Using Plant Phenology and Landsat-8 Satellite Data to Quantify Water Use by Onion Crop in the Mesilla Valley, New Mexico

Abstract

Non-storage summer dry onion crop is among the top 10 agricultural commodities in New Mexico (NM), USA. In 2000, NM was ranked the second in the nation as the leading state in growing summer dry onion. According to USDA statistical records, onion production or sales in NM was valued at $91.4 million. Mesilla Valley is one of the major onion-producing regions of NM. Due to many years of drought in the region and the concern for climate change, irrigation managers and decision makers are interested in quantifying water use or evapotranspiration (ET) and the number of acreage of onion crop grown in the Valley. This information can then be used for managing the scarce water resources of the region. Plant phenology, Landsat-8 satellite data, and USDA crop data were used to identify onion crops in the Valley (area of about 47,000 ha) and to determine their consumptive water use or ET using remote sensing Regional ET Estimation Model (REEM) from 2014 through 2016. Time series of NDVI clearly identified Fall and Spring-season onion crops in the Valley. REEM estimated Spring-season onion crop maximum ET of 973 mm in 2015 and 975 mm in 2016 during the growing season. These values compared reasonably well to ET estimates of 894 and 955 mm for the same periods (i.e. 2015 and 2016) using FAO-56 crop coefficient based method. The methodology presented could be used in other regions to identify onion crops and their consumptive water use.