Temperature-based prediction of harvest date in winter and spring cereals as a basis for assessing viability for growing cover crops
Introduction
Cropping systems in temperate continental and maritime climates are defined by a growing season and an off-season. During the off-season, spring sown annual crops cannot be grown due to unfavourable conditions, e.g. low temperature and/or high precipitation. The precipitation surplus and lack of plant cover may lead to soil erosion and nitrate leaching losses (e.g. Erisman et al., 2008). To reduce these negative environmental effects and to enhance soil fertility, cover crops (also called catch crops) are grown after the main crop (e.g. De Notaris et al., 2018). However, in some years and under unfavourable climatic conditions, the preceding cash crop cannot be harvested in time to ensure timely and adequate establishment and growth of the cover crops.
In Denmark, efforts have been given to reduce nitrogen (N) leaching from agricultural land negatively affecting quality of the aquatic environment (Dalgaard et al., 2014). However, despite success in lowering the concentration of nitrate in the stream runoff, there is still need for further reductions in many catchments in Denmark to meet sufficient quality standards for coastal ecosystems (Odgaard et al., 2019). Cover crops have been identified as one of the most effective ways of reducing nitrate leaching and the N loadings to the aquatic environments (Askegaard et al., 2011; Hashemi et al., 2018). However, the effectiveness of cover crops in reducing nitrate leaching varies considerably between years, depending on the growing conditions for the cover crops (Zhao et al., 2020). It is, in particular, the duration of adequate temperatures for growth in the autumn that determines the success of the cover crops (De Notaris et al., 2018). Therefore, late harvest of the main crop in the cool temperate conditions of Denmark reduces the chance of a vigorous and successful cover crop.
The Danish national legislation to meet requirements of the EU Nitrates Directive and the EU Water Framework Directive requires farmers to grow cover crops on a stipulated part of their farmland. This provision has increased over time in an effort to mitigate the N leaching losses from agriculture (Dalgaard et al., 2014). These governmental regulations require that cover crops are sown no later than 20 August, which for autumn-sown cover crops means that the main crops (primarily cereals) should be harvested by this time. Recent experience has shown that farmers in northern parts of the country in many years have had difficulties in harvesting the cereal crops by 20 August, either due to late maturity of the cereals or due to unfavourable harvest conditions. The late harvesting caused by unfavourable weather has called for dispensation on the date for sowing the cover crops. Thus, there is a need to quantify how frequent such conditions occur and if other methods of establishing cover crops should be implemented in regions, where harvest often occurs later than August 20th. This will require a model capable of reliably predicting the date of harvest of cereal crops. The information provided by the model can be used for supporting new legislations to reduce the levels of nitrate leaching.
Phenology models simulate the timing of developmental stages of crops, based on air temperature and day length (e.g. (Olesen and Bindi, 2002; Pullens et al., 2019; Trnka et al., 2014)). Such models have low complexity and can predict development until physiological crop maturity. The duration of the period from physiological maturity to harvest depends on a range of other factors, in particular the weather conditions governing the preharvest drying of the grain and straw (Atzema, 1993; Olesen and Mikkelsen, 1985) as well as field readiness, the conjunction of the soil trafficability and workability of the field (Edwards et al., 2016; Hutchings et al., 2012). Therefore, a separate model is needed for simulating the period between the maturity and harvest dates. Such a model is not readily available, requiring the development of a model that aligns with the simplicity of the phenology model.
The objectives of this study were 1) to calibrate a phenology model (Olesen et al., 2012) to simulate crop phenology and predict the date of maturity of winter wheat and spring barley, which are the primary cereal crops in Denmark, 2) to develop, calibrate and validate a model for predicting harvest date in winter wheat and spring barley, 3) to assess the spatial and temporal variability in harvest date of winter wheat and spring barley in Denmark, and 4) to assess the effect of the variation in harvest date on the suitability for growing cover crops in Denmark.
Section snippets
Material and methods
This study used four different methodological approaches to address each objective of the study and are described in different sections.
Calibration and cross-validation of phenology model
The results of the calibration and cross-validation of the models from sowing date to maturity for spring barley and winter wheat are shown in Table 2, Table 3. The standard deviation of temperature sum requirements is derived from the cross-validation.
The model predictions of emergence for spring barley show a higher variation than the observations, while at maturity, the model results are within the range of measured days after sowing (data not shown). Anthesis is a developmental stage that
Model performance
This study used a simple method for estimating harvest date for spring barley and winter wheat, based on air temperature and day length. The results show that a simple model solely based on air temperature is efficient and sufficient to estimate the harvest date for spring barley and winter wheat on the national scale. The results of the simple model (Fig. 5) are close to the measured harvest dates (Fig. 2). In practice, the harvest date is also affected by other factors, such as harvest
Conclusions
In this study, we show that a simple phenology model for date of maturity with the addition of a simple temperature sum to calculate the period from maturity to harvest can be used to accurately predict the historical harvest dates of spring barley and winter wheat in Denmark. The model was calibrated using large datasets and can be used to make predictions for the current growing season by using the recorded air temperature to estimate the harvest date in a given year. The presented method is
CRediT authorship contribution statement
Johannes W.M. Pullens: Conceptualization, Methodology, Software, Investigation, Writing - original draft. Claus A.G. Sørensen: Resources, Writing - review & editing. Jørgen E. Olesen: Supervision, Conceptualization, Resources, Writing - review & editing.
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgements
The study was conducted as part of the policy support for the Ministry of Environment and Food of Denmark. The data from the field experiments under the agricultural advisory services was kindly provided by Jon Birger Pedersen, SEGES. The authors also want to thank the Associate Editor Enli Wang and the two anonymous reviewers for their useful suggestions and comments.
References (48)
- et al.
Nitrate leaching from organic arable crop rotations is mostly determined by autumn field management
Agric. Ecosyst. Environ.
(2011) A model for the prediction of the moisture content of cereals at harvesting time with realtime weather data
J. Agric. Eng. Res.
(1993)- et al.
Nitrogen leaching: a crop rotation perspective on the effect of N surplus, field management and use of catch crops
Agric. Ecosyst. Environ.
(2018) - et al.
Manipulating cover crop growth by adjusting sowing time and cereal inter-row spacing to enhance residual nitrogen effects
F. Crop. Res.
(2019) - et al.
Assessing the actions of the farm managers to execute field operations at opportune times
Biosyst. Eng.
(2016) - et al.
Cover crop and cereal straw management influence the residual nitrogen effect
Eur. J. Agron.
(2020) - et al.
Scaling-up the AFRCWHEAT2 model to assess phenological development for wheat in Europe
Agric. For. Meteorol.
(2000) - et al.
Potential benefits of farm scale measures versus landscape measures for reducing nitrate loads in a Danish catchment
Sci. Total Environ.
(2018) - et al.
Growing degree-days: one equation, two interpretations
Agric. For. Meteorol.
(1997) - et al.
River flow forecasting through conceptual models part I - A discussion of principles
J. Hydrol. (Amst)
(1970)
Soil water contents for tillage: a comparison of approaches and consequences for the number of workable days
Soil Tillage Res.
Targeted set-aside: benefits from reduced nitrogen loading in Danish aquatic environments
J. Environ. Manage.
Consequences of climate change for European agricultural productivity, land use and policy
Eur. J. Agron.
Duration of vegetative and generative development phases in oat cultivars released since 1921
F. Crop. Res.
Risk factors for European winter oilseed rape production under climate change
Agric. For. Meteorol.
A soil and agroclimatic model for estimating machinery work-days: the basic model and climatic sensitivity
Soil Tillage Res.
Phenological development in spring cereals: response to temperature and photoperiod under northern conditions
Eur. J. Agron.
Productivity of organic and conventional arable cropping systems in long-term experiments in Denmark
Eur. J. Agron.
Crop growth and nitrogen turnover under increased temperatures and low autumn and winter light intensity
Agric. Ecosyst. Environ.
Autumn-based vegetation indices for estimating nitrate leaching during autumn and winter in arable cropping systems
Eur. J. Agron.
Crop Evapotranspiration-guidelines for Computing Crop Water requirements-FAO Irrigation and Drainage Paper 56
Heading date is not flowering time in spring barley
Front. Plant Sci.
Winter cover crop seeding rate and variety affects during eight years of organic vegetables: I. Cover crop biomass production
Agron. J.
Policies for agricultural nitrogen management—trends, challenges and prospects for improved efficiency in Denmark
Environ. Res. Lett.
Cited by (12)
Faba bean and spring barley in sequence with catch crops: Grain yields and nitrate leaching
2024, Field Crops ResearchDelaying sowing of cover crops decreases the ability to reduce nitrate leaching
2023, Agriculture, Ecosystems and EnvironmentThermo-gas dynamics affect the leaf canopy shape and moisture content of aquaponic lettuce in a modified partially diffused microclimatic chamber
2022, Scientia HorticulturaeCitation Excerpt :The coefficient Q10, a variation in a certain trait for every 10 °C differentiation, has been utilized to determine the sensitivity of plant organs (Frantz et al., 2004). The temperature has been used as a basis for predicting when the physiological maturity of certain CROPSYS-included crops in any phenological phase of sowing, maturity, and harvest (Pullens et al., 2021). Humidity, as related to temperature, affects the physiology of both roots and leaves (Hikosaka et al., 2017).
An IoT Based Secure Smart Farming
2023, Proceedings of the International Conference on Circuit Power and Computing Technologies, ICCPCT 2023A Crop Harvest Time Prediction Model for Better Sustainability, Integrating Feature Selection and Artificial Intelligence Methods
2022, Sustainability (Switzerland)