Soil Fertility Research Articles

Soil fertility in mixed crop-livestock farming systems of Punjab, Pakistan: The role of institutional factors and sustainable land management practices

CONTEXTSoil salinization is a significant environmental challenge prevalent in arid and semi-arid regions, causing adverse effects on crop yields and jeopardizing household food security. Previous research has examined the influence of institutional dynamics and the adoption of sustainable land management practices in bolstering agricultural output, and some have investigated the interplay among socioeconomic determinants, institutional frameworks, and the uptake of climate-resilient and sustainable methodologies, or the association between soil health and agricultural productivity. Yet, there has been a lack of studies that considered this relationship altogether and their role in enhancing soil fertility. OBJECTIVEWe investigate the relationship among socioeconomic and institutional factors, adoption of sustainable land management practices, and the resulting changes in soil fertility between 2016 and 2019 within the context of mixed crop-livestock farms in the three irrigated agroecological zones of Punjab, Pakistan. A household survey was conducted in 2019 to complement soil attributes data collected by the Government of Punjab in 2016. Households that implemented sustainable land management practices between 2016 and 2019 were analysed to investigate the effect of various factors on soil fertility, including the adoption of sustainable land management practices and their influence on soil fertility dynamics. METHODSA structural equation model was employed to examine the relationship among exogenous variables, moderating variables, and endogenous variables, to explain their collective influence on soil fertility between the two periods. RESULTS AND CONCLUSIONSThe key findings highlight the significant role of institutional factors, including access to formal information channels such as extension services, demonstration trials, and credit facilities, alongside secure land rights, in predicting the adoption of sustainable land management practices such as gypsum application, laser land leveling, farmyard manuring, and agroforestry. Furthermore, specific SLM practices, particularly agroforestry featuring intercropping with Acacia spp. and farmyard manure application, exhibited positive impacts on change in soil organic matter, albeit with agroforestry showing a negative influence on soil phosphorus levels. The adoption of gypsum and LLL displayed positive effects on soil phosphorus levels over time, contrasting with LLL's adverse impact on soil organic matter. SIGNIFICANCEOur findings suggest that soil fertility benefits from policies enacted through public-private partnerships that lead to improved access to sustainable land management information, reduced credit barriers, establishment of local soil testing facilities, and expedited land entitlement processes. These findings highlight the critical role of collaborative partnerships and institutional arrangements in enhancing agricultural productivity and environmental sustainability.

Mitigation of greenhouse gas emissions through shade systems and climate-smart soil fertility interventions in cocoa landscapes in the Semi-deciduous ecological zone of Ghana

Mitigation of greenhouse gas emissions through shade systems and climate-smart soil fertility interventions in cocoa landscapes in the Semi-deciduous ecological zone of Ghana

Nitrogen Supply from Soil Organic Matter: Predictors and Implications for Recommended Nitrogen Application Rates in Northern Highbush Blueberry

Nitrogen (N) management is a key component to maintaining high productivity of northern highbush blueberry (Vaccinium corymbosum L.) and nitrogen is often supplied by applying ammonium-based fertilizers. It can also be supplied through mineralization of soil organic matter (SOM), although the amount released by SOM is difficult to predict and not always considered in the development and implementation of N fertility programs. Laboratory and field experiments were conducted to estimate the timing and magnitude of net N mineralization from SOM throughout the growing season, identify soil properties that can be measured commercially and used to predict net N mineralization across a range of SOM, and determine whether N requirements for maximizing yield and fruit quality of blueberry vary across soils with different amounts of SOM. The laboratory experiment was conducted for 6 months using soil samples collected from 10 representative commercial blueberry fields in northwest Washington. The soils contained 2% to 42% soil organic carbon (SOC). The mean net N mineralization rates were fastest during the first 3 to 4 months of incubation, corresponding to the period during which N uptake reaches its maximum in blueberry. Results indicated that the soil total N may be a useful predictor of the N supply from SOM (6.34 ± 1.13 kg⋅ha−1 increase in net N mineralization with each 0.1% increase in total N), but there was substantial variability in the N supply that could not by explained by the total N (P < 0.001; r2 = 0.433). The field experiment was conducted from 2019 to 2021 and included four mature, regionally representative, commercial fields of ‘Duke’ blueberry. The fields contained 3% to 28% SOC and were each fertilized with low, medium (control), or high N rates, corresponding to 33 to 50, 67 to 84, or 102 to 118 kg⋅ha−1 N per year, respectively. Although soil inorganic N levels suggested that N mineralization was substantial at sites with higher SOM, sites with lower SOM did not require more fertilizer N than those with higher SOM. Under the conditions of this experiment, even the lowest N rates were sufficient to sustain production for at least 3 years at each site. The findings of this study indicate that SOM may be an important contributor to N fertility in managed blueberry systems, and that yield and fruit quality can be maintained across various N fertilizer rates, including at rates <50 kg⋅ha−1 N. However, the long-term impacts of reducing N application rates remain unclear, and future research should monitor long-term changes in plant health and soil fertility associated with reduced N applications across diverse soils and production systems.

Genotype-specific nonphotochemical quenching responses to nitrogen deficit are linked to chlorophyll a to b ratios

Non-photochemical quenching (NPQ) protects plants from photodamage caused by excess light energy. Substantial variation in NPQ has been reported among different genotypes of the same species. However, comparatively little is known about how environmental perturbations, including nutrient deficits, impact natural variation in NPQ kinetics. Here, we analyzed a natural variation in NPQ kinetics of a diversity panel of 225 maize (Zea mays L.) genotypes under nitrogen replete and nitrogen deficient field conditions. Individual maize genotypes from a diversity panel exhibited a range of changes in NPQ in response to low nitrogen. Replicated genotypes exhibited consistent responses across two field experiments conducted in different years. At the seedling and pre-flowering stages, a similar portion of the genotypes (∼33%) showed decrease, no-change or increase in NPQ under low nitrogen relative to control. Genotypes with increased NPQ under low nitrogen also showed greater reductions in dry biomass and photosynthesis than genotypes with stable NPQ when exposed to low nitrogen conditions. Maize genotypes where an increase in NPQ was observed under low nitrogen also exhibited a reduction in the ratio of chlorophyll a to chlorophyll b. Our results underline that since thermal dissipation of excess excitation energy measured via NPQ helps to balance the energy absorbed with energy utilized, the NPQ changes are the reflection of broader molecular and biochemical changes which occur under the stresses such as low soil fertility. Here, we have demonstrated that variation in NPQ kinetics resulted from genetic and environmental factors, are not independent of each other. Natural genetic variation controlling plastic responses of NPQ kinetics to environmental perturbation increases the likelihood it will be possible to optimize NPQ kinetics in crop plants for different environments.

Internet of Things(IoT) Application for Crop Prediction and Fertilizer Suggestion Using Machine Learning Techniques

Abstract: Agriculture serves as the primary source of income globally, particularly in regions like the Indian subcontinent. However, modern challenges such as unpredictable weather patterns, water scarcity, and market fluctuations necessitate the adoption of advanced farming techniques. Soil fertility depletion, caused by various factors, further exacerbates these challenges, leading to decreased crop yields. To solve these problems, our project utilizes modern technology, specifically leveraging machine learning techniques. By integrating an NPK sensor with a web application, our goal is to give farmers practical insights into their soil's nutrient composition. Upon collecting nitrogen, phosphorus, potassium, and pH levels from the soil, these values are entered into the application. Compared to traditional farming methods, our project offers several advantages. Firstly, it empowers farmers with accurate and timely information about their soil's nutrient levels, giving them the ability to make wise decisions.

Does the universal adaptive strategy theory apply to natural regeneration in heterogeneous subtropical karst forests?

The universal adaptive strategy theory (UAST) describes how the ecological strategy of plants changes along the succession after disturbance. However, whether it applies to those off-peak successional pathways in extremely heterogeneous forests is uncertain. This study established a series of forest dynamic plots along the natural regeneration in subtropical karst forests, and aimed to verify whether UAST applied to the succession in extremely heterogeneous forests. By measuring the dominant plant functional traits (PFTs) and quantifying the plant ecological strategy spectrum, we found that the PFTs varied significantly along the natural regeneration, as did plant ecological strategies. Further results showed that the C- and S-strategy dominated the community-level ecological strategy spectrum. In addition, the C-strategy gradually increased along the natural regeneration, while the S-strategy exhibited a decreasing trend. The community spatial structure and abiotic factors including soil physicochemical properties and topographic factors jointly drove the ecological strategy spectrum of the plant community, with the community spatial structure playing a more important role. This study provided clear evidence to support Grime’s CSR theory and the UAST, which emphasized the abiotic stress conditions supported the S-strategy plants, while the C-strategy would dominate in relative fertile soil conditions.

Exploring the potential of Canavalia ensiformis for phytoremediation of B10 biodiesel-contaminated soil: insights on aromatic compound degradation and soil fertility

The widespread use of petroleum-based fuels poses a significant environmental problem due to the risks associated with accidental spills. Among the treatments available, phytoremediation is increasingly accepted as an effective and low-cost solution. This study aimed to evaluate the degradation of the aromatic fraction of biodiesel B10 and the soil fertility analysis in artificially contaminated soils treated with phytoremediation. The experimental design consisted of a 3x3 factorial, with three types of soil treatment: control, autoclaved, and planted with C. ensiformis L, and three levels of B10 biodiesel contamination: 0, 1, and 2%, to simulate spills of 30,000 and 60,000 L ha−1. The soil was analyzed at three depths: 0–10, 10–20, and 20–30 cm. The results indicated that aromatic compound degradation after phytoremediation was superior to 92,76% and 88,65% for 1% and 2% B10 soil contamination, respectively. The fuel contamination affected soil fertility, reducing the availability of phosphorus and zinc while increasing the Total Organic Carbon (TOC), pH, and the availability of manganese and iron for plants.

Impact of biological manure substitution on grain yield, nitrogen recovery efficiency, and soil biochemical properties

Fertilization plays a crucial role in ensuring global food security and ecological balance. This study investigated the impact of substituting innovative biological manure for chemical fertilization on rice (Oryza sativa L) productivity and soil biochemical properties based on a three-year experiment. Our results suggested rice yield and straw weight were increased under manure addition treatment. Specifically, 70% of total nitrogen (N) fertilizer substituted by biological manure derived from straw, animal waste and microbiome, led to a substantial 13.6% increase in rice yield and a remarkable 34.2% boost in straw weight. In comparison to the conventional local farmer practice of applying 165 kg N ha−1, adopting 70% of total N plus biological manure demonstrated superior outcomes, particularly in enhancing yield components and spike morphology. Fertilization treatments led to elevated levels of soil microbial biomass carbon and N. However, a nuanced comparison with local practices indicated that applying biological manure alongside urea resulted in a slight reduction in N content in vegetative and economic organs, along with decreases of 10.4%, 11.2%, and 6.1% in N recovery efficiency (NRE), respectively. Prudent N management through the judicious application of partial biological manure fertilizer in rice systems could be imperative for sustaining productivity and soil fertility in southern China.

A Bibliometric Analysis on Research Progress of Earthworms in Soil Ecosystems

The earthworm, as a soil engineer, plays highly important roles in the soil ecosystem for shaping soil structure, promoting soil fertility, regulating microbial community composition and activities and decomposing soil pollutants. However, the research progresses on this important soil fauna have rarely been reviewed so far. Therefore, we conducted a bibliometric analysis of the literature published during 1900–2022, which was collected from the Web of Science Core Collection (WoS). The results showed that three periods (1900–1990, 1991–2005 and 2006–2022) could be identified in terms of the intensity of publications on the topic, and the number of publications kept increasing since 2006. The United States produced the highest publication record at the country scale, whereas Chinese Academy of Sciences was the most productive institution. Chinese institutions and authors played an active and prominent role during 2018–2022. Soil Biology & Biochemistry was the most popular journal for the topic-related research. In these publications, Professor Lavelle P was the most influential author. Based on a citation network of the top 50 cited papers, four hotspots were identified, i.e., the ecological effects of earthworms, the impact of agricultural activities on earthworms, earthworm ecotoxicology and earthworm invasion. Moreover, “impact”, “biodiversity”, “oxidative stress”, “diversity”, “response”, “Eisenia fetida” and “exposure” were the emerging and active topics in recent years. This study can help us to better understand the relevant subject categories, journals, countries, institutions, authors and articles and identify the research hotspots and emerging trends in the field of soil earthworm research.

Mangrove sediments-associated bacterium (Bacillus sp. SW7) with multiple plant growth-promoting traits promotes the growth of tomato (Solanum Lycopersicum)

Global food production intensification presents a major hurdle to ensuring food security amidst a growing world population. Widespread use of chemical fertilizers in recent decades has risked soil fertility, compounded by the challenges posed by climate change, particularly in arid regions. To address these issues, adopting plant growth-promoting (PGP) bacteria stands out as a promising solution, offering multifaceted benefits to arid agroecosystems. We isolated a bacterial strain, SW7, from mangrove sediment, characterised the entire genome followed by phylogenetic analyses, and evaluated its in-vitro PGP activity. Subsequently, we examined its impact on tomato seed germination and plant growth. The strain SW7 exhibited growth on 11% NaCl, survival at 50°C, and possessed multiple PGP traits such as significant increase in seed germination rate (60.60 ± 38.85%), phosphate (83.3 g L−1) and potassium (39.6 g L−1) solubilization and produced indole acetic acid (3.60 ppm). Additionally, strain SW7 tested positive for ammonia, catalase, and oxidase enzyme production. The strain SW7 genome consists of 5.1 MB with 35.18% G+C content. Through genome-based phylogenetic and orthoANI analyses, the strain was identified as a novel Bacillus species, designated herein as Bacillus sp. SW7. In an eight-week shade-house experiment, inoculation of strain SW7 improved, leaf number, leaf density, leaf area index and mass water of tomatoes. Additional parameters, like chlorophyll a, chlorophyll b and carotenoids were not affected in SW7-inoculated tomatoes. In conclusion, Bacillus sp. SW7 exhibits multiple PGP traits and an adaptive capacity to high temperature and salinity, positioning it as a potential candidate for elevating the productivity of arid agroecosystems.

Soil Fertility Mapping Using GIS in Sirur Sub-Watershed of Kundagol Taluk of Dharwad District, Karnataka, India

Aims: To identify available nutrient constraints in soils and to generate soil fertility maps using remote sensing and GIS of Sirur sub-watershed in northern dry zone of Karnataka. Place and Duration of Study: The study was carried out in the Sirur sub-watershed (4D5B5j) located in Kundagol taluk of Dharwad district, Karnataka during 2022-24. Methodology: Soil samples (601) from Sirur sub-watershed in northern dry zone of Karnataka were drawn at 320 m x 320 m grid interval and assessed for fertility parameters. Analytical data was interpreted and statistical parameters like range, mean, standard deviation and coefficient of variation were calculated for each parameter. Soil fertility maps were prepared for each parameter using interpolation technique. Results: Soils were neutral to alkaline in reaction and non-saline. Soil organic carbon content was low to medium. Available nitrogen and phosphorus were low to medium, available potassium was high and sulphur was medium to high. Regarding available micronutrients, iron, copper and manganese were sufficient in the soils whereas Zn was deficient in about half of the sub-watershed area and B content was medium to high. Conclusion: The major constraints in sub-watershed are low content of OC, poor status of available N, P2O5 and Zn indicating their immediate attention for sustained crop production.

Role of rhizospheric microbial enzymes in plant growth promotion, antagonism, and sustainable agriculture: A review

Plant growth-promoting rhizobacteria (PGPR) offer eco-friendly alternatives to chemical fertilizers, promoting sustainable agriculture by enhancing soil fertility, reducing pathogens, and aiding in stress resistance. In agriculture, they play a crucial role in plant growth promotion through the production of agroactive compounds and extracellular enzymes to promote plant health and protection against phytopathogens. In the rhizosphere, diverse microbial interactions, including those with bacteria and fungi, influence plant health by production of antimicrobial compounds. The antagonism displayed by rhizobacteria plays a crucial role in shaping microbial communities and has potential applications in developing a natural and environmentally friendly approach to pest control. The rhizospheric microbes showcase their ecological importance and potential for biotechnological applications in the context of plant-microbe interactions. The extracellular enzymes produced by rhizospheric microbes like amylases, chitinases, glucanases, cellulases, proteases, and ACC deaminase contribute to plant processes and stress response emphasizing their importance in sustainable agriculture. Moreover, this review highlights the new paradigm including artificial intelligence (AI) in sustainable horticulture and agriculture as a harmonious interaction between ecological networks for promoting soil health and microbial diversity that leads to a more robust and self-regulating agricultural system for protecting the environment in the future. Overall, this review emphasizes microbial interactions and the role of rhizospheric microbial extracellular enzymes which is crucial for developing eco-friendly approaches to enhance crop production and soil health.

Analysis of soil fertility status on rice (Oryza sativa L.) planted land in Polewali District, Polewali Mandar Regency

Rice is the main food commodity in Indonesia. The main abiotic factor affecting rice productivity is soil fertility. This study aimed to determine the soil fertility status (SFS) of paddy fields in Polewali District, Polewali Mandar Regency, West Sulawesi. The research was conducted by surveying soil characteristics supported by soil chemical analysis at the Laboratory of Soil Science and Environmental Conservation, Faculty of Agriculture, Universitas Muslim Indonesia. The research was conducted in Polewali District, with the survey area consisting of 4 land map units (LMU). Soil fertility status was determined based on the criteria of each soil fertility parameter, namely: soil pH, organic C-content, cation exchange capacity, available P, Potassium content, and base saturation. The results showed that the SFS in Polewali District was classified as low. Only the base saturation parameters in LMU-2 and LMU-3 were classified as high. In addition, all parameters were only classified as very low to medium at all LMUs. Low C-organic content and very low P and K content are the main limiting factors for SFS. Recommended land management to improve soil fertility is the addition of organic matter that can increase total nitrogen and C-organic in the soil and the application of manure. Keywords: Soil fertility status, paddy fields, rice plants

Effects of P-solubilizing bacteria Cereibacter sphaeroides ST16 and ST26 on soil fertility, P uptake, and rice yield grown on salt-affected soils under greenhouse conditions

Effects of P-solubilizing bacteria Cereibacter sphaeroides ST16 and ST26 on soil fertility, P uptake, and rice yield grown on salt-affected soils under greenhouse conditions

Effects of Biochar and Straw Amendment on Soil Fertility and Microbial Communities in Paddy Soils

Effects of Biochar and Straw Amendment on Soil Fertility and Microbial Communities in Paddy Soils

Effects of Organic Fertilizer with Different Degrees of Maturity on Bacteria in Saline–Alkali Soil

Soil microorganisms are important components of soil ecosystems, and their diversity plays an important role in maintaining their functional stability. Organic fertilizer is an important measure for improving soil fertility in agronomic practice. The effects of organic fertilizer on soil microbial diversity and community structure are different with different degrees of maturation. In this study, uncomposted organic fertilizer (R), high-temperature organic fertilizer (H), cooling organic fertilizer (C), and decomposed organic fertilizer (D) were applied, and the 16S rRNA gene sequences of bacteria in soil were analyzed via high-throughput sequencing technology to understand the effects of organic fertilizer with different degrees of maturation on bacterial diversity and community structure in saline soil. Compared with no fertilization, the uncomposted organic fertilizer, high-temperature organic fertilizer, and decomposed organic fertilizer treatments significantly reduced soil bacterial diversity: the decomposed organic fertilizer treatment significantly reduced soil bacterial richness, the cooling organic fertilizer treatment had no significant effect on soil bacterial diversity and bacterial richness, Proteobacteria representing soil nutrients significantly increased under the cooling organic fertilizer treatment, and the relative abundance of Firmicutes significantly decreased. These four organic fertilizers, with different degrees of maturation, significantly increased the beneficial bacterium Bacillus and nitrile-based degrading bacteria but also significantly increased the potential pathogenicity of the soil, and there was no significant difference between the four treatments. In addition, during a cooling period, the organic fertilizer treatment helped to increase the population of oxidative-stress-tolerant bacteria. The application of organic fertilizer during a cooling period to saline–alkali soil is more helpful in improving its nutrient levels.

Green Manuring with Oilseed Rape (Brassica napus L.) Mitigates Methane (CH4) and Nitrous Oxide (N2O) Emissions in a Rice-Ratooning System in Central China

The use of oilseed rape (OS, Brassica napus L.) as a winter green manure is crucial for enhancing soil fertility and reducing chemical N application in paddy fields. However, the impacts of replacing varying amounts of chemical N with OS on CH4 and N2O emissions in paddy soils have not been well evaluated. In this study, GHG emissions, soil properties and OS decomposition in a rice-ratooning system with different OS-urea N replacement rates (0%, 25%, 50%, 75% and 100%) were investigated. Our results indicate that 84.7–90.7% of the initial C and 97.5–98.4% of the N were released during the 192-day decomposition process, and that the mineralization patterns of net C and net N in the OS residue were consistent with a single exponential decay model. The lowest CH4 emissions (9.97 g m−2) were observed at 0% OS, while the highest N2O emissions (0.40 g m−2) were observed at this level of substitution. Conversely, the highest CH4 emissions (20.71 g m−2) and lowest N2O emissions (0.07 g m−2) were observed at 100% OS. Compared to 0% substitution, 25% substitution significantly decreased GWP and GHGI without reducing rice grain yield. Environmental parameters such as soil redox, NH4+-N and residual N and C were shown to be significantly associated with CH4 emissions, whereas soil redox, NH4+-N and residual C were the main drivers of N2O emissions. In conclusion, 25% substitution of OS was the most cost-effective measure for balancing greenhouse gas emission and rice yield.

Response of Soil Microbial Community Structure and Diversity to Mixed Proportions and Mixed Tree Species in Bamboo–Broad-Leaved Mixed Forests

Bamboo and broad-leaved mixed forests have been widely recognized for their advantages in maintaining ecological balance, improving soil fertility, and enhancing biodiversity. To understand the effects of mixed broad-leaved tree species and mixing ratios on soil microbial communities in bamboo and broad-leaved mixed forests, we quantified the structure and diversity responses of soil microbial communities to tree species and mixing ratios using high-throughput sequencing of the 16 S rRNA gene. Three bamboo and broad-leaved tree mixed forests were studied, including bamboo–Castanopsis chinensis Hance mixed forest (CCB), bamboo–Alniphyllum fortune (Hemsl.) Makino mixed forest (AFB), and bamboo–Choerospondias axillaris (Roxb.) B. L. Burtt & A. W. Hill mixed forest (CAB). We assessed the impact of tree species and mixing ratios on soil microbial communities by measuring soil properties and the diversity and composition of soil microbes. The results indicate that soil properties and the diversity and composition of microbial communities are highly dependent on broad-leaved tree species in mixed forests. The mixing ratios had a more pronounced effect on microbial diversity than on richness. In CAB, diversity peaked at mixing ratios of 10%–20% and 20%–40%. The presence of broad-leaved trees significantly altered the relationships among soil bacteria, with CAB showing the highest stability, likely due to the increased diversity and quantity of litter from Choerospondias axillaris. Our results show that the choice of broad-leaved tree species and their mixing ratios significantly influence soil microbial diversity and composition in bamboo–broad-leaf mixed forests. An optimal mixing ratio in CAB can maximize bacterial diversity and stability, providing insights for forest management and promoting ecosystem health and sustainability.

Impact of cropping systems on soil quality

The agricultural intensification process implemented during the last 20 years consisted of replacing a crop-pasture rotation system with a continuous no-till cropping system that affected the functional properties of the soil in the medium term. The hypothesis of this study was that the annual cropping intensification process could be characterized, at the commercial level, by soil property indicators that capture changes in the pathway of cropping systems (CSs) in the medium term. The objectives were: i) to identify CSs based on land use; and ii) to characterize soil properties associated with different CSs. Based on this, a database was built with the land use description from 2014 to 2020 of 45 farms belonging to farmers associated with FUCREA and AUSID. A Principal Component Analysis (PCA) was performed with 14 land use indicators to select those that best summarized all the information. The selected indicators were pasture-crop ratio (PCR), soybean frequency during the summer annual cropping phase (SSbCF), intensification of annual cropping phase index (IAI), and intensity of soil use index (ISI). By performing a Cluster Analysis with these indicators, the following CSs were identified: pasture-crop rotation (ROT-PC), continuous cropping with high frequency of C4 photosynthesis species (CC_Corn), and continuous cropping with high frequency of soybean (CC_Soybean). Based on the identified CS, 64 representative sites were selected within a 60 km radius from the coordinates −33.17 S and −57.80 W, Uruguay's most influential annual cropping area, assessing 46 soil properties sensitive to changes in their management in the medium term and capable of affecting productivity. A PCA was used to select the properties that best summarized the information. A Linear Discriminant Analysis (LDA) with the selected variables and the identified CS groups determined a loss in soil fertility (organic carbon and electrical conductivity) and nutrient availability (potassium), which is related to CS diversification (CC_Soybean> CC_Corn>ROT-PC).

Yield and Fruit Characteristics of Tomato Crops Grown with Mineral Macronutrients: Impact of Organo-Mineral Fertilizers through Foliar or Soil Applications

The utilization of plant biostimulants has gained importance as a strategy by which to improve plant productivity and soil health. Two independent trials were conducted across two seasons (2021 and 2023) to evaluate the effects of foliar or soil applications of various commercial organo-mineral fertilizers (Futuroot®, Radicon® Amifort®) with biostimulant action that is exerted on yield and fruit characteristics of processing tomato crops (cv Taylor F1) that have been exposed to mineral macronutrients. These treatments were administered three times during the season: at the transplanting, pre-flowering and berry development stages. In the first trial, conducted in two fields characterized respectively by low and high fertility, foliar applications of Radicon®, which is based on humic acid and amino acids, increased the leaf greenness index SPAD compared with the control. Furthermore, the leaf green colour intensity (SPAD index), measured during the reproductive phases of the tomato exhibited a positive correlation (R2 = 0.726) with the marketable yield obtained. This increase in marketable yield was significant in the biostimulant treatment compared with the control in both soils, especially in the soil characterized by lower fertility (16.1%), when compared with the more fertile soil (6.8%). In the second trial, conducted in the low-fertility field mentioned above, soil applications of all biostimulants (Futuroot®, Radicon® and the combinations [Radicon® + Amifort-Plus®]) significantly increased the marketable yield by 27.8%, 13.5% and 27.7%, respectively, compared with the control. The most significant beneficial effects of both Futuroot® and [Radicon® + Amifort®] could be attributed to the combination of humic acids and auxins, cytokinins or microelements (Zn, Mn, MgO) present in the formulation of these products. Furthermore, the increase in marketable yield obtained when Radicon® was applied to leaves was higher (16.1%) than that observed with soil application (13.5%). In both trials, no relevant effects of biostimulant products were observed on most of the physicochemical characteristics of tomato fruits. In conclusion, the biostimulants based on humic acid and amino acids combined with chemical fertilizers tested in the present study and applied by fertigation were more effective in improving tomato yield, and therefore they can be recommended for efficient agricultural production.