Long-term Field Experiment Research Articles

Reducing Application of Nitrogen Fertilizer Increases Soil Bacterial Diversity and Drives Co-Occurrence Networks.

Reducing nitrogen fertilizer application highlights its role in optimizing soil bacterial communities to achieve sustainable agriculture. However, the specific mechanisms of bacterial community change under these conditions are not yet clear. In this study, we employed long-term field experiments and high-throughput sequencing to analyze how varying levels of nitrogen application influence the soil bacterial community structure and co-occurrence networks. The results show that reducing the nitrogen inputs significantly enhances the diversity and evenness of the soil bacterial communities, possibly due to the diminished dominance of nitrogen-sensitive taxa, which in turn liberates the ecological niches for less competitive species. Furthermore, changes in the complexity and stability of the bacterial co-occurrence networks suggest increased community resilience and a shift toward more mutualistic interactions. These findings underline the potential of reduced nitrogen application to alleviate competitive pressures among bacterial species, thereby promoting a more diverse and stable microbial ecosystem, highlighting the role of competitive release in fostering microbial diversity. This research contributes to our understanding of how nitrogen management can influence soil health and offers insights into sustainable agricultural practices.

Over 50 years of a field experiment on cropping systems in Bałcyny, Poland: Assessing pesticide residues in soil and crops from the perspective of their field application history

Many agricultural problems can be illustrated and solved through long-term field experiments. Since 1967, an experiment has been conducted in Bałcyny, Poland, to compare continuous cropping with growing crops in crop rotation. The experiment also provides information on the history of chemical crop protection, which may have influenced soil and crop contamination with pesticide residues. In this study, fields of winter rye in continuous cropping (CCrye) and a 5–6-field crop rotation (CRrye) were used as an example to investigate the occurrence of pesticides in soil and grain in the context of previous use of chemical crop protection products. Two levels of crop protection were also examined: herbicide (since the 1972/73 growing season) and fungicide (since 1982/83) application (HF) and control treatment (CT; no herbicides since 1972/73, no fungicides since 1982/83). Insecticides were used only when absolutely necessary. Between 1967 and 2019, 58 different active substances were applied to the fields selected for this study. Soil and grain samples collected in 2019 after rye harvest were analyzed for the presence of 441 and 496 different substances, respectively. Only DDT and its metabolites were detected in soil, even though DDT was not applied to the fields after 1967. The concentration of ΣDDT (sum of all metabolites and isomers) ranged from 038 to 130 µg kg–1 soil and exceeded the limit set in Poland (120 µg kg–1) under CRrye-HF treatment. In winter rye grain, no pesticide residues were found. The results show that long-term rational use of less persistent pesticides does not lead to contamination of the soil or the test cereal grain, but DDT continues to threaten the environment five decades after its probable last use. The study points to the value of comprehensive long-term recording for providing a retrospective assessment of pesticide exposure. Long-term field experiments facilitate this approach.

Microbially induced calcium carbonate precipitation to combat desertification: A field application experiment

Combating desertification and recovering vegetation can help resolve global ecological problems. Microbially induced calcium carbonate precipitation is a natural and widespread phenomenon that has been a green and efficient approach for environmental issues. However, long-term field experiments are lacking and microbially induced calcium carbonate precipitation biological routes for desert restoration is unclear. Therefore, we investigated soil wind erosion resistance and soil characteristics via mixed methodology involving field and laboratory experiments and revealed the biological route. Our objective was to evaluate sand fixation efficiency and clarify the biological route. Results demonstrated that (1) microbially induced calcium carbonate precipitation produced sand cement, increased soil hardness, and changed soil characteristics. (2) Compared with CK, 25%, 50% and 75% treatments (MICP treatment from low to high concentration) reduced soil loss by 34.93%, 31.62% and 51.93%, respectively, and wind erosion decreased by 69.09%–77.27% at highest wind speed. (3) The 75% treatment had the greatest effect on wind erosion resistance. (4) Microbial activity changes the mechanism of wind erosion which meteorological effects change from direct to indirect after treatment. These results can address challenges and overcome the natural disadvantages of microbially induced calcium carbonate precipitation and contribute to technologies for combating desertification using soil microbial approaches.

Application and Experimental Substantiation of the Radioecological Model for Prediction in Behavior 90Sr in Cultivated Soil-Crop System: A Case Study of Two Experimental Agricultural Fields.

The radioactive fission product 90Sr has a sufficient half-life (28.8 years) to be detected long after its appearance in the environment. After its uptake into the soil-edible plant system, it enters the food chain and represents a potential source of contamination that threatens human health. Due to these facts, tracking the distribution of the artificial radionuclide 90Sr in the soil-edible plant system is a subject of intense research. The tracking of the 90Sr radionuclide distribution in the soil profile, as well as in the crops on the long-term experimental fields was carried out using beta radiation spectrometry. The radiochemical analytical method was used to analyze the 90Sr content in cultivated soil and crops. The conducted study focused on the experimental substantiation of the developed model for predicting the behavior of 90Sr in the cultivated soil-crop system. The results of using the applied radioecological model for the transfer of 90Sr from the soil to the above-ground part of crops showed a relatively good agreement with the experimentally determined values of the soil-crop transfer factor, which indicates that the used model can be successfully applied for the prediction of the behavior of 90Sr in the soil-soil solution-crop system.

Conservation tillage enhances the sequestration and iron-mediated stabilization of aggregate-associated organic carbon in Mollisols

Conservation tillage practices, which involve minimal or no soil disturbance and crop residue retention, are known to help preserve soil organic carbon (SOC). However, the mechanisms underlying the minerals-mediated chemical and physical stabilization of SOC remain unclear. Here, a long-term field experiment was initiated in 2012 to investigate the effects of tillage managements on the contents and chemical composition of SOC density fractions, iron oxides transformation and aggregate stability in Mollisols. We utilized three treatments: conventional tillage (CT) without crop residue, reduced tillage (RT) and no tillage (NT) with straw mulching. Compared to CT, RT and NT significantly increased SOC content by 13.6 % and 17.9 % in the 0–20 cm soil layer due to an increase in the aromatic compound contents. Furthermore, NT and RT increased the mean weight diameter by 17.7 % and 10.7 %, respectively, indicating increased aggregate stability compared to CT. Additionally, the contents of amorphous iron oxides (Feo) and complex iron oxides (Fep) increased under NT and RT by 10.6–14.4 % and 12.7–41.1 %, respectively, in bulk soil and silt + clay fractions within macroaggregates (>0.25 mm). The contents of Feo and Fep were strongly positively correlated with aggregate stability (p < 0.001, r2 = 0.64), and promote the physical protection of SOC. Both NT and RT enhanced the aromatic-C content and aromatic-C/aliphatic-C ratio by 13.6 %–24.6 % and 16.5 %–38.9 % in macroaggregates compared with CT. Moreover, the aromatic-C/aliphatic-C ratio increased with increasing Feo plus Fep contents (p < 0.001, r2 = 0.73), which led to an increased in the recalcitrant-C proportion, and this shift was benefit for the accumulation of mineral-associated OC. These results indicate that long-term conservation tillage can augment the accessibility of Fe for binding C, possibly by forming organo-Fe complexes, which subsequently improve soil aggregation, and thus promoted the chemical stability and long-term sequestration of SOC in Mollisols of Northeast China.

РОСТОВЫЕ ПРОЦЕССЫ КУКУРУЗЫ В ЗАВИСИМОСТИ ОТ УДОБРЕНИЙ НА ЧЕРНОЗЕМАХ ВЫЩЕЛОЧЕННЫХ РСО-АЛАНИЯ

In a long-term stationary field experiment that was established in 1971 on leached chernozem underlain by pebbles under conditions of field crop rotation the effect of systematic application of fertilizers for hybrid corn on plant growth processes was studied. It was found that the fertilized variants increased relative to the control: the growth of plants in height, the increase in leaf surface area, the accumulation of raw and dry biomass, increased photosynthetic potential. From the fertilized options, the calculated option N310P324K139 stood out for the better for the planned yield of 8.0 t/ha. In this variant at the end of the growing season the average height of the plant was 256 cm versus 247 cm in the control; the leaf surface area was 60056 versus 49392 m2/ha in the control; the photosynthetic potential was 3.08 million m2/ha.day versus 2.53 at the control; the amount of dry biomass is 22.5 versus 15.0 t/ha at the control. According to all indicators the double dose of N140P80K180 was in second place: respectively accordingly 255 cm, 56,808 m2/ha, 2.87 million m2/ha.day, 20.4 t/ha. Of the equivalent options a double dose of NPK had some advantage over manure+NPK (trend).

Effects of Deep Vertical Rotary Tillage on Soil Water Use and Yield Formation of Forage Maize on Semiarid Land

Forage maize is one of the most important feed crops for livestock production, and is mainly grown in northwest China. However, their growth is often stressed by limited soil water availability due to the arid climate. To provide more soil moisture, a high-efficiency tillage technique was required to make crops effectively use soil moisture in deep soil layers. Deep vertical rotary tillage is a promising choice for this purpose. In this study, a long-term (2020–2022) field experiment consisting of three treatments, i.e., traditional tillage (TT), deep rotary tillage (DT), and deep vertical rotary tillage (VRT), was carried out in semiarid areas of Loess Plateau, northwest China, to investigate the effects of VRT on soil water storage (SWS), phase crop evapotranspiration (ETc) during the pre- and post-flowering periods, dry matter accumulation, grain yields and the water use efficiency (WUE) of forage maize. The results showed that VRT significantly improved the absorption of soil moisture from deep layers, especially in dry years. During the pre-flowering period of a dry year (2020), VRT decreased SWS by 7.6%–10.0% in the 60–180 cm layer, and by 17.6%–18.5% in the 180–300 cm layer, respectively, compared to DT and TT. As a result, VRT increased ETc during the pre-flowering period by 6.1% and 9.2%, respectively. In wet years (2021 and 2022), VRT increased total ETc by 2.0%–7.9% in 2021, and by 10.1%–14.9% in 2022, respectively. On average, VRT increased the dry matter weight per plant by 1.0%–7.8%, grain yields by 2.4%–38.6%, biomass yields by 3.4%–16.2%, and WUE by 10.1%–30.0%, respectively. Particularly, the benefit of VRT for increasing yields and WUE was more noticeable in dry years. It can be concluded that VRT is a drought-tolerant and yield-boosting tillage technique that is suitable for rain-fed forage maize in semiarid areas of Loess Plateau, northwest China.

Predictive monitoring of soil organic carbon using multispectral UAV imagery: a case study on a long-term experimental field

Effective monitoring of the soil organic carbon (SOC) content at the field scale is crucial for supporting sustainable agricultural practices. This study evaluates the utility of multispectral data acquired by an unmanned aerial vehicles (UAV) during bare soil conditions for predicting the SOC content of a long-term experimental field site (LTE) in Saxony-Anhalt, Germany. Our methodology involves constructing predictive models using multiple algorithms (CUBIST, MARS, linear regression) and applying image correction techniques to enhance prediction accuracy by mitigating the influence of confounding factors such as crop residuals. Among the tested models, the CUBIST algorithm, combined with a pixel selection strategy employing a 2 m radius and stratified image correction, demonstrates the most promising results, achieving an R-squared value of 0.54 and an RMSE of 1.9 g kg−1. Spatial distribution maps generated by this optimized model effectively depict the impact of organic fertilization on the SOC content, although the clarity of these patterns varies depending on the image processing method and algorithm used. Our findings highlight the potential of utilizing UAV-derived multispectral data for SOC monitoring at the LTE scale. However, further research is warranted to assess the generalizability of this approach to agricultural fields with lower SOC variability.

Phosphorus fertilizer input threshold shifts bacterial community structure and soil multifunctionality to maintain dryland wheat production

As an important factor affecting crop yield in agroecosystems, phosphorus (P) fertilizer addition can significantly alter the soil microbial community, functional gene composition, and multifunctionality. However, the major factors that determine wheat grain yield and the changes in wheat yield caused by the P fertilizer input threshold in dryland wheat production have not been adequately characterized. Based on a long-term field experiment (18 years) with five P addition gradients (0, 50, 100, 150, and 200 kg P2O5 ha−1 yr−1) in the Loess Plateau of China, amplicon (16 S rRNA) and metagenomic sequencing were used to investigate the effects of long-term P fertilization on soil bacterial communities, rhizosphere microbial functions, soil multifunctionality, and wheat grain yield. Long-term P input significantly affected the compositions and functions of the soil bacterial communities. Conversely, long-term high-P treatment (P200) inhibited soil bacterial diversity and soil P cycling genes but increased carbon (C) cycling genes and soil multifunctionality. Meanwhile, there is a threshold of P fertilizer (71.6−78.1 kg ha−1 yr−1) input for wheat grain yield, beyond which the grain yield of wheat did not significantly increase. In addition, the rhizosphere selection effect significantly increased the complexity of the rhizosphere network and microbial interactions and directed the recruitment of microorganisms and genes with special functions to maintain wheat grain yield. Therefore, this study revealed that the threshold of P fertilizer input can provide a basis for reducing P fertilizer and regulating microorganisms to maintain soil multifunctionality and network complexity in the dryland agriculture system of the Loess Plateau to maintain wheat grain yield.

Reducing industrial inputs – a prerequisite for the transition to sustainable agriculture

This article provides the results of a long-term field experiment carried out at the ICC "Selectia" with the aim of studying the influence of irrigation and fertilisation on the production capacity and productivity of the soil and, at the same time, on soil fertility. Another long-term field experiment aimed to study the action and interaction of crop rotation, tillage, and fertilisation systems in the absence of chemical means of disease, pest and weed control. As a result, it was found that winter wheat responds to irrigation, unlike sugar beet, which responds more to soil fertilisation. Grain maize does not react to crop rotation and fertilisation. Irrigation reduces organic matter content throughout the soil profile. By following the crop rotation with the inclusion of perennial grass mixtures it is possible to reduce the costs of tillage and the use of mineral fertilisers. The additional use of mineral fertilisers as a result of the action or the effect of manure management in the soil is not agronomically and economically justified.

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.

Soil Organic Carbon Dynamics in the Long-Term Field Experiments with Contrasting Crop Rotations

Trends in soil organic carbon (SOC) were analyzed in the soils from the oldest Czech long-term field experiment, the Prague-Ruzyně Long-Term Fertilizer Experiment, conducted on Haplic Luvisol since 1955. The aim of the work was to compare the long-term dynamics of SOC in contrasting crop rotations and different fertilization regimes. The trial design includes two crop rotations (CR): simple CR with two-year rotation of sugar beet and spring wheat, and multi-crop rotation (MCR) with nine crops. Four fertilization treatments were chosen for SOC analysis: unfertilized control, only mineral fertilization (NPK), farmyard manure application (FYM), as well as FYM and NPK application. SOC content was significantly affected by both fertilization and crop rotation practices. In the simple CR, both the unfertilized control and the NPK treatment exhibited a consistent decline in SOC content over the study period, with percentages decreasing from an initial 1.33% in 1955 to 1.15% and 1.14%, respectively. Although the FYM and FYM + NPK treatments showed an increase in SOC content in the 1990s, a gradual decline was recorded in the last two decades. This decrease was not observed in MCR: positive C balances were recorded in all treatments within MCR, with the largest increase in SOC stock occurring when NPK was combined with FYM. In contrast, over the last decade, C balances have decreased in simple CR for all treatments except FYM. This trend coincides with changes in the local climate, particularly rising temperatures. The results indicate that diversified crop rotations and FYM fertilization are effective in mitigating the negative impacts of changing environmental conditions on SOC stocks.

Influence of biodestructors on sequestration of labile carbon compounds in the soil

Ukraine stands as a testament to agricultural wealth due to its fertile soils, most notably, its significant share of the world’s chornozem. Rich soil is fundemantal to agricultural production, and therefore the success of the agricultural industry heavily relies on the fertility of the soil. However, modern agricultural practices in Ukraine, have led to increased anthropogenic impact on soils, affecting their biodiversity and humus content. In this regard, it is becoming increasingly important to perform comprehensive studies of microbiological, biochemical and chemical processes in the soil in response to different agricultural interventions. The urgent need to restore natural ecosystems to preserve their biodiversity and ensure ecological stability poses new scientific challenges, emphasizing the importance of urgent measures aimed at protecting the environment from pollution and degradation. This research aims to explore the effects of biodestructors on the deposition of labile carbon compounds in the soil during long-term consistent corn cultivation. The research was conducted during 2020–2023 within the framework of a stationary field experiment of the scientific research department of the «Druzhba Nova» in Varva village, Chernihiv region. The soil is a typical low-humus chornozem with the experiment focusing on a monoculture corn crop rotation. The DKC 4351 corn hybrid was sown at a density of 82 thousand units per hectare, employing a three-part experiment design: 1) a UAN control at 32–28 l/ha, 2) Ecostern Classic at 2 l/ha combined with UAN 32–28 l/ha, and 3) Ecostern Bacterial at 2 l/ha alongside Ecostern Trichoderma at 1 l/ha and UAN 32–28 l/ha. In the present study, the influence of biodestructors on soil’s agrochemical and microbiological indicators, as well as corn yield was evaluated. In a long-term stationary field experiment conducted on a typical low-humus chornozem, we investigated the influence of microbial preparations — plant residue biodestructors — on the deposition of labile carbon compounds in the soil under continuos corn cultivation. The application of Ecostern Classic and a combination of Ecostern Bacterial + Ecostern Trichoderma biodestructors resulted in an increase of labile carbon content by 0.11% and 0.18%, respectively, compared to the control. The aim of further analysis was to determinate the dynamics of the organic matter transformation coefficient, which is a marker of enhanced microbiological activity in the soil and a predominance of organic matter synthesis over its mineralization. In treatments utilizing biodestructors, this indicator was significantly higher than control values throughout the study. The survival of the fungal bioagent from Ecostern Classic and Ecostern Trichoderma bioproducts in the soil was monitored by assessing the population dynamics of the Trichoderma genus species. Results demonstrated an increase by an average of 19 thousand CFU/g with Ecostern Classic and by 34 thousand CFU/g with the combined use of Ecostern Bacterial with Ecostern Trichoderma, compared to 28 thousand CFU/g in control soil samples. This may indirectly indicate a successful colonization of the bioagent in treated soils. Using BIOTREX technology to evaluate the soil’s ecophysiological diversity, we found that the diversity index increased from 3.66 in control samples to between 4.87 and 5.61 in treatments with biodestructors. According to the further BIOTREX assessment, the use of biodestructors not only increased soil biodiversity, but also improved soil health. The application of these biodestructors also significantly boosted corn grain yield with an increase of 0.32 t/ha with Ecostern Classic treatment and 0.18 t/ha with the combined use of Ecostern Bacterial with Ecostern Trichoderma, compared to control.

Effect of Soil Acidification on Temperature Sensitivity of Soil Respiration

Soil pH significantly impacts microbial activity and community assembly, which in turn determines the temperature sensitivity (Q10) of soil respiration. Due to the high soil acidification in China, it is necessary to understand how soil acidification impacts Q10. Here, the Q10 of soil respiration was examined in a long-term field experiment (1982–present) with different soil pH caused by fertilization management. In this experiment, we selected treatments with neutral pH: (1) no crops and fertilization (CK); (2) crops without fertilization (NF); low pH with (3) crops with chemical fertilization (NPK); and (4) crops with chemical fertilization combined with wheat straw incorporation (WS). Under natural soil temperature changes, we observed that soil acidification lowered the Q10 value of soil respiration. Considering only temperature changes, the Q10 of soil respiration was strongly associated with microbial community composition, alpha diversity, and soil ammonium nitrogen. Considering the interaction between soil pH and temperature, warming strengthened the negative effect of soil pH on the Q10 of soil respiration, and the pathway through which soil pH mediated Q10 included not only microbial community composition, alpha diversity, and biomass but also the soil’s available phosphorus. This work enhanced our insights into the relationships between Q10, temperature, and soil pH by identifying important microbial properties and key soil environmental factors.

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.

Uptake of technetium-99 by food crops under field conditions

Long-term field experiments have been carried out in the Chornobyl Exclusion zone to determine parameters describing technetium (99Tc) transfer into five food plants (Lettuce, Radish, Wheat, Bean, and Potato) from four types of soil, namely Podzoluvisol, Greyzem, Phaeozem, and Chernozem. Technetium was added to the soils under field conditions in a pertechnetate form. In the first two years, soil type had little effect on Tc uptake by plants. In the first and second years after contamination, the concentration ratios (CR), defined as 99Tc activity concentration in the crop (dry weight) divided by that in the soil (dry weight), for radish roots and lettuce leaves ranged from 60 to 210. For potato tubers, the CR was d 0.4–2.3, i.e., two orders of magnitude lower than for radish and lettuce, and for summer wheat grain it was lower at 0.6 ± 0.1. After 8–9 years, root uptake of 99Tc by wheat decreased by 3–7 fold (CR from 0.016 ± 0.005 to 0.12 ± 0.034) and only 13–22 % of the total 99Tc added remained in the upper 20 cm soil layers. The time taken for half of the added 99Tc to be removed from the 20-cm arable soil layer due to vertical migration and transfer to plants was short at c. 2–3 years.

Crop rotational diversity can mitigate climate-induced grain yield losses.

Diversified crop rotations have been suggested to reduce grain yield losses from the adverse climatic conditions increasingly common under climate change. Nevertheless, the potential for climate change adaptation of different crop rotational diversity (CRD) remains undetermined. We quantified how climatic conditions affect small grain and maize yields under different CRDs in 32 long-term (10-63 years) field experiments across Europe and North America. Species-diverse and functionally rich rotations more than compensated yield losses from anomalous warm conditions, long and warm dry spells, as well as from anomalous wet (for small grains) or dry (for maize) conditions. Adding a single functional group or crop species to monocultures counteracted yield losses from substantial changes in climatic conditions. The benefits of a further increase in CRD are comparable with those of improved climatic conditions. For instance, the maize yield benefits of adding three crop species to monocultures under detrimental climatic conditions exceeded the average yield of monocultures by up to 553 kg/ha under non-detrimental climatic conditions. Increased crop functional richness improved yields under high temperature, irrespective of precipitation. Conversely, yield benefits peaked at between two and four crop species in the rotation, depending on climatic conditions and crop, and declined at higher species diversity. Thus, crop species diversity could be adjusted to maximize yield benefits. Diversifying rotations with functionally distinct crops is an adaptation of cropping systems to global warming and changes in precipitation.

Productivity and energy-efficiency indices for diversified rice (Oryza sativa) based cropping systems in West Central Table Land Zone of Odisha

A long-term field experiment was conducted at Chiplima, Odisha, under irrigated medium land condition during 2006–07 to 2012–13, to evaluate the production potential and economics of 10 rice (Oryza sativa L.)-based crop ping systems. Rice–maize (Zea mays L.)–cowpea [Vigna unguiculata (L.) Walp.] and rice–groundnut (Arachis hypogaea L.)–bottle gourd [Lagenaria siceraria (Molina) Standl.] cropping systems recorded significantly higher average rice equivalent yield (19.55 and 18.57 t/ha, respectively) than the other systems evaluated, the relative production efficiency being 85.8 and 76.5% over the rice–groundnut system. Rice-based 3-cropping systems hav ing groundnut as winter (rabi) crop had higher land-use efficiency (83%). Rice–maize–cowpea recorded the high est irrigation water-use efficiency (230 kg REY/ha), whereas rice–groundnut–bottle gourd recorded the highest ap parent nutrient use efficiency (60.8 kg REY/kg NPK applied). Rice–maize–cowpea also recorded the highest en ergy-use efficiency (5.89), energy-output efficiency (1,240 MJ/ha/day) and energy productivity (0.34 kg REY/MJ). Rice–maize–cowpea had the highest employment generation efficiency (124.7%), followed by rice–groundnut bottle gourd (120.5%) and rice–groundnut–cowpea (120.0%). Rice–maize–cowpea gave the highest net returns of 135,087/ha, followed by rice–groundnut–bottle gourd system ( 111,777/ha). Rice–maize–cowpea system showed the highest system profitability ( 370/ha/day) and crop profitability ( 500/ha/day). This system also gave the highest benefit: cost ratio (2.56), with highest relative production efficiency (85.8%) and relative economic effi ciency (168.5%) compared to rice–groundnut system.

Pasture-crop rotations modulate the soil and rhizosphere microbiota and preserve soil structure supporting oat cultivation in the Pampa biome

Mixed systems of grain and livestock production based on pasture-crop rotations are a promising strategy to promote agriculture resilience and allow an ecological intensification of agriculture yet little is known about underlying processes in soil. To test the hypothesis that pasture-crop rotations preserve soil structure and select for beneficial soil and rhizosphere microbiota, supporting soil health and grain production, a long-term field experiment under no-tillage was studied. The experiment evaluated a gradient of land use intensities and vegetation diversities, from highly intensive continuous cropping to the least intensive system i.e. a nearby natural grassland, with two intermediate land use intensities i.e. short pasture-crop rotation and long pasture-crop rotation. Soil health was assessed based on soil physicochemical properties, microbial (Bacteria/Archaea and Fungi) community diversity and composition and oat performance. Pasture-crop rotations preserved soil bulk density and larger aggregates better than continuous cropping. High-throughput amplicon sequencing of 16S rRNA gene and ITS fragments revealed that the pasture-crop rotations fostered taxa that are associated with soil structure maintenance and selected potential plant-beneficial bacterial genera in the oat rhizosphere (i.e. Bosea, Devosia and Microbacterium), that may have contributed to the observed increase in N uptake, N accumulation and biomass in oat. In summary, this study shows that pasture-crop rotations are an ecologically sustainable alternative to continuous cropping in the Uruguayan Pampa biome.

Disentangling the effects of mineral fertiliser N, P and K on microbial biomass, necromass and ionome in soil from the Askov long-term field experiment

Given the increasingly recognised importance of microbial biomass (MB) in soil organic carbon (SOC) sequestration, knowledge of the microbial ionome beyond carbon (C), nitrogen (N) and phosphorus (P) becomes crucial. The microbial ionome could indicate nutritional restrictions related to MB growth and microbial necromass C (MN-C) accumulation. In this study, soils receiving different combinations of mineral N, P and potassium (K) were sampled in the Askov long-term field experiment, Denmark, and analysed for MB elemental composition including N, P, K, magnesium (Mg), manganese (Mn) and zinc (Zn) using fumigation-extraction and ICP-OES. Furthermore, bacterial, archaeal and fungal gene abundance was determined by qPCR as microbial community shifts may relate to microbial ionome shifts. MN-C was determined by amino sugar analysis. MB-C was unaffected by fertiliser treatments and not correlated with MN-C. N fertilisation increased MN-C. N and K additions increased plant-derived SOC, indicating the importance of N for microbial and plant-derived SOC accumulation. Availability of P and K increased MB-P and MB-K, respectively, and reduced the MB-C:P ratio but not MB-C:K. N fertilisation reduced the pH and increased Mn availability which increased MB-Mn and reduced MB-C:Mn. ITS1 gene copies responded positively to P availability. A reduced MB-C:Mn ratio was associated with a relative increase in fungal gene copy abundance. This was linked to an increase in SOC, indicating a positive link between Mn availability, fungal abundance and SOC level, yet this was not reflected in MN-C accumulation, but by the accumulation of plant-derived SOC, possibly due to reduced plant C turnover.