Agricultural Field Experiments Research Articles

Modeling maize growth and nitrogen dynamics using CERES-Maize (DSSAT) under diverse nitrogen management options in a conservation agriculture-based maize-wheat system

Agricultural field experiments are costly and time-consuming, and often struggling to capture spatial and temporal variability. Mechanistic crop growth models offer a solution to understand intricate crop-soil-weather system, aiding farm-level management decisions throughout the growing season. The objective of this study was to calibrate and the Crop Environment Resource Synthesis CERES-Maize (DSSAT v 4.8) model to simulate crop growth, yield, and nitrogen dynamics in a long-term conservation agriculture (CA) based maize system. The model was also used to investigate the relationship between, temperature, nitrate and ammoniacal concentration in soil, and nitrogen uptake by the crop. Additionally, the study explored the impact of contrasting tillage practices and fertilizer nitrogen management options on maize yields. Using field data from 2019 and 2020, the DSSAT-CERES-Maize model was calibrated for plant growth stages, leaf area index-LAI, biomass, and yield. Data from 2021 were used to evaluate the model's performance. The treatments consisted of four nitrogen management options, viz., N0 (without nitrogen), N150 (150 kg N/ha through urea), GS (Green seeker-based urea application) and USG (urea super granules @150kg N/ha) in two contrasting tillage systems, i.e., CA-based zero tillage-ZT and conventional tillage-CT. The model accurately simulated maize cultivar’s anthesis and physiological maturity, with observed value falling within 5% of the model’s predictions range. LAI predictions by the model aligned well with measured values (RMSE 0.57 and nRMSE 10.33%), with a 14.6% prediction error at 60 days. The simulated grain yields generally matched with measured values (with prediction error ranging from 0 to 3%), except for plots without nitrogen application, where the model overestimated yields by 9–16%. The study also demonstrated the model's ability to accurately capture soil nitrate–N levels (RMSE 12.63 kg/ha and nRMSE 12.84%). The study concludes that the DSSAT-CERES-Maize model accurately assessed the impacts of tillage and nitrogen management practices on maize crop’s growth, yield, and soil nitrogen dynamics. By providing reliable simulations during the growing season, this modelling approach can facilitate better planning and more efficient resource management. Future research should focus on expanding the model's capabilities and improving its predictions further.

Impacts of Harmful Algal Blooms (HABs) on Agriculture: A Short Communication

agriculture, which requires clean water, healthy soil, and adequate nutrients, is crucial to meet the growing demand for food and fiber. Over application of nutrients to meet demand has degraded surface water quality, leading to accelerated eutrophication. Cultural eutrophication is a process by which aquatic ecosystems such as ponds, lakes, and estuaries become so enriched with nutrients—primarily nitrogen and phosphorus—as to become unusable for safe consumption and ecological purposes. Eutrophication has intensified due to climate change. Increased temperatures, intense storms, and drought can drive the formation of eutrophic and hypereutrophic conditions. Hypereutrophication results in the rapid proliferation of algae and phytoplankton, resulting in algal blooms. Harmful algal blooms (HABs), including the proliferation of cyanobacteria, which can produce cyanotoxins such as microcystins and cylindrospermopsin, can also grow in hypereutrophic conditions. These toxins can detrimentally impact humans, wildlife, and agricultural systems (e.g., fish, livestock, and crops). Fish that ingest algal toxins may suffer from liver damage and oxidative stress, with varying effects depending on the type of fish, the amount of exposure, and the duration of exposure to toxins. Additionally, a few studies report livestock death after drinking water contaminated with byproducts of HABs such as microcystin, nodularin, cylindrospermopsin, anatoxin-a, guanitoxin, and saxitoxin. The available research on the effects of microcystin on crops, vegetables, and fruits consistently demonstrates their negative impact. This short communication article summarizes the literature published between 2012 and 2022 documenting the impact of microcystins on agricultural commodities, particularly livestock and various crops. Although awareness has increased, few publications have discussed microcystin-related livestock deaths in recent years. However, numerous global studies have highlighted the harmful effects of microcystins on crops, fruits, and vegetables. The researchers suggest that in cases where the levels of microcystin exceed the standards established by the World Health Organization, careful monitoring is needed. Human exposure to microcystin may occur through the consumption of livestock, crops, and vegetables contaminated by microcystins through drinking or irrigation. More research is needed to understand the fate and transport mechanisms of microcystins in various agricultural settings, including controlled, simulated, and field experiments.

Climate change causes spatial shifts in the productivity of agricultural long-term field experiments

Long-term field experiments (LTE) are highly valuable infrastructures in agricultural- and soil sciences for understanding the long-term impacts of climate and management practices. While they are designed to run under constant conditions, climate change is expected to affect site conditions considerably. This needs to be quantified when interpreting experimental results and when redesigning the experimental setup. One way to achieve this is by utilizing vegetation growth and carbon dynamics, specifically the Net Primary Productivity (NPP), as a spatially explicit indicator. NPP facilitates the assessment and interpretation of yield performance in LTEs under future climatic conditions. Our study estimated the changes in NPP for 271 LTE sites in Germany, comparing a baseline (2000–2020) with two scenarios (2081–2100) that were based on the Shared Socioeconomic Pathways (SSPs) (SSP245) and SSP585) by the Intergovernmental Panel on Climate Change (IPCC). We used the NASA-CASA biogeochemical model to calculate NPP in baseline and IPCC scenarios using Germany as a test case. LTEs were grouped by land use (crop types) and soil information (soil type, texture), drawing on the geodata infrastructure “BonaRes Repository”. The total annual terrestrial NPP for the baseline was calculated as 202.4 Mt C (sum of forests, grasslands, and arable lands) in Germany, while total NPP was up to 56.0 Mt C for different land use types. For both scenarios, NPP was projected to increase in LTEs located in southern Germany, indicating increased crop productivity, while a decrease was projected for the central Germany. The decrease in NPP of numerous LTEs in central Germany was estimated to extend to the LTEs in the eastern part corresponding to the worst-case scenario SSP585. Explicitly, the use of the multi-model ensemble mean as the climate driver in modelling may overestimate projected NPP by reducing inter-annual variability, highlighting the importance of methodological choices for accurate future projections. Besides, the results indicated that poor soils are projected to experience a further decline in productivity, primarily attributed to escalating water scarcity. Conversely, soils with high quality are likely to witness enhanced productivity, largely driven by the extension of the growing seasons. The outcomes of this study provide a basis for considering the future conditions of German LTEs and facilitate distinguishing between the effects of climate change and the impact of agricultural management on productivity at the regional level. These outputs enable planning and developing research strategies for selecting future LTE sites and redesigning existing or newly planned experiments. Moreover, the integrated modelling framework presented here highlights the potential of LTE data for large-scale modelling studies of ecosystem functions.

Does soil history decline in influencing the structure of bacterial communities of Brassica napus host plants across different growth stages?

Soil history has been shown to condition future rhizosphere microbial communities. However, previous experiments have also illustrated that mature, adult plants can "re-write," or mask, different soil histories through host plant-soil community feedbacks. This leaves a knowledge gap concerning how soil history influences bacterial community structure across different growth stages. Thus, here we tested the hypothesis that previously established soil histories will decrease in influencing the structure of Brassica napus bacterial communities over the growing season. We used an on-going agricultural field experiment to establish three different soil histories, plots of monocrop canola (B. napus), or rotations of wheat-canola, or pea-barley-canola. During the following season, we repeatedly sampled the surrounding bulk soil, rhizosphere, and roots of the B. napus hosts at different growth stages-the initial seeding conditions, seedling, rosette, bolting, and flower-from all three soil history plots. We compared composition and diversity of the B. napus soil bacterial communities, as estimated using 16S rRNA gene metabarcoding, to identify any changes associated with soil history and growth stages. We found that soil history remained significant across each growth stage in structuring the bacterial bulk soil and rhizosphere communities, but not the bacterial root communities. This suggests that the host plant's capacity to "re-write" different soil histories may be quite limited as key components that constitute the soil history's identity remain present, such that the previously established soil history continues to impact the bacterial rhizosphere communities, but not the root communities. For agriculture, this highlights how previously established soil histories persist and may have important long-term consequences on future plant-microbe communities, including bacteria.

Response of soil microbiota to various soil management practices in 100-year-old agriculture field and identification of potential bacterial ecological indicator

The study aimed to comprehensively investigate the structural dynamics of a soil microbial community within a 100-year agricultural field experiment. The experimental design encompasses three distinct soil management practices, namely monoculture, five–year rotation, and random rotation, each with or without the incorporation of legumes and manure. Soil microbial communities were determined by the Next-Generation Sequencing (Illumina MiSeq analysis) of both the V3 and V4 hypervariable regions of the 16S rRNA gene for bacteria and Archaea, as well as ITS1 for fungi. In all soils, dominant bacterial phyla were Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi, and dominant orders were Actinomycetales, Rhizobiales, Acidimicrobiales, and Sphingomonadales. However, dominant fungal phyla were Ascomycota, Basidiomycota, and Zygomycota, and dominant fungal orders were Pleosporales, Eurotiales, Hypocreales, or Mortierellales. Compared to fallow land, agricultural soil management affected the microbial community of the soil, reducing the ratio of oligotrophs (e.g. Acidobacteria and Armatimonadetes) to copiotrophs (Actinobacteria or Gemmatimonadetes). Moreover, agricultural soil management contributed to an increased number of plant growth-promoting bacterial groups (PGPB), antagonistic to many fungal (e.g., Fusarium spp.) and bacterial pathogens (e.g., Bukholderiales, Xanthomonadales). However, generally in the study, there were no significant differences in microbial communities between monoculture and crop rotations. Moreover, two taxa can be considered as potential indicators of “healthy soil”: the nitrifying bacteria Nitrospira spp. whose abundance was strongly dependent on nitrogen, potassium, phosphorus, organic carbon, and soil pH, and the PGP fungi of the genus Mortierellla which depended mainly on nitrogen and pH. Finally, the genus Mortierellla was generally the most abundant in agricultural soils, especially in the five–year rotation with legumes, while fallow soils did not favour these microorganisms. In conclusion, various soil management practices strongly affect the soil microbiota and thus their ability to support land productivity.

An open‐source metadataset of running European mid‐ and long‐term agricultural field experiments

AbstractMid‐term (MTEs, 5–20 years) and long‐term (LTEs, 20+ years) field experiments are key sources of information to design future climate‐smart agriculture. Within the European Joint Program SOIL (EJP SOIL), we built the EJP SOIL‐MTE/LTE metadataset that contains metadata from 240 MTEs/LTEs across Europe. Metadata collected included precise descriptions of the treatments (combination of factors such as tillage, crop type/rotation, amendments/fertilizers, grazing and pest/weed management), soil and crop measurements and pedo‐climatic information. Using different figures and dashboards, an overview of those MTEs/LTEs is presented and specific research themes (tillage systems, residue management, amendment type and cover crops) are further analysed within their pedo‐climatic context. An interactive web portal developed in collaboration with the BonaRes project (https://lte.bonares.de), enables users to explore the metadataset and find relevant MTEs/LTEs for specific combinations of practices (e.g. all MTEs/LTEs that investigate cover crops on a Cambisol in no‐tillage system). Finally, a SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis of the metadataset was carried out to highlight the potential contribution of MTEs/LTEs to a harmonized European soil observation and monitoring approach. We propose that the metadataset could be elaborated with metadata from other existing MTEs/LTEs in Europe or even worldwide.

Trait-based cropping of brassicaceous plants: Effects on ecosystem services and crop yield

Diversification of agroecosystems through mixed cropping can facilitate multiple ecosystem services that may improve yields. Intercrops may repel pests and nourish natural enemies while trap crops lure pests away from target crops. A small-scale agricultural field experiment was conducted in 2018 and 2020 in Finland to study how intercropping of brassicaceous plants and faba bean (Vicia faba) affects yield and quality of a target crop (white cabbage (Brassica oleracea var. capitata)), herbivory on the target crop, and effects of the insect communities linked to the observations. The study was conducted with five different plot arrangements in each year. Broccoli (Brassica oleracea var. italica) or turnip (Brassica rapa var. rapa) were located at the perimeters of 6 × 6 m plots as trap crops. They were planted either alone or with yellow rocket (Barbarea sp). Faba bean was planted as an intercrop in the most complex designs. Cabbage head fresh weight was greatest in the most complex plot type, which included cabbage, broccoli, yellow rocket and faba bean and the head weight was significantly greater than in the cabbage monocrop or the plots with a broccoli-only trap crop. Turnip was included in the experiment in 2020 and efficiently attracted flea beetles and pollen beetles. In 2020, the turnip trap crop alone and the most complicated designs with broccoli or turnip combined with yellow rocket and faba bean significantly reduced P. xylostella abundance in the middle of the plot. Possibilities to use trait-based cropping systems in white cabbage production are discussed.

A new Rothamsted long-term field experiment for the twenty-first century: principles and practice

Agriculture faces potentially competing societal demands to produce food, fiber and fuel while reducing negative environmental impacts and delivering regulating, supporting and cultural ecosystem services. This necessitates a new generation of long-term agricultural field experiments designed to study the behavior of contrasting cropping systems in terms of multiple outcomes. We document the principles and practices of a new long-term experiment of this type at Rothamsted, established at two contrasting sites in 2017 and 2018, and report initial yield data at the crop and system level. The objective of the Large-Scale Rotation Experiment was to establish gradients of system properties and outcomes to improve our fundamental understanding of UK cropping systems. It is composed of four management factors—phased rotations, cultivation (conventional vs reduced tillage), nutrition (additional organic amendment vs standard mineral fertilization) and crop protection (conventional vs smart crop protection). These factors were combined in a balanced design resulting in 24 emergent cropping systems at each site and can be analyzed at the level of the system or component management factors. We observed interactions between management factors and with the environment on crop yields, justifying the systems level, multi-site approach. Reduced tillage resulted in lower wheat yields but the effect varied with rotation, previous-crop and site. Organic amendments significantly increased spring barley yield by 8% on average though the effect again varied with site. The plowed cropping systems tended to produce higher caloric yield overall than systems under reduced tillage. Additional response variables are being monitored to study synergies and trade-offs with outcomes other than yield at the cropping system level. The experiment has been established as a long-term resource for inter-disciplinary research. By documenting the design process, we aim to facilitate the adoption of similar approaches to system-scale agricultural experimentation to inform the transition to more sustainable cropping systems.

Biochar and Manure from Cattle Fed Biochar as Agricultural Amendments Alter CH4 Oxidation in a Gray Luvisol

Greenhouse gases (GHG) emissions from agricultural practices contribute 14% of anthropogenic emissions to the atmosphere, and novel practices to reduce these emissions, including feeding cattle a modified diet, are of interest. This study examines how additions of manure from cattle fed a regular diet or a diet supplemented with 2% biochar, and biochar at 5 or 10 Mg ha−1, impact GHG emissions in a Gray Luvisol agricultural field experiment. Emissions of CH4 and N2O were monitored, and soil samples were collected to analyze exchangeable NPKS, microbial biomass, total C and N, electrical conductivity, and pH. Wheat (Triticum aestivum) was planted, and grain yield measured. We calculated the yield-based emission factor (EFyield) and cumulative area-based GHG emissions emission factor (EFarea). The results showed an up to 98.5% change in the inhibition of CH4 oxidation from biochar-manure + biochar at 5 and 10 Mg ha−1 compared to the CT. The biochar in biochar-manure may have acted as a biocide to methanotrophs, causing a reduction in the release of CH4 over time. Yet, there were no significant differences in N2O emissions amongst treatments. Therefore, biochar-manure + biochar at 5 and 10 Mg ha−1 applications may impact total GHG emissions and improve grain productivity and protein content compared to BM alone.

Design of Agricultural Field Experiments Accounting for both Complex Blocking Structures and Network Effects

We propose a novel model-based approach for constructing optimal designs with complex blocking structures and network effects for application in agricultural field experiments. The potential interference among treatments applied to different plots is described via a network structure, defined via the adjacency matrix. We consider a field trial run at Rothamsted Research and provide a comparison of optimal designs under various different models, specifically new network designs and the commonly used designs in such situations. It is shown that when there is interference between treatments on neighboring plots, designs incorporating network effects to model this interference are at least as efficient as, and often more efficient than, randomized row–column designs. In general, the advantage of network designs is that we can construct the neighbor structure even for an irregular layout by means of a graph to address the particular characteristics of the experiment. As we demonstrate through the motivating example, failing to account for the network structure when designing the experiment can lead to imprecise estimates of the treatment parameters and invalid conclusions.Supplementary materials accompanying this paper appear online.

Soil organic carbon sequestration in agricultural long-term field experiments as derived from particulate and mineral-associated organic matter

Soil organic matter (SOM) is indispensable for soil health and, in the context of climate change, is considered a significant CO2 sink. Improving agricultural management to increase long-term soil organic carbon (SOC) stocks for mitigating climate change requires tools that estimate short and long-cycling SOM pools. In this study, we analyzed changes in fast-cycling particulate organic matter (POM) and slow-cycling mineral-associated organic matter (MAOM) induced by common management practices, i.e., fertilization and crop rotation in topsoils from 25 Central European long-term field experiments. When relating MAOM-C contents to recent MAOM-C saturation levels, estimated sequestration potentials were only met in coarse-textured soils under appropriate agricultural management or fine-textured soils under extreme organic fertilization. Soil texture, organic fertilization, and below-ground OC inputs through root exudates and root biomass were decisive for estimating MAOM-C, allowing for calibration of a mixed-effects model (Nakagawa’s: marginal R2m = 0.6, conditional R2c = 0.89). While the models containing soil texture and organic fertilization parameters can be validated and generalized (R2 = 0.43), the below-ground OC input predictor substantially decreases the generalizability of the validated models (R2 = 0.14). According to quantile regression models, we estimate the average difference in MAOM-C concentration between well-managed and control site (without organic fertilization) topsoils to 4.1 mg g−1 soil. In dependence on the soil bulk density, this amounts to 1.38 – 1.84 t ha−1 MAOM-C stocks or 5.06 – 10.1 t ha−1 CO2-equivalents. POM-C was difficult to predict (R2 = 0.28), presumably due to strong POM dynamics. The POM-C / MAOM-C ratio can inform on the effects of agricultural practices in before/after management change comparisons. Under increasing SOC concentration, an increasing POM-C / MAOM-C ratio indicates that the effects of organic fertilization do not transfer to real effects on long-term SOC sequestration. Because MAOM-C depends on soil texture, this ratio is also a covariate of soil texture, limiting it for comparisons between sites with different textures. However, our data indicate that agricultural long-term field experiment soils constantly approximate MAOM-C saturation when the POM-C/MAOM-C ratio is >0.35. This ratio might be used as a management goal to prevent organic over-fertilization and N loss, especially on coarse-textured soils. Thereby, the POM-C / MAOM-C ratio can help to optimize SOC management and sequestration on agricultural soils and support climate change mitigation strategies in Central Europe.

Yield Adjustment Using GPR-Derived Spatial Covariance Structure in Cassava Field: A Preliminary Investigation

Many processes concerning below-ground plant performance are not fully understood, such as spatial and temporal dynamics and their relation to environmental factors. Accounting for these spatial patterns is very important as they may be used to adjust for the estimation of cassava fresh root yield masked by field heterogeneity. The yield of cassava is an important characteristic that every breeder seeks to maintain in their germplasm. Ground-Penetrating Radar (GPR) has proven to be an effective tool for studying the below-ground characteristics of developing plants, but it has not yet been explored with respect to its utility in normalizing spatial heterogeneity in agricultural field experiments. In this study, the use of GPR for this purpose was evaluated in a cassava field trial conducted in Momil, Colombia. Using the signal amplitude of the GPR radargram from each field plot, we constructed a spatial plot error structure using the variance of the signal amplitude and developed GPR-based autoregressive (AR) models for fresh root yield adjustment. The comparison of the models was based on the average standard error (SE) of the Best Linear Unbiased Estimator (BLUE) and through majority voting (MV) with respect to the SE of the genotype across the models. Our results show that the GPR-based AR model outperformed the other models, yielding an SE of 9.57 and an MV score of 88.33%, while the AR1 × AR1 and IID models had SEs of 10.15 and 10.56% and MV scores of 17.37 and 0.00%, respectively. Our results suggest that GPR can serve a dual purpose in non-destructive yield estimation and field spatial heterogeneity normalization in global root and tuber crop programs, presenting a great potential for adoption in many applications.

Co-Compost Application of Magnesium Salts and Orthophosphate Adjusted Biochar and Cyanobacteria for Fixing Nitrogen, Improving Maize Quality, and Reducing Field Nutrient Loss

To solve the problem of nitrogen loss and harmful gas emissions in the co-composting of cyanobacteria with other wastes and agricultural non-point source pollution in the Chaohu Lake Basin (CHLB), this study selected cyanobacteria as the main material, spent mushroom and rice hulls as excipients, and biochar (B) and Mg2+/PO43− salt as an additive. The nitrogen fixation rate, maturity, toxicity, and fertilizer efficiency indexes were analyzed to explore the best rate of biochar application. Additionally, three different fertilization treatments (C0: No fertilization, CF: Chemical fertilizer, OF: Organic fertilizer) were applied to agricultural field experiments in the CHLB. The results showed that the cyanobacteria composting experiment with 10% B as additives had the lowest cumulative NH3 emission (603.00 g) and the highest nitrogen fixation rate (61.54%). We used this compost product for maize cultivation in field experiments. The results show that OF treatment can reduce field nutrient loss, and the increase in the rate of soil TN fixation was as follows: OF (18.62%) > CF (10.34%) > C0 (−9.66%). Moreover, the TN and TK losses in runoff were 33.33% and 22.74% lower than CF in farmland runoff. The OF treatment increased the content of crude fat, crude protein, and crude starch by 4.40%, 8.34%, and 2.66% compared with the CF treatment, respectively. Overall, the N, P, and K source agronomic coefficients of cyanobacteria organic fertilizer were 1.424, 1.001, and 1.16, respectively. These results indicated that cyanobacterial organic fertilizer could replace chemical fertilizer to reduce agricultural non-point source pollution and improve maize quality. Meanwhile, the amendment of B and Mg/P salt additives could reduce air pollution and improve the quality of compost products. This study provides a theoretical basis and reference for nitrogen fixation and extension of multiple wastes co-composting field experiments.

中華人民共和國 건설 초기 과학계의 사상투쟁-樂天宇의 미추린학설 수용을 중심으로-

In the Yan''an(延安) period, during the natural science movement and mass production movement initiated by the Communist Party of China in 1941, agricultural and forestry biologists led by Le Tianyu(樂天宇) actively accepted the Michurin(米丘林) theory. In the development of the Nanniwan(南泥灣) and the large-scale agricultural production movement, Le Tianyu actively used the breeding method of Michurin and the vernalization treatment method of Lysenko(李森科). In addition, he also took the lead in combining the agricultural experience of the farmers in the border area(邊區) with the genetics of Michurin to popularize it to the public. Therefore, Michurin''s theory has attracted much attention because of its "seeking truth from facts(實事求是)" method of combining theory with practice. Based on this experience, Le Tianyu organized the Michurin society(米丘林學會) on February 19, 1949. The Michurin society has formed a trinity relationship with the College of agriculture, North China University(華北大學農學院) and its agricultural biological science research room(農業生物科學硏究室), combining education, experiment and research. The Michurin society has compiled the farmer''s experience in the agricultural field and crop mating methods into a book and popularized them to farmers. More importantly, Michurin society focuses on agricultural field experiments and direct exchanges with farmers, taking the lead in knowledge production and popularization based on farmers'' and rural experience. Through this, the Communist Party of China formulated a "practical" and "popularity" agricultural policy, which also made a certain contribution to the increase of agricultural productivity in the early period of the people''s Republic of China. However, in September 1949, with the establishment of Beijing Agricultural University(北京農業大學), the opposition between the Michurin school led by Le Tianyu and the genetics of Mendel-Morgan school led by Li Jingjun(李景均) was officially launched. As Le Tianyu reorganized the University''s curriculum to focus on new genetics, and reorganize disciplines centered on "production disciplines"，the discontent in the University spread. The Communist Party of China demoted Le Tianyu, the culprit of the Agricultural University incident, to the Chinese Academy of Sciences(中國科學院), and command of the Michurin society led by him was transferred to the All China Federation of Natural Sciences(中華全國自然科學專門學會聯合會). The Communist Party of China denied the connection between Le Tianyu and Michurin''s theory, and regarded the "Nongda incident(農大事件)" as a problem of Le Tianyu''s personal thoughts and attitudes. In addition, the Communist Party of China held a symposium on biological science work(生物科學工作座談會) in 1952, and published the argument of "fighting for the Michurin direction of biological science(爲堅持生物科學的米丘林方向而鬥爭)", branded Le Tianyu as a "sectarian" and a "narrow empiricist". If we reflect on the relationship between science and politics or between science and the socialist revolution, then the influence of Michurin''s theory on the Chinese scientific community should be negatively evaluated. Because Le Tianyu used the Michur in theory to overthrow the Mendel-Morgan school, the Communist Party of China has ideologized science and turned science into a political maidservant. But "what way does science work and what role does it play in socialist construction?", this is an issue that transcends the political level and requires in-depth study. From this perspective, Le Tianyu''s acceptance of Michurin''s theory triggered a revolution, in the production structure of scientific knowledge in China, attach importance to the "experience" of rural areas and the "practical" value of production sites, in the production and popularization of scientific knowledge, it established the line of "Populism". Therefore, by examining the role and significance of Michurin''s theory in the history of Chinese Science in the early 1950s, we should get rid of the way of explaining the relationship between science and politics from the perspective of the dichotomy of affirmation and negation. We should re-examine the multi-layer relationship and interaction between science and the socialist revolution.

The Influence of Some Secondary Tillage Implement and Mixing Organic Residues on Some Physical Properties of Soil at the Beginning and End of the Oat (Triticum aestivum L.) Growing Season

The study was conducted in one of the fields affiliated to the Agricultural Research Station at the University of Basra, Karmat Ali site. The agricultural field experiment was carried out by dividing the field land according to the Randomized Complete Block Design (RCBD) in a one-time split plots design, where the main plots represent smoothing machines and sub-plots, the levels of organic residues and three replicators. The soil was plowed with a moldboard plow at a depth of 25-30 cm, and the organic residues were mixed with the soil by use of secondary tillage equipment. While the area of the experimental unit was (150 * 250) cm2, a distance of 2m was left between the experimental sectors and units to ensure that there was no overlap between the treatments. Seeds of oats were planted for all experimental units after the implementation of the treatments and at a seeding rate according to the recommendation followed in the region. Soil characteristics are measured for depths (0-15, 15-30) cm and for two periods (beginning and end of the plant growing season), and plant growth and yield indicators are measured at the end of the growing season. The aim of the research is to study the effect of adding levels of manure residues mixed with the surface layer in different ways on soil characteristics at the beginning and end of the oat crop growing season. The results of the experiment indicate the superiority of the spring cultivator and the percentage of adding organic residues (40 tons. Ha-1) over the rest of the machines and fertilization treatments by achieving the lowest apparent density at the beginning and end of the oats growing season, which amounted to 0.992 and 1.113 Mg m-3, respectively. In addition, they have achieved the highest the percentage of total porosity was 62.56 and 57.97 %, respectively. It also gave the highest weighted average diameter, which reached 0.859 and 0.688 mm, respectively. In addition, it gave the lowest soil penetration resistance, which reached 0.887 and 1.130 MPa, respectively.

Validation of the Taguchi method on the example of evaluation of willow biomass production factors under environmental stress

Climate change requires the introduction of crop production technologies that guarantee stable yields under exposure to extreme weather events. The main focus should be on the reliability of yields, even if it implies a reduction in agricultural outputs. In the theory and practice of industrial experiments, Taguchi methods have been deployed to identify production technologies that are most resilient to the random effects of uncontrollable disrupting production factors. This is the first ever study where the Taguchi method was deployed in an agricultural field experiment to identify the levels of two fundamental production factors (genotype and planting density) that were most effective in stabilizing willow (Salix spp. L) biomass yields under variable uncontrollable abiotic and biotic stresses in annual harvest rotation. The analysis was based on the results noted in the first 12 consecutive years of a long-term field experiment in northern Poland. The results of the analysis involving the Taguchi method were validated under field conditions, and they were logical and consistent with the results of statistical analyses that are widely applied in this type of research. Uncontrollable stressors significantly influenced the levels of the least resilient production factors that were identified by the Taguchi method. The research assumptions were validated, which suggests that the Taguchi method could be considered in field experiments.

Indole and quinolizidine alkaloids from blue lupin leach to agricultural drainage water

Phytotoxins are produced in plants including agricultural crops. Lupins and other plants of the Fabaceae family produce toxic alkaloids. These alkaloids have been studied in food and feed, however, the environmental fate of alkaloids produced by cultivated lupins is largely unknown. Therefore, we conducted an agricultural field experiment to investigate the occurrence of indole and quinolizidine alkaloids in lupin plant tissues, soil, soil pore water and in drainage water. During the field experiment, alkaloids were regularly quantified (median concentrations) in lupin (13–8.7 × 103 ng/g dry weight (dw)), and topsoils at depth 0–5 cm (0.1–10 ng/g dw), and depth 15–30 cm (0.2–8.5 ng/g dw), soil pore water (0.2–7.5 ng/L) and drainage water samples (0.4–18 ng/L). Lupanine was the dominant alkaloid in all collected samples. Cumulative amounts of alkaloids emitted via drainage water were around 0.1–11 mg/ha for individual alkaloids over one growing season. The total cumulative amount of alkaloid in drainage water was 14 mg/ha, which is a very small amount compared to the mass of alkaloid in the lupin biomass (11 kg/ha) and soil (0.02 kg/ha). Nearly half of the alkaloids were exported in the drainage water during high flow events, indicating that alkaloids transport preferentially via macropores. These findings indicate that drainage from lupin cultivated areas contribute to surface water contamination. The environmental and ecotoxicological relevance of alkaloids as newly identified aquatic micropollutants in areas with agricultural activities have yet to be assessed.

Disentangling the impact of contrasting agricultural management practices on soil microbial communities – Importance of rare bacterial community members

Agriculture has a strong effect on soil microbial communities, but it is still unclear how different management practices drive their diversity and composition. To disentangle the effects of temporally contrasting crop management practices on soil microbial abundance and prokaryotic diversity, we analysed samples from a long-term agricultural field experiment, in which plant residues were exported (RE) or returned to soil, i.e., restituted (RR), over a period of 60 years. For 2.5 years, we followed a cropping sequence of maize, winter wheat and barley, in which, as an additional treatment, wheat cultivation was diversified once with pea intercropping. Based on soil-extracted DNA, abundances of bacteria, archaea and fungi were analysed by domain-specific qPCR and the diversity and composition of the prokaryotic community by 16S rRNA gene amplicon sequencing. The abundance of bacteria and fungi, but not for archaea, increased with the long-term restitution, but this effect was only detectable in spring due to their stabilized abundance during winter. The long-term effect of crop restitution on bacterial diversity became tangible when rare and dominant community members were differentiated, with higher sensitivity shown for the rare. In contrast, the cropping sequence equally affected members of both groups. The short-term effect of crop diversification by intercropping was much stronger in the C-depleted RE soils, than in RR soils where the C-loss was compensated, indicating that crop residue restitution increased the environmental resilience of soil microbial communities. Finally, we could confirm that rare bacterial community members, suspected to represent more oligotrophs and synergistic bacteria, formed stronger network structures to each other than the dominant, suspected to be more copiotrophic and competitive. Therefore, our results emphasize the importance to consider the response of rare microbial community members when evaluating long-term effects of agricultural management on the soil microbiome.

The Askov long‐term field experiment (1894–2021) represents a unique research platform#

AbstractLong‐term agricultural field experiments are essential for quantifying changes in soil properties and associated crop productivity that occur slowly but continue over long periods. Initiated in 1894 in the South of Denmark, the Askov long‐term experiment (LTE) is among the few LTEs in the world that continued for more than 125 years. The experiment compares different rates of nitrogen, phosphorus, and potassium applied in mineral fertilizers or animal manure with abundant treatment replicates. With well‐managed treatments, detailed yield records, and a soil archive dating back to 1923, today the Askov‐LTE represents a unique platform for research not envisioned at the start of experiments. Here, we provide a short description of site characteristics and experimental layout, examples of historic crop yields and changes in soil carbon (C) content. We provide short overviews of some of the studies that have used the Askov‐LTE as a research platform. These include crop yield‐related research; models simulating changes in soil C; availability of soil P reserves; indicators of biological, chemical, and physical soil quality; and studies related to prehistoric archaeology. Finally, we offer some reflections on long‐term field experimentation.

Cropping systems impact changes in soil fungal, but not prokaryote, alpha-diversity and community composition stability over a growing season in a long-term field trial.

Crop harvest followed by a fallow period can act as a disturbance on soil microbial communities. Cropping systems intended to improve alpha-diversity of communities may also confer increased compositional stability during succeeding growing seasons. Over a single growing season in a long-term (18 year) agricultural field experiment incorporating conventional (CON), conservation (CA), organic (ORG) and integrated (INT) cropping systems, temporal changes in prokaryote, fungal and arbuscular mycorrhizal fungi (AMF) communities were investigated overwinter, during crop growth and at harvest. While certain prokaryote phyla were influenced by cropping system (e.g. Acidobacteria), the community as a whole was primarily driven by temporal changes over the growing season as distinct overwinter and crop-associated communities, with the same trend observed regardless of cropping system. Species-rich prokaryote communities were most stable over the growing season. Cropping system exerted a greater effect on fungal communities, with alpha-diversity highest and temporal changes most stable under CA. CON was particularly detrimental for alpha-diversity in AMF communities, with AMF alpha-diversity and stability improved under all other cropping systems. Practices that promoted alpha-diversity tended to also increase the similarity and temporal stability of soil fungal (and AMF) communities during a growing season, while prokaryote communities were largely insensitive to management.