendments derived from agro-wastes, offer promising perspectives for supplying appropriate quantities of nutrients to reduce or replace mineral fertilisers and offset their economic and agroecological costs. Although the viability of microbial bioeffectors in small-grain agroecosystems was largely under question, non-microbial bioeffectors and certain combination options represent more efficient and cost-effective uses of this technology. Their widely reported abiotic stress priming functions and crop productivity enhancement under poor growing conditions may improve yield stability and financial resilience in small-grain Mediterranean CA systems. Finally, multi-species cover crops subjected to adaptive multi-paddock (AMP) grazing as a phase within the crop rotation may reduce weed pressure, enhance soil multi-functionality, and resilience against environmental stresses. To validate the potential of these technologies in Mediterranean small-grain systems, more long-term and context-specific research is called for.