Long-term Field Experiment Research Articles

Effect of increasing rate of P fertilization on available P content in soil and plant uptake: implications for P management

The application of phosphorus (P) is necessary for sustainable crop production. Its application rate is often based on soil analysis. However, the P availability is not always properly evaluated for optimal P management. The effect of long-term P fertilization on soil P availability, yield, and plant uptake of P was investigated using data from a long-term field experiment. We hypothesized that: 1) an increasing rate of P fertilization increases soil P content, yield, and P uptake, and 2) annual change of P uptake and P content increases from negative to positive values at an increasing rate of P addition. Different strategies of P management were evaluated using experimental results. Increasing inputs of P in mineral or organic form increases soil P content. However, the effect on yield is limited and unused P accumulates in soil. High yield ensuring strategy of P fertilization is therefore not useful as a way of P management. Results suggest that keeping soil P content in the range of 50–80 mg P kg−1 and organic fertilization (and probably also legume cropping) are useful ways of using P from fertilizers or soil reserves. Results also suggest that Mehlich III soil test brings useful information for P management.

An active-optical reflectance sensor in-field testing for the prediction of winter wheat harvest metrics

The ambition of this study was to justify the possibility of wheat trait prediction using NDVI from a newly developed Plant-O-Meter sensor. Acquired data from Plant-O-Meter was matched with GreenSeeker's, which was designated as a reference. The experiment was carried out in the field during the 2022 growing season at the long-term experimental field. The experimental design included five different winter wheat genotypes and 20 different NPK fertilizer treatments. The GreenSeeker sensor always gave out NDVI values that were higher than those of the Plant-O-Meter by, on average, 0.029 (6.36%). The Plant-O-Meter sensor recorded similar NDVI values (94% of the variation is explained, p<0.01). The Plant-O-Meter's NDVIs had a higher CV for different wheat varieties and different sensing dates. For almost all varieties, GreenSeeker exceeded Plant-O-Meter in predicting yields for the early (March 21st) and late (June 6th) growing seasons. NDVIGreenSeeker data improved yield modeling performance by an average of 5.1% when compared to NDVIPlant-O-Meter; in terms of plant height prediction, NDVIGreenSeeker was 3% more accurate than NDVIPlant-O-Meter and no changes in spike length prediction were found. A compact, economical and user-friendly solution, the Plant-O-Meter, is straightforward to use in wheat breeding programs as well as mercantile wheat production.

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.

Influence of the dynamics of stocks of mobile forms of nitrogen in gray forest soil and the use of fertilizers on the yield of oats under various weather conditions

In a long-term field experiment on the gray forest soils of the Vladimir opole, the influence of mineral fertilizers and the aftereffect of cattle manure, their interaction on the yield of oats going 2nd crop after the occupied steam, and the dynamics of mobile nitrogen forms under various weather conditions were studied. The determining role of ammonium nitrate nitrogen in the composition of NPK and the aftereffect of cattle manure in increasing the yield of oats has been established. The results of the study indicated that the culture was fed mainly with the nitrate form of nitrogen. A high degree of correlation was revealed between the reserves of N-NO3 in the soil layer of 0–40 cm, formed as a result of the transformation of soil nitrogen and fertilizers to oat seedlings, and its yield (0.981 R2 0.787). The influence of fertilizers and weather conditions on the formation of nitrate nitrogen reserves in the phases of growth and development of oats and their dynamics, ensuring the achievement of high grain yield and quality, are determined. Depending on weather conditions and fertilizer systems, the coefficients of using N-NO3 formed during the growing season of oats for nitrogen removal by grain (40.7–66.6%), grain and straw (58.3–75.0%), grain, straw and crop-root residues (71.2–88.6%) are calculated. In nitrogen-fertilized variants, on average, at 4 levels of manure aftereffect (0, 40, 60 and 80 t/ha), they were highest when using a single dose of N40P40K40, when using a double dose of N80P80K80, they significantly decreased. On average, at 4 levels of mineral fertilizer application (0, P40K40, N40P40K40 and N80P80K80), the utilization coefficients of N-NO3 formed during the growing season with the aftereffect of manure of 60 t/ha were maximum. When N80P80K80 is combined with the aftereffect of organic fertilizers of 80 t/ha, the highest losses of N-NO3 due to denitrification and leaching are possible.

Cover crops improve soil structure and change organic carbon distribution in macroaggregate fractions

Abstract. Soil structure is sensitive to intensive soil management. It can be ameliorated by a reduction in soil cultivation and stimulation of plant and microbial mediators for aggregate formation, with the latter being a prerequisite and measure for soil quality. Cover crops (CCs) are part of an integrated approach to stabilize or improve soil quality. Thereby, the incorporation of diverse CC mixtures is hypothesized to increase the positive effects of CC applications. This study entailed an investigation of the legacy effect of CCs on soil aggregates after three crop rotations in the second main crop (winter wheat) after the last CC treatment. Four CCs (mustard, phacelia, clover, and oat) cultivated in pure stands and with a fallow treatment were compared to a mixture of the four CC species (Mix4) and a highly diverse 12-plant-species mixture (Mix12) in a long-term field experiment in Germany. The organic carbon (OC) distribution within macroaggregate fractions (16–8, 8–4, 4–2, 2–1, and <1 mm) and their aggregate stability were measured by dry- and wet-sieving methods, and the mean weight diameter (MWD) was calculated from water-stable aggregates. The results showed that, compared to the fallow, all CCs increased the MWD between 10 % and 19 % in soil under the following main crop. The average MWD increase over the fallow was slightly higher for CC mixtures (16 %) than for single CCs (12 %). Most of the OC (67.9 % on average) was stored in the <1 mm aggregate fraction, highest in the topsoil and decreasing with soil depth. The intermediate fractions (8–4 mm, 4–2 mm, 2–1 mm) stored 8.5 %, 10.5 %, and 11.0 % of the total OC, while 2.1 % was stored in the 16–8 mm fraction. Higher MWD improvement at the 20–30 cm depth also indicates additional benefits from a reduction in the cultivation depth. Structural equation modelling (SEM) suggests that single CCs were more likely to increase OC storage in small macroaggregates <1 mm, while CC mixtures were more likely to increase OC in the largest fraction (8–16 mm). Different individual CC species or mixtures exhibited varying involvement in the formation of different aggregate fractions. We provide evidence that litter quality, root morphology, and rhizosphere input, which affect microbial mediators of aggregate formation, might be the main reasons for the observed differences between CC treatments. Cover crops are valuable multifunctional tools for sustainable soil management. Here, we showed that they contribute to structure amelioration in arable soils. Increasing the functional diversity of plant species in CC mixtures could be a strategy to further enhance the positive effects of CCs in agroecosystems.

Assessment of the impact of methods of biologization of the agrocenosis of apple trees (<i>Malus domestica</i> Borkh.) on soil fertility and plant productivity

The influence of methods of biologization of the agrocenosis of the orchard, including soil blackening with cereal-legume mixtures of perennial grasses in combination with the introduction of biofertilizers of various spectrum of action, on soil fertility and productivity of apple trees (Malus domestica Borkh.) has been studied. The study was carried out in a two-factor long-term field experiment on meadow soils of the Salgir River valley (Republic of Crimea). It was revealed that the biologization of the agrocenosis of the apple tree contributed to the enrichment of the soil with organic matter, increased the content of its active components, led to the accumulation of mobile forms of phosphorus and potassium with a slight decrease in the content of nitrate nitrogen in the soil. At the same time, the concentration of nutrients in the leaves of the apple tree, including nitrogen, increased. All this contributed to an increase in the yield of fruits. Quantitative relationships between indicators of soil fertility and productivity of apple trees have been revealed. The obtained dependencies allowed us to build a model of productivity of Golden Delicious apple trees during the biologization of its agrocenosis. The most effective combination of the studied methods of biologization is the use of soil blackening with a cereal-bean mixture 3 (CBM3) with bacterization of the root system of an apple tree with a nitrogen-fixing strain (NFS).

The Complex Effect of Different Tillage Systems on the Faba Bean Agroecosystem.

The interactions of the different factors in differently tilled faba bean agroecosystems are still insufficiently studied and evaluated. For these reasons, we studied the results of a long-term field experiment, which was carried out in the Research Station of Vytautas Magnus University, Agriculture Academy (Lithuania). The aim of this study is to comprehensively evaluate the effect of the deep ploughing (DP), shallow ploughing (SP), deep cultivation, chiseling (DC), shallow cultivation-disking (SC), and no-tillage (NT) systems for the faba bean agroecosystem on the complex interactions of the indices, the relations among the indices, and the strength of the impact; the study employs the integrated evaluation method, which uses the complex evaluation index (CEI). CEI values showed that the NT system had a greater effect on the increase of soil aggregate stability (61%), the decrease of CO2 emissions (12%), and the increase of seed yield (6%) than the DP system. However, the NT system had 36% and 20% higher effect on weed density and biomass increase than DP. CEI values of the DP system were often minimal, i.e., close to 1, which showed the DP system's ineffectiveness.

Long-term liming changes pasture mineral profile

There is limited information on changes of pasture mineral concentrations over the long-term in response to liming. A long-term field experiment was conducted to assess the influence of lime application on (a) changes in pasture mineral composition over time; and (b) key pasture mineral concentrations and ratios important to animal health. Perennial and annual pastures with or without lime application were sampled annually over 12 years and analysed for macro- and micro-minerals. Mineral ratios and indices were calculated to assess the potential impact on animal health. Liming increased the concentrations of calcium, sodium and silicon, but decreased the concentrations of micro-nutrients including copper, zinc and manganese. The same trend was found in both annual and perennial pastures although there were some fluctuations between years. Liming increased the calcium:phosphorus ratio and the dietary cation–anion difference but reduced the tetany index on both annual and perennial pastures. These findings suggest a potential benefit to improve animal health outcomes for some disorders on the limed pastures. However, the reduced concentrations of some trace elements following liming potentially decreases antioxidant capacity and requires further research.

Влияние севооборотов на плодородие выщелоченных чернозёмов Южного Урала

Abstract. The purpose of the research was to establish the degree of influence of crop rotations and mineral nutrition backgrounds on the fertility of leached chernozem. A comparative assessment of the main nutrition elements of humus, nitrogen of easily hydrolyzable, mobile phosphorus of plants in dynamics in the conditions of the northern forest-steppe of the Chelyabinsk region, in various crop rotations on two fertilization backgrounds P and NP was carried out. Methods. The research was carried out in a long-term field experiment on the land-use territory of the Chelyabinsk Research Institute from 1998 to 2021. Humus, total nitrogen and easily hydrolyzable nitrogen were determined in soil samples according to the method of I. V. Tyurin and M. M. Kononova in the modification of V. N. Kudeyarov, mobile phosphorus according to F. V. Chirikov. Results. According to the results of our research, it was found that, on average, over the years of observations 1998–2021, the humus content due to the crop rotation factor changed by 0.2 %, according to the fertilization backgrounds by 0.8 %. The nitrogen content of the total over the years of research increased in all crop rotation options from 20 to 55 %, regardless of the background fertilization. As a result of the conducted studies, it was found that the nitrogen content of the easily hydrolyzed significantly depends on the background of mineral nutrition and the conditions of the year, on average for 1998–2021, the decrease in nitrogen of the easily hydrolyzed was 17–22 %. On average, according to the variants of the experiment for 1998–2021, the process of assimilation of liquid phosphorus against the background of NP is more intensive by 8 %. A strong correlation was established between the productivity of crop rotations and total nitrogen against the background of P in 1998 and 2013, nitrogen easily hydrolyzed in 1998 and 2021, mobile phosphorus for all the years of research. The scientific novelty. Monitoring of the assessment of the state of soil fertility makes it possible to monitor, as well as diagnose the degree of anthropogenic impact, make appropriate adjustments to ensure high productivity of crop rotations in a changing climate.

Liming effects on microbial carbon use efficiency and its potential consequences for soil organic carbon stocks

Climate-smart agriculture aims amongst others at protecting and increasing soil organic carbon (SOC) stocks. The allocation of metabolised carbon (C) between soil microbial growth and respiration, i.e. C use efficiency (CUE) is crucial for SOC dynamics. We hypothesised that raising soil pH would alleviate CUE-limiting conditions and that liming could thus increase CUE, thereby supporting SOC accrual. This study investigated whether CUE can be manipulated by liming and how this might contribute to SOC stock changes. The effects of liming on CUE, microbial biomass C, abundance of microbial domains, SOC stocks and OC inputs were assessed for soils from three European long-term field experiments. Field control soils were additionally limed in the laboratory to assess immediate effects. The shift in soil pHH2O from 4.5 to 7.3 with long-term liming reduced CUE by 40 %, whereas the shift from 5.5 to 8.6 and from 6.5 to 7.8 was associated with increases in CUE by 16 % and 24 %, respectively. The overall relationship between CUE and soil pH followed a U-shaped (i.e. quadratic) curve, implying that in agricultural soils CUE may be lowest at pHH2O = 6.4. The immediate CUE response to liming followed the same trends. Changes in CUE with long-term liming contributed to the net effect of liming on SOC stocks. Our study confirms the value of liming as a management practice for climate-smart agriculture, but demonstrates that it remains difficult to predict the impact on SOC stocks due its complex effects on the C cycle.

Spectral Data Processing for Field-Scale Soil Organic Carbon Monitoring

Carbon sequestration in soils under agricultural use can contribute to climate change mitigation. Spatial–temporal soil organic carbon (SOC) monitoring requires more efficient data acquisition. This study aims to evaluate the potential of spectral on-the-go proximal measurements to serve these needs. The study was conducted as a long-term field experiment. SOC values ranged between 14 and 25 g kg−1 due to different fertilization treatments. Partial least squares regression models were built based on the spectral laboratory and field data collected with two spectrometers (site-specific and on-the-go). Correction of the field data based on the laboratory data was done by testing linear transformation, piecewise direct standardization, and external parameter orthogonalization (EPO). Different preprocessing methods were applied to extract the best possible information content from the sensor signal. The models were then thoroughly interpreted concerning spectral wavelength importance using regression coefficients and variable importance in projection scores. The detailed wavelength importance analysis disclosed the challenge of using soil spectroscopy for SOC monitoring. The use of different spectrometers under varying soil conditions revealed shifts in wavelength importance. Still, our findings on the use of on-the-go spectroscopy for spatial–temporal SOC monitoring are promising.

Влияние бобовых культур и удобрений на продуктивность севооборотов и плодородие почвы

Abstract. The purpose of researches is influence legume crops and mineral fertilizers on crop rotation productivity and soil fertility elements in the conditions of Kaluga region. Methods. The research was carried out in a long-term stationary field experiment on gray forest medium loamy soil. The laying of field experience, observations, records and generalization of research results were carried out in accordance with generally accepted methodological recommendations. Results. It was found that the studied factors had an insignificant effect on the weed propensity, which, against the background of mineral fertilizers and with an increase in the share of legumes in the structure, was slightly higher. On average, during the fourth rotation, the highest crop productivity was obtained in a crop rotation with 40% saturation with legumes, both against the background of fertilization (38.6 c/ha of grain units) and without their use (32.6 c/ha of grain units). Applying of mineral fertilizers contributed to an increase in crop rotation productivity by 18–24 %. On average, for crop rotations, 6.4 c/ha of grain units or 22 % were obtained by applying mineral fertilizers in addition to a background without fertilizers. It’s noted that use of mineral fertilizers had a positive effect on the change some indicators of soil fertility. Availability of exchangeable forms potassium increased by 27 % and mobile phosphorus by 54 % compared to options without fertilizers. And in comparison with the initial state, the content of K2O without fertilizers increased by 17 and by 54 mg/kg of soil against the background of their use, and the content of P2O5 decreased by 27 mg/kg of soil and increased by 66 mg/kg, respectively. With an increase in the share of legumes in the structure of crop rotations from 30 % to 60 %, there was a slight increase in soil fertility, especially against the background of mineral fertilizers. Scientific novelty. The issues of influence legumes and mineral fertilizers on productivity of the fourth rotation of crop rotations and elements soil fertility were considered.

Temperature Matters More than Fertilization for Straw Decomposition in the Soil of Greenhouse Vegetable Field

As the largest organic carbon input to agroecosystems, crop straw can solve the problem of soil quality degradation in greenhouse vegetable fields, harmonize the balance between soil nutrients and energy, and improve soil quality to maintain the sustainable production of greenhouse vegetables. However, the microbial mechanism of the straw decomposition process under different temperatures and fertilization treatments in greenhouse vegetable soils has not been clarified. Soil samples were used to investigate the biology of straw decomposition in the soil at three incubation temperatures (15, 25, and 35 °C) through a soil incubation experiment (60 d) under different fertilization treatments. Fertilization treatments for this long-term field experiment included chemical fertilizer (CF), substitution of half of the chemical N fertilizer with manure (CM), straw (CS), or combined manure and straw (CMS). The results showed that soil hydrolase activities tended to decrease with increasing temperature during straw decomposition. Compared with the CF, organic substitutions (CM, CMS, and CS) increased soil β-glucosidase, β-cellobiosidase, N-acetyl-glucosaminidase, and β-xylosidase activities during straw decomposition. Soil CO2 emission rates were the highest at each incubation temperature on the first day, rapidly declining at 25 °C and 35 °C and slowly declining at 15 °C. The soil CO2 cumulative emissions tended to increase with increasing temperature under different fertilization treatments. PCA showed that the responses of soil enzyme activities to temperature at 7, 15, and 30 d of straw decomposition were stronger than those of fertilization. In summary, both fertilization treatment and incubation temperature could influence soil CO2 emissions by affecting soil physicochemical properties and enzyme activities during straw decomposition, whereas incubation temperature had a stronger effect on straw decomposition than fertilization, as indicated by PLS-PM and three-way ANOVA. Considering the influence for fertilization on the straw decomposition process at different incubation temperatures, the straw applications (CMS and CS) were more suitable to temperature changes.

The microbial community, nutrient supply and crop yields differ along a potassium fertilizer gradient under wheat–maize double-cropping systems

Soil microorganisms play critical roles in ecosystem function. However, the relative impact of the potassium (K) fertilizer gradient on the microbial community in wheat-maize double-cropping systems remains unclear. In this long-term field experiment (2008–2019), we researched bacterial and fungal diversity, composition, and community assemblage in the soil along a K fertilizer gradient in the wheat season (K0, no K fertilizer; K1, 45 kg ha−1 K2O; K2, 90 kg ha−1 K2O; K3, 135 kg ha−1 K2O) and in the maize season (K0, no K fertilizer; K1, 150 kg ha−1 K2O; K2, 300 kg ha−1 K2O; K3, 450 kg ha−1 K2O) using bacterial 16S rRNA and fungal internally transcribed spacer (ITS) data. We observed that environmental variables, such as mean annual soil temperature (MAT) and precipitation, available K, ammonium, nitrate, and organic matter, impacted the soil bacterial and fungal communities, and their impacts varied with fertilizer treatments and crop species. Furthermore, the relative abundance of bacteria involved in soil nutrient transformation (phylum Actinobacteria and class Alphaproteobacteria) in the wheat season was significantly increased compared to the maize season, and the optimal K fertilizer dosage (K2 treatment) boosted the relative bacterial abundance of soil nutrient transformation (genus Lactobacillus) and soil denitrification (phylum Proteobacteria) bacteria in the wheat season. The abundance of the soil bacterial community promoting root growth and nutrient absorption (genus Herbaspirillum) in the maize season was improved compared to the wheat season, and the K2 treatment enhanced the bacterial abundance of soil nutrient transformation (genus MND1) and soil nitrogen cycling (genus Nitrospira) genera in the maize season. The results indicated that the bacterial and fungal communities in the double-cropping system exhibited variable sensitivities and assembly mechanisms along a K fertilizer gradient, and microhabitats explained the largest amount of the variation in crop yields, and improved wheat-maize yields by 11.2–22.6 and 9.2–23.8% with K addition, respectively. These modes are shaped contemporaneously by the different meteorological factors and soil nutrient changes in the K fertilizer gradients.

Effects of agro based organic amendments on growth and cadmium uptake in wheat and rice crops irrigated with raw city effluents: Three years field study

Cadmium (Cd) accumulates in the vegetative tissues of rice and wheat crops, posing a serious threat in the food chain. A long-term field experiment was conducted to investigate the effects of rice husk biochar (RHB), farm manure (FM), press mud (PrM), and poultry manure (PM) on the growth, yield, and economics of wheat and rice crops grown with sewage water. The results showed that RHB increased wheat plant height (27%, 66%, 70%), spike-length (33%, 99%, 56%), straw yield (21%, 51%, 49%), and grain yield (42%, 63%, 65%) in year-1, year-2, and year-3, than respective controls. For rice crop, RHB showed the maximum increase in plant height (64%, 92%, 96%), spike length (55%, 95%, 90%), straw yield (34%, 53%, 55%), and grain yield (46%, 66%, 69%) each year (2019–2021), compared to their respective controls. The Cd immobilization was increased by the application of RHB while other treatments followed FM > PrM > PM > control in each year of wheat and rice crops. For year-1, benefit-cost ratio remained maximum with the application of FM while for the 2nd and 3rd years in sequence, RHB proved more economical than other treatments and consistently produced wheat and rice with lower Cd concentration than FM, PrM, and PM in grains. This long-term experiment suggested that the application of organic amendments consistently increased biomass of rice and wheat and decreased the Cd concentration in tissues. The RHB remained more effective compared with FM, PrM, and PM in terms of yield, low Cd accumulation and economics of rice and wheat crops.

Biological and experimental factors that define the effectiveness of microbial inoculation on plant traits: a meta-analysis.

Bacterial and fungal microbiomes associated with plants can significantly affect the host's phenotype. Inoculating plants with one or multiple bacterial and fungal species can affect specific plant traits, which is exploited in attempts to increase plant performance and stress tolerance by microbiome engineering. Currently, we lack a comprehensive synthesis on the generality of these effects related to different biological (e.g. plant models, plant traits, and microbial taxa) and experimental factors. In a meta-analysis, we showed that the plant trait under consideration and the microbial taxa used to inoculate plants significantly influenced the strength of the effect size. In a methodological context, experiments under sterilized conditions and short-term periods resulted in larger positive effects on plant traits than those of unsterilized and long-term experiments. We recommend that future studies should not only consider (short-term) laboratory experiments with sterilized plants and single inoculants but also and more often (long-term) field or greenhouse experiments with naturally occurring microbial communities associated with the plants and inoculated consortia including both bacteria and fungi.

Biochar and organic fertilizer applications enhance soil functional microbial abundance and agroecosystem multifunctionality

Biochar and organic fertilizer are widely supported to maintain crop production and sustainable development of agroecosystems. However, it is unclear how biochar and organic fertilizer alone or in combination regulate soil functional microbiomes and their relationships to ecosystem multifunctionality (EMF). Herein, a long-term (started in 2013) field experiment, containing five fertilization treatments, was employed to explore the effects of biochar and organic fertilizer applications on the EMF (based on 18 functional indicators of crop productivity, soil nutrient supply, element cycling, and microbial biomass) and the functional microbiomes of bulk soil and rhizosphere soil [normalizing the abundances of 64 genes related to carbon (C), nitrogen (N), phosphorus (P), and sulphur (S) cycles]. Compared with single-chemical fertilization, biochar and organic fertilizer inputs significantly enhanced most ecosystem-single functions and, in particular, the EMF significantly increased by 18.7–30.1%; biochar and organic fertilizer applications significantly increased the abundances of soil microbial functional taxa related to C-N-P-S cycles to varying degree. The combined application of biochar and organic fertilizer showed a better improvement in these indicators compared to using them individually. Most functional microbial populations in the soil, especially the taxa involved in C degradation, nitrification, nitrate-reduction, organic P mineralization, and S cycling showed significantly positive associations with the EMF at different threshold levels, which ultimately was regulated by soil pH and nutrient availability. These results highlight the strong links between soil microbiomes and agroecosystem functions, as well as providing scientific support for inclusion of biochar in agricultural production and services with organic amendments.Graphical

Why do we make changes to the long-term experiments at Rothamsted?

The long-term field experiments at Rothamsted in south-east England (UK) are an important resource that has been used extensively to study the effects of land management, atmospheric pollution and climate change on soil fertility and the sustainability of crop yields. However, for these and other long-term experiments around the world to remain useful, changes are sometimes needed. These changes may be required to ensure that the experiment is not compromised by e.g. acidification or weeds, but often they are needed to ensure that the experiment remains relevant to current agricultural practice, e.g. the introduction of new cultivars and the judicious use of pesticides. However, changes should not be made just for the sake of change or to investigate aspects of management that could be better resolved in a short-term experiment. Rather, modifications should only be made after carefully considered discussion, involving scientists from different disciplines. It must be remembered however that there are limitations to what can be achieved in one experiment. In this paper we give examples of why certain changes were made to the Rothamsted experiments and what the results of those changes have been. We also highlight the value of archiving crop and soil samples for future studies.

THE EFFECT OF AMENDMENT AND FERTILIZATION ON SOME CHEMICAL CHARACTERISTICS OF THE SOIL

The paper presents the results obtained from the long-term experimental field within Agricultural Research Station Livada. The experience included 6 variants in which manure, amendments (CaCO3) and mineral fertilization with NPK were applied. The soil samples were collected at a depth of 0-20 cm after 5 years from the application of manure. By applying CaCO3 0.5t/ha/year the pH was maintained at the value of 6.0 and with 0.7 t/ha/year the pH value was maintained at 7.0. The amendment potential of the manure that was applied in a dose of 20 t/ha determined an increase in pH from 4.56 to 5.28 after 55 years of application. Long-term fertilization with 20 manure + N100P70K60 increased the level of soil total nitrogen supply from low to medium. Fertilization with manure + N100P70K60 led to high accumulations (highly significant compared to fertilization with manure alone) of phosphorus, accumulations stimulated in the amended varieties.Amending acidic soils with limestone (calcium carbonate) and proper fertilization are essential for maintaining and improving soil quality.

Evaluation and Selection of Bromegrass Genotypes under Phosphorus and Water Scarcity towards the Development of Resilient Agriculture Focusing on Efficient Resource Use

The relationship between phosphorus (P) availability and water restriction was explored in this study, focusing on its impact on phosphorus use efficiency (PUE) and water use efficiency (WUE) in various bromegrass (Bromus spp.) genotypes. Under controlled conditions, five bromegrass genotypes, as well as one ryegrass (Lolium perenne) cultivar, were compared by subjecting them to two P levels and two watering regimes. It was determined that combining water and phosphorus limitations led to reduced plant productivity. Initially, the ryegrass outperformed the bromegrass, but this result declined over time, while bromegrass exhibited consistent stability. Notably, under P and water stress, enhanced root development was observed in bromegrass compared to that in ryegrass. Distinct patterns of PUE and WUE allowed for the categorization of bromegrass genotypes into three groups. Genotype 3457 emerged as the most efficient, scoring 20 out of 24, while Pro 94-49 A achieved a score of only 10 out of 24. This study suggests that the drought resilience of bromegrass may be linked to increased root growth during the early vegetative stages, which potentially facilitates improved P acquisition. However, further validation through long-term field experiments is needed. The insights from this study are potentially valuable for use in shaping plant breeding programs by revealing the plant adaptation mechanisms for both P and water absorption.