Sustainable Fertility Management Research Articles

The Western Greece Soil Information System (WΕSIS)—A Soil Health Design Supported by the Internet of Things, Soil Databases, and Artificial Intelligence Technologies in Western Greece

Soil quality is vital for ecosystem stability, impacting human, plant, and animal health. Traditional soil quality assessments are labor-intensive and costly, making them unsuitable for smart agriculture. To overcome this, Internet of Things (IoT) and artificial intelligence (AI) technologies are employed for sustainable agriculture, enabling real-time data collection and analysis, trend identification, and soil health optimization. The Western Greece Soil Information System (WΕSIS) offers open-access data and services for soil health and sustainability. It includes modules for soil quality indicators, sustainable fertilization management zones, soil property distribution, prediction, mapping, statistical analysis, water management, land use maps, digital soil mapping, and crop health calculation. Integrating the IoT and AI allows for real-time and remote monitoring of soil conditions, managing soil interventions adaptively and in a data-driven way, enhancing soil resources’ efficiency and sustainability, and increasing crop yield and quality. AI algorithms assist farmers and regional stakeholders in optimizing production lines, methodologies, and field practices, reducing costs and increasing profitability. This promotes a circular economy, a soil- and climate-resilient future, biodiversity protection targets, and enhanced soil fertility and productivity. The proposed IoT/AI technical architecture can underpin the development of soil health monitoring platforms, integrating data from various sources, automating data collection, and providing decision support tools.

Enhancing the nutritional value of sweet pepper through sustainable fertilization management

IntroductionThe need for healthy foods has become a major concern in our modern world, as the global population continues to grow and environmental challenges intensify. In response to these challenges, researchers have started to explore a range of sustainable solutions, including organic farming practices, precision agriculture, and the development and testing of innovative biofertilizers. Consistent with these ideas come the aim of this study, which sets out to give new insights into the cultivation of two sweet pepper cultivars with economic and nutritional importance in Romania.MethodsTwo sweet pepper cultivars (Blancina and Brillant), chemically (Nutrifine®), organically (Orgevit®) and biologically (Micoseed®) fertilized were cultivated over the course of two years (2019 and 2020), between April and October, in high-tunnel, by following a split-plot design with three replications. Production parameters (number of fruits, fruit weight, yield), proximate composition (water content, dry matter, total soluble solids, acidity, ash), the content of phytonutrients (polyphenols, lycopene, β-carotene, antioxidant activity), phytochemical composition (phenolic compounds) and minerals (macro- and micro-elements) were analyzed in order to determine the impact of fertilization on the quality of sweet peppers.ResultsThe results showed that the biological and organic fertilizations had a significant positive impact on most of the parameters analyzed, starting with yield and continuing with acidity, phytonutrient content (total phenolic content, lycopene, β-carotene), antioxidant activity and phytochemical composition (chlorogenic acid, p-coumaric acid, quercetin and isoquercetin). Only in the case of mineral content, the chemical treatment gave better results compared with the organic and biological fertilizers.ConclusionOverall, this study provides valuable information on the potential of organic and biological fertilizers to enhance the nutritional value of sweet peppers from Blancina F1 and Brillant F1 cultivars, paving the way for subsequent research aimed at achieving superior quality and increased yields.

Assessing environmental impacts of chemical fertilizers and organic fertilizers in Sri Lankan paddy fields through life cycle analysis

The application of fertilizer is a very important activity in paddy cultivation as it is one of the yield-determining factors. But the use of chemical fertilizer is a matter of debate as it is suspected as a cause of many prevailing health problems and comparatively large amounts of environmental pollution. Therefore, the focus of this study was to carry out a proper life cycle analysis on the application of chemical and agricultural waste-based organic fertilizers considering all the important steps such as collection of raw material, manufacturing, transportation, and application fields. The integration application of chemical and organic fertilizers was considered with two different ratios. Characterized results reveal that chemical fertilizer application has the highest impact on all selected categories, while organic fertilizer application has lower impact.The combination of chemical and organic fertilizers shows that reducing the proportion of chemical fertilizers reduces environmental impacts. Additionally, the study identifies the processes that significantly contribute to each impact category, such as urea production for climate change and freshwater ecotoxicity, and composting and field application for human toxicity and terrestrial acidification. Normalized results show that switching to organic fertilizers could reduce up to 82.4% of the current environmental impact. Therefore, an integrated approach will give more benefits in many ways. These findings provide valuable insights for policymakers and farmers in making informed decisions regarding sustainable fertilizer management.

Effects of Organic Amendments on Phenol Oxidase, Peroxidase, Urease, and Nitrogen Mineralization: A Laboratory Incubation Study

Mitigating climate change and enhancing fertility in agricultural systems require the adoption of more sustainable fertilizer management practices. Applications of recycled organic materials, such as animal and green wastes, can promote soil carbon stabilization via changing extracellular enzyme activities while providing the necessary nitrogen (N) for plant growth. The goals of this study were to quantify the effects of compost type (cow manure, green manures, mixtures of green and cow manure at various proportions, and inorganic fertilizers) on (1) enzyme activity (phenol oxidase, peroxidase, and urease), and (2) mineralized N under laboratory incubation at 30 °C over an eight-week period. The lowest oxidative enzyme activities (phenol oxidase and peroxidase) were found in the soil treated with a mixture of 50% cow manure and 50% green manure (2.45 μmol h−1 g−1) and a mixture of 30% cow manure and 70% green manure (3.21 μmol h−1 g−1) compared to all other fertilizer treatments. The highest phenol oxidase activity was found in soils amended with green manures (3.52 μmol h−1 g−1), while the highest peroxidase activity was found in soils amended with a mixture of 70% cow manure and 30% green manure (5.68 μmol h−1 g−1). No significant differences were found in total net mineralized N content among all organic fertilizer treatments, but these were significantly lower than total net mineralized N in soil treated with inorganic fertilizers. These results indicate similar effects of organic amendments and mixtures in providing plant-available N, but different effects on lignin-degrading enzyme activities, which may lead to differences in soil organic carbon cycling and long-term C storage depending on which organic amendment is utilized.

Operationalizing the Sustainable Fertilizer Management Global Initiative at National Level: A Conceptual Framework

Humanity is tasked with finding a balance between the need to increase the amount of food and the negative socio-environmental and economic consequences of the irrational use of fertilisers. At the global level, a number of initiatives have been launched to consolidate countries' efforts to address this problem. However, existing national fertiliser management systems and policies are characterised by insufficient consistency and low efficiency. This study aims to formulate a conceptual framework for developing a national sustainable fertiliser management system that meets the principles set out in existing global initiatives. Through the generalisation of the content of existing intergovernmental initiatives on sustainable fertiliser management, the subject composition was formulated, and estimates of the relationship between fertiliser application and public health (through the number of cancer diseases) through the use of regression analysis methods, assessment of economic damage from irrational fertilisation served as a substantiation (illustration of the importance of highlighting) of components covering: awareness, knowledge, tools. The national sustainable fertiliser management system is considered three-dimensional integrity containing the following interrelated components: government, fertiliser production and supply industries, and users. The functioning of this system is seen as a continuous process of raising awareness, generating and transferring knowledge, selecting and applying appropriate tools, and improving fertiliser application practices in accordance with the principles of sustainable development, with the leading role of government. The process of raising awareness of all actors of the system about the problem of irrational fertilisation is proposed to be considered in a broader context – through the demonstration of negative consequences not only for the environment (soil condition), but also from the standpoint of the impact on public health and related consequences – through the assessment of economic damage caused by pollution and consumption of food containing harmful substances. The main principles of interaction of subjects in this system should be the following: professionalism, transparency, information support, etc. Special attention should be paid to the formulation of a set of strategic goals that would lay the foundation for the development of control and evaluation procedures, a system for monitoring and reviewing mechanisms for economic incentives for fertiliser use, considering the social and environmental aspects of fertiliser use

Intercropping of Cauliflower with Lettuce Is More Effective for Sustainable Fertilizer Management and Minimizing Environmental Risks

Intercropping systems are one of the sustainable agricultural models as they play an important role in protecting soil fertility, efficient use of resources, maintaining stable yields, and reducing the effectiveness of diseases and pests. The aim of this study was to investigate the effects of intercropping (IC) cauliflower (Brassica oleracea L. var. botrytis) with leaf lettuce (Lactuca sativa L. var. crispa) on the yield and quality parameters of cauliflower and to evaluate the overall productivity of the system under different nitrogen fertilization rates (160, 200, and 240 kg N ha−1). Our results showed that the leaf chlorophyll value (SPAD), plant weight, leaf weight, head diameter, head height, head weight, and total yield of cauliflower were found to increase as the nitrogen dose increased in both the monocropping (MC) and IC systems. The most efficient nitrogen fertilizer doses for cauliflower were 234.7 kg ha−1 for MC and 176.6 kg ha−1 for IC, respectively. When the intercropping system was used the total yield (cauliflower and lettuce) was higher than the yield of cauliflower (MC) for the same total area and fertilizer amount. The land equivalent ratio (LER) values were greater than 1 in the intercropping system at all fertilization rates, which indicated that the IC system was more productive than the MC system for the same unit of land. Our findings also showed that intercropping was an effective method to increase fertilizer use efficiency and the soil organic matter, nitrogen content, plant available P, K, Mg, Zn, Fe, Mn, and Cu. In conclusion, while intercropping cauliflower with lettuce did not adversely affect the yield of cauliflower, it enabled harvesting more plants (cauliflower and lettuce) from the same land area by using the same amount of fertilizer, which makes intercropping a sustainable, economical, and ecological model that increases the land-use and fertilizer-use efficiencies.

Effect of Hypoxic Stress and Levels of Mn on the Physiology and Biochemistry of Phyllostachys praecox.

Hypoxic environments have an adverse effect on the growth and development of P. praecox, and this is accompanied by the production of reducing substances such as Fe and Mn. In this study, the effect of hypoxic stress and Mn concentrations on leaf chlorophyll contents, root morphology, root activity, element absorption, antioxidant enzymes, and respiratory enzyme system of P. praecox were evaluated in a hydroponics environment. The results revealed that application of Mn2+ during hypoxic stress enhanced leaf chlorophyll contents and boosted up the indexes of the root system. The root activity of P. praecox was reduced with stresses of hypoxia. The treatment of Mn2+ initially improved and then decreased the root activity of P. praecox, and attained its maximum with application of 300 μmol/L Mn2+ compared with control. The indexes of antioxidant enzymes of P. praecox were higher than that of 8 mg/L oxygen concentrations except for variable superoxide dismutase (SOD) in the treatment of 300 μmol/L Mn2+ with hypoxia stress. The application of Mn had inhibited the absorption of mineral elements in P. praecox. The activities of pyruvate decarboxylase (PDC), alcohol dehydrogenase (ADH), and lactic dehydrogenase (LDH) were initially improved and then diminished with hypoxia stress. It is concluded that hypoxia is a key factor affecting the growth and degradation of P. praecox, while combining it with the increase of Mn concentration enhances the damage to Phyllostachys pubescens. Our research is helpful for the sustainable management and scientific fertilization management of Phyllostachys praecox.

Comparative Study between Urea and Biogas Digestate Application towards Enhancing Sustainable Fertilization Management in Olive (Olea europaea L., cv. ‘Koroneiki’) Plants

Organic fertilization is a promising strategy to decrease N mineralization rates and high N losses via leaching and denitrification, thus synchronizing N application with N uptake for crops. A 230-day experiment with olive plants was realized under greenhouse conditions to compare urea and biogas digestate (BD) application on the growth, nutrient uptake, and physiological performance of Olea europaea L. plants. The following treatments were applied: (i) UREA, (ii) UREA + DCD (nitrification inhibitor), (iii) BD, (iv) BD + DCD, (v) acidified BD, (vi) acidified BD + DCD, (vii) CONTROL (typical native Marl soil type, without fertilizer application). Under BD application, significantly higher levels of organic matter, Olsen P, and exchangeable K compared to UREA were found. Significantly lower main shoot length and total plant biomass were recorded in the CONTROL soil compared to BD. Foliar N was lower in the ACID.BD and ACID.BD + DCD treatments, while leaf P was lower in UREA. The highest PSII activity was recorded in UREA + DCD, while the highest photosynthetic rate and intercellular CO2 concentration were determined in UREA. It is expected that these data will constitute a first comparative approach between urea and BD application in olive plants, which should be carefully considered, towards boosting sustainable fertilization in the frame of circular economy strategy.

N limitation increases along a temperate forest succession: evidences from leaf stoichiometry and nutrient resorption

Abstract Forest productivity and carbon (C) sequestration largely depend on soil N and P availability. To date, however, the temporal variation of nutrient limitation along forest succession is still under debate. Leaf stoichiometry and nutrient resorption are important indicators for predicting nutrient limitation of plant growth. Here, we measured nitrogen (N) and phosphorus (P) concentrations in green leaves and leaf litter for all woody species at four stages of temperate forest succession, and analyzed how abiotic and biotic factors affect leaf stoichiometry and nutrient resorption along forest succession. At the individual scale, leaf N and P concentrations had a significant increase at the end of the succession, while no change in leaf N:P ratio was detected. Nitrogen resorption efficiency (NRE) increased significantly with succession, but P resorption efficiency (PRE) first increased and then decreased. Significant increases in NRE:PRE ratios only occurred at the end of the succession. Moreover, plant N cycling was less responsive to soil nutrient than P cycling. At the community scale, we found that leaf N and P concentrations first decreased and then increased along forest succession, which were mainly affected by Shannon–Wiener index and species richness. Leaf N:P ratio significantly varied with succession and was mainly determined by community-weighted mean diameter at breast height (DBH). NRE increased and was significantly influenced by species richness and DBH, while PRE was relatively stable along forest succession. Thus, the NRE:PRE ratios significantly increased, indicating that N limitation is exacerbated with the temperate forest succession. These results might reflect the intense interspecific competition for limiting resource in a higher biodiversity community. In conclusion, our findings highlight the importance of biotic factors in driving forest ecosystem nutrient cycling and provide valuable information for sustainable fertilizer management practices in China’s temperate and boreal forests.

English

Nutrient leaching limits sustainable fertility management of tropical sandy soils. Therefore, phosphate leached from NPK 15:15:15 (NPK), sole compost (SC), phospho-compost (PC), poultry manure (PM), fresh Gliricidia sepium leaves (GL) and integrated (INTG) fertilizers applied at 40 kgP2O5 ha-1 and an unamended soil (AC) in leaching columns containing 2.5 kg soil were studied. Each soil was simulated for leaching at 2, 4, 6, 8, 10 and 12 weeks after cowpea seed sowing. Fertilizer application significantly reduced total leachate volume (TLV) over AC in the order of AC > SC > NPK > INTG > PC > GL > PM. Total phosphate leached (TPL) was  the highest (1505.3 mg l-1) in GL followed by 436.5, 229.7, 69.0, 33.4, 30.5 and 0.0 mg l-1 from NPK, INTG, AC, PM, SC and PC, respectively. The PC, PM and INTG produced significantly higher dry shoot (DSW) and root (DRW) weights, N and P uptake. Cowpea grain weight (CGW) was significantly higher (2.42 g plant-1) in INTG over AC (0.99 g plant-1). Significant negative correlation was between TLV and DSW, CGW, N and P uptake and between TPL and soil available P, N and P uptake. Stabilized organic (PC and SC) and integrated fertilizers (INTG) are therefore suitable for reduced phosphate leaching in sandy soil. Key words: Chemical fertilizers, Leaching column, NPK 15:15:15, phospho-compost, phosphate leachate losses, soil nutrient leaching.

Концептуальні положення сталого менеджменту добрив в Україні

The article presents the results of the analysis of the main national and international documents, which are evidence of how the global deterioration of the quality and state of soil resources catalyzed the process of awareness by the international community of the need to develop and implement mechanisms for preserving the productive and ecological functions of the soils of agrocenoses in order to achieve a neutral level of land degradation. One of the main blocks of sustainable management of soil resources is the sustainable management of fertilizers, the use of which significantly increases the productivity of agricultural crops, affects the quality of the soil, but may have certain environmental risks. The purpose of the research is to define conceptual approaches to sustainable fertilizer management that are harmonized with the requirements of the International Fertilizer Code and adapted to the conditions of Ukraine. The research was conducted using general scientific, structural-functional and abstract-logical methods. The analysis of the current national base of regulatory documents regarding the management of soil resources and fertilizers indicates its improvement, including through the ratification and implementation of international regulatory documents. Within the framework of the international integration of the country, a conceptual approach to the sustainable management of fertilizers in Ukraine is proposed, which is aimed at reorienting the vector of actions from "controlling the impact" to "preventing the impact", where the object of action is the soil, and the subject of action is fertilizers. Subjects of ensuring sustainable management of fertilizers - authorities, manufacturers of fertilizers, including from secondary raw materials, scientific institutions of the National Academy of Agrarian Sciences and the State Institution "Soil Protection Institute of Ukraine", higher educational institutions of agronomic and environmental specialties, organizations and associations of various forms of ownership , whose activities concern fertilizers, agrochemical laboratories and farms of various forms of ownership. Sustainable fertilizers management, harmonized with international guidelines, is based on such principles as objectivity, representativeness, regulation, scientificity, systematicity, causality, environmental friendliness, benchmarking and informativeness. Based on the results of the analysis, a set of measures to ensure the sustainable management of fertilizers in Ukraine is proposed, which consists of interconnected and complementary blocks – regulatory, organizational, informational and technological (fertilizer production and application), which have a number of relevant tasks aimed at ensuring a balanced and standardized application of fertilizers in the country's agriculture, preservation of productive and ecological functions of soils, prevention of the development of degradation processes in order to achieve their neutral level, guarantee of food stability and ecological security of the country.

Estimating Soil Loss for Sustainable Crop Production in the Semi-deciduous Forest Zone of Ghana

Quantitative information on soil loss is relevant for devising soil conservation and crop management strategies to ensure sustainable fertility management and crop production. Estimations from runoff/erosion plots are expensive and laborious and thus requiring the exploration of other less expensive but reliable methods such as modeling. This study aimed to estimate current and future rates of soil loss for conservation planning toward sustainable crop production in the semi-deciduous forest zone of Ghana. The Universal Soil Loss Equation (USLE), which took into consideration the rainfall characteristics of the study area, inherent soil physicochemical and hydraulic properties, variations in slopes and terrain differences, land cover types, and soil management practices, was employed to estimate the magnitude and rate of soil loss in the study area. Output from three regional climate models (RCMs) from Coordinated Regional Climate Downscaling Experiment including CCCma-CanESM2, GFDL-ESM2M, and HadGEM2-ES were used to estimate the impact of climate change on soil erosion in the study area. The results showed that soil loss estimated for bare soils was high ranging from 12.7 to 163.8 t ha−1 year−1 largely due to variation in slopes coupled with soil physicochemical and hydraulic properties. The simulated annual soil losses under various land cover options showed variable degrees of soil loss for maize cultivation under conventional tillage (8.2–106.5 t ha−1 year−1), soya bean monocropping (4.4–57.3 t ha−1 year−1), and low soil loss for oil palm plantation with grass or leguminous cover (2.5–32.8 t ha−1 year−1). Evaluation of the RCMs showed excellent performance for CCCma-CanESM2 and GFDL-ESM2M. Predictions of climate change impact using outputs from CCCma-CanESM2 and GFDL-ESM2M indicated that 9–39% increase in soil loss is expected by 2070, and it will be more severe (16–42%) by 2100. The model predictions indicate that the adoption of site-specific land cover management strategies such as tree–cover crop intercropping and reduced tillage has a huge potential to reduce soil loss and sustain soil fertility. The model can be used as an advisory tool for mapping areas for appropriate cropping systems for a particular site.

Diversity and spatial distribution of soil diatoms along a natural altitudinal gradient in the High Atlas (Morocco)

Microscopic algae especially diatoms (Class Bacillariophyceae) are an important component of biological soil crusts (or biocrust) communities in arid and semi-arid environments. In Morocco, a largely arid and semi-arid African Mediterranean country, the soil diatom diversity and ecology remain unexplored, unlike aquatic diatoms. This study aims to understand the spatial distribution of soil diatoms and to investigate the effects of soil properties and land use on their diversity and taxonomic composition in the region of Marrakesh (Morocco). Five sampling sites with different land use and vegetation cover were selected along a natural altitudinal gradient in the Ourika watershed (from the humid mountain highlands of Oukaimeden at 2634 m (High Atlas) to the arid Haouz plain at 765 m). Biological soil crusts were taken and soil physicochemical characteristics (soil moisture and texture, pH, electrical conductivity, total organic carbon, ammoniacal nitrogen, available phosphorus) were measured at five locations and two seasons (February and May). The spatial distribution of soil diatom communities and associated influencing factors were investigated via statistical analysis using Canonical Correspondence Analysis (CCA). A total of 27 diatom taxa belonging to 16 genera were recorded. The results showed that the distribution of soil diatoms was mainly influenced by altitude, bioclimate, substratum type, land use and vegetation cover. These environmental factors induce spatial variability in the soil physicochemical properties. Diatom composition and species richness were correlated with soil moisture, pH, texture, conductivity, nutrient and organic matter content. Diatoms showed higher species richness in siliceous soils of high altitudinal humid grassland dominated by acidophilous and neutral taxa with a preference for low conductivity. In contrast diatom communities of forests and sedimentary lowland arid steppe were relatively species poor, dominated by typically alkaliphilous and halophilous soil species. This exploratory survey provides a first account of the diatom assemblages of biological soil crusts over an altitudinal range in Morocco, necessary for understanding their structure and ecological function, including improving soil condition and sustainable fertility management.

Reductions in the deposition of sulfur and selenium to agricultural soils pose risk of future nutrient deficiencies

Atmospheric deposition is a major source of the nutrients sulfur and selenium to agricultural soils. Air pollution control and cleaner energy production have reduced anthropogenic emissions of sulfur and selenium, which has led to lower atmospheric deposition fluxes of these elements. Here, we use a global aerosol-chemistry-climate model to map recent (2005–2009) sulfur and selenium deposition, and project future (2095–2099) changes under two socioeconomic scenarios. Across the Northern Hemisphere, we find substantially decreased deposition to agricultural soils, by 70 to 90% for sulfur and by 55 to 80% for selenium. Recent trends in sulfur and selenium concentrations in USA streams suggest that catchment mass balances of these elements are already changing due to the declining atmospheric supply. Sustainable fertilizer management strategies will need to be developed to offset the decrease in atmospheric nutrient supply and ensure future food security and nutrition, while avoiding consequences for downstream aquatic ecosystems.

Combined effect of trees and soil fertility management practices on millet yields in the Sahel

Tree/shrub species are used in farmer fields of sahelian agroforestry parklands to conserve and restore degraded lands, improve soil fertility and increase crop yield. A field study was conducted to investigate the effect of five tree species (Annona senegalensis, Balanites aegyptiaca, Faidherbia albida, Guiera senegalensis and Piliostigma reticulatum) on soil fertility and crop yield under different fertility management practices in semi-arid Niger. Three factors (tree species, positions to tree trunk and fertilizer management) and four levels of fertilizer microdosing management (DAP, NPK, manure and control) were investigated. We found that tree species improved soil fertility and crop yield differently. F. albida, improved the soil quality far better than other four tree species for all soil nutrients analyzed. The highest millet yield was recorded under P. reticulatum and F. albida for both grain (1011 and 1005 kg ha−1, respectively) and straw yields (3662 and 3786 kg ha−1, respectively). The yield was found to be two- to four-folds higher under direct tree crown compared to close neighborhood or treeless outside. The combined tree species and fertilizer effect were additive and the positive effect can extend to the outside crown. However, the combined effect of mineral fertilizer with tree species on yield was better than that of manure. Integrated tree species and moderate fertilizers was effective and can be used as a sustainable fertility management practice in Sahelian countries where organic amendment is frequently scarce and it is difficult for smallholder farmers to adopt high recommended mineral fertilizer for crop production. Further investigations are needed to assess the economic performance and the long-term sustainability of the integrated trees and soil fertility management in the Sahel.

Nitrogen and Sulfur Recycling and Diagnostic in Cover Crop-Maize Systems

It remains uncertain how oat (Avena sativa L.) and hairy vetch (Vicia villosa Roth.) impact both nitrogen (N) and sulfur (S) recycling in cover crop-maize (Zea mays L.) systems as well as N and S diagnostic methods in maize. Field trials were conducted at three sites in the southeastern Argentinean Pampas to evaluate the effect of oat, hairy vetch, and bare fallow combined with four N and S fertilization treatments (unfertilized, N-, S-, and NS-fertilized) on maize. Soil N and S content at maize sowing, chlorophyll meter reading (CMR) at silking, and grain yield were determined. Overall, soil NO3−-N content (0–60 cm) at maize sowing was hairy vetch > bare fallow > oat, while SO4−2-S content was hairy vetch > bare fallow = oat. Maize yield response to N was predicted from soil NO3−-N content (R2 = 0.80). The CMR was negatively correlated with cover crop residue quality (carbon (C)/N and C/S ratios). Also, CMR accurately predicted variations in maize grain yield. In the unfertilized treatment, maize yield was hairy vetch > bare fallow > oat, in two of the three sites. There was no yield response to N or S with hairy vetch. Oat and hairy vetch differentially affected N and S recycling in cover crop-maize cropping systems. Soil NO3−-N and SO4−2-S content at maize sowing combined with CMR are reliable diagnostic tools to assess maize N and S, allowing for sustainable fertilization management.

Partial substitution of organic nitrogen with synthetic nitrogen enhances rice yield, grain starch metabolism and related genes expression under the dual cropping system.

Improving grain filling in the presernt farming systems is crucial where grain filling is a concern due to the extreme use of chemical fertilizers (CF). A field experiment was conducted at the experimental station of Guangxi University, China in 2019 to test the hypothesis that cattle manure (CM) and poultry manure (PM) combined with CF could improve rice grain filling rate, yield, biochemical and qualitative attributes. A total of six treatments, i.e., no fertilizer (T1), 100% CF (T2), 60% CM + 40% CF (T3), 30% CM + 70% CF (T4), 60% PM + 40% CF (T5), and 30% PM + 70% CF (T6) were used in this study. Results showed that the combined treatment T6increased starch metabolizing enzymes activity (SMEs), such as ADP-glucose phosphorylase (ADGPase) by 8 and 12%, soluble starch synthase (SSS) by 7 and 10%, granule bound starch synthesis (GBSS) by 7 and 9%, and starch branching enzyme (SBE) by 14 and 21% in the early and late seasons, respectively, compared with T2. Similarly, higher rice grain yield, grain filling rate, starch, and amylose content were also recorded in combined treatments. In terms of seasons, higher activity of SMEs , grain starch, and amylose content was noted in the late-season compared to the early season. The increment in these traits was mainly attributed to a lower temperature in the late season during the grain filling period. Furthermore, our results suggested that an increment in starch accumulation and grain filling rate were mainly associated with the enhanced sink capacity by regulating key enzyme activities involved in Suc-to-starch conversion. In-addition, RT-qPCR analysis showed higher expression levels of AGPS2b, SSS1, GBSS1, and GBSE11b genes, which resultantly increased the activities of SMEs during the grain filling period under combined treatments. Linear regression analysis revealed that the activity of ADGPase, SSS, GBSS, and SBE were highly positively correlated with starch and amylose accumulation. Thus, we concluded that a combination of 30% N from PM or CM with 70% N from CF is a promising option in terms of improving rice grain yield and quality. Our study provides a sustainable fertilizer management strategy to enhance rice grain yield and quality at the lowest environmental cost.

Yield and Nutritional Response of Greenhouse Grown Tomato Cultivars to Sustainable Fertilization and Irrigation Management.

Tomato is considered one of the most important crops worldwide from nutritional and economic standpoints, and, in this respect, sustainable production should be a prime objective, particularly in terms of fertilization and irrigation management. The aim of this study was to compare the effects of two fertilization types (chemical or organic) and two irrigation regimes (67% or 100% of evapotranspiration replenishment) on biometrical, biochemical, and yield parameters of three indeterminate cultivars of tomato grown in a greenhouse. The results showed that the effect of organic fertilization was better compared to chemical fertilization for lycopene accumulation and antioxidant activity, as well as for the lower concentrations of any of the macroelements in the tomato fruits; therefore, organic fertilization can be used as an alternative to chemical fertilization in sustainable horticulture. In each cultivar under the same fertilization type, the effect of irrigation was significant on yield and the number of fruits, but the 100% evapotranspiration restoration did not enhance the fruit concentration of all the macroelements and microelements compared to 67% irrigation regime. Higher concentrations of macro- and microelements in the chemically fertilized fruits compared to the organic ones, regardless of the cultivar and the irrigation regime, suggest that the inorganic substances are more easily absorbed by plants under a protected environment. Organic fertilization positively affected the lycopene and antioxidant activities of tomato fruits, thus proving to be a valuable alternative to chemical fertilization in sustainable agriculture, although the product premium quality also depends on the cultivar used.

Comparative agronomic effectiveness of two agrowastes and NPK fertilizer on the performance of Amaranthus caudatus

Production of agricultural wastes is increasing while soils are progressively losing organic matter due to intensive cultivation and climatic conditions. This makes the recycling of organic wastes a useful alternative to incineration, landfill or rubbish dumps. The effects of two agro- wastes and mineral fertilizer on growth and yield of leaf amaranth were assessed in a pot experiment at the Teaching and Research Farm, Ekiti State University, Ado-Ekiti. Treatments consisted of poultry manure (PM) and palm oil mill effluent (POME) each applied at 8 and 16MT/ha while NPK 15-15-15 was applied at 150, 200kgha-1 and no fertilizer as control. Seeds of amaranthus caudatus variety were sown in plastic pot (50x20x40cm) containing 20kg top soil. Treatments were arranged in a randomized complete block design replicated three times. Data were taken on plant height, stem girth, number of leaves plant-1, leaf area, root length, fresh weight, dry weight, edible yield and above ground plant weight at 6 weeks after planting. The results revealed that the agrowastes significantly (p<0.05) resulted in better performance of leaf amaranth. Application of 16MT/ha PM gave the highest fresh and edible weight of 211.23 and 98.80g respectively. POME also performed better than NPK fertilizer in some of the parameters measured. This indicated that PM and POME could serves as an alternative sources of nutrient to mineral fertilizer for leaf amaranth and also a sustainable fertility management strategy for crop production.
 Keywords: amaranth, palm oil mill effluent, organic fertilizer, NPK fertilizer, utilization

Precision Agriculture Application for Sustainable Nitrogen Management of Justicia brandegeana Using Optical Sensor Technology

Over-fertilization is a common practice in ornamental nursery production. Oftentimes, visual analysis is used to determine plant nutrient levels, leading to less accurate estimates of fertilizer application. This study focused on exploring the suitability of two non-destructive sensors, Soil Plant Analysis Development (SPAD-502) and GreenSeekerTM, for measuring plant tissue nutrient uptake. Florikan Top-Dress fertilizer 12N-6P-8K was applied to Justicia brandegeana in various increments (0, 10, 20, 30, 40, and 50 g) to simulate plants with deficient to excessive nitrogen rates. Various parameters were recorded including Normalized Difference Vegetation Index (NDVI) and SPAD readings, soil leachate analysis (nitrates and phosphate), and total leaf carbon:nitrogen (C:N). The NDVI and SPAD readings were recorded biweekly for three months after the initial controlled release fertilizer (CRF) treatments. Leaf C:N was analyzed through dry combustion while nitrates and phosphate were determined from soil leachate. Results suggest that the smaller amount (20 g) of CRF is as effective in providing N to J. brandegeana as larger amounts (30, 40, 50 g). Implementation of this fertilizer regimen will result in reduced agricultural nutrient runoff and overall negative environmental impacts. Application of optical sensor technology using SPAD and GreenSeekerTM showed promising results in determining the fertilizer requirements of J. brandegeana. This method could serve as a guideline for nursery producers and landscape personnel as a fast and non-destructive tool for sustainable fertilizer management practices within the ornamental plant industry.