Small, But Significant Declines In Crop Productivity On Low Fertility Soils

Abstract

Agricultural yields are susceptible to losses during extreme weather events related to climate change, jeopardizing food security. Yield losses may be mediated by underlying quality or variation of agricultural land in soil fertility, topography, drainage, and growing degree days. For instance, crops grown on poor quality land may be more susceptible to the negative consequences of climate variation as compared to crops grown on high quality land. This study investigated yield response for corn, soybeans, and pasture to different land qualities across Ontario from 2011 to 2017. Yield is approximated using the Normalized Difference Vegetation Index (NDVI), which is a satellite-derived measure of biomass production. For three focal crops (soybean, corn, and pasture), the average maximum NDVI and the coefficient of variance (CV) of maximum NDVI were aggregated at a provincial and county scale for each land quality classification. Relatively stable CV values were evident across all land qualities, yet certain counties showed greater variation in productivity on poor quality land suggesting greater susceptibility to extreme weather. Over 7 years, there were small but significant declines in NDVI in response to poor quality land for all three crop types. This suggests that agricultural producers cannot overcome the biophysical limitations of poor quality land on crop yield. Understanding differential crop productivity responses to land quality can help producers mitigate crop losses to climatic variation, thus equally stabilizing food availability.