Rye Monoculture Research Articles

Species richness and functional diversity enhance winter annual forage productivity and nutritive value

AbstractWinter annual forages can extend grazing into the cool‐season in the US southeast, however uncertainty regarding potential tradeoffs between winter annual mixtures versus monocultures exists. We examined increasingly species‐rich and functionally diverse winter annual forage mixtures at two Florida locations to evaluate impacts of including more plant species with distinct traits (e.g., different maturities and nitrogen [N] scavenging vs. N2‐fixing capabilities) on forage accumulation (FA), nutritive value, and evenness of forage distribution across the cool‐season compared with a rye (Secale cereale L.) monoculture. Furthermore, we quantified the N2‐fixing potential of winter annual legumes to measure their contribution to soil fertility and ecosystem N cycling. We found that greater species richness enhanced total cool‐season FA at both sites, ranging from 0.92 to 4.38 Mg DM ha−1 in Gainesville and 6.48 to 9.11 Mg DM ha−1 in Marianna. In Marianna, where legumes accounted for approximately 25% or more of the biomass accumulated by winter annual forage mixtures, legume inclusion enhanced forage shoot N concentration. Furthermore, >50% of the N in legume tissues derived from the atmosphere, supplying 0.18–2 kg N ha−1 in Gainesville and 30–52 kg N ha−1 in Marianna. Altogether, our data suggest that species richness enhanced winter annual forage production and legume inclusion improved forage nutritive value although these responses were site‐specific. Thus, our multi‐site study provides information that can guide decision‐making regarding appropriate winter annual forage selections to increase cool‐season forage production in the southeastern United States.

Carbon Storage Potential and Carbon Dioxide Emissions from Mineral-Fertilized and Manured Soil

Two important goals of sustainable agriculture are food production and preserving and improving soil health. The soil organic carbon content is considered an indicator of soil health. The evaluation of the methods to increase the soil organic carbon content in long-term experiments is usually carried out without considering its environmental effects, (e.g., CO2–C soil emission). This study hypothesized that sandy soils have a low carbon storage potential, and that the carbon accumulation in the soil is accompanied by increased CO2–C emissions into the atmosphere. The study was carried out as a long-term fertilization experiment in Central Poland using a rye monoculture. The changes in the soil organic carbon content (SOC), CO2–C emissions from soil, and plant yields were examined for two soil treatments: one treated only with mineral fertilizers (CaNPK) and one annually fertilized with manure (Ca + M). Over the 91 years of the experiment, the SOC content of the manure-fertilized treatment increased almost two-fold, reaching 10.625 g C kg−1 in the topsoil, while the content of the SOC in the soil fertilized with CaNPK did not change (5.685 g C kg−1 in the topsoil). Unlike mineral fertilization, soil manuring reduced the plant yields by approximately 15.5–28.3% and increased the CO2–C emissions from arable land. The CO2–C emissions of the manured soil (5365.0 and 5159.2 kg CO2–C ha−1 in the first and second year of the study, respectively) were significantly higher (by 1431.9–2174.2 kg CO2–C ha−1) than those in the soils that only received mineral fertilizers (3933.1 and 2975.0 kg CO2–C ha−1 in the first and second year of the study, respectively). The results from this experiment suggest that only long-term fertilization with manure might increase the carbon storage in the sandy soil, but it is also associated with higher CO2–C emissions into the atmosphere. The replacement of mineral fertilizers with manure, predicted as a result of rising mineral fertilizer prices, will make it challenging to achieve the ambitious European goal of carbon neutrality in agriculture. The increase in CO2–C emissions due to manure fertilization of loamy sand soil in Central Poland also suggests the need to research the emissivity of organic farming.

Does Drone Data Allow the Assessment of Phosphorus and Potassium in Soil Based on Field Experiments with Winter Rye?

The evaluation of the nutrient content in the soil, such as potassium and phosphorus, is very important, especially in precision agriculture, where the fertilizer rate should be adjusted to field variability in terms of nutrient content. Soil chemical analysis is time-consuming and expensive, and dense soil sampling is not always possible. In recent years, remote sensing methods have been used to assess the within-field variability of soil and crop nutritional status. The main aim of this study was to evaluate the relationship between UAV-derived spectral reflectance for winter rye in a long-term experiment for different fertilization with phosphorus and potassium. The study was conducted in 2022 in two field experiments in which winter rye was cultivated in monoculture and with crop rotation. The experiments were located in central Poland in Skierniewice. Statistical analyses were performed using univariate and multivariate methods, e.g., analysis of correlation, regression, and principal component analysis (PCA). The effect of phosphorus and potassium fertilization on the UAV-derived spectral reflectance of winter rye was weak, weaker in comparison to the effect of nitrogen fertilization. The effect of phosphorus and potassium fertilization on spectral reflectance was stronger in the experiment with monoculture than in the experiment with crop rotation. On the basis of correlation coefficients and PCA, negative relationships were proven between available soil potassium and spectral reflectance in the range of blue, green, and red bands and positive with red edge and near-infrared bands. The first principal component (PC1) was very strongly correlated with almost all spectral bands, either positively or negatively. The correlation of potassium and phosphorus content was very weak with PC1 in the experiment with crop rotation, while in the experiment with rye monoculture, the correlation was slightly stronger, indicating a stronger effect of nutrient deficiency in monoculture.

UAV-Derived Spectral Indices for the Evaluation of the Condition of Rye in Long-Term Field Experiments

The aim of the study was to evaluate the effect of various fertilization treatments, including nitrogen, potassium and phosphorus fertilization, in long-term experiments for selected UAV (unmanned aerial vehicle)-derived spectral vegetation indices (NDVI—Normalized Difference Vegetation Index, NDRE—Normalized Difference Red Edge Index, VARI—Visible Atmospherically Resistant Index, TGI—Triangular Greenness Index, SIPI2—Structure Insensitive Pigment Index 2, LCI—Leaf Chlorophyll Index, BNDVI—Blue Normalized Difference Vegetation Index, GNDVI—Green Normalized Difference Vegetation Index, MCARI—Modified Chlorophyll Absorption in Reflective Index) based on multispectral (bands in the range of visible light and near infra-red) images of winter rye. The strongest effect on the studied vegetation indices was nitrogen fertilization, which discriminated values of most of the vegetation indices. The effect of phosphorus and potassium fertilization on the studied vegetation indices was much weaker. The treatments with nitrogen fertilization had significantly higher values of most vegetation indices in comparison to treatments without nitrogen. This was confirmed by principal component analysis (PCA), in which treatments without nitrogen fertilization were very different in comparison to all other treatments where nitrogen fertilization was applied. The effect of phosphorus and potassium fertilization on most of vegetation indices was relatively weak and not significant in most experiments. Only for rye cultivated in monoculture was the effect of phosphorus fertilization significant for most of vegetation indices in early growth stages. In later growth stages (heading and flowering) the effect of phosphorus fertilization was significant in rye monoculture for the SIPI2 vegetation index. Mean SIPI2 was higher for the fertilization treatment CaNPK in comparison to CaKN (without P fertilization). The effect of potassium fertilization on the studied vegetation indices was very weak, and in most cases not significant. The effect of nitrogen fertilization on vegetation indices was much stronger than effect of both potassium and phosphorus fertilization.

Mixed planting reduces the shaping ability of legume cover crop on soil microbial community structure

Cover crop species and management are the key factors for reaping maximum benefits. Current studies lack a comprehensive assessment of the effects of cover crop species and planting patterns on soil properties, plant properties, and rhizosphere microbial communities at the full-blooming stage. A field experiment was conducted for 8 years (2011–2018) in Tianjin (fluvo-aquic soil) in China to compare various cover crops (hairy vetch, February orchid and rye) under different planting patterns (monoculture or mixed culture) in terms of cover crop biomass, soil physicochemical and biological properties, and rhizosphere microbial communities through high-throughput sequencing. The following groups were established: CK (winter fallow; the control), FO (February orchid monoculture), RY (rye monoculture), HV (hairy vetch monoculture), FOHV (February orchid–hairy vetch mixed culture), and RYHV (rye–hairy vetch mixed culture). RY had the highest biomass and nitrogen (N) uptake, and HV had the lowest biomass and highest N content. Mixed culture produced biomass higher in amount than the average biomass of monocultures of each individual species. RYHV showed a higher amount of biomass and uptake of nutrients, especially N. Cover crop planting significantly increased soil organic matter content (22.45 %–33.22 %), N levels (78.28 %–412.04 %), and available phosphate (9.70 %–45.03 %) and potassium (20.71 %–56.62 %) levels, but no significant differences in soil pH and total phosphorus content were found among the treatments. FO and HV treatments showed higher increments in soil biological properties: soil microbial biomass C (Cmic) and soil microbial biomass N (Nmic) and nematode density than the RY treatment. Mixed planting further promoted these properties, and FOHV treatment showed the highest values, which indicated improved soil properties. HV treatment significantly reduced bacterial and fungal diversity and the number of operational taxonomic units. These effects can be alleviated by mixed planting with FO and RY. Principal component analysis showed that the bacterial and fungal communities in the control were distinct from those in the cover crop treatments, and the difference was the greatest in the HV treatment. However, mixed planting with FO and RY reduced this difference between HV and CK. Structural equation model integration and analysis confirmed that the bacterial community was primarily regulated by soil physicochemical properties, whereas the fungal community was primarily regulated by plant properties. Soil biological properties affected bacterial and fungal communities, and mixed planting alleviated the impact of hairy vetch on soil microbial communities.

Corn yield and nitrogen recovery following rye (Secale cereale L.) in monoculture and polyculture service crops

Planting service crops (SCs) with late summer manure applications has been promoted as an agronomic practice to capture manure nitrogen (N) and release it to the following season’s cash crop, thereby reducing fertilizer N requirements. The present study explored this hypothesis using a cereal rye ( Secale cereale L.) monoculture SC, along with two polyculture SCs (4 species and 12 species) both containing rye, planted after winter wheat ( Triticum aestivum L.) harvest, in systems with and without liquid hog manure. The following spring, SC regrowth was chemically terminated 1 week prior to corn ( Zea mays L.) planting, and a sidedress N application was made at the 6–8 leaf stage to half of the plots. Corn N accumulation and final grain yield were reduced up to 20% following the rye monoculture in both years, even though SCs did not reduce soil mineral N nor partial plant-available N over the corn-growing season. Additionally, the sidedress N application could not overcome the yield loss associated with rye. Thus, this study did not observe N release by SCs to the following cash crop and demonstrates that yield loss can occur when corn follows rye SCs irrespective of changes in plant available N. This research reinforces the importance of selecting appropriate species and their proportions in polycultures, to mitigate negative impacts of SCs, especially those of rye on corn.

The Effect of Monoculture, Crop Rotation Combinations, and Continuous Bare Fallow on Soil CO2 Emissions, Earthworms, and Productivity of Winter Rye after a 50-Year Period.

One of the main goals of the 21st century’s developing society is to produce the necessary amount of food while protecting the environment. Globally, particularly in Lithuania and other northern regions with similar climatic and soil conditions, there is a lack of data on the long-term effects of crop rotation under the current conditions of intensive farming and climate change. It has long been recognized that monocultures cause soil degradation compared to crop rotation. Research hypothesis: the long-term implementation of crop rotation makes a positive influence on the soil environment. The aim of our investigation was to compare the effects of a 50-year-long application of different crop rotations and monocultures on soil CO2 emissions, earthworms, and productivity of winter rye. Long-term stationary field experiments were established in 1966 at Vytautas Magnus University Experimental Station (54°53′ N, 23°50′ E). The study was conducted using intensive field rotation with row crops, green manure crop rotations, three-course rotation, and rye monoculture. Pre-crop had the largest impact on soil CO2 emissions, and more intensive soil CO2 emissions occurred at the beginning of winter rye growing season. Rye appeared not to be demanding in terms of pre-crops. However, its productivity decreased when grown in monoculture, and the optimal mineral fertilization remained lower than with crop rotation, but productivity remained stable.

Toward an Investigation of Diversity and Cultivation of Rye (Secale cereale ssp. cereale L.) in Germany: Methodological Insights and First Results from Early Modern Plant Material

Rye (Secale cereale ssp. cereale L.) is a secondary domesticate, considered to have originated as a weed in wheat fields and to have developed traits of domestication by evolving similar physiological and morphological characteristics to those of wheat. Although it migrated into Europe as a weed possessing domestication traits, it became one of the most significant crops grown in large parts of Europe from the medieval period onward. Within the modern borders of Germany, rye was grown using at least two divergent cultivation practices: eternal rye monoculture and three-field rotation. The straw of rye was used to produce Wellerhölzer, which are construction components in traditional half-timbered houses that have enabled a desiccated preservation of the plant remains. In order to assess the impact of cultivation practices, local environmental conditions and genetic variation on the genetic diversification of rye, we seek to integrate well-established archaeobotanical methods with aDNA sequencing of desiccated plant remains obtained from Wellerhölzer from Germany. In the current contribution, we present a proof of concept, based on the analysis of plant remains from a Wellerholz from the Old Town Hall of Göttingen. We use arable weed ecology to reconstruct cultivation practices and local environmental conditions and present a phylogenetic analysis based on targeted loci of the chloroplast and nuclear genome. Our results emphasise that the study of desiccated remains of plants from Wellerhölzer offer a unique opportunity for an integration of archaeobotanical reconstructions of cultivation practices and local environment and the sequencing of aDNA.

The Influence of Long-Term Different Crop Rotations and Monoculture on Weed Prevalence and Weed Seed Content in the Soil

Equally effective way to achieve sustainable farming and the challenge set by the European Commission on 20 May 2020: proper crop rotation and thus reduction of the quantity of on-farm chemicals. Long-term stationary field experiments were established in 1966 at Vytautas Magnus University Experimental Station (54°53′ N, 23°50′ E). The study was conducted with intensive, three-course, field rotation with row crops, for green manure crop rotations, and rye monoculture as well during the last 5-year period of a 50-year investigation to determine the effect of crop rotation combinations and rye monoculture on weed density and seed bank and grain yield. In cereal crops, weed counting was performed twice: weed density was determined before the application of herbicides, and weed counting was done before the harvest. Weed seedlings were counted, their botanical species were determined, annual and perennial weed number was estimated. Weed seed bank was established before primary tillage in soil. The results obtained confirmed the hypothesis that with climate change and intensive farming, long-term crop rotations are likely to increase crop productivity, reduce weeds and weed seed banks in the soil, and thus contribute to maintaining agroecosystem sustainability. The winter rye 1000 grain weight and yield decreases as weed mass increases showing strong negative correlations: y = 475.56 − 11.93x, r = −0.91, p ≤ 0.05; y = 82.97 −14.82x, r = −0.97, p ≤ 0.01. Reseeding of rye crops leads to a growing prevalence of weeds such as Equisetum arvense L. and Mentha arvensis. Crop structures these days are dominated by cereals, which inevitably increase the spread of weeds, and therefore, the importance of crop rotations increases in the context of intensive farming.

Soil Respiration under 90 Year-Old Rye Monoculture and Crop Rotation in the Climate Conditions of Central Poland

This study, aimed at assessing the rate of soil respiration under different crop rotation and fertilization conditions, was carried out on long-term (since 1923) experimental plots with rye monoculture and 5-crop rotation in Skierniewice (Central Poland). The treatments included mineral-organic (CaNPK+M) and organic (Ca+M) fertilization (where M is farmyard manure). Soil respiration was measured in situ by means of infrared spectroscopy using a portable FTIR spectrometer Alpha. CO2 fluxes from CaNPK+M-treated soils under cereals cultivated in monoculture and crop rotations were not statically different. Respiration of soil under lupine cultivated in crop rotation was higher than under cereals. N-fertilization and its succeeding effect increased soil respiration, and significantly altered its distribution over the growing season. Our results indicate that in the climatic conditions of Central Europe, respiration of sandy soils is more dependent on the crop species and fertilization than on the crop rotation system. Omission of mineral fertilization significantly decreases soil respiration. The CO2 fluxes were positively correlated with soil temperature, air temperature, and soil content of NO3− and NH4+.

Nitrogen fixation and productivity of winter annual legume cover crops in Upper Midwest organic cropping systems

Legume cover crops can play a valuable role in maintaining and increasing soil quality and nitrogen availability, but are infrequently grown in the Upper Midwest due to short growing seasons with minimal management windows; cold, wet springs; and harsh winters. This study was performed to assess the viability of winter annual legume species in northern climates as a potential source of nitrogen (N) fertility to a 75-day sweet corn (Zea mays convar. saccharata var. rugosa) cash crop in Lamberton and Grand Rapids, MN in 2016 and 2017. Treatments included medium red clover (Trifolium pratense), two cold-hardy ecotypes of hairy vetch (Vicia villosa Roth), a cereal rye-hairy vetch biculture (Secale cereale L., Vicia villosa Roth), cereal rye as a non-legume control, and a fallow weed-free control. Legumes were split into rhizobia inoculated and non-inoculated treatments. Inoculation had no effect on nodulation, biomass production, or N fixation likely due to competition with endogenous rhizobia strains. The rye monoculture and biculture produced the most biomass at all site-years averaging 7.7 and 7.0 Mg ha−1 respectively while the two vetch ecotypes averaged 4.5 and 3.9 Mg ha−1. Both vetch ecotypes contributed among the most nitrogen in all site-years, contributing up to 211 kg N ha−1 from aboveground biomass. Data from natural abundance isotopic approaches indicate that 75% of vetch tissue N in Grand Rapids and 59% of vetch tissue N in Lamberton was derived from atmospheric N fixation, with equal or higher percent fixation of vetch in biculture at all site-years. More studies should be performed to better understand controls on N fixation of legume cover crops in cold climates.

Long-term crop rotation effects on winter and spring cereals productivity

A long-term field experiment was carried out at the Experimental Station of the VDU Agriculture Academy (formerly Aleksandras Stulginskis University), Institute of Agroecosystems crop rotation collection (equipped in 1967), during 2015–2017. The soil of the Experimental site is moderately fine textured Calc(ar)i-Endohypogleyic Luvisol. The research was carried out on winter rye (Secale cereale L.) ‘Matador’, winter wheat (Triticum aestivum L.) ‘Skagen’ and 71 spring barley (Hordeum vulgare L.) ‘Orphelija’, which were sown in 8 different crop rotations after different preceding crops and rye monoculture. The aim of the experiment was to investigate the effect of long-term crop rotation combinations on testing crops yield and productivity indicators. In many cases, rye productivity indicators were lower during 50-year monocropping. The best productivity indicators were obtained by growing rye in them in grass and fallow crop sequences, and for winter wheat in fallow with vetch–oat mixture for fodder and after manure application. In rye these indicators were more dependent on the precipitation amount and the amount of the sum of temperature during the period of generative organ formation. Among these indicators and the number of productive stems, a statistically strong and medium strength correlation interaction was identified: r = 0.83, P ≤ 0.01; r = 0.90, P ≤ 0.05; r = 0.58, P ≤ 0.05; r = 0.85, P ≤ 0.01; and winter weat r = 0.87, P ≤ 0.01; r = 0.89, P ≤ 0.01. The highest winter wheat productivity was established in crop rotation after perennial grasses and leguminous crops. Crop yield in monoculture decreases, but the optimal amount of mineral fertilizers saves lower but stable yields. Spring barley is less dependent on preceding crop, so it can be grown after winter cereals. However, they are more productive when sown after row crops and in crop rotations where one of the rotation members is fertilized with organic fertilizers.

Effect of long-term organic and mineral fertilisation on selected physico-chemical soil properties in rye monoculture and five-year crop rotation

Abstract The research was carried out continuously since 1923 in a permanent fertilisation experiment at the Experimental Station of SGGW in Skierniewice. The objective of the research was to determine the effect of long-term fertilisation (Ca, CaNPK, NPK) and crop rotation systems (rye monoculture without fertilisation with manure and five-field rotation with legume crop and manure fertilisation) on selected physical and chemical soil properties. Long-term fertilisation caused various degrees of change in many physio-chemical properties in three soil horizons (Ap, Eet, Bt): pH in KCl, cation exchange capacity, total exchangeable bases, base saturation, content of carbon, nitrogen and mineral forms of nitrogen (NO3, NH4) as well as the carbon-nitrogen ratio. The combined manure and mineral fertilisation increased the sorption capacity, total exchangeable bases, base cation saturation and total content of C and N in comparison to organic or mineral fertilisation. As a result of lime application, an increase in these parameters was determined with the exception of total contents of carbon and nitrogen, showing no differences or a decrease. A positive effect was confirmed in five-field crop rotation, which improves physicochemical soil properties in comparison to cereal monoculture. The C:N ratio narrows down with growing depth because more nitrogen than carbon migrates down the soil profile.

Managing Ecosystem Services with Cover Crop Mixtures on Organic Farms

Core Ideas Mixtures provided BNF while maintaining non‐BNF services equivalent to cereal rye. Winter pea in mixture with a brassica provided the same N input as sole‐planted pea. Crimson clover fixed more N than red clover in the overwintering cover crop period. Brassica mixtures matched or exceeded rye N retention and weed suppression in fall. Participants supported use of cover crop mixtures on diversified vegetable farms. Cover crops are central to an ecological approach to nutrient management that could reduce N losses from agroecosystems. Mixed‐species cover crops that include multiple functional groups, such as legumes and non‐legumes, may improve sustainability by supplying an organic N source to fields while providing other ecosystem services, such as N retention and weed suppression. This on‐farm experiment determined the contributions of two‐ and three‐species cover crop mixtures, which combined legumes, brassicas, and cool‐season grasses, to management‐relevant ecosystem services. In August 2015, we planted mixture treatments of interest with participating farmers on nine Michigan vegetable farms. We also included a cereal rye (Secale cereale L.) monoculture treatment, which is the most common overwintering cover crop in the region. In fall 2015 and spring 2016, we measured aboveground biomass production, biological N fixation (BNF), N assimilation and N retention in aboveground biomass, and weed suppression and compared the results with a no–cover crop control. Overall, we did not find consistent benefits of cover crop mixtures compared with cereal rye for individual services other than BNF. However, several mixtures that included legume species provided BNF while maintaining the same level of weed suppression and N retention as sole‐planted cereal rye. Farmers indicated support for the use of cover crop mixtures on diversified vegetable farms, although some expressed concerns about legume seed costs and disease risk with brassica cover crops. On‐farm experimentation allowed us to address ecological questions of direct relevance to farmers within actual social and environmental contexts.

Soil phosphorus sorption properties in different fertilization systems

The study aimed at the evaluation of the accumulation and vertical distribution of different forms of phosphorus (P) in reference to phosphorus sorption properties subject to mineral (NPK), mineral-organic (NPK + M), and organic (M) fertilisation. It was carried out in a long-term experimental field in Skierniewice (Central Poland) conducted since 1923 under rye monoculture. Total P content in the M and NPK soil profile was similar and lower than in the NPK + M soil. The content of organic P in A<sub>p</sub> and E<sub>et</sub> horizons of both manured soils was similar and higher than in the NPK soil. The Langmuir P sorption maximum (S<sub>max</sub>) in the studied soils ranged from 39.7 to 90 mg P/kg, while the Freundlich P sorption coefficient a<sub>F</sub> ranged from 6.9 to 41.9 mg P/kg. Higher variability of parameters related to the binding energy from the Lanqmuir (k) and Freundlich (a<sub>F</sub>) equations was determined between soil horizons than between the fertilisation systems. Nonetheless, in M and NPK + M soils, sorption parameters a<sub>F</sub> and S<sub>max</sub> and binding energy (k, b<sub>F</sub>) were considerably lower than in the NPK soil. The content of water extracted P in manured soils was higher than in the NPK soil.

Functional traits in cover crop mixtures: Biological nitrogen fixation and multifunctionality

Abstract Cover crop mixtures with complementary plant functional traits including biological nitrogen fixation (BNF) may supply nitrogen (N) to farm fields while simultaneously providing other ecosystem functions such as N retention and weed suppression (i.e., multifunctionality). Understanding variation in these relationships across farms can help advance trait‐based research in agroecology and ecological approaches to nutrient management. This on‐farm experiment explored the contributions of two‐ and three‐species cover crop mixtures, which combined legumes, brassicas and cool season grasses, to ecosystem functions across a gradient of soil fertility levels driven by farm management history. I evaluated the predictions that functional trait diversity of the cover crops would explain variation in multifunctionality, and that legume biomass and BNF within mixtures would be inversely correlated with indicators of soil N availability from organic matter across the farm gradient. Ecosystem functions varied widely across farms. As expected, functional diversity was a significant predictor of multifunctionality, although the relationship was weak. Cover crop mixtures had significantly greater multifunctionality than a cereal rye monoculture, though not at the highest observed levels of each function, indicating trade‐offs among functions. Linear regression models showed that legume biomass and BNF were negatively correlated with soil properties indicative of N availability from soil organic matter, whereas non‐legume and weed biomass were positively correlated with other measures of soil fertility. Synthesis and applications. Cover crop mixtures can increase functional diversity within crop rotations. Designing mixtures with complementary plant traits may be particularly effective for increasing multifunctionality and agroecosystem sustainability. On‐farm research to understand variation in biological nitrogen fixation, which is both a plant trait and a key ecosystem function, across heterogeneous soil conditions, can inform management of soil fertility based on ecological principles.

Nitrous oxide emissions from the soil under different fertilization systems on a long-term experiment

The research aimed at the assessment of N<sub>2</sub>O emission from agricultural soils subject to different fertilization conditions. It was carried out on a long-term experiment field in Skierniewice in Central Poland maintained with no alterations since 1923 under rye monoculture. The treatments included mineral (CaNPK), mineral-organic (CaNPK + M) and organic (Ca + M) fertilization. Measurements were conducted during the growing periods of 2012 and 2013. N<sub>2</sub>O emissions from the soil were measured in situ by the means of infrared spectroscopy using a portable FTIR spectrometer Alpha. N<sub>2</sub>O fluxes over the measurement periods showed high variability with range 0.13–11.20 g N<sub>2</sub>O-N/ha/day (median 2.87, mean 3.16) from mineral treated soil, 0.23–11.06 g N<sub>2</sub>O-N/ha/day (median 3.64, mean 3.33) from mineral-organic treated soil and 0.25–12.28 g N<sub>2</sub>O-N/ha/day (median 3.14, mean 3.55) from organic treated soil. N<sub>2</sub>O fluxes from manure-treated soils were slightly higher than those from soils treated exclusively with mineral fertilizers. N<sub>2</sub>O fluxes were positively correlated with soil temperature, air temperature, and content of both, NO<sub>3</sub><sup>–</sup> and NH<sub>4</sub><sup>+</sup>, in the soil (0–25 cm) and, to a lesser degree, negatively correlated with soil moisture. Based on the measured N<sub>2</sub>O flux and its relationship with environmental factors it can be concluded that both, nitrification and denitrification the are important sources of N<sub>2</sub>O in mineral soils of Central Poland, where the average soil water-filled pore space during the growing period range from 22–35%. Under the climate, soil and fertilization conditions in Central Poland, the N<sub>2</sub>O emission from cultivated soils during the growing period is approximately estimated as 0.64–0.73 kg N/ha.

Monoculture and Mixture Effects of Green Manure Crops on Soil Quality, Weed Suppression and Organic Red-pepper Production

Organic farming is rapidly expanding worldwide. Crop growth in organic systems greatly depends on the functions performed by soil microbes, and nutrient supply weed suppression by green manure crops input. Four red-pepper production systems were compared: 1) bare ground (conventional system); 2) hairy vetch monoculture; 3) rye monoculture; and 4) hairy vetch-rye mixture. Soil inorganic N reached the peak at 30 DAI and hairy vetch monoculture was the highest (192 mg kg -1 ) and soil total carbon was fluctuated sporadically during the experiment. Carbohydrate and phenolic compounds in soil kept significantly higher in green manure crops systems from 10 DBI to 30 DAI, however the level was the maximum at 10 DBI (carbohydrate) and 30 DAI (phenolic comounds). Incorporation of green manure crops residue enhanced soil microbial biomass C and N throughout the growing season except that MBN in rye was reduced after incorporation. Green manure crops systems suppressed weed occurrence and, in particular, it was prominent in rye monoculture. Mineral elements composition and production in red-pepper fruits were markedly decreased in green manure crops systems although hairy vetch monoculture has come close to bare ground (NPK-applied). Therefore, it was suggested that higher biomass production should be performed not only to improve soil quality and suppress weeds but to yield suitable red-pepper fruits in green manure crops-based organic farming.

The influence of long-term mineral and organic fertilization on the soil weeds seed bank in winter rye monoculture

The influence of long-term mineral and organic fertilization on the soil weeds seed bank in winter rye monoculture

Stability and composition of soil organic matter control respiration and soil enzyme activities

Relationships between soil organic matter (SOM) molecular composition, thermal stability and decomposability by soil enzymes and microbes are largely unknown. We incubated soils from unfertilized and NPK-fertilized neighboring field plots of a long-term rye (Secale cereale) monoculture experiment and investigated relationships between changes in the molecular-chemical composition of SOM, the CO2 flux and the activities of enzymes. Pyrolysis-field ionization mass spectrometry (Py-FIMS) showed larger ion intensities in the NPK-fertilized than in the unfertilized soil at start of the incubation, only small changes in composition and thermal stability in the unfertilized soil, and a preferential reduction in thermally stable components as well as general shifts towards lower pyrolysis temperature after three weeks of incubation in the NPK-treatment. We found evidence that thermally labile and stable proportions of various compound classes were differently susceptible to decomposition, depending on the fertilization history of the soil. Irrespective of fertilization treatment, peaks in xylanase activity after 7 days of incubation followed by decreasing values were reflected by the ratio of xylan (m/z 114) to xylose (m/z 132) marker signals in the Py-FI mass spectra. Thus, the study proved that (1) SOM composition was changed due to long-term rye cropping without and with NPK-fertilization, (2) the modified SOM composition affected the decomposability and microbial parameters under optimized conditions and (3) the thermal properties of individual compound classes derived from Py-FI mass spectra can be sensitive predictors of microbial decomposition.