Cereal production has increased substantially in the last few decades in South Asia, primarily attributable to intensification rather than expansion of agricultural land area. Intensification has occurred through high-yielding seed varieties, irrigation, fertilizer and pesticide inputs. Moreover, intensification has largely been achieved through multiple cropping, i.e. increasing the number of crops per year from the same field. However, agricultural production is highly variable on an interannual basis and dependent on climate. Agriculture in the region, particularly India, is predicted to be one of the most vulnerable in the world to climate change.

The monsoon (roughly June to October) season is the main growing season for crops, primarily rice, in India. Farmers sometimes plant a second crop, often wheat and pulses, in the winter season (roughly November to February) where irrigation is available. Considerable research focusses on the vulnerability of the monsoon crop to climate change. This project focusses on the vulnerability of the winter crop. Specifically, we address the following: which remote sensing tools are most appropriate to map cropping intensity (number of crops per year)?; how much and where are farmers switching between single and double cropping?; and which climatic, biophysical and demographic variables are associated with variability in winter cropping? Understanding these temporal and spatial dynamics of winter cropping, and factors associated with interannual variability in the extent of winter cropping, can inform decisions about adaptation to climate change and impacts on food security.

The phenological profile obtained from the Enhanced Vegetation Index (EVI) from the MODIS sensor indicates the number of crops per year (Figure 1).The webinar discussed the challenges for identifying winter cropping, particularly in light of the small field sizes in South Asia (Figure 2). We developed a scaling approach with data from multiple sensors (Quickbird, Landsat and MODIS) to estimate percent cropped area during the winter season.

Figure 1. Example of phenological profile from MODIS Enhanced Vegetation Index to identify a) single and b) double cropped pixels.

Figure 2. Illustration of small field size from Quickbird relative to 30m resolution of Landsat and 250m resolution of MODIS.

Based on the estimates of winter cropped area for 2000 to 2012, we identify the climate, biophysical and demographic factors associated with winter cropping by focusing on regions for which we have field knowledge – a semi-subsistence area in central India and a more commercially-oriented agricultural area in western India. In central India, we find that daytime winter temperature is negatively associated winter cropping, suggesting that adaptation measures (e.g., heat tolerant crops) are needed to adapt to projected winter warming. In western India, irrigation is more common so crops are more resilient to variability in precipitation, but temperature is also negatively associated with winter cropping. Irrigation may not be sufficient to overcome negatives impacts on agriculture with climate change. We are also exploring the influence of labor dynamics on cropping patterns. Read more about the project.