Crop Fertilizer Research Articles

Missing phosphorus legacy of the Anthropocene: Quantifying residual phosphorus in the biosphere.

A defining feature of the Anthropocene is the distortion of the biosphere phosphorus (P) cycle. A relatively sudden acceleration of input fluxes without a concomitant increase in output fluxes has led to net accumulation of P in the terrestrial-aquatic continuum. Over the past century, P has been mined from geological deposits to produce crop fertilizers. When P inputs are not fully removed with harvest of crop biomass, the remaining P accumulates in soils. This residual P is a uniquely anthropogenic pool of P, and its management is critical for agronomic and environmental sustainability. Managing residual P first requires its quantification-but measuring residual P is challenging. In this review, we synthesize approaches to quantifying residual P, with emphasis on advantages, disadvantages, and complementarity. Common approaches to estimate residual P are mass balances, long-term experiments, soil test P trends and chronosequences, with varying suitability or even limitations to distinct spatiotemporal scales. We demonstrate that individual quantification approaches are (i) constrained, (ii) often complementary, and (iii) may be feasible at only certain time-space scales. While some of these challenges are inherent to the quantification approach, in many cases there are surmountable challenges that can be addressed by unifying existing P pool and flux datasets, standardizing and synchronizing data collection on pools and fluxes, and quantifying uncertainty. Though defined as a magnitude, the distribution and speciation of residual P is relatively less understood but shapes its utilization and environmental impacts. The form of residual P will vary by agroecosystem context due to edaphoclimatic-specific transformation of the accumulated P, which has implications for management (e.g., crop usage) and future policies (e.g., lag times in P loading from non-point sources). Quantifying the uncertainty in measuring residual P holds value beyond scientific understanding, as it supports prioritization of monitoring and management resources and inform policy.

The impact of climate and potassium nutrition on crop yields: Insights from a 30-year Swiss long-term fertilization experiment

Climate change will strongly influence agricultural practices in the future. In order to promote resource-efficient agriculture, it is important to analyse the impact of climate variation on crop yields. In this study, we report yields of spring wheat, winter barley, maize, potato and sugar beet from the long-term crop rotation and fertilization experiment Demo in Switzerland and analyze their response to different climate variables (e.g., annual and seasonal temperature, precipitation, evapotranspiration, number of heat days and days of heavy rainfall). In addition, we investigate the impact of readily plant-available soil potassium (K) on the relationship of crop yields and precipitation. Annual and summer temperatures increased by 1 °C and 1.5 °C, respectively, over the observation period, and both the number of heat days and days of heavy rainfall increased in summer. Rising summer temperatures have a negative impact on all crop yields, which was most prominent for spring wheat, potato and maize. Annual, spring and summer precipitation show varying effects on different crops. For maize, soil K has a mediating effect on yield reductions under low spring precipitation. Yields are significantly reduced by 1 t ha−1 per 100 mm reduction of precipitation below a soil K threshold of 7 mg K kg−1 soil. Based on these results and the future climate scenarios for Switzerland, crop rotations with less heat-sensitive species and early-maturing varieties should be considered. In order to keep future irrigation demands and costs as low as possible, the soil K fertility classes in the Swiss K fertilization guidelines might need to be revisited. Our study is one of a few long-term observations that show the impact of climate variation on crop yields and highlights the potential of K management as a climate change adaptation measure.

Utilizing Cow Manure Waste (Bos Taurus) as Organic Fertilizer in Labuan Lelea Village, Labuan District, Donggala Regency, Central Sulawesi

This community service activity has been conducted in Labuan Lelea Village, Labuan District, Donggala Regency, Central Sulawesi Province, in collaboration with the local farming community. They face challenges regarding how to utilize cattle manure waste as environmentally friendly organic fertilizer. The objective of this community service is: 1) To provide knowledge to the farming community in Labuan Lelea Village on how to utilize cattle manure waste as organic fertilizer, as a substitute for inorganic fertilizers, which are known for their chemical content, scarcity, and fluctuating prices annually; 2) To promote organic fertilizers as an environmentally friendly alternative to inorganic fertilizers in agricultural lands; 3) To enhance the knowledge of farming communities regarding the effective utilization of cattle manure waste as organic fertilizer for both food crops and horticultural plants. The method employed in this activity is a participatory approach, wherein a team including Community and Student Service Learning Program (KKN) participants and local community members actively collaborate in fostering good cooperation between extension workers and farmers. The primary target audience of this training is farming communities engaged in plantation, food crops, and horticultural cultivation. The outcomes of this community service activity include increased awareness of how to utilize cattle manure waste (Bos Taurus). This process requires minimal investment as cattle waste, sawdust, and rice husks are all freely available materials, thus serving as a substitute for inorganic fertilizers which contain chemical substances and are environmentally unfriendly.

Changes of soil fertility and yield of crops when applying fertilizers in a grain-arable crop rotation of the central black-earth region for a short and long time

Aim of the investigations was to reveal changers in soil fertility and yield of main crops in a grain-arable crop rotation with fertilizer effect in 1st rotation (short -term application) and 10th rotation (long-term application) under conditions of the Central Black-Earth Region. The work was performed in a long-term field experiment using low-humic leached chernozem under conditions of Voronezh region. The data of 1936–1945 (1st crop rotation) and 2018–2022 (10th rotation) years were analyzed. The experiment scheme including saturation of 1 ha of arable land with fertilizers: without fertilizers, N10P10K10 + 2.8 t/ha of manure, N20P20K20 + 2.8 t/ha of manure, N30P30K30 + 2.8 т t/ha of manure, and N10P10K10 + 5.6 t/ha of manure. Change of soil fertility in the layer of 0–20 cm from 1 to 10 rotation under influence of fertilizers appeared as increase of hydrolytic acidity (by 5.26… 83.3 %), exchange K2O content (by 18.9…74.4 %), cation exchange capacity (by 27.8…35.7 %) and mobile P2O5 (by 7.81…9.00 %) (when using N20P20K20 + 2,8 t/ha of manure and N30P30K30 + 2,8 t/ha of manure); also, decrease of humus content by 0.41…0.73 %, N-NO3 by 25.3…47.7 % and P2O5 by 13.3–31.6 % in the control and in the variants with N10P10K10 + 2.8 or 5.6 t/ha of manure was noted. Long-term application of fertilizers in a crop rotation improved grain yield of barley by 11.3…50.1 %, oats by 4.0…51.2 %, winter wheat by13.4…30.6 % and sugar beet roots by 15.0…36.7 %, and reduced green mass of a clover 6.1…23.0 %. But, in addition, it increased by-products’ yield of each crop by 6.1…23.0 %. Productivity of the fertilized arable land per 1 ha increased by 3.30…18.3 % from 1st to 10th rotation (minus yield improvement by 0.96 thousand grain units/ha due to cultivation of more productive modern varieties). Long-term application of N30P30K30 + 2.8 т t/ha of manure ensured the greatest level of crop rotation soil fertility and productivity. This was achieved by twice-repeated application of N135P135K135 for sugar beet and one application of 25 t/ha of manure in fallow during 9-field crop rotation.

CHALLENGES AND OPPORTUNITIES TO DESIGN FUTURE CROPS: GATEWAY TO SUSTAINABLE AGRICULTURE IN 21ST CENTURY

The global food production system is facing numerous challenges due to factors such as population growth, climate change, limited resources, and environmental preservation. To address these challenges, various strategies can be employed to develop future crops that are more productive, nutritious, and resilient. One strategy is to improve the yield potential of existing crops by developing new high-yielding cultivars. This can be achieved through the development of new varieties that can produce more grain under optimal conditions. Additionally, improving the nutritional quality of crops is important to address nutrient deficiencies. Synthetic biology and metabolic engineering methods can be used to develop crops with enhanced nutritional value. Efficient utilization of agricultural resources is another important aspect of crop improvement. This includes developing crops that use water and nutrients more efficiently, reducing the need for irrigation and fertilizers, and minimizing environmental impacts. Increasing the resistance of crops to pests, diseases, and extreme weather events can also help reduce the use of pesticides and minimize crop losses. The domestication of wild or semi-wild plants through genetic manipulation offers new opportunities for crop design. These plants may have high nutritional value, stress tolerance, and specialized metabolites that can be incorporated into cultivated crops. Similarly, the domestication of orphan or neglected plants can contribute to crop improvement by incorporating unique traits. Genetic improvement through the transfer of genes from wild relatives or other species can also enhance crop productivity. Advancements in genomics and genetic technologies can aid in the identification and transfer of beneficial alleles. Agronomic improvements, such as maximizing the effectiveness of crop protection agents and fertilizers while minimizing their environmental impact, can also contribute to crop performance. The emerging field of synthetic biology offers opportunities for developing novel biological devices and systems that can further enhance crop productivity and resilience. Overall, these strategies can help address the challenges faced by the global food production system.

Analysis of yellow mealworm (Tenebrio molitor) frass as a resource for a sustainable agriculture in the current context of insect farming industry growth

With the ongoing rapid growth of the human population, the industrial development of mass insect rearing for feed and food is gaining momentum. This approach has proved to be a more efficient and effective alternative to traditional livestock to produce animal protein. In this context, the Tenebrio molitor production sector emerges as highly promising in the edible insect market, being among the most commonly bred species in the large-scale insect rearing industry. A recent modification of the European regulatory framework in this matter has authorized insect-produced feed for pigs and poultry, which will boost the creation of new insect industries, resulting in huge quantities of frass, the insect excrement, that could be valorized. This by-product holds substantial amounts of nutrients and advantageous microorganisms that have enormous potential for organic farming. It typically exhibits high organic content and an abundance of essential nutrients like nitrogen (N), phosphorus (P), and potassium (K), alongside a narrow carbon (C) to nitrogen (N) ratio. In addition to providing plants with essential macronutrients, frass has been discovered to boost soil microbial biomass and introduce biomolecules and microbes that foster plant growth. The study of utilizing frass in sustainable agriculture is a relatively new and actively researched field in recent years. By conducting a comprehensive review of peer reviewed works, this article highlights the advantages associated with the effects of its use as organic fertilizer. Among these, the effect of frass as (1) a plant growth promoter and productivity enhancer and as (2) phytofortifyer against biotic and abiotic stresses, has been underlined in recent studies. With regard to its promoting effect, it has been observed that the effects of frass depend very much on its dose and the type of crop, with remarkably favorable results in many of the tests carried out. Hence, frass derived from the mass rearing of yellow mealworm for feed and food, could serve as an important and potent source of organic fertilizer in intensive horticultural crops or in high-value woody crops, contributing to a more sustainable agriculture, which can decrease the use of conventional synthetic agrochemicals.

Soil gross N2O emission and uptake under two contrasting agroforestry systems: riparian tree buffer versus alley-cropping tree row

In addition to the removal of excess mineral nitrogen (N) via root uptake, trees in agroforestry systems may mitigate negative effects of high N fertilization of adjacent crops by enhancing complete denitrification of excess mineral N aside from root uptake. Presently, little is known about the potential for NO3− reduction through denitrification (conversion to greenhouse gas N2O and subsequently to non-reactive N2) in contrasting agroforestry systems: riparian tree buffer versus tree row of an upland alley-cropping system. Our study aimed to (1) quantify gross N2O emissions (both N2O + N2 emissions) and gross N2O uptake (N2O reduction to N2), and (2) determine their controlling factors. We employed the 15N2O pool dilution technique to quantify gross N2O fluxes from 0 to 5 cm (topsoil) and 40 to 60 cm (subsoil) depths with seasonal field measurements in 2019. The riparian tree buffer exhibited higher topsoil gross N2O emissions and uptake than the alley-cropping tree row (P < 0.03). Gross N2O emissions were regulated by N and carbon (C) availabilities and aeration status rather than denitrification gene abundance. Gross N2O uptake was directly linked to available C and nirK gene abundance. In the subsoil, gross N2O emission and uptake were low in both agroforestry systems, resulting from low mineral N contents possibly due to N uptake by deep tree roots. Nonetheless, the larger available C and soil moisture in the subsoil of riparian tree buffer than in alley-cropping tree row (P < 0.05) suggest its large potential for N2O uptake whenever NO3− is transported to the subsoil.

Green Manure for Sustainable Crop Production: A Review

Green manuring is an economical and eco-friendly scientific approach to achieve more resilient and sustainable food production for agricultural systems. Incorporation of green manure improves soil condition by increasing soil physical, chemical and biological properties such as organic matter, availability of nitrogen, phosphorus and potassium and also improves soil structure by preventing soil erosion, increasing water holding capacity etc. Green manure acts as a natural fertilizer, releasing nutrients into the soil as it decomposes and increases the nutrient content in the soil and shows positive effect on plant growth and development. Addition of green manure crops contribute to greater fixation of atmospheric nitrogen, and when decomposed, makes the nitrogen availability in the soil, reducing the need for synthetic nitrogen fertilizers in crops. Furthermore, it has a significant impact on several plant growth and yield parameters, resulting in increased agricultural productivity and ecosystem health.

Animal Detection based Smart Farming in Animal Repellent Using AI and Deep Learning

The combination of artificial intelligence (AI) and deep learning in agriculture has ushered in a new era in agriculture with new solutions designed to solve many problems. This paper presents an animal killing system for smart agriculture that uses artificial intelligence and deep learning to reduce the growing problem of animal damage. As the world population continues to grow, increasing food availability is important; Therefore, it is critical to protect crops from wild animals and pests. Deforestation due to livestock farming has become one of the largest human-wildlife conflicts due to human interference with habitats and deforestation. Wild animals can kill farmers working in the fields, causing major crop losses. Farmers suffered huge crop losses due to wild animals such as elephants, wild boars and deer attacking agriculture. Protecting crops from wild animals is one of the biggest concerns of today's farmers. There are many ways to solve this problem, both lethal (such as shooting and trapping) and non-lethal. (such as railings, pesticides, organic matter, netting or electric fencing). The sensor rotates around the lens and uses DCNN software to detect the target. If an animal is found, it sends a message to the Animal Repellent Module with information on the type of ultrasound that should be produced based on the animal. The development of drones with controlled flight control, as well as lightweight and powerful hyperspectral snapshot cameras that can be used to calculate crop biomass growth and fertilization status, responds to complex agricultural management strategies. KEYWORDS: Animal detection, VGG-Net, Bi-LSTM, convolutional neural network, activity recognition, video surveillance, wild animal monitoring, alert system.

Integrated Application of Silicic and Humic Acid Seed Priming for Enhanced Germination and Yield of Lentil (Lens culinaris L.)

Background: Lentil is second most important nutritionally dense pulse crop of India due to its ability to fix nitrogen, helps to maintain soil fertility and increase yield of other crops grown in rotations. Seed priming is a good innovative technology for improvement of emergence and plant stand under various stress conditions and also could enhance various defense mechanisms in seeds against biotic and abiotic stresses. The present study aimed to examine the effect of seed priming with silicic acid (3 mM @18 hr), humic acid (600 ppm @18 hr) and combination of humic and silicic acid (100 ppm + 1 mM @ 16 hr), that may reduce harmful effect of stress at seedling stage and improve early seedling vigor. Methods: In this field-laboratory investigation during 2022-2023, seed quality and yield quality attributing parameters i.e. germination percentage, seed vigor index-I and II, total chlorophyll, emergence percentage, final plant stand, final plant stand emergence, plant height, secondary branches, tertiary branches, number of pod per plant, average number of pod per plant, pod cluster, seed yield per plot and yield per plot were recorded in both laboratory and field conditions. Result: The results demonstrated a positive effect of seed priming on seed quality parameters against the stress. The highest seed quality and yield quality attributing parameter was recorded in treatment (T5) combination of humic and silicic acid as compare to control. The chemical priming with combination of humic and silicic acid was found to be most effective treatment to enhance plant stand establishment against stress.

Assessing biochar and zeolite for enhanced agricultural sustainability of swine manure

Swine manure is an alternative to synthetic fertilizers for providing crop nutrients. However, transportation costs, nutrient leakage, and gaseous emissions associated with using swine manure as fertilizer limit its agronomic benefits and cause environmental issues. In this study, we report the efficacy of nutrients (P as ortho-P and N as NH4+) recovery scheme from swine manure by batch equilibration and column leaching studies using different combinations of two biochars (untreated control biochar; control-BC and iron-modified biochar; iron-BC) and one zeolite with SiO2/Al2O3 = 30:1. Batch study employed different adsorbents (control biochar, followed by iron-BC, and zeolite) to obtain maximum adsorption (98.3% and 35.4%) and optimum desorption (66% and 18%) of P and N from the manure solution (1:5). A series of sand-matrix columns using the best combination of control-BC, iron-BC, and zeolite recovered 13,800 mg kg−1 of P and 4000 mg kg−1 of N from manure solution after tenth cycles of leaching events. XRD and SEM-EDS analyses revealed the association of P with N and Mg, suggesting the adsorption of nutrients mostly through co-adsorption with manure colloids and precipitation as struvite. A series of soil-matrix column studies and a corn seed germination test were conducted to test the nutrient leaching/crop fertilization efficiencies using the recovered adsorbents. Inclusively, results showed that a proper combination of biochar and zeolite could effectively recover and concentrate nutrients from swine manure to develop crop fertilizer for easy transport and use in sustainable agriculture.

Impact of diversified cropping systems and fertilization strategies on soil microbial abundance and functional potentials for nitrogen cycling

Diversified cropping systems and fertilization strategies were proposed to enhance the abundance and diversity of the soil microbiome, thereby stabilizing their beneficial services for maintaining soil fertility and supporting plant growth. Here, we assessed across three different long-term field experiments in Europe (Netherlands, Belgium, Northern Germany) whether diversified cropping systems and fertilization strategies also affect their functional gene abundance. Soil DNA was analyzed by quantitative PCR for quantifying bacteria, archaea and fungi as well as functional genes related to nitrogen (N) transformations; including bacterial and archaeal nitrification (amoA-bac,arch), three steps of the denitrification process (nirK, nirS and nosZ-cladeI,II) and N2 assimilation (nifH), respectively. Crop diversification and fertilization strategies generally enhanced soil total carbon (C), N and microbial abundance, but with variation between sites. Overall effects of diversified cropping systems and fertilization strategies on functional genes were much stronger than on the abundance of bacteria, archaea and fungi. The legume-based cropping systems showed great potential not only in stimulating the growth of N-fixing microorganisms but also in boosting downstream functional potentials for N cycling. The sorghum-based intercropping system suppressed soil ammonia oxidizing prokaryotes. N fertilization reduced the abundance of nitrifiers and denitrifiers except for ammonia-oxidizing bacteria, while the application of the synthetic nitrification inhibitor DMPP combined with mineral N reduced growth of both ammonia-oxidizing bacteria and archaea. In conclusion, this study demonstrates a strong impact of diversified agricultural practices on the soil microbiome and their functional potentials mediating N transformations.

Effects of aflatoxin B1 on metabolism- and immunity-related gene expression in Hermetia illucens L. (Diptera: Stratiomyidae)

Contamination of food products with mycotoxins such as aflatoxin B1 (AFB1) poses a severe risk to human health. Larvae of the black soldier fly (BSFL), Hermetia illucens (Diptera: Stratiomyidae), can successfully metabolize AFB1 without any negative consequences on their survival or growth. Organic waste streams contaminated with mycotoxins can be upcycled into protein-rich BSFL as an alternative feed for livestock and the left-over feed residue into nutrient-rich crop fertilizers. However, the underlying mechanisms that allow BSFL to metabolize AFB1 are unknown. In this study, five-day-old BSFL were fed with either a control or an AFB1-spiked (20 μg/kg) diet to elucidate the underlying mechanisms. Larval samples were collected at three timepoints (6 h, 24 h and 72 h) and subjected to RNA-Seq analysis to determine gene expression patterns. Provision of an AFB1-spiked diet resulted in an up-regulation of 357 and a down-regulation of 929 unique genes. Upregulated genes include multiple genes involved in AFB1 metabolism in other (insect) species. Downregulated genes were generally involved in the insects' growth, development, and immunity. BSFL possesses a diverse genetic arsenal that encodes for enzymes capable of metabolizing AFB1 without trade-offs on larval survival. In conclusion, the adverse impact of AFB1 exposure on immunity-related processes is observed in the transcriptomic response, and is indicative of a trade-off between detoxification and immune responses.

Changes in soil N2O emissions and nitrogen use efficiency following long-term soil carbon storage: Evidence from a mesocosm experiment

Policy and market incentives are rapidly expanding to promote soil organic carbon (SOC) sequestration in global croplands. Evidence suggests that long-term increases in SOC can influence both crop yield and nitrogen (N) fertilizer requirements, with the potential to help address two important sustainability challenges. However, increases in SOC may also trigger higher soil nitrous oxide (N2O) emissions, which would represent an important tradeoff for climate change mitigation. We tested the hypothesis that long-term increases in SOC are associated with higher crop yields and fertilizer N use efficiency (NUE), but at the cost of higher N2O emissions. Wheat was grown in two soils (SOClow and SOChigh) under three N fertilizer rates (0, 100, and 200 kg N ha−1) in a mesocosm experiment. Soils were obtained (0–25 cm) from a 22-yr field experiment on no-till and cover cropping in California. Results indicate that total biomass and grain yield were higher for SOClow than SOChigh at 100 kg N ha−1 but not the other N levels. Crop N uptake was also 28% greater for SOClow at 200 kg N ha−1, resulting in higher overall NUE. Soil N2O emissions increased for SOChigh by 25–112% compared to SOClow, likely due to long-term changes in labile C and N pools, microbial activity, and soil structure influencing porosity and gas diffusion. While there are well-documented crop and environmental benefits from enhancing SOC in agricultural soils, results from this study suggest that changes in soil N2O emissions should be considered to accurately determine net GHG emission reductions.

HarvestMax: A Predictive Model for Crop Yield and Fertilizer Optimization

HarvestMax: A Predictive Model for Crop Yield and Fertilizer Optimization

Smart Agriculture Automation System using ML

Abstract: The "Smart Agriculture Automation System using Machine Learning" project envisages a future where farming transcends manual labor and embraces data-driven automation. In response to the escalating demand for food amidst a burgeoning global population, traditional farming methods are rendered insufficient. However, Smart Agriculture Automation Systems offer a transformative solution by enhancing crop production efficiency and maintaining yield quality. Climate changeinduced challenges such as erratic weather patterns and heightened pest attacks further underscore the necessity for innovation in agriculture. At the heart of this system lies real-time sensor data, enabling precision farming practices that optimize resource utilization while fostering environmental sustainability. Leveraging Machine Learning algorithms, the system not only predicts and mitigates agricultural challenges but also detects early signs of crop diseases and nutrient deficiencies. This proactive approach ensures higher yields minimizes manual tasks and minimizes wastage. The integration of IoT technology enables remote monitoring and seamless data exchange, unlocking capabilities such as precise crop prediction, weather forecasting, and fertilizer recommendations. By analyzing historical data alongside current environmental factors, these systems accurately forecast crop yields and offer insights for informed decision-making in planting and harvesting cycles. Smart Agriculture Automation Systems embody adaptability, sustainability, and accessibility, heralding a new era of intelligent and efficient modern farming. This project integrates the Internet of Things (IoT) sensors and an innovative marketplace to revolutionize the agricultural landscape. Through this system, we aim to empower farmers with data-driven insights,

Peculiarity of the early metabolomic response in tomato after urea, ammonium or nitrate supply

Nitrogen (N) is the nutrient most applied in agriculture as fertilizer (as nitrate, Nit; ammonium, A; and/or urea, U, forms) and its availability strongly constrains the crop growth and yield. To investigate the early response (24 h) of N-deficient tomato plants to these three N forms, a physiological and molecular study was performed.In comparison to N-deficient plants, significant changes in the transcriptional, metabolomic and ionomic profiles were observed. As a probable consequence of N mobility in plants, a wide metabolic modulation occurred in old leaves rather than in young leaves. The metabolic profile of U and A-treated plants was more similar than Nit-treated plant profile, which in turn presented the lowest metabolic modulation with respect to N-deficient condition. Urea and A forms induced some changes at the biosynthesis of secondary metabolites, amino acids and phytohormones. Interestingly, a specific up-regulation by U and down-regulation by A of carbon synthesis occurred in roots. Along with the gene expression, data suggest that the specific N form influences the activation of metabolic pathways for its assimilation (cytosolic GS/AS and/or plastidial GS/GOGAT cycle). Urea induced an up-concentration of Cu and Mn in leaves and Zn in whole plant.This study highlights a metabolic reprogramming depending on the N form applied, and it also provide evidence of a direct relationship between urea nutrition and Zn concentration. The understanding of the metabolic pathways activated by the different N forms represents a milestone in improving the efficiency of urea fertilization in crops.

Terrestrial bioassays for assessing the biochemical and toxicological impact of biosolids application derived from wastewater treatment plants

Wastewater treatment plants (WWTP) are facilities where municipal wastewater undergoes treatment so that its organic load and its pathogenic potential are minimized. Sewage sludge is a by-product of this process and when properly treated is preferentially called “biosolids”. These treatments may include some or most of the following: thickening, dewatering, drying, digestion, composting, liming. Nowadays it is almost impossible to landfill biosolids, which however can well be used as crop fertilizers. Continuous or superfluous biosolids fertilization may negatively affect non-target organisms such as soil macro-organisms or even plants. These effects can be depicted through bioassays on terrestrial animals and plants. It has been shown that earthworms have been affected to various degrees on the following endpoints: pollutants' bioaccumulation, viability, reproduction, avoidance behavior, burrowing behavior. Collembola have been affected on viability, reproduction, avoidance behavior. Other terrestrial organisms such as nematodes and diplopods have also shown adverse health effects. Phytotoxicity have been caused by some biosolids regimes as measured through the following endpoints: seed germination, root length, shoot length, shoot biomass, root biomass, chlorophyll content, antioxidant enzyme activity. Very limited statistical correlations between pollutant concentrations and toxicity endpoints have been established such as between juvenile mortality (earthworms) and As or Ba concentration in the biosolids, between juvenile mortality (collembola) and Cd or S concentration in the biosolids, or between phytotoxicity and some extractable metals in leachates or aquatic extracts from the biosolids; more correlations between physicochemical characteristics and toxicity endpoints have been found such as between phytotoxicity and ammonium N in biosolids or their liquid extracts, or between phytotoxicity and salinity. An inverse correlation between earthworm/collembola mortality and stable organic matter has also been found. Basing the appropriateness of biosolids only on chemical analyses for pollutants is not cost-effective. To enable risk characterization and subsequent risk mitigation it is important to apply a battery of bioassays on soil macro-organisms and on plants, utilizing a combination of endpoints and established protocols. Through combined analytical quantification and toxicity testing, safe use of biosolids in agriculture can be achieved.

Influence of crop rotation, irrigation, fertilization, and tillage on the aggregate property and soil wind erosion potential in the floodplain of the Yellow River

The floodplain of the Yellow River (FPYR) is threatened by severe soil erosion. Soils are often susceptible to wind erosion owing to their coarse-textures and weak aggregation, yet studies are yet to describe the ability of soils to resist wind erosion in this region. Accordingly, this study aimed to quantify how soil wind erosion potential is affected by soil aggregate properties, such as dry aggregate geometric mean diameter (GMD), aggregate geometric standard deviation (GSD), aggregate stability, and soil bulk density, and to assess the effects of soil type, crop rotation, irrigation, fertilization, and tillage treatments on these aggregate properties in the main wind erosion area across the FPYR. Significant differences in GMD and aggregate stability were found between crop rotation treatments, whereas crop rotation marginally affected the soil bulk density. Further, the impact of management practices on aggregate properties differed for each soil type. The soil aggregate erodible fraction (EF) in the FPYR ranged from 1.14 to 82.73% across sites, with a mean of 26.14% across soil types and management practices, which was lower than that previously reported in other wind erosion regions. We incorporated these measured EFs into the Revised Wind Erosion Equation (RWEQ) to evaluate the wind erosion risk of the FPYR. The results indicated that the central FPYR was more susceptible to wind erosion than the other regions, although the total wind erosion potential in the FPYR was small. Adoption of soil conservation practices could help minimize wind erosion and improve atmospheric quality in the region.

Design and Test of Disturbed Fertilizer Strip-Ejection Device with Vertical Pendulum Bar Based on Discrete Element Method

Fertilizer can improve the yield of crops per unit area, and uniform fertilizer discharge can improve the fertilizer utilization rate. Therefore, it is meaningful to improve the performance of fertilizer-discharge devices in order to improve the modernization level of crop field fertilizer management. To address the problems of operational smoothness, stability and poor uniformity of fertilizer discharge, and other difficult problems encountered with strip fertilizer-discharge devices, this study designs a disturbed fertilizer strip-discharge device with a vertical pendulum. The main factors affecting the performance of fertilizer discharge were the wedge angle of the push-disturbing main pendulum bar (PMPB), the inclination angle of the aided-stirring pendulum pick (APP), the flow gap of the pendulum bar (FGPB), and the operation frequency of the swing-rod combination (SRC). The discrete element method (DEM) was used to establish a simulation model of the fertilizer device to explore the influence of the main factors on the performance of fertilizer discharge, with the coefficient of variation (CV) of fertilizer discharge uniformity and fertilizer discharge accuracy (FDA) used as the evaluation indices. The results show that the factors affecting the CV of fertilizer discharge uniformity and FDA were, in order of priority, the operation frequency of the SRC, the FGPB, the wedge angle of the PMPB, and the inclination angle of the APP. The optimal parameters after rounding were as follows: the wedge angle of the PMPB was 45°, the inclination angle of the APP was 46°, the operation frequency of the SRC was 188 times/min, and the FGPB was 4.5 mm. At this point, the model predicted that the CV of fertilizer discharge uniformity would be 10.53%, and that the FDA would be 3.19%. Using the optimal parameters for bench test verification, it was found that the wedge angle of the PMPB was 45°, the inclination angle of the APP was 46°, the operation frequency of the SRC was 188 times/min, the FGPB was 4.5 mm, the CV of the uniformity of the fertilizer discharge was 11.06%, and the FDA was 3.51%. In the test, the fertilizer-discharge device was stable and had good adaptability to different fertilizers. The results of this study can provide a theoretical reference for the development of precision strip-fertilizer application devices.