The Impact of Climate and Its Variability on Crop Yield and Irrigation

Abstract:

As the global population grows and the climate changes, having a secure food supply is increasingly important especially under water stressed-conditions. Although irrigation is a positive climate adaptation mechanism for agriculture, it has a potentially negative effect on water resources. It is therefore important to understand how crop yields due to irrigation are affected by climate variability and how irrigation may buffer against climate, allowing for more resilient agricultural systems. Efforts to solve these barely exposed questions can benefit from comprehending the influence of climate variability on crop yield and irrigation water use in the past.

To do this, we use historical climate data，irrigation water use data and rainfed and irrigated crop yields over the US to analyze the relationship among climate, irrigation and delta crop yields, gained by subtracting rainfed yield from irrigated yield since 1970. We find that the increase in delta crop yield due to irrigation is larger for certain climate conditions, such that there are optimal climate conditions where irrigation provides a benefit and other conditions where irrigation proves to have marginal benefits when temperature increased to certain degrees. We find that crop water requirements are linked to potential evapotranspiration, yet actual irrigation water use is largely decoupled from the climate conditions but related with other causes. This has important implications for agricultural and water resource system planning, as it implies there are optimal climate zones where irrigation is productive and that changes in water use, both temporally and spatially, could lead to increased water availability without negative impacts on crop yields. Furthermore, based on the exposed relationship between crop yield gained by irrigation and climate variability, those models predicting the global harvest will be redress to estimate crop production in the future more accurately.