Winter Wheat Production Research Articles

Correlation of structural indicators of winter wheat with grain productivity influenced by contrasting meteorological conditions in the central region

Field research was carried out in the nursery of competitive variety testing in 2018-2022 on the selection fields of ISA-a branch of the FSBI FNAC VIM of the Ryazan region. The objects of the study were the hydrothermal conditions of the region and the structural elements of the productivity of the best varieties of their own selection: Viola, Felicia, Galatea, Anfisa, Boyarka, Ivita, Vimitsa (GSI), Adarka (GSI) and 3 promising lines with consistently high yields over the years of research. The revealed interrelations between yield and the elements of productivity that determine it in the continuously changing external conditions of the Central region of the Non-Chernozem zone of the Russian Federation allowed us to establish that such indicators as "number of plants before harvesting" - r=+0.887, "mass of 1000 grains" - r=+0.806, "number of productive stems" - r=+0.613 and "plant height" - r=+0.494 have the main influence on the formation of productivity of winter wheat varieties/lines selected for analysis. The main factor limiting the productivity of grain crops in the area of our research is the lack of atmospheric moisture. The amount of precipitation and the SCC of the growing season significantly affect the "height of plants" (r=+0.761...+0.863), "number of productive stems" (r=+0.556...+0.687), "ear length" (r=+0.598...+0.684), "coefficient of productive bushiness" (r=+0.592...+0.723), "the number of grains in the ear" (r=+0.304...+0.484), "the mass of grain from the ear" (r=+0.301...+0.506). The sum of effective temperatures had a negative relationship (r≥-0,500) with almost all elements of productivity.

Physiological Characteristics, Crop Growth and Grain Yield of Twelve Wheat Varieties Cultivated in the North China Plain

Climate change and water resource shortages have become important problems limiting winter wheat production in the North China Plain (NCP). Understanding the physiological characteristics of different wheat varieties and their relationship with crop growth and yield is of great importance for addressing climate change through a scientific approach, adopting reliable wheat varieties, and ensuring food production. This study was conducted throughout three winter wheat seasons from 2018 to 2021. The crop growth, physiological indicators, crop yields, and water productivity (WP) of 12 wheat varieties widely cultivated in the NCP were measured to investigate the relationships between physiological characteristics and crop yield. The results showed that among the three wheat seasons, the maximum plant height of each wheat variety was relatively stable, while the changes in maximum plant density (PDm), maximum leaf area index (LAIm), and maximum dry matter (DMm) were highly variable. The gas exchange parameters and fluorescence parameters of wheat flag leaves varied with growth stage, and certain varieties were sensitive to water stress. The wheat grain yield, seasonal crop evapotranspiration (ETa), and WP of the 12 varieties were similar in the 2019–2020 and 2020–2011 seasons and were approximately 25%, 7%, and 19% higher than those in the 2018–2019 season, respectively, in which there were consecutive cool events in the winter and spring. Generally, the grain yields were positively correlated with PDm, LAIm, DMm, ETa, the harvest index, and WP, at a significance level of 0.01. The high-yield wheat varieties had higher photosynthetic rates in the middle and late grain-filling stages. Based on these relationships, high-yield wheat varieties may be selected to address climate change in the NCP as well as other regions in the world. Considering the variations in yield and WP in the three different climatic conditions, we recommend Yingbo700, Lunxuan103, Shimai26, Shinong086, Han6172, and Hanong1412 as high-yield and drought-resistant wheat varieties to be used in the NCP.

Winter wheat productivity under different systems of typical black soil cultivation and under climatic changes in the conditions of the Left-Bank Forest Steppe

The article highlights the influence of different tillage systems and climate changes on the formation of winter wheat productivity, yield and quality indicators in the conditions of the Left-Bank Forest-Steppe. Taking into account the crop importance in Ukraine's food security and its place in world exports, the importance of effective methods development to improve technological performance due to the decrease in the share of high quality grain suitable for milling and baking purposes is emphasized. In particular with the climate changes it is necessary to use of moisture-saving technologies and the introduction of crop rotations with a scientifically based choice of crops with plastic properties to unstable soil and climatic conditions. In the course of the research it was determined how winter wheat productivity is affected by tillage methods – plowing, disking and no-till technology on the example of typical black soil. The analysis of weather conditions was carried out, which revealed that uneven distribution of precipitation with long periods without rain or with high rain intensity during all stages of crop ontogeny are the factors limiting yields and reducing grain quality. At the same time the importance of mineral fertilizers in regulating grain yields and quality under rapid climate changes was also determined. Increased average monthly indicators, characterizing the weather conditions during the studied periods, created risks for the full growth and development of cultivated plants, that was described in detail in the article. According to the research results it was found that the highest yield indexes of winter wheat were obtained during of N120P60K90 application, that in 2021, under traditional plowing, provided 5.2 t/ha of high quality grain with a protein content of 16.4 % and gluten content of 30.45 %. Also in terms of crop yield level and quality indicators the variant of soil protection technology no-till differed little, which produced 4.88 t/ha of grain with a protein content of 15.6 % and 28.7 % of gluten in a favorable 2021. Key words: climate changes, short-term crop rotation, tillage, no-till technology, winter wheat, crop yield, grain quality.

THE IMPORTANCE OF BREEDING PROGRESS IN WINTER WHEAT PRODUCTION

The impact of breeding on winter wheat yields and the use of the generated yield potential in production were assessed. The results of trials of Research Centre for Cultivar Testing (COBORU) from 1966-2022, data from the Seed Inspection (IN) from 1986-2001 and Plant Health And Seed Inspection (PIORiN) from 2002-2023 regarding the varietal structure of seed production of winter wheat and production data on wheat yield in production were used according to Statistics Poland. To assess the effects of breeding, the method of changing the yield potential of varieties was used. In this method, we use indexes determining the yield-producing capacity of individual varieties in relation to the standard. Changes in yield trends in variety experiments and production were analyzed. The growing importance of the variety as a factor enabling further increase in yield and the effect of breeding on the increase in yield potential has been demonstrated despite limitations in the use of nitrogen fertilization and chemical plant protection products. The existing yield gap between trials and production, amounting to approximately 55%, indicates great opportunities to further increase yields in production through better use of the yield potential of varieties created by breeding.

Розвиток фотосинтетичних процесів та зернова продуктивність пшениці озимої за біологізованих систем удобрення

Розвиток фотосинтетичних процесів та зернова продуктивність пшениці озимої за біологізованих систем удобрення

An assessment of the vulnerability to climate change of winter wheat and summer maize production in Shandong Province, China

An assessment of the vulnerability to climate change of winter wheat and summer maize production in Shandong Province, China

Productivity and grain quality of winter wheat varieties depending on the fractional nitrogen top dressings and seeding rates

The study was carried out in the Kostroma region on soddy-podzolic soils with an average degree of cultivation in 2019–2022, with three repetitions of a field trial. The purpose of the study was to estimate the effect of different doses of nitrogen top dressings applied at critical phases of plant development on productivity and grain quality of winter wheat at seeding rates of 2, 4, and 6 million germinating kernels per hectare. There have been studied 5 winter wheat varieties of domestic breeding, such as ‘Moskovskaya 39’ (a standard variety), ‘Moskovskaya 40’, ‘Moskovskaya 56’, ‘Nemchinovskaya 57’ and ‘Nemchinovskaya 85’. The used agrotechnology corresponds to the zonal one in the Kostroma region. As a result of the study there has been identified a productivity variation from 2.9 to 3.7 t/ha depending on a variety. The largest productivity was formed by the variety ‘Moskovskaya 56’ with the use of a triple dose of nitrogen at a seeding rate of 6 million germinating kernels per hectare, which significantly exceeded the control variant on 0.5 t/ha. There has been estimated an influence of doses of nitrogen top dressings on technological parameters and flour properties of winter wheat grain. There has been found that the high content of crude protein (17.44–19.41 %), gluten (28.16–35.80 %) and hardiness (65.9–74.6 %) was demonstrated by the variety ‘Moskovskaya 40’. There has been also established a large hardiness of the variety ‘Nemchinovskaya 57’ (62.5–75.0 %). The largest 1000-grain weight (42.0–45.2 g) has been found in the variety ‘Moskovskaya 56’. Through three years of the study, there has been proved a stable response of the studied varieties to the improvement of productivity and n qualitative indicators as a result of the use of doses of nitrogen top dressings for winter wheat crops.

A comparison of moderate and high spatial resolution satellite data for modeling gross primary production and transpiration of native prairie, alfalfa, and winter wheat

Although agroecosystems have a significant potential to offset carbon dioxide (CO2), the amount of CO2 captured can vary significantly depending on management practices. Accurate estimation of gross primary production (GPP) and transpiration (T) of agroecosystems at the field scale are essential for the study of food security and water resource management. To date, the carbon and water fluxes data products for commercial agroecosystems are limited, mostly at the moderate spatial resolution (MSR, hundreds of meters), which cannot be used to assess the temporal dynamics of GPP and T at the field scale. This study used the vegetation photosynthesis model (VPM) and vegetation transpiration model (VTM) to estimate field-level daily GPP (GPPVPM) and T (TVTM), respectively, in native prairie, alfalfa (Medicago sativa L.), and winter wheat (Triticum aestivum L.) in central Oklahoma, USA. We evaluated the reliability and advantages of vegetation indices (enhanced vegetation index, EVI and land surface water index, LSWI) in monitoring the land surface phenology using moderate spatial resolution data from Moderate Resolution Imaging Spectroradiometer (MODIS) and high spatial resolution (HSR, tens of meters) data from Landsat and Sentinel-2. The accuracy of GPPVPM and TVTM estimates at different spatial scales was evaluated using GPP (GPPEC) and evapotranspiration (ETEC) from the eddy flux tower sites, respectively. Results demonstrate the capacity of VPM and VTM to estimate the field-level carbon and water flux dynamics and their responses to weather conditions. The use of HSR vegetation indices helped to address certain challenges faced by MSR indices, especially in capturing the crop phenology in smaller areas with conservation measures or disturbances. The findings highlight the importance of using HSR GPP estimates to reduce uncertainty in quantifying CO2 fluxes for croplands and grasslands. The findings also demonstrate the ability of the models to track field-level vegetation phenology, carbon uptake, and water use in agroecosystems under different management practices.

The effect of injury on the sowing seed qualities of winter bread wheat varieties during harvesting and post-harvest processing

The current paper has presented the study results for the period of 2020–2022 to determine the effect of injury on the quality indicators of seed material in primary seed production of winter wheat varieties (‘Stanichnaya’, ‘Etyud’, Asket, ‘Lidiya’ and ‘Ambar’) during harvesting and post-harvest processing of seeds. There has been established that at different stages of technology in agricultural machines and grain cleaning equipment, during grain production, there was damage to the seed material. There have been identified certain types of injuries that most significantly worsen the sowing quality of seeds and reduce winter wheat productivity. The purpose of the study was to estimate the sowing seed qualities of winter bread wheat varieties of different maturity groups developed by the FSBSI «ARC «Donskoy» depending on their injury by the combine harvester and grain cleaning machines in the primary stages of seed production. The estimation of the quality of winter wheat seed material was carried out on the material obtained during winter wheat harvesting, such as manual threshing (control), threshing with the combine ‘Wintersteiger Classic’, after seed cleaning and sorting equipment VIM-1 «Selection» and Petkus K-531 «Gigant». When harvesting with the combine ‘Wintersteiger Classic’, two threshing modes were used: 1) recommended – 1500 rpm-1; 2) with a reduced speed of the threshing drum – 1000 rpm-1. There has been found that the highest level of seed injury was observed when threshing with a grain harvester (33–54 %). There has been determined that, depending on the type of the trial, the germination energy indicators varied from 89 to 98 %, and laboratory germination from 94 to 99 %. Caryopsis with damage in the embryo area had a high germination rate in laboratory conditions. With an increase in microtraumas, field germination has decreased by 4–17 % compared to the control. The maximum injury and reduction in field germination of seeds was observed in the varieties of the early maturing group. Post-harvest processing of seeds has led to an increase in the percentage of their injury by 1–6 %, regardless of the type of equipment used.

Label-Free Quantitative Proteomics Reveal the Mechanisms of Young Wheat (Triticum aestivum L.) Ears’ Response to Spring Freezing

Late spring frost is an important meteorological factor threatening the safe production of winter wheat in China. The young ear is the most vulnerable organ of the wheat plant to spring frost. To gain an insight into the mechanisms underpinning young wheat ears’ tolerance to freezing, we performed a comparative proteome analysis of wheat varieties Xumai33 (XM33, freezing-sensitive) and Jimai22 (JM22, freezing-tolerant) under normal and freezing conditions using label-free quantitative proteomic techniques during the anther connective tissue formation phase (ACFP). Under freezing stress, 392 and 103 differently expressed proteins (DEPs) were identified in the young ears of XM33 and JM22, respectively, and among these, 30 proteins were common in both varieties. A functional characterization analysis revealed that these DEPs were associated with antioxidant capacity, cell wall modification, protein folding, dehydration response, and plant–pathogen interactions. The young ears of JM22 showed significantly higher expression levels of antioxidant enzymes, heat shock proteins, and dehydrin under normal conditions compared to those of XM33, which might help to prepare the young ears of JM22 for freezing stress. Our results lead to new insights into understanding the mechanisms in young wheat ears’ response to freezing stress and provide pivotal potential candidate proteins required for improving young wheat ears’ tolerance to spring frost.

OPTIMIZATION OF WINTER WHEAT NUTRITION WITH ZERO TILLAGE TECHNOLOGY IN THE RAINFED ZONES OF SOUTHERN KAZAKHSTAN

The promising research showcased the results of herbicides’ uses, considering the quantitative composition of weeds with zero tillage technology of winter wheat cultivation. It revealed that when treating wheat seeds with the growth stimulator Vimpel (0.5 l/t) and micro-fertilization with Oracle (1.0 l/t) simultaneously etching with the fungicide Bunker (0.4 l/t), as well as, early spring treatment of crops in the tillering phase of winter wheat with the same stimulator (Vimpel, 0.5 l/ha) and micro-fertilization (Oracle multicomplex, 2.0 l/ha) simultaneous with the herbicide “Ballerina” (0.5 l/ha) application, the number of preserved plants before harvesting was 286.1 pcs./m2, reaching a height of 88.9 cm, with a productive bushiness of 1.15 pcs., grains per spike (22.2), 1000-grain weight (34.8 g), and collected dry grains at a standard humidity (22.1 c/ha). It was also evident that the competitive productivity of winter wheat also emerged when treating wheat seeds with biological fertilizer Biobars–M (1.0 l/t), the crop at the tillering stage with Biobars–M (0.5 l/ha), and the earring phase (0.7 l/ha). Similarly, using growth stimulants Vimpel and micronutrient Oracle multicomplex enhanced the grain yield with reduced cost of production (USD 61.3–66.0/kg) compared with the control version (USD 78.6 /kg). On one hectare of winter wheat crop, the net income ranged from USD 289.55 to 443.56.

Influence of varietal characteristics of winter wheat and weather conditions on lodging resistance and productivity

Growing technologies and variety selection are crucial for increasing yields and improving the quality of winter wheat grain. The area under winter wheat is the largest in Ukraine, which is associated with the production of high-quality grain. The aim of the study was to determine the influence of weather conditions and variety characteristics on winter wheat plant height, internode length, lodging resistance, productivity factor and yield during the years under study. In the course of the study, the following generally accepted methods were used: systematic approach, system analysis approach, analytical synthesis approach, field approach and statistical approach. The article presents data on the results of research with 20 varieties of soft winter wheat in the conditions of the Training and Practical Centre of Mykolaiv National Agrarian University from 2017 to 2023. Agricultural technology for growing winter wheat varieties is widespread in the steppes of southern Ukraine. The influence of weather conditions and varietal characteristics on lodging resistance and productivity of winter wheat was investigated. The results showed that the optimum plant height of winter wheat varieties ranged from 82.1 to 84.5 cm, and the highest yield was 6.32 t/ha in Staleva and 6.68 t/ha in Duma Odeska. A significant effect of varietal traits on stem length, second and last internode, number of stems formed per 1 m2 , grain weight in the ear and lodging resistance of winter bread wheat was established. Plants of the tested winter soft wheat varieties Staleva, Dyvo, Katarina, Felix, Ozerna, PONTICUS, Faust, Glaucus have a very high (9.0 points) resistance to lodging regardless of the weather conditions of the year. Ukrainian varieties Duma Odeska (6.68 t/ha) and Staleva (6.32 t/ha) achieved higher productivity. The obtained scientific results of the research contribute to the widespread use of the studied winter wheat varieties of this reasonably climatic zone and contribute to further improvement of grain production

Sub‐soil plastic film mulch promotes the growth and yield improvement of winter wheat in coastal saline–alkali soil

AbstractCrop yields are seriously threatened in saline–alkali areas with shallow groundwater levels and high evaporation. Mulching can effectively alleviate salt stress on crops in drylands, but there is limited research on winter wheat (Triticum aestivum L.) mulching in coastal saline–alkali areas. To investigate the effect of plastic film mulching on the growth and yield of wheat in coastal saline–alkali soil, three field management measures were designed: bare ground (CK), plastic film mulch (PM), and sub‐soil plastic film mulch (PMF). Compared with CK, PM and PMF significantly increased wheat grain yield by 128.2%–313.2% and 187.8%–537.0%, respectively, over the two study stages. The movement of salt to the surface is inhibited after mulching; as a result, PMF and PM significantly decreased the electric conductivity in shallow soil (0–20 cm) by 31.1% and 23.8%, on average, compared to CK, resulting in a significant increase in dry matter accumulation (DM) for winter wheat throughout the growing season. Moreover, PMF increased the overall DM by increasing the dry matter accumulation per plant (DMP), while PM achieved a similar effect to PMF by increasing the number of tillers. Compared with PM, PMF had a better inhibitory effect on shallow soil salinity, significantly increasing the effective number of spikes, effective tillering rate, DMP, and spike weight at harvest; promoting vegetative and reproductive growth of wheat fields; and ultimately increasing yield. PMF can be used to improve winter wheat production in coastal saline–alkali soils.

The Effect of Cropping Systems on Environmental Impact Associated with Winter Wheat Production—An LCA “Cradle to Farm Gate” Approach

The demand for wheat production is increasing and is associated with environmental effects. To sustain the increased demand, there is a need to find sustainable methods of wheat production. The choice of cropping system can significantly affect the environmental burden of agricultural production systems. This study presents the results of monitoring emission loads resulting from winter wheat cultivation under different cropping systems: organic unfertilized (ORG), organic fertilized (ORG-F), conventional unfertilized (CON), and conventional fertilized (CON-F). The system boundaries include all the processes from “cradle to farm gate” and the functional unit was 1 kg of wheat grain. The primary data were obtained from experimental field trials and secondary data from Ecoinvent v3.5, WFLDB, and Agri-footprint v5.0 databases. The results of this study are related to eight impact categories. The SimaPro 9.2.0.1 software and ReCiPe Midpoint (H) V1.13/Europe Recipe H were used for calculation. The results show that fertilized variants recorded higher environmental impacts compared to the unfertilized variants. The results indicate that ORG-F was more environmentally friendly compared to the CON-F variant at the expense of lower yields. Overall, ORG imposes the lowest environmental impact and is deemed to be more environmentally friendly.

Better Inversion of Wheat Canopy SPAD Values before Heading Stage Using Spectral and Texture Indices Based on UAV Multispectral Imagery

In China’s second-largest wheat-producing region, the mid-lower Yangtze River area, cold stress impacts winter wheat production during the pre-heading growth stage. Previous research focused on specific growth stages, lacking a comprehensive approach. This study utilizes Unmanned Aerial Vehicle (UAV) multispectral imagery to monitor Soil-Plant Analysis Development (SPAD) values throughout the pre-heading stage, assessing crop stress resilience. Vegetation Indices (VIs) and Texture Indices (TIs) are extracted from UAV imagery. Recursive Feature Elimination (RFE) is applied to VIs, TIs, and fused variables (VIs + TIs), and six machine learning algorithms are employed for SPAD value estimation. The fused VIs and TIs model, based on Long Short-Term Memory (LSTM), achieves the highest accuracy (R2 = 0.8576, RMSE = 2.9352, RRMSE = 0.0644, RPD = 2.6677), demonstrating robust generalization across wheat varieties and nitrogen management practices. This research aids in mitigating winter wheat frost risks and increasing yields.

Dryland Winter Wheat Production and Its Relationship to Fine-Scale Soil Carbon Heterogeneity—A Case Study in the US Central High Plains

Soil carbon plays a key role in maintaining soil quality, but its direct impact on crop yields depends on the interplay of different factors. This study aims to study fine–spatial variation soil properties and their effect on grain productivity in fallow–wheat cropping systems in the US central High Plains. We evaluate wheat yields in relation to soil macro and micronutrients, total C (TC), and texture as well as subtle variations in field elevation. To document soil–yield relationships at a fine spatial scale, soil sampling (0–15 and 15–30 cm depths) was conducted using a regular 30 m grid spacing in eleven adjacent fields. Interpolated yield maps indicated that the availability of key nutrients and textures contributed to the spatial distribution of wheat productivity. Random forest (RF) showed that these soil attributes were able to explain slightly under 30% of the spatial variation in crop yields. Our findings demonstrate that TC can often serve as a reliable proxy for delineating yield-based management zones, even in inherently low C soils. In addition, Fe, Zn, SO4-S, sand, and subtle topographic changes were also critical factors affecting wheat yield. Our results highlight that developing management zones in these soils relying exclusively on soil information is not straightforward. However, the high level of within-field spatial variability observed needs to be addressed.

Increased ground-level O3 during the COVID-19 pandemic in China aggravates human health risks but has little effect on winter wheat yield

In January 2020, the novel coronavirus (COVID-19) outbreak emerged in China, prompting the enforcement of stringent lockdown measures nationwide to contain its spread. Multiple studies have demonstrated that these measures successfully reduced the levels of air pollutants except for ozone (O3). However, the potential risks of nationwide O3 changes during this period remain uncertain. To address this gap, we evaluated the ecological and health effects of O3 using hourly O3 data from 1 January to 17 June in both 2020 and 2019. Our results indicated that all health and ecological indicators, except SUM06 (sum of all hourly O3 over 60 ppb), during the COVID-19 pandemic in 2020 increased most obviously in Stages 2 and 3 with the strictest control measures, compared to the same period in 2019. The national premature deaths due to short-term O3 exposure during Stages 2–3 in 2020 totaled 146,558 (95% CI: 79,386–213,730) for all non-accidental causes and 82,408 (95% CI: 30,522–134,295) for cardiovascular diseases, increasing by 18.78% and 18.76% in 2019, respectively. The most significant increase in health risks occurred in Hubei, followed by Jiangxi, Zhejiang, Hunan, and Shaanxi. In addition, the estimated national winter wheat production losses (WWPL) attributable to O3 amounted to 50.6 and 51.1 million metric tons for 2019 and 2020, respectively. Among the major winter wheat-producing provinces, Anhui and Jiangsu experienced a larger increase in WWPL, while Shandong and Hebei suffered a greater decrease in 2020 compared to 2019, resulting in little overall change in WWPL between the two years. These findings provided direct evidence of the harmful effects of O3 during the COVID-19 pandemic and serve as a valuable reference for future air pollution control.

ВЛИЯНИЕ АГРОМЕТЕОРОЛОГИЧЕСКИХ ФАКТОРОВ НА ПРОДУКТИВНОСТЬ ЗЕРНОВЫХ КУЛЬТУР ПО МУНИЦИПАЛЬНЫМ РАЙОНАМ САРАТОВСКОЙ ОБЛАСТИ

The paper presents the results of studying the influence of modern agrometeorological conditions on the yield of different groups of grain crops in the municipal districts of the Saratov oblast. The climatic trends of the recent two decades are analyzed for five weather stations (Khvalynsk, Balashov, Saratov, Ershov, and Aleksandrov Gai). For the Saratov weather station, a longer period (1941-2022) is analyzed. There is an increase in the heat availability and aridity of the territory. The analysis of the dynamics of the crop yield distribution and variability has shown that the most favorable conditions of crop cultivation are formed in the Balashov municipal district. Operational forecast models of the maximum and minimum productivity of winter wheat are developed, which makes it possible to predict a yield with a monthly lead time.

Grazing summer cover crops mix impact on carbon[sbnd]nitrogen cycling, soil water, and wheat yields

Summer fallow practice is common in the US semiarid Southern Great Plains ecoregion. Its primary objective is to store water to enhance winter wheat production for grain and grazing. Prior research on replacing fallow with legume cover crops (CC) (green manure) reported a yield loss through soil moisture depletion for winter wheat. Recent research has shown the potential of grass CC to enhance soil physical properties compared to legume CC. Cost-benefit analyses of CC make it difficult to justify their adoption. Grazing, however, offers an opportunity to mitigate CC costs. The impact of a grazed CC mix on stored soil water, CN cycling, intercropping, and wheat yields was evaluated. Although CC used soil moisture early in the growing season and nitrate+nitrite-N, they recharged soil moisture by the critical wheat seeding and dormancy-breaking periods. In the summer of 2014, net mineralization in CC increased nitrate+nitrite-N by 10-fold compared to 2013 concentrations, resulting in no significant differences in yields in 2015. Nitrate+nitrite-N was reduced by 28% in 2015 compared to the preceding year due to CC growth and net nitrate+nitrite-N immobilization in residues, resulting in 25% less yield in CC treatments in 2016 compared to no-till (NT) fallow. Grazed and ungrazed CC enhanced organic N by up to four times that in NT fallow and sequestered particulate organic N and C by 7–17% and 6–10%, respectively, in micro-aggregates. Despite reducing biomass by 56%, grazing did not differ from most ungrazed measured soil parameters, offering the potential for mitigating CC production costs.

A multitemporal index for the automatic identification of winter wheat based on Sentinel-2 imagery time series

ABSTRACT Timely and accurate monitoring of the spatial distribution of wheat is crucial for wheat field management, growth monitoring, yield estimation and prediction. In this study, a multitemporal index, termed the winter wheat mapping index (WWMI), was constructed for automatic winter wheat mapping on the basis of Sentinel-2 enhanced vegetation index (EVI) time series and wheat phenological features. Henan, an important winter wheat production province in China, was selected as the study area. Zhumadian, the primary wheat-growing city in Henan, was the test area. Both empirical and automatic threshold (Otsu) methods were adopted to calculate the optimal threshold of the WWMI. The performance of WWMI in winter wheat mapping was compared at object-oriented and pixel-based levels. The proposed WWMI separated winter wheat and nonwinter wheat areas well, thus achieving highly accurate winter wheat mapping. In Zhumadian, the empirical threshold method performed better than the Otsu method, but the former relied on official statistics to iteratively adjust the WWMI threshold. In Henan, the mapping accuracy achieved by the Otsu method was higher than that achieved by the empirical threshold method, with mean relative errors (MREs) of 6.78% and 19.87% at the municipal and county levels, respectively. This was because, compared with the empirical threshold method, the Otsu method did not rely on official statistics and adaptively determined the optimal threshold of the WWMI for each city in Henan, thus fully considering wheat growth state differences in different cities. In addition, the object-oriented WWMI performed better than the pixel-based WWMI in wheat mapping. The results further demonstrated the feasibility of combining the WWMI with the Otsu method for automatic winter wheat mapping at large extents, which will provide a theoretical basis for identifying other food crops.