Climate‐driven simulation of global crop sowing dates

Abstract

Aim To simulate the sowing dates of 11 major annual crops at the global scale at high spatial resolution, based on climatic conditions and crop-specific temperature requirements.Location Global.Methods Sowing dates under rainfed conditions are simulated deterministically based on a set of rules depending on crop-and climate-specific characteristics. We assume that farmers base their timing of sowing on experiences with past precipitation and temperature conditions, with the intra-annual variability being especially important. The start of the growing period is assumed to be dependent either on the onset of the wet season or on the exceeding of a crop-specific temperature threshold for emergence. To validate our methodology, a global data set of observed monthly growing periods (MIRCA2000) is used. ResultsWe show simulated sowing dates for 11 major field crops world-wide and give rules for determining their sowing dates in a specific climatic region. For all simulated crops, except for rapeseed and cassava, in at least 50% of the grid cells and on at least 60% of the cultivated area, the difference between simulated and observed sowing dates is less than 1 month. Deviations of more than 5 months occur in regions characterized by multiple-cropping systems, in tropical regions which, despite seasonality, have favourable conditions throughout the year, and in countries with large climatic gradients. Main conclusionsSowing dates under rainfed conditions for various annual crops can be satisfactorily estimated from climatic conditions for large parts of the earth. Our methodology is globally applicable, and therefore suitable for simulating sowing dates as input for crop growth models applied at the global scale and taking climate change into account.

Implications of accounting for land use in simulations of ecosystem carbon cycling in Africa

“…For temperate cereals, an upper temperature limit of 15 • C for the coldest month for growth is set to avoid their parameterization in tropical climates, following . The main modifications in the model compared to LPJ-mL as described by Bondeau et al (2007) are a new phenology scheme, coupling LAI and leaf C mass on a daily time step, a dynamic potential heat unit (PHU) calculation based on local climate conditions in each grid cell, simulation of regeneration and recovery of vegetation by creating a new natural vegetation stand following cropland abandonment and a revised calculation of crop sowing dates following Waha et al (2012). Crop irrigation is treated differently in LPJ-GUESS compared to LPJ-mL.…”

“…The modelled crop yield represents potential optimal yield, limited by climate and CO 2 only. The relative degree of limitation by temperature and precipitation to the sowing dates -or the absence of such limitation in perennially moist areas (where incoming solar radiation generally limits plant production) -was determined based on the local climatology (Waha et al, 2012) (Fig. 2).…”

The impact of climate change mitigation on water demand for energy and food: An integrated analysis based on the Shared Socioeconomic Pathways

“…Photosynthesis modeling in LPJmL follows a modified approach by Farquhar et al (1980). Sowing dates are dynamically calculated based on climatic and crop conditions (Waha et al, 2012).…”

Estimating sowing and harvest dates based on the Asian summer monsoon

“…In the General Large Area Model (GLAM; Challinor et al, 2004a), the sowing date can be estimated by the model based on the soil moisture conditions, with the crop sown when surface soil moisture exceeds a specified threshold during a given time window and crop emergence occurring at a specified time after sowing. Waha et al (2012) base their estimates of sowing dates at the global scale on climatic conditions and cropspecific temperature thresholds, therefore providing a suitable method for taking climate change into account. However, the Waha et al (2012) method is not really intended for use in irrigated multiple cropping regions.…”

“…Waha et al (2012) base their estimates of sowing dates at the global scale on climatic conditions and cropspecific temperature thresholds, therefore providing a suitable method for taking climate change into account. However, the Waha et al (2012) method is not really intended for use in irrigated multiple cropping regions. Elliott et al (2015) describe how sowing dates are defined in the GGCMI project.…”