Wheat Biomass Research Articles

Coefficient of variation method combined with XGboost ensemble model for wheat growth monitoring.

Obtaining wheat growth information accurately and efficiently is the key to estimating yields and guiding agricultural development. This paper takes the precision agriculture demonstration area of Jiaozuo Academy of Agriculture and Forestry in Henan Province as the research area to obtain data on wheat biomass, nitrogen content, chlorophyll content, and leaf area index. By using the coefficient of variation method, a Comprehensive Growth Monitoring Indicator (CGMI) was constructed to perform fractional derivative processing on drone spectral data, and correlation analysis was performed on the fractional derivative spectra with a single indicator and CGMI, respectively. Then, grey correlation analysis was carried out on differential spectral bands with high correlation, the grey correlation coefficients between differential spectral bands were calculated, and spectral bands with high correlation were screened and taken as input variables for the model. Next, ridge regression, random forest, and XGboost models were used to establish a wheat CGMI inversion model, and the coefficient of determination (R2) and root mean squared error (RMSE) were adopted for accuracy evaluation to optimize the wheat optimal growth inversion model. The results of the study show that: using the data of wheat biomass, nitrogen content, chlorophyll content and leaf area index to construct the comprehensive growth monitoring indicators, the correlation between the wheat growth monitoring indicators and the spectra was calculated, and the results showed that the correlation between the comprehensive growth monitoring indicators and the single indicator correlation had different degrees of increase, and the growth rate could reach 82.22%. The correlation coefficient between the comprehensive growth monitoring indexes and the differential spectra reached 0.92 at the flowering stage, and compared with the correlation coefficient with the original spectra at the same period, the correlation coefficients increased to different degrees, which indicated that the differential processing of spectral data could effectively enhance the spectral correlation. The three models of Random Forest, Ridge Regression and XGBoost were used to construct the wheat growth inversion model with the best effect at the flowering stage, and the XGBoost model had the highest inversion accuracy when comparing in the same period, with the training and test sets reaching 0.904 and 0.870, and the RMSEs were 0.050 and 0.079, so that the XGBoost model can be used as an effective method of monitoring the growth of wheat. To sum up, this study demonstrates that the combination of constructing comprehensive growth monitoring indicators and differential processing spectra can effectively improve the accuracy of wheat growth monitoring, bringing new methods for precision agriculture management.

Integrated management of cheat (Bromus secalinus L.) and downy brome (Bromus tectorum L.) in Oklahoma grain-only winter wheat

Abstract In Oklahoma, downy brome and cheat are difficult-to-control winter annual grasses. In the past, cheat infested most of the winter wheat hectares harvested in Oklahoma. Biotypes that are cross-resistant to acetolactate synthase–inhibiting herbicides have left growers with minimal management options for conventional and herbicide-tolerant systems. Field trials near Lahoma, Oklahoma, in 2019–2020 and 2020–2021 evaluated integrated management of cheat and downy brome using three strategies: planting date (optimal, delayed, and late), cultivar selection (high and low competitiveness), and herbicide choice (no herbicide, sulfosulfuron at 35.2 g ai ha−1 and pyroxsulam at 18.4 g ai ha−1). Visual control, weed species present, wheat biomass at heading, and grain yield data were collected. In 2019–2020, 8 to 9 wk after treatment, visual control increased by 15% with the delayed planting compared with the optimal planting date and 14% with the late planting date. In 2020–2021, similar control (∼99%) was recorded for delayed and late plantings with 23% greater control than the optimal timing. Due to a lack of weed coverage, weed biomass in 2019–2020 had no response to planting date, cultivar, or herbicide treatment. Downy brome biomass during 2020–2021 was approximately 90% lower with delayed to late planting dates than the optimal planting date. In the same year, downy brome and cheat biomass were low (≤0.4 and 0.2 g m−2) and 98% less after an herbicide application than a nontreated area. Wheat grain yield at the optimal planting date was greater than yields from delayed and late plantings in 2019–2020. A delay in planting from the optimal date to delayed or late timings decreased wheat yield by 14% and 21%, respectively. In 2020–2021, wheat yield from the late planting was reduced by 57% compared with the optimal planting yield. Delaying the planting date and the use of a common herbicide can suppress cheat and downy brome, but a decline in wheat yield may occur.

In situ charcoal production in Acacia decurrens‐based taungya system improved soil properties and productivity of three agricultural crops in the highlands of Ethiopia

AbstractShort‐term in situ charcoal production‐induced changes in soil properties and crop productivity of acidic soil in Acacia decurrens‐based taungya system were assessed in the Guder watershed of northwestern Ethiopia. Data were collected through field study, pot experiment and interviews with local farmers. The field study involved a survey of 36 paired charcoal production kiln sites and adjacent reference sites in 18 croplands to analyse soil physicochemical properties and productivity of tef (Eragrostis tef), barley (Hordeum vulgare) and wheat (Triticum aestivum). A pot experiment was undertaken with wheat to investigate seed germination and chemical fertilizer needs at charcoal production sites. Local farmers were interviewed for their perceptions and management practices. The production and short‐term presence of charcoal in kiln sites significantly increased sand fraction, pH, organic carbon, available phosphorous, exchangeable Mg2+ and exchangeable K+ compared with the reference sites. Charcoal production practice raised pH by 0.83 units, organic carbon, available P and exchangeable K+ by 40%, 92% and 303%, respectively. Exchangeable acidity and exchangeable Al3+ were lowered by over 80% at kiln sites. Both aboveground biomass and grain yield of tef, barley and wheat were, on average, 135% higher at kiln sites than at the reference sites. Furthermore, crops grown at kiln sites were taller and had greener and larger leaves. Farmers' responses indicated higher crop productivity and reduced inorganic fertilizer application at kiln sites. Results from the pot experiment provided evidence of faster seed germination, enhanced crop productivity and reduced inorganic fertilizer needs in charcoal‐treated soils. The study suggests that the inclusion of charcoal remnants and heating can increase carbon storage, improve soil properties which promote crop productivity and reduce the need for inorganic fertilizer in degraded, acidic agricultural soil.

CFD MODELING OF THE COMBUSTION OF UKRAINIAN AND BIOMASS IN A FLARE BOILER UNIT TPP-210a

To increase the amount of energy produced with the bioresources use is the most important step in environmentally friendly electricity production. An analysis of the computer modeling results of pellet and biomass burning processes in the furnace chamber of the TPP-210a steam boiler was carried out. The scientific novelty of the work consists of determining the possibility and perspective of using non-design types of fuel, such as gas coal of domestic production and solid biomass (instead of anthracite), as a raw material base of existing boiler units. On the basis of this analysis, it was determined that the model allows to quite accurately assess the aerodynamic structure of the flow in the burners and the boiler furnace. Such a precise assessment is possible if the thermophysical properties of the burning fuel are accurately specified. The average integral temperature of the combustion products in the fuel during the gas coal burning is higher than while burning other fuels in the form of pellets from the sunflower husk and from biomass of spring wheat and winter wheat. The biomass used in the modeling has a similar chemical composition; therefore, the temperature distributions in the case of their burning are also similar. Subsequently, the results of the research can be used to increase the efficiency of the combustion process when burning biofuel and to modernize fuel-burning systems of low-power boilers of industrial and municipal thermal engineering, the housing-and-utilities sector, etc.

Estimating winter wheat biomass by coupling the CBA-Wheat model and multi-spectral remote sensing

Estimating winter wheat biomass by coupling the CBA-Wheat model and multi-spectral remote sensing

Mycorrhizal effects on crop yield and soil ecosystem functions in a long-term tillage and fertilization experiment.

It is well understood that agricultural management influences arbuscular mycorrhizal (AM) fungi, but there is controversy about whether farmers should manage for AM symbiosis. We assessed AM fungal communities colonizing wheat roots for three consecutive years in a long-term (> 14 yr) tillage and fertilization experiment. Relationships among mycorrhizas, crop performance, and soil ecosystem functions were quantified. Tillage, fertilizers and continuous monoculture all reduced AM fungal richness and shifted community composition toward dominance of a few ruderal taxa. Rhizophagus and Dominikia were depressed by tillage and/or fertilization, and their abundances as well as AM fungal richness correlated positively with soil aggregate stability and nutrient cycling functions across all or no-tilled samples. In the field, wheat yield was unrelated to AM fungal abundance and correlated negatively with AM fungal richness. In a complementary glasshouse study, wheat biomass was enhanced by soil inoculum from unfertilized, no-till plots while neutral to depressed growth was observed in wheat inoculated with soils from fertilized and conventionally tilled plots. This study demonstrates contrasting impacts of low-input and conventional agricultural practices on AM symbiosis and highlights the importance of considering both crop yield and soil ecosystem functions when managing mycorrhizas for more sustainable agroecosystems.

Moth bean and tepary bean as green nitrogen sources in intensive winter wheat cropping systems

Use of cover crops have been suggested to increase agricultural sustainability by providing multiple ecosystems services. Replacing summer fallow with drought tolerant legumes could serve both as a cover and a green source of N for winter wheat (Triticum aestivum L.) and help mitigate economic and environmental problems by increasing resilience of agroecosystems in the United States (US) Southern Great Plains (SGP). Field experiments were conducted in 2018 and 2019 at the USDA - ARS Oklahoma and Central Plains Agricultural Research Center near El Reno, OK. The overall objective of the study was to quantify the potential of two summer legumes, tepary bean [Phaseolus acutifolius (A.) Gray] and moth bean [Vigna aconitifolia (Jacq.) Marechal], as green sources of N for winter wheat production in comparison with soybean [Glycine max (L.) Merr.]. The PROC MIXED procedure of the SAS statistical software was used to analyze biomass production by legumes, their impacts on soil water, soil N and yield of winter wheat, and N transfer from green N biomass to following winter wheat. Green N crops did not differ in biomass production, but soybean provided 22 % and 40 % more N than tepary bean and moth bean, respectively. Soil water was reduced under all green N crops than summer fallow at termination of green N crops and wheat planting. Biomass of green N crops increased N content in soils at wheat planting. Grain yield of winter wheat was significantly higher under tepary bean (5295 kg ha−1) than soybean (4300 kg ha−1), moth bean (4560 kg ha−1) and the control treatment (4323 kg ha−1). Nitrogen recovery in wheat biomass was greater under moth bean and tepary bean compared to soybean. Both moth bean and tepary bean could serve as green sources of N for winter wheat in the US SGP.

USING UAV-DERIVED PLANT HEIGHT AS AN ESTIMATOR FOR BIOMASS AND N-UPTAKE

Abstract. In Precision Agriculture applications, the knowledge of the N-uptake of crops in a spatial context is a precondition for precise N-fertilization. Therefore, non-destructive methods to determine N concentration or N-uptake of crops are of key interest. In this contribution, we will present an approach based on UAV-based crop height analysis to estimate N-uptake. The hypothesis is that biomass can be very well estimated using UAV-derived crop height. It is also known that biomass is highly correlated with N-uptake. Hence, we propose to use UAV-derived crop height as a direct estimator for N-uptake. We will present results from a winter wheat field trial comprising six varieties, three different N amounts, and five repetitions. Multitemporal models have been created from data of the growing season 2020 with a promising performance for biomass (R2 = 0.91) and N-uptake (R2 = 0.72). The two linear regression models have been applied to a similar independent data set from the following year, 2021. The results are promising for biomass (R2 = 0.82) and N-uptake (R2 = 0.75). Based on our findings, we conclude that UAV-derived crop height - as a structural crop trait - can robustly serve as an estimator for biomass and N-uptake in winter wheat.

Synthetic bacterial community derived from Astragalus mongholicus and plant-plant interactions inhibit cadmium uptake by modulating gene expression, antioxidant system and carbohydrate metabolism under cadmium contaminated soil

In this study we evaluated an alternative strategy to inhibit cadmium (Cd) uptake with synthetic bacterial community (SynCom) in cereal-legume intercropping under Cd contaminated soil. The results exhibited that intercropping coupled with SynCom inoculation promoted wheat biomass and inhibits Cd uptake in shoot (−65.05%), root (−34.66%) and grain (−74.45%) over monoculture without inoculation under Cd stress. However, antioxidant enzyme activities were significantly increased with SynCom inoculation in wheat grown on Cd contaminated soil irrespective of intercropping. SynCom inoculation considerably increased cytoplasmic invertase, vacuolar invertase, hexokinase, phosphoglucoisomerase, glucose-6-phosphate dehydrogenase, phosphofructokinase and SuSy while decreased the activities of ADP-Glucose pyrophosphorylase, aldolase, fructokinase, phosphoglucomutase and UDP-glucose pyrophorylase irrespective of intercropping under Cd stress. Furthermore, the expressions of gene encoding heavy metal stress were significantly decreased with the SynCom inoculation in roots. The expression of TaHMA3-b in root was downregulated by SynCom inoculation in wheat grown under Cd stress. The expressions of gene encoding heavy metal stress in shoot were downregulated by SynCom inoculation over other treatments. These findings not only offered useful information for future study of interaction mechanisms between intercropping and SynCom inoculation, but also demonstrated a suitable technological approach for remediation coupled with agro-production in mildly to substantially Cd polluted soil.

Nano-iron and AM fungi inoculation in dryland wheat field: A sustainable alternative to plastic film mulching

ContextPlastic film mulching is a primary cultivation measure in the dryland agricultural areas of northwest China, but comes with the drawback of plastic pollution. To overcome this issue, the biological inoculants such as arbuscular mycorrhizal (AM) with nanotechnology might be a critical pathway, but their positive effects on plants are context-dependent and vary with species, application method, concentration, size, surface charge, and other physio-chemical properties. There is so far limited information available on the combined effects of AM fungi with nanoparticles in agriculture. ObjectivesThis study aimed to investigate the potential of iron nanoparticles (FeNPs) in combination with AMF regarding wheat productivity maintenance and its driving mechanism. MethodsHerein, we used a completely randomized block design for the field experiments in the years 2018 and 2019. We conducted two field experiments using nanopriming of seeds with iron nanoparticles (FeNPs) and AMF in two growing seasons in 2018 and 2019 on wheat (Triticum aestivum L., cv. Longchun29) in the field. Each plot had a 5 m × 5 m total area having 6 rows of 0.2 m spacing and 0.5 m buffer strip among the neighboring plots. There were 8 treatments in the field experiment, and each treatment was repeated 3 times, including four nano iron concentration seed soaking treatments (0 mg L-1, 5 mg L-1, 10 mg L-1, 15 mg L-1) and two inoculation treatments of arbuscular mycorrhizal fungi (inoculated with Gi and non-inoculated). ResultsCombined treatments with arbuscular mycorrhizal fungi and iron nanoparticles led to significant increases in wheat biomass and yield across 2018 and 2019. When compared with control treatment there was an increase of 111% in biomass for the year 2018 and a 102% increase was observed for the year 2019; while the increase in the yield percent when compared to control was 91% in 2018 and 85% in 2019 respectively. Water use efficiency for yield (WUE) increased by 92% in 2018 and 57% in 2019. The colonization rate of AMF + FeNPs 10 mg L-1 treatment increased by 223%, 88%, and 211%, respectively compared with control at the jointing, anthesis, and maturity stage in 2018; and increased by 48%, 37%, and 56% respectively in the year 2019. FeNPs at 10 mg L-1 led to small increases in total organic carbon (TOC), total nitrogen (TN), microbial biomass carbon and nitrogen (MBC), and (MBN), in both growing seasons, and AMF inoculation further significantly increased these carbon fractions by 2.6%, 20%, 21% and 26% in 2018; while 1.3%, 14.8%, 12.5%, and 35% in 2019 respectively. ConclusionThe combined treatments of FeNPs and AMF at an optimal concentration (10 mg L-1) significantly increased net economic income by 229% in 2018 and 138% in 2019 when compared to the control. In this study, wheat aboveground biomass and yield and other related parameters have been improved under field trials, which verified that AMF inoculation alongside FeNPs, can play a beneficial role in promoting dryland spring wheat. ImplicationsTaken together, the co-inoculation with FeNPs and AMF displayed a promising perspective in green production with the potential replacement of plastic film mulching in semiarid dryland regions.

English

Global warming stimulates soil salinization and calcification, resulting in phosphorus (P) deficiency in arid and semiarid regions worldwide. Phosphate-solubilizing bacteria (PSB) can enhance phosphorus availability, but their role has been less explored under arid and semiarid climatic conditions. A two-year consecutive field experiment was conducted to assess the effectiveness of PSB loading onto seeds, organic, and mineral fertilizers. The trial followed a randomized complete block design (RCBD) with three replications for each treatment. There were five treatments: T1 was the uninoculated control with no fertilizer (Control), T2 was uninoculated with recommended NPK (NPK), T3 was PSB-inoculated wheat seeds (PSB-Seed), T4 was PSB-inoculated organic fertilizer (PSB-OF), and T5 was PSB-inoculated mineral fertilizer (PSB-MF). Results revealed that inoculation with PSB onto seeds, organic, or mineral fertilizer had a more pronounced impact not only on the vegetative development and yield of wheat but also on P contents in grains. It was observed that the PSB-inoculated mineral fertilizer treatment responded well, showing noticeable wheat biomass accumulation, grain yield, and improved P uptake in grain and straw. Interestingly, the highest uptake of nitrogen (N) in wheat grain was observed with both PSB-inoculated organic fertilizer treatment and PSB-inoculated mineral fertilizer treatment, highlighting the efficacy of slow-release nitrogen from organic fertilizer in addition to the impact of PSB. In conclusion, PSB inoculation on organic or mineral fertilizer has substantial potential in enhancing crop productivity and combating P deficiency in arid and semi-arid regions.

Effect of crop rotational position and nitrogen supply on root development and yield formation of winter wheat

The lower yield of wheat grown after wheat (second wheat) compared with the first wheat after a break crop is frequently attributed to fungal disease occurrence, but has also been found without visible disease infection; thus, other factors might be responsible for the lower yield of the second wheat. The aims of this study were to analyze the effects of growing wheat as first and second wheat after oilseed rape, as well as monoculture in a long-term field experiment over three years on (i) aboveground biomass formation, root development and nutrient acquisition during the growing season, (ii) take-all occurrence, and (iii) grain yield and yield components. Subsoil root length density of winter wheat was significantly higher after oilseed rape as pre-crop than after wheat, which was independent of take-all occurrence. Differences in wheat aboveground biomass occurred at early growth stages and were persistent until harvest. Grain yield loss correlated well with take-all disease severity in a wet year but yield differences among crop rotational positions occurred also in a dry year without visible fungal infection. Thus, an effect of the crop rotational position of wheat beyond take-all disease pressure can be assumed. Overall, wheat root length density might be the key to understand wheat biomass formation and grain yield in different crop rotational positions.

Optimum Yaramila (N23P10S5) Blend Formulation and Its Fertilization for Growth and Yield of Wheat in Enderta District, South Eastern Tigray

Fertilizer use in Ethiopia has focused mainly on the application of nitrogen and phosphorous fertilizers in the form of di-ammonium phosphate and urea for almost all cultivated crops for the last several years. Such unbalanced application of plant nutrients may aggravate the depletion of other important nutrient elements in soils such as S and micro-nutrients. Present study was conducted in Tigray region Enderta district with the objective of evaluating Yaramila (23-10-5, N: P2O5: S) and its rate on yield of wheat crop. In this trial five treatments were included and it was laid out in Randomized Complete Block Design (RCBD) with three replications. The results indicated that biomass, grain, and straw yields of wheat responded to the additional yaramila levels. But, these levels did not beat recommended NP and the maximum grain yield was obtained at the recommended NP. The yaramila@200kg/ha level has almost equal levels of N and P with the recommended NP and additional sulfur levels but the yield and yield components of wheat were not significantly higher than recommended NP even with additional NP adjusted. This implies that either the sulfur or the formulation of blending decreased nitrogen and phosphorus efficiency. Hence, nitrogen and phosphorus are the yield limiting nutrients rather than sulfur for wheat. Moreover, Yaramila blended based on this formulation as source of sulfur is not a suitable fertilizer for wheat growth in the study. So, other alternative sources of sulfur rather than yaramila should be used for wheat production.

Wheat biomass, yield, and straw-grain ratio estimation from multi-temporal UAV-based RGB and multispectral images

Wheat biomass, yield, and straw-grain ratio estimation from multi-temporal UAV-based RGB and multispectral images

Layered-Strip Fertilization Improves Nitrogen Use Efficiency by Enhancing Absorption and Suppressing Loss of Urea Nitrogen

Appropriate deep application of fertilizer is the key basis for improving nitrogen use efficiency (NUE). However, the effects of different deep application methods and fertilizer types on nutrient migration, NUE and biomass in wheat season are unclear. Therefore, in this study, a barrel planting test with multilayer fertilization (15N labeled urea (U) and coated urea (CU)) was conducted in a long-term positioning trial of winter wheat in the North China Plain (NCP). We quantified the migration of fertilizer N (Ndff) in soil–plant–atmosphere and its effects on wheat biomass and NUE based on surface (Usur, CUsur), layered-strip (Ustr, CUstr) and layered-mix fertilization (Umix, CUmix) of U and CU. Compared with surface fertilization, the concentration of mineral N in root zone (0–40 cm) was increased by Ustr and Umix (8.6–50.3%), and the concentration of ammonium N was decreased by CUstr and CUmix (49.6–76.0%), but there was no change in the nitrate N. The biomass and total N absorption of wheat tissues (straw and root) were increased by 12.3–38.9% under Ustr and CUstr. Meanwhile, the distribution of Ndff in the 0–10 cm soil was decreased under Ustr and CUstr, but it was increased in the 10–30 cm soil, thereby promoting the absorption of Ndff in wheat tissues by 12.3–28.7%. The rates of absorption and loss of Ndff were the highest (57.6–58.5%) and the lowest (4.5%) under Ustr and CUstr, respectively, compared with other treatments. Consequently, layered-strip fertilization optimized the migration and utilization of Ndff within the soil–plant–atmosphere system. This approach equalized distribution, enhanced absorption and minimized losses of Ndff, resulting in an increase in NUE by 9.6–16.7%. Under the same treatment, CU was more suitable for crop nutrient requirements than U, which was more conducive to the improvement of NUE. Our findings will provide a scientific basis for the precise directional fertilization of winter wheat in the NCP.

Using structure-from-motion to estimate cover crop biomass and characterize canopy structure

ContextVariability in biomass production poses a challenge for growers when using cover crops for weed control. However, most methods for assessing cover crop biomass are laborious and impractical on a field scale. ObjectiveThe goal of the present study was to determine the feasibility of using Structure-from-Motion (SfM) photogrammetry to estimate biomass in cereal rye (Secale cereale L.) and winter wheat (Triticum aestivum L.) cover crops by correlating biomass with 3-D point cloud pixel density and crop height. MethodsPoint clouds were generated using a SfM algorithm from RGB (red, green, and blue) videos collected by a hand-held GoPro camera over sixteen crop fields in North Carolina, Iowa, and Maryland, USA, throughout two growing seasons (2021–2023). Crop height, leaf area index (LAI), and photosynthetically active radiation (PAR) were also measured. ResultsBiomass was positively correlated with crop height for both cereal rye (R2 = 0.621) and wheat (R2 = 0.55). LAI was positively correlated with biomass accumulation and crop height for both species, increasing linearly in rye and exponentially in wheat. Conversely, PAR penetration below the canopy decreased with biomass accumulation and crop height in both species, with a more rapid extinction in wheat than rye. Point cloud pixel density showed a positive linear relationship with biomass in rye but saturated after 2.5 tonnes ha−1 (2500 kg ha−1). In wheat, point cloud pixel density was weakly and negatively correlated with biomass due to a denser canopy causing faster saturation of tissue detection by SfM point clouds. However, considering crop height and point cloud density integrating them both in the model allowed obtaining a positive relationship with biomass through levels of 8 tonnes ha−1 (8000 kg ha−1) in both species. When models were validated with independent data, predicted and measured biomass were positively correlated for both rye (R2 = 0.86) and wheat (R2 = 0.78). ConclusionsBased on the results, using SfM to generate 3-D point clouds can provide a more accurate estimation of biomass than canopy height alone by capturing species-level differences in canopy architecture. ImplicationsThe results of this study suggest that SfM can potentially be used as a non-destructive tool for growers to monitor biomass production in cereal cover crops other systems such as energy/forage crops, which can help inform management decisions and conserve resources.

Plot Layout Method of Field Experiment for Wheat with Border Irrigation Based on Soil Water Content Heterogeneity

The objective of this research was to improve the accuracy and representativeness of experimental plot studies by determining the optimum plot area and replication number for winter wheat with border irrigation. Considering the spatial distribution of soil water content, the border effect in relation to crop growth, and the lateral seepage of soil water, we sought to study and optimize the area and specifications of irrigation experiment plots with different levels and replicates. The results show that the experimental irrigation plot consisted of two parts—the core area and the guard area. The most suitable area for the experiment plot core area, with a single level and without replicates, was 60–80 m2. The core experimental area can be arranged with two replicates per 40 m2, with differences in soil moisture content between the treatments reaching more than 15% at the two experiment levels. Each plot comprised two replicates, or if they were 20 m2, then they contained three replicates; when the soil moisture contents differed between 10% and 15%, the area of each replicate plot was 80 m2, comprising two replicates, or 30 m2 with three replicates. When the difference in soil moisture content between the treatments exceeded 15% with the three experimental levels, the area of each plot was 30 m2 and they contained two replicates, or 20 m2 containing three replicates; at differences of 10% to 15%, each replicate plot was 50 m2 containing two replicates, or 30 m2 with three replicates. The experimental plots were rectangular, with irrigation furrows dug lengthwise; therefore, the plots had aspect ratios between 7:1 and 5:1. The width of the buffer area was over 60 cm. The effect of the border on plant height and LAI for winter wheat primarily emerged with one to three rows (20–60 cm) at the jointing stage, while the effect on grain yield and biomass in winter wheat mainly emerged with one to two rows (20–40 cm). The conclusions of this research will inform the development of surface irrigation methods for silt loam in northern Henan, as a reference for optimizing experiment plots employing border irrigation with different soil textures.

Aboveground wheat biomass estimation from a low-altitude UAV platform based on multimodal remote sensing data fusion with the introduction of terrain factors

Aboveground wheat biomass estimation from a low-altitude UAV platform based on multimodal remote sensing data fusion with the introduction of terrain factors

No differences in soil structure under winter wheat grown in different crop rotational positions

Yield decline in wheat grown after wheat is frequently attributed to fungal disease occurrence, but it is also found without visible disease infection. Thus it is hypothesized that other factors such as N supply or soil structural degradation may lead to wheat yield decline when grown after wheat. The aims of this study were to analyze if (i) the crop rotational position of winter wheat causes differences in soil structure at the beginning of the growing season and (ii) the soil structure is related to differences in wheat biomass formation by this date. Different soil structural properties under winter wheat as well as total aboveground biomass of wheat grown in different crop rotational positions (monoculture, first, second and third wheat after oilseed rape) were investigated in two long-term field experiments with contrasting soil texture. At both field sites, no significant effect of the crop rotational position in any of the analyzed soil structural parameters was found. Wheat biomass in spring was on average 54% higher for wheat grown after oilseed rape compared to second and third wheat after oilseed rape or monoculture. In conclusion, growth reduction of wheat cultivated after wheat was not linked to soil structure as measured in spring.

Unmanned Aerial System-Based Wheat Biomass Estimation Using Multispectral, Structural and Meteorological Data

Rapid estimation of above-ground biomass (AGB) with high accuracy is essential for monitoring crop growth status and predicting crop yield. Recently, remote sensing techniques using unmanned aerial systems (UASs) have exhibited great potential in obtaining structural information about crops and identifying spatial heterogeneity. However, methods of data fusion of different factors still need to be explored in order to enhance the accuracy of their estimates. Therefore, the objective of this study was to investigate the combined metrics of different variables (spectral, structural and meteorological factors) for AGB estimation of wheat using UAS multispectral data. UAS images were captured on two selected growing dates at a typical reclaimed cropland in the North China Plain. The spectral response was determined using the highly correlated vegetation index (VI). A structural metric, the canopy height model (CHM), was produced using UAS-based multispectral images. The measure of growing degree days (GDD) was selected as a meteorological proxy. Subsequently, a structurally–meteorologically weighted canopy spectral response metric (SM-CSRM) was derived by the pixel-level fusion of CHM, GDD and VI. Both correlation coefficient analysis and simple function fitting were implemented to explore the highest correlation between the measured AGB and each proposed metric. The optimal regression model was built for AGB prediction using leave-one-out cross-validation. The results showed that the proposed SM-CSRM generally improved the correlation between wheat AGB and various VIs and can be used for estimating the wheat AGB. Specifically, the combination of MERIS terrestrial chlorophyll index (MTCI), vegetation-masked CHM (mCHM) and normalized GDD (nGDD) achieved an optimal accuracy (R2 = 0.8069, RMSE = 0.1667 kg/m2, nRMSE = 19.62%) through the polynomial regression method. This improved the nRMSE by 3.44% compared to the predictor using MTCI × mCHM. Moreover, the pixel-level fusion method slightly enhanced the nRMSE by ~0.3% for predicted accuracy compared to the feature-level fusion method. In conclusion, this paper demonstrated that an SM-CSRM using pixel-level fusion with canopy spectral, structural and meteorological factors can obtain a good level of accuracy for wheat biomass prediction. This finding could benefit the assessment of reclaimed cropland or the monitoring of crop growth and field management in precision agriculture.