Irrigation is essential to sustain crop production in water limited region. Irrigation increases crop yield by fulfilling crop's water demand, and the added water also creates an evaporative cooling effect which mitigates heat stress of crop. How much contribution of these two in the irrigation-induced yield increase is unclear. (decompose these two).
Here we use satellite data (statistical model) and maize yield data, an irrigation prevalent crop production state in the US, in Nebraska, to quantify the contribution of cooling and water supply. Compared with rainfed maize, irrigated maize has a much lower land surface temperature (LST) (than rainfed) during growing season. accompanied with higher EVI (value) and x% higher yield. according to MODIS satellite data vegetation index, especially in hot and dry counties. The cooling effect declines from dry to wet counties, with smaller EVI and yield differences, especially under dry the difference in yield. with the largest.
The added water meets
The purpose of irrigation is to supply adequate amount of water when rainfall is not sufficient or timely to meet the crops’ water needs.
by supplying water to fulfill crops’ water needs, or by cooling to mitigate the heat stress.