Winter Wheat Monoculture Research Articles

Improving the sustainability of arable cropping systems by modifying root traits: A modelling study for winter wheat

AbstractModifying root systems by crop breeding has been attracting increasing attention as a potentially effective strategy to enhance the sustainability of agriculture by increasing soil organic matter (SOM) stocks and soil quality, whilst maintaining or even improving yields. We used the new soil‐crop model USSF (Uppsala model of Soil Structure and Function) to investigate the potential of this management strategy using winter wheat as a model crop. USSF combines a simple (generic) crop growth model with physics‐based descriptions of soil water flow, water uptake and transpiration by plants. It also includes a model of the interactions between soil structure dynamics and organic matter turnover that considers the effects of physical protection and microbial priming on the decomposition of SOM. The model was first calibrated against field data on soil water contents and both above‐ground and root biomass of winter wheat measured during one growing season in a clay soil in Uppsala, Sweden using the GLUE method to identify five ‘acceptable’ parameter sets. We created four model crops (ideotypes) by modifying root‐related parameters to mimic winter wheat phenotypes with improved root traits. Long‐term (30‐year) simulations of a conventionally tilled monoculture of winter wheat were then performed to evaluate the potential effects of cultivating these ideotypes on the soil water balance, soil organic matter stocks and grain yields. Our results showed that ideotypes with deeper root systems or root systems that are more effective for water uptake increased grain yields by 3% and SOM stocks in the soil profile by ca. 0.4%–0.5% in a 30‐year perspective (as an average of the five parameter sets). An ideotype in which below‐ground allocation of dry matter was increased at the expense of stem growth gave even larger increases in SOM stocks (ca. 1.4%). An ideotype combining all three modifications (deeper and more effective root systems and greater root production) showed even more promising results: compared with the baseline scenario, surface runoff decreased while yields were predicted to increase by ca. 7% and SOM stocks in the soil profile by ca. 2%, which is roughly equivalent to ca. 20% of the 4‐per‐mille target (https://4p1000.org/).

Супресивен ефект на почвата към ризоктонийно кореново гниене, индуциран чрез имитирана монокултура на пшеница

Disease decline and induction of soil suppressiveness by continuous (5-6 years) monoculture with susceptible plant-host have been reported for various crop-pathogen systems. The present study achieves the goal of inducing suppressive effect in soil towards Rhizoctonia root rot (Rhizoctonia solani AG 4) through monoculture of winter wheat (Triticum aestivum L.). Twenty four high-quality wheat (c. Exotic) seeds were planted in plastic containers, each containing 1.1 L Alluvial-Meadow (sandy-clay) soil (Eutric Fluvisols, according to FAO classification). According to the treatment applied, the resulting plants were grown for 0-4 successive short cropping cycles, each lasting three months. Disease suppressiveness was measured in a bioassay in which the experimental units were rectangular, plastic containers (26 x 6 x 8 cm), with drainage holes in the bottom and detachable trays allowing for manual irrigation from the bottom of the container, 7 cm height of the column of tested soil in each container and a two-row crop of wheat (c. Exotic, 2 rows x 12 plants, 2 x 3 cm plant spacing). The spread of the disease was measured from a focus (point) source of inoculum of the pathogen – 20 inoculum grains from a pure culture developed on autoclaved (30 min at 121 °C) barley, introduced into the soil at the beginning of both rows after emergence of the plants. Immediately after termination of the soil suppressiveness test, the abundance of the major groups of soil microorganisms were determined in rhizosphere soil in each treatment by using the method of decimal dilutions and subsequent culturing on agar media. Separately, bacteria of the genus Pseudomonas were isolated from the rhizosphere soil on King’s medium. The antagonistic activity of 10 Pseudomonas spp. isolates from each treatment was tested against R. solani AG 4 in vitro by the double culture method. The monoculture of wheat imitated under controlled conditions resulted in a significant (P<0.05) reduction of the spread of Rhizoctonia root rot from the source of infection. Furthermore, statistically significant differences (P<0.05) were also found between the individual treatments with pre-cultivation of wheat: with the increase in the number of cultivation cycles from one to four, there was a significant reduction in disease spread – by 19.5%, 31.0%, 40.5% and 54.8%, respectively, as compared to the untreated control. Simultaneously, no substantial alterations were observed in the population densities of the monitored groups of microorganisms in the rhizosphere of the experimental plants, including ammonifying and spore-forming bacteria, microscopic fungi, Actinomycetes and bacteria, utilizing mineral N. With the increase in soil suppressiveness from the first to the fifth growing cycle of the crop, a significant increase in the average antagonistic activity of the isolated Pseudomonas spp. against R. solani AG 4 was observed. The thesis is argued that shattering rachis of the ripe ear in wild forms conditioned a continuous “natural” monoculture in which bread wheat and its predecessors grew and evolve during the prehistoric era. We speculate that this condition, along with the lack of genes for resistance to necrotrophic pathogens, have given rise to evolutionary stable defence mechanism and the latter based on mutualistic relationships between the host-plant and bacteria that naturally inhabit rhizosphere and exhibiting high antagonistic (antibiotic) activity against soil-borne plant pathogens. A manifestation of this mechanism is the increasing suppressive response of the soil and the disease decline during or after continuous wheat monoculture. The results obtained in this study are discussed in the light of the microbial eco-evolutionary dynamics in the plant rhizosphere. The progressively increasing pathogen-antagonistic activity of Pseudomonas spp. isolates is discussed as an example of “rapid microbial evolution”, accomplished by possible horizontal gene transfer within one or more successive cultivation cycles of the wheat crop.

Impact of cropping and tillage system on take-all disease of winter wheat (Gaeumannomyces graminis var. tritici)

Diseases induced by Gaeumannomyces graminis var. tritici (G. g. tritici) are the most important wheat root diseases in all cropping areas around the world and significantly reduces yield and quality of wheat grain. A multi-year field experiment was used to evaluate infestation of winter wheat roots by G. g. tritici. The experimental factors included: I. cropping system (CS): 1) crop rotation (CR): pea – winter wheat – spring barley; 2) monoculture of winter wheat (MON); and II. tillage system (TS): 1) CT – conventional tillage, 2) RT – reduced tillage, and 3) NT – no-tillage. The following cultivation treatment were applied: a shallow ploughing after previous harvest and pre-sowing ploughing in the CT system; double cultivation instead of both aforementioned ploughing treatments in the RT system; and glyphosate in NT system. A cultivation set, consisting of a cultivator, a string roller, and a harrow, was used before wheat sowing. The value of the index of winter wheat roots infestation by G. g. tritici was significantly higher in the monoculture than in crop rotation. The value was also higher in NT than in CT system. In wheat monoculture with NT system, the percentage of highly and severely infested plants was higher than in crop rotation with CT system.

The Effects of Various Long-Term Fertilizer Applications on Soil Carbon Fractions in a Winter Wheat Monoculture Area

The Loess Plateau in China has long grappled with issues such as chronic soil erosion, poor soil structure, and diminished organic matter. Soil organic carbon plays a crucial role in enhancing soil fertility, and fertilization is a key tool that influences it. In a comprehensive field experiment, we examined five fertilization methods: no fertilization (CK); traditional fertilization used by local farmers (FP); nutrient-balanced fertilization with nitrogen, phosphorus, and potassium (OF); chemical fertilizers used in conjunction with organic fertilizers (OFM); and chemical fertilizers paired with bio-organic fertilizers (OFB). Our findings revealed that the OFM and OFB treatments were the most effective, explaining 84.35% and 81.26% of the variation in soil carbon sequestration, respectively. Further, the OF, OFM, and OFB treatments demonstrated superior effectiveness compared with the FP treatment in enhancing the soil carbon fractions. However, these fertilization patterns did not significantly alter the active-to-inert carbon ratio of the soil. OF, OFM, and OFB treatments enhanced the stability of soil carbon pools more than FP treatment. In structural equation modeling, factors such as microbial biomass nitrogen and phosphorus, soil pH, and β-N-acetyl glucosidase indirectly exhibited a limiting effect on the carbon pool stability index (CPSI), while β-glucosidase displayed an indirect positive correlation with the carbon fractions. In contrast, dissolved organic carbon, low-molecular-weight organic carbon, high-molecular-weight organic carbon, and crop yield demonstrated direct positive correlations with the CPSI. Consequently, both a balanced application of chemical fertilizers and the combination of organic and chemical fertilizers were effective in enhancing and sustaining the soil’s organic carbon content, thereby contributing to soil fertility stability. To this end, this study can inform the efficient selection and use of fertilizers, improving crop yield and soil carbon content.

Cephalosporium stripe disease, crop yield and selected soil properties as influenced by straw management in a micro-plot experiment with winter wheat monoculture

Cephalosporium stripe disease, crop yield and selected soil properties as influenced by straw management in a micro-plot experiment with winter wheat monoculture

The Nitrogen Cycling Key Functional Genes and Related Microbial Bacterial Community α−Diversity Is Determined by Crop Rotation Plans in the Loess Plateau

Soil nitrogen cycling microbial communities and functional gene α−diversity indicate soil nitrogen cycling ecological functions and potentials. Crop rotation plans affect soil nitrogen fractions and these indicators. We sequenced soil samples from four crop rotation plans (fallow, winter wheat monoculture, pea-winter wheat-winter wheat-millet rotation, and corn-wheat-wheat-millet rotation) in a long-term field experiment. We examined how microbial communities and functional gene α−diversity changed with soil nitrogen fractions and how nitrogen fractions regulated them. Planting crops increased the abundance and richness of nitrogen cycling key functional genes and bacterial communities compared with fallow. The abundance and richness correlated positively with nitrogen fractions, while Shannon index did not. The abundance increased with soil total nitrogen (STN) and potential nitrogen mineralization (PNM), while Shannon index showed that nitrogen cycling key functional genes increased and then decreased with increasing STN and PON. Introducing legumes into the rotation improved the α−diversity of nitrogen cycling key functional genes. These results can guide sustainable agriculture in the Loess Plateau and clarify the relationship between nitrogen fractions and nitrogen cycling key functional genes.

No-tillage with straw mulching improved grain yield by reducing soil water evaporation in the fallow period: A 12-year study on the Loess Plateau

No-tillage with straw mulching (NTS) during the fallow period is an effective measure for storing precipitation and reducing soil water evaporation on the Loess Plateau of China. However, the duration of this effect of NTS during the fallow period in different cropping systems and different precipitation types is unclear. Therefore, a 12-year field experiment of two tillage methods (NTS; and conventional tillage, CT), in three cropping systems (winter wheat monoculture, WW; spring maize monoculture, MM; and winter wheat-spring maize rotation, WM) were conducted to evaluate the effect of NTS on grain yield, precipitation storage, soil water status, soil evaporation rate and cumulative soil evaporation during the fallow period in different precipitation types. Additionally, the duration for which NTS reduced soil evaporation was calculated using the linear-platform model. Our results showed that compared to CT, NTS increased precipitation storage by 35.3, 47.1 and 53.5 mm under WW, by 31.5, 31.5 and 40.4 mm under MM and by 53.2, 30.2 and 50.3 mm under WM in the wet, normal and dry fallow periods, respectively, at depths of 0–200 cm. As a result, the soil water storage at sowing was higher under NTS than that under CT. The linear-platform model showed that NTS was effective in reducing soil water evaporation for 86, 95 and 126 days under WW, 87, 81 and 110 days under MM, and 95, 104 and 121 days under WM in wet, normal and dry fallow periods, respectively. Additionally, we found that there was a large amount of cumulative soil water evaporation after the abovementioned durations in MM and WM. The path analysis indicated that NTS improved grain yields indirectly by reducing cumulative soil evaporation and increasing the soil water status at the sowing stage. Capturing precipitation when the fallow period is > 125 days may further improve yield.

Influence of predecessors on species diversity of weeds in winter wheat crops in the Eastern Forest-Steppe of Ukraine

Goal. Determine the species composition of weeds, their dominant role and establish the type and level of weediness of winter wheat crops by cultivation on black fallow, after peas for grain and winter wheat as forecrops in the Eastern Forest-Steppe of Ukraine.
 Methods. The research was carried out by means of route surveys in field experiments located in a stationary nine-field steam-grain-row crop rotation and in a monoculture of winter wheat.
 Results. In total, according to the results of research in 2011—17, 63 species of weeds were found in crops. In the conditions of crop rotation in the fields of winter wheat after black fallow and peas for grain, 50 species and 45 species were found, respectively, and in monoculture — 41 species. The largest number of spring early and late weeds (41—49%), and the second and third places were occupied by wintering, winter and biennial (33—37%) and perennial (18—22%). The main weeds in the crops were: after black fallow — Setaria glauсa, Chenopodium album, Amaranthus retroflexus, Solanum nigrum, Fumaria officinalis, Polygonum lapathifolium, Cyclachaena xanthifolia, Delphinium consolida, Viola arvensis, Erigeron canadensis, Cirsium arvense; after peas for grain — S. glauсa, Echinochloa crus-galli, C. album, A. retroflexus, S. nigrum, F. officinalis, P. lapathifolium, Stachys annua, Malva neglecta, Polygonum aviculare, D. consolida, Thlaspi arvense, V. arvensis, C. arvense, Convolvulus arvensis; after winter wheat — S. glauсa, E. crus-galli, Ambrosia artemisiifolia, Fallopia convolvulus, Lactuca serriola, Capsella bursa-pastoris, D. consolida, Matricaria inodora, Crepis tectorum. In winter wheat crops, the largest share of dominance and subdominance, respectively, were Solanum nigrum L. (71%) and Setaria glauca (L.) Beauv. (71%) after peas for grain. The type of weediness of winter wheat crops depended on the predecessor. In monoculture, there was a higher level of weediness of winter wheat than in crop rotation.
 Conclusions. Rational selection of predecessors creates the basis for successful weed control in winter wheat crops.

Podobieństwo glebowego banku nasion i aktualnego zachwaszczenia łanu pszenicy ozimej w różnych systemach produkcji rolnej

The aim of the research was a comparison of soil seed bank, formed by the influence of different crop production systems (organic, integrated, conventional and monoculture of winter wheat) with weed infestation in the winter wheat. The study was conducted at the Experimental Station of the Institute of Soil Science and Plant Cultivation – State Research Institute in Osiny (Lublin province), where these crop production systems, characterised by different crop rotations and agricultural practices, have been compared since 1994. The assessment included the analysis of weed species composition and the number of weeds in winter wheat cultivated in different crop production systems as well as the weed seed stock in the 0–20 cm soil layer under winter wheat. The soil seed bank and winter wheat infestation was analysed using ecological indices: Shannon's diversity index (H') and Simpson's dominance index (SI). 
 The number of weed seed species in the soil was higher than the number of weed species in a winter wheat canopy in all compared systems. The difference between the number of species in a canopy and in the soil was the smallest in the organic system. The monoculture of winter wheat was characterised by the lowest diversity of weed flora and soil seed bank. Shannon and Simpson indices showed the bigger similarity between soil seed bank and weed infestation in the organic system and the lowest in conventional one and monoculture. Small differences of species number in weed seed stock in the compared systems and the narrow ranges of Shannon and Simpson indices suggest smaller dynamics of change of soil seed bank than weed flora.

Weed flora in crop rotation and winter wheat monoculture

Aim of study: The goal of the study described in this manuscript was to evaluate qualitative and quantitative changes in weed flora infesting winter wheat stands grown in crop rotation and wheat monoculture. Area of study: South-eastern Poland, Europe (2018-2020). Material and methods: The experiment was established in the system of randomized blocks (25 m x 6 m) in three replications. Winter wheat was sown in (1) crop rotation (CR): potato – winter wheat – peas – winter barley; and (2) in monoculture (MON). Weed infestation was evaluated in two terms: (1) at the tillering stage and (2) at the waxy maturity stage of winter wheat. Main results: The number and air-dry weight of weeds evaluated in both terms were higher in MON than in CR. Before wheat harvest, its plots in MON were massively infested by Apera spica-venti and significantly populated by Avena fatua and Anthemis arvensis. In this evaluation term, the weeds of the upper and middle levels accounted for 88.4% of the whole weed community in CR and for 97.7% in MON. In both terms of evaluation, greater biodiversity of the weed community was observed in CR than in MON. Research highlights: Indicators used to assess the weed flora in crop rotation and monoculture, i.e. weed species composition, number and air-dry weight of weeds, weed distribution in wheat crop levels, and Shannon-Wiener's diversity index.

Multi-Criteria Assessment of the Economic and Environmental Sustainability Characteristics of Intermediate Wheatgrass Grown as a Dual-Purpose Grain and Forage Crop

Kernza® intermediate wheatgrass [IWG; Thinopyrum intermedium (Host) Barkworth & Dewey] is a novel perennial cool-season grass that is being bred for use as a dual-purpose grain and forage crop. The environmental benefits of perennial agriculture have motivated the development of IWG cropping systems and markets for perennial grain food products made with Kernza, but the economic viability and environmental impact of IWG remain uncertain. In this study, we compared three-year cycles of five organic grain production systems: an IWG monoculture, IWG intercropped with medium red clover, a continuous winter wheat monoculture, a wheat–red clover intercrop, and a corn–soybean–spelt rotation. Economic and environmental impacts of each cropping system were assessed using enterprise budgets, energy use, greenhouse gas (GHG) emissions, and emergy indices as indicators. Grain and biomass yields and values for production inputs used in these analyses were obtained from experimental data and management records from two separate field experiments conducted in New York State, USA. Grain yield of IWG averaged 478 kg ha−1 yr−1 over three years, equaling approximately 17% of winter wheat grain yield (2807 kg ha−1 yr−1) over the same period. In contrast, total forage harvested averaged 6438 kg ha−1 yr−1 from the IWG systems, approximately 160% that of the wheat systems (4024 kg ha−1 yr−1). Low grain yield of IWG greatly impacted economic indicators, with break-even farm gate prices for Kernza grain calculated to be 23% greater than the current price of organic winter wheat in New York. Energy use and GHG emissions from the IWG systems were similar to the annual systems when allocated per hectare of production area but were much greater when allocated per kg of grain produced and much lower when allocated per kg of biomass harvested inclusive of hay and straw. Emergy sustainability indices were favorable for the IWG systems due to lower estimated soil erosion and fewer external inputs over the three-year crop cycle. The results show that the sustainability of IWG production is highly dependent on how the hay or straw co-product is used and the extent to which external inputs can be substituted with locally available renewable resources. Integrated crop–livestock systems appear to be a viable scenario for the adoption of IWG as a dual-use perennial grain and forage crop.

Quantitative and Qualitative Responses of Soil Water-Extractable Organic Matter to Carbon and Nitrogen Management Practices in Loess Soil

Soil-dissolved organic matter (DOM) drives the carbon (C) and nitrogen (N) cycles in agroecosystems. Despite many studies on DOM dynamics, hardly any attention has been directed toward DOM quality, particularly DOM composition. The aim of this study was to elucidate how C and N management practices alter soil water-extractable organic matter (WEOM) in a loess soil agroecosystem. Field experiments were conducted with a winter wheat monoculture. Three N fertilization rates (0, 120, and 240 kg ha−1 year−1) were applied for 17 years (2002–2019), combined with five C practices (zero, low, and high rates of sheep manure or wheat straw) for three years (2016–2019). The results reveal that soil organic carbon (SOC) and water-extractable organic carbon (WEOC) concentrations in the topsoil (0–20 cm) were increased by organic amendments considerably but were not affected by N fertilization. The fluorescence excitation–emission matrix spectra (EEM) of WEOM were resolved to two humic-like components (C1 and C2) and two soluble microbial byproduct-like components (C3 and C4). The proportions of C1 and C2 were increased, while the proportion of C3 was decreased by both C and N management practices. In conclusion, organic amendments increased both WEOM quality and its proportion of humic-like components, whereas N fertilization increased the proportion of humic-like components without variations of WEOM quality in the topsoil of loess soil.

Organic amendments affect soil organic carbon sequestration and fractions in fields with long-term contrasting nitrogen applications

Organic amendments are widely used to both manage soil organic C (SOC) and improve soil fertility in agro-ecosystems. However, crop production and the mechanisms of SOC sequestration following organic amendment may be affected by long-term differential N fertilizations, hence driving the dynamics in SOC fractions in cultivated fields. Our 3-yr (2016–2019) field experiment evaluated the responses of SOC sequestration and SOC fractions to organic amendments in soils with long-term contrasting N applications in a winter wheat monoculture system. We compared wheat straw return (St) and farmyard manure application (Fm) in soils with either long-term (2002–2019) N absence (-N) or normal N application (+N). Both St and Fm increased SOC stocks in the 0–20-cm layer, but Fm increased it more than St did. However, St exhibited a greater SOC sequestration rate in +N soils than that in –N soils, whereas Fm exhibited both a lower SOC sequestration rate and efficiency in +N soils than in –N soils. SOC increased across all fractions in all soils after both St and Fm. However, compared with –N soils, +N soils exhibited a lower SOC increase, specifically in the very labile fraction after St, but in the non-labile fraction after Fm. St, Fm, and +N all increased the soil C management index (CMI), but only +N increased wheat yield and its sustainable yield index (SYI). Those relationships indicated that both straw and manure amendments were responsible for both SOC sequestration and increasing the CMI, and N input was fundamentally responsible for an increased SYI and associated plant-C input. Consequently, straw return was expected to be more effective at sequestering SOC when applied to soil having had adequate long-term N application, whereas farmyard manure application was likely more effective when applied in N-deficient soil. Our field study findings provide empirical evidence that soil N availability affects SOC sequestration capacities following organic amendments, and that impacts strategies aimed at further increasing soil fertility improvements via organic amendment, especially considering that different agro-ecosystems are subject to different fertilization regimes.

The Cumulative Effect of Various Tillage Systems and Stubble Management on the Biological and Chemical Properties of Soil in Winter Wheat Monoculture

Agricultural practices, including tillage systems and postharvest residue management, strongly affect a wide range of soil properties. Depending on the degree of soil inversion, both negative and beneficial changes of its structure, chemical composition, and biological activity may occur as a result of these treatments. The three-year experiment was carried out on the soil under winter wheat (cv. Arktis) monoculture. The effect of various tillage systems and stubble management on the soil environment’s biological and chemical features was investigated. The total number of microorganisms (TNM); bacteria (B); actinobacteria(A); fungi (F); soil respiratory activity (SR); pH in 1 M KCl (pH); organic carbon content (OC); content of available phosphorus (Pa); potassium (Ka); magnesium (Mg); and content of total nitrogen (TN) and mineral nitrogen forms were determined in soil samples. It was shown that manure application was the factor with the greatest influence on soil properties. The manure fertilization resulted in a higher number of microorganisms in arable soil. Conventional tillage procedures combined with manure application increased the amounts of available forms of phosphorus, potassium, magnesium, and mineral nitrogen. Introduction of the chopped straw in the field enhanced the beneficial effect of manure on soil properties.

Effects of Different Tillage Intensities on Physicochemical and Microbial Properties of a Eutric Fluvisol Soil

The physicochemical and microbial properties of soil under long-term monoculture of winter wheat were studied to assess the effects of two tillage systems of different intensities: reduced (RT) and conventional (CT). The research was carried out on an 18-year-old experimental field at Grabów (eastern Poland) between 2018 and 2020. The RT (ploughless) and the CT (mouldboard ploughing) systems with machine operating depths of up to 10 and 25 cm, respectively, were used. The analysed parameters were as follows: soil texture, pH, readily dispersible clay content (RDC), soil organic matter (SOM), carbon from particulate organic matter (POM-C), hot- and cold-water-extractable organic carbon (HWEC, CWEC) and nitrogen (HWEN, CWEN), soil basal respiration (SBR), microbial biomass carbon (MBC) and nitrogen (MBN), nitrification potential (NP), dehydrogenases (DEH), and acid (ACP) and alkaline (ALP) phosphatases activities. Several single soil quality indices, including: metabolic (qCO2) and microbial (MicQ) quotients, enzymatic pH level indicator (EpHI), stratification ratio (SR), and metabolic potential index (MP) were calculated. The use of RT resulted in increased SOM and, therefore, in decreased RDC and increased values of soil stability, POM-C, HWEC, CWEC, HWEN, CWEN, MBC, and MBN in relation to CT. The MicQ, EpHI, SR, and MP well reflected the effects of RT and CT systems on soil and appeared to be useful in soil quality assessment. The results showed the beneficial effects on soil of the less intensive RT system in comparison with CT. Statistical analysis showed the significance of differences between tillage systems and interrelationships between the studied soil quality parameters.

Long‐term effects of straw mulching coupled with N application on soil organic carbon sequestration and soil aggregation in a winter wheat monoculture system

AbstractStraw mulching can be affected by N fertilization rate with regard to improving soil organic carbon (SOC) lability, which modifies the net accumulation of SOC and soil aggregation. We conducted a 14‐yr field experiment to determine how straw mulching coupled with N application rates affects crop yield, SOC sequestration as a net gain of SOC, and soil aggregation in a winter wheat (Triticum aestivum L.) monoculture system. Six combinations of two cultivation practices, conventional cultivation (CC) and straw mulching (SM), and three N application rates (0, 120, and 240 kg N ha–1) were compared. Results revealed that SM did not affect wheat yield throughout the 14 yr of cultivation, but increased the SOC stock, SOC lability, and the carbon management index (CMI) in surface soil (0–20 cm). Instead, N application, N120 and N240, increased the wheat production almost equally, and followed a trend for increasing SOC stock: N240 > N120 > N0; however, a different trend for increasing SOC lability and soil CMI (N120 > N240 > N0). Soil macro‐aggregation was increased by SM but decreased with increasing N application. Principal component analysis (PCA) indicated that organic C input was the key to improving SOC sequestration, SOC lability, and soil macro‐aggregation rather than N input, especially high N input (N240) reduced SOC lability and soil aggregation in soil. Consequently, medium N application (N120) may be expected to couple with straw direct‐returning for improving soil productivity and quality in this agro‐system.

Effects of tillage systems on wheat and weed water relationships over time when growing together, in semiarid conditions

AbstractWater availability directly influences interactions and competition between weeds and crops. This article is based on the idea that relative water content (RWC) indicates the water uptake within plants and that it is possible to explain the water relationships between plants that are growing together. A field experiment carried out for 3 years (2013–2014, 2014–2015 and 2015–2016) compared the short‐term effects of years and tillage systems on wheat grain yield, weed density, wheat‐RWC, weed‐RWC and soil water content (SWC), at tillering and flowering stages in a winter wheat monoculture system. The three tillage treatments were conventional tillage (CT), minimum tillage (MT) and no‐tillage (NT). Wheat grain yield was low all years of study, because of low interannual rainfall, and we did not observe differences between tillage systems. Weed density was also affected by year and not by tillage systems. Lowest winter rainfall (73.4 mm from Nov to Feb) in the last year of the study (2015–2016), decreased the weed density in all tillage systems. Despite the rainfall variability over the 3 years of study, the NT system presented higher weed density (73 plants/m2) than MT and CT systems (39.83 and 46.33 plants/m2). We also observed a higher number of weed species for the NT system, facilitated by a high soil water storage in this system. The wheat‐RWC, at tillering stage, varied with years and tillage systems; we found that high winter rainfall (2013–2014) led to higher values in CT (64.5%) compared with MT (52.9%) and NT plots (52.9%). Weed‐RWC values did not vary and SWC was greater in NT than in CT and MT. At flowering stage, the year (2015–2016) with highest spring rainfall favoured higher wheat‐RWC in NT (56.9%) compared with CT (48.3%). However, the lowest spring rainfall coincided with the lowest weed‐RWC, (18% in NT plots) and SWC was always higher in NT soils. The results showed that climatic conditions affected the water competence dynamics between weeds and wheat in different ways. Seemingly, weeds can tolerate a lack of water availability until crop tillering stage independently of tillage system; however, the competition for water was not a problem as crops overcame the high weed density by flowering stage.

The effect of crop rotation and fungicide seed treatment on take-all in winter cereals in Lithuania

Agricultural production is increasingly based on monoculture farming in Lithuania, which inevitably exacerbates the problems caused by a rising incidence of soil borne diseases. Take-all (Gaeumannomyces graminis), formerly a minor disease, has become common causing substantial damage to winter wheat and winter barley. The aim of the present study was to analyze the influence of different rotation sequences on take-all occurrence and to investigate disease control options with seed treatment fungicides fluquinconazole and silthiofam during the 2014–2015 growing seasons. The total amount of Gaeumannomyces graminis var. tritici (Ggt) and G. graminis var. avenae (Gga) DNA in the roots of winter wheat seedlings grown in the soil collected from different rotations was measured. Significantly higher DNA concentrations of Ggt/Gga were detected in the roots of seedlings grown in the soil of winter barley monoculture, compared to the winter wheat monoculture. Comparable amount of Ggt/Gga DNA in winter wheat seedlings was determined in the soil of winter wheat monoculture and winter wheat after oil seed rape (OSR) in both seasons, while in the second winter wheat it was considerably lower. Higher take-all incidence and disease index were established in winter barley than in winter wheat monoculture. Nevertheless in the rotation with one-year OSR, take-all incidence and disease index were significantly reduced compared to the monoculture and second winter wheat. The highest grain yield of winter wheat in both years was achieved in the rotation with OSR. The tested seed treatment fungicides fluquinconazole and silthiofam resulted in a significant reduction in take-all occurrence and a slight increase in grain yield. The findings of this study demonstrate that the OSR was the most valuable tool for management of take-all in wheat.

CROP MANAGEMENT EFFECT ON CHEMICAL AND BIOLOGICAL PROPERTIES OF SOIL

This study was aimed at evaluating the effect of crop rotation and various tillage systems onthe chemical and biological properties of soil in the years 2013-2015. The first order factorincluded cropping systems: a) crop rotation (pea – winter wheat – spring wheat) and b)monoculture of winter wheat, whereas the second order factor were tillage systems:1) conventional (CT), 2) reduced (RT) and 3) No-tillage (NT). In the autumn season, in the CTsystem, shallow ploughing (at the depth of 10–12 cm) and pre-winter ploughing (25–30 cm)were applied for pea and spring wheat crops, whereas shallow ploughing and pre-sow ploughing(20–22 cm) were applied for winter wheat crop; in the RT system, only a cultivator was appliedfor spring wheat and pea crops as well as a cultivator and a tillage set for winter wheat; in theNT system glyphosate was applied on all plots as well as a cultivator and a tillage set were usedbefore winter wheat sowing. The study demonstrated that the soil sampled from plots with croprotation contained more organic C and available forms of P, K and Mg and that it wascharacterized by a higher activity of dehydrogenase, phosphatase and urease than the soilsampled from monoculture. In addition, it was characterized by a higher number of earthwormsthan the soil from monoculture. The RT and NT systems affected an increase in the contents oforganic C and total N and in the enzymatic activity of soil, compared to the CT system.

Soil physical properties of agriculturally reclaimed area after lignite mine: A case study from central Poland

For the assessment of the extent of post-mine land degradation, arranging management practices for sustainable land use, and evaluation of reclamation success research on soil physical properties plays a significant role. The aim of this study was to quantify and interpret the effects of varied agricultural reclamation methods in order to assess which of the treatments yielded higher soil quality with respect to its physical state. Basic physical and chemical parameters (texture, particle and bulk density, total porosity, total organic carbon and pH), soil water characteristic curves, water and air permeability, structure of the soil damaged by mining in the area of internal dumping ground PĿtnów (Central Poland) were therefore measured. The soil samples were taken from the following 5 different variants of over 30-year-long reclamation: black fallow (BF), monoculture of winter wheat (WW), monoculture of winter wheat with a single application in 1992 of lignite dust (WW+L), monoculture of alfalfa with orchard grass in the proportion of 90/10% (A+G), and spontaneous succession (SS). We collected from each treatment: 12 soil cores for soil water and air properties; 6-kg composite bulk samples for basic physical and chemical properties of soil; 1 undisturbed soil block for structure analysis. The reclamation methods applied on the post-mining grounds influenced in a diverse manner the physical state of the 0⿿10cm layer of the developed technogenic soil. Bulk density values generally decreased with the increase of number of factors potentially loosening the soil structure. The studied plots had sandy loam or loamy sand texture which determined their overall air and water properties. The soils were characterized by high macroporosity and favourable content of water available for plants. Less beneficial conditions of the soil were associated with air and water permeability. The present studies indicated that spontaneous succession, with the highest typological diversity of vegetation, contributed to the most preferred soil physical state. Remaining variants of reclamation (including black fallow without vegetation) also provided sufficient air and water relations in the soils. However, it should be emphasised that plants play an important role in TOC accumulation and ensuring relative stability of soil structure. Therefore rehabilitation of post-mining grounds involving vegetation is recommended.