Evapotranspiration losses for pepper under plastic mulch and shallow water table conditions

Use of literature crop coefficient (K (c)) values for quantifying evapotranspiration (ETc) under non-standard conditions such as plastic mulch, shallow water table, and sub-tropical conditions can lead to inaccurate ETc estimates. A 5-year experiment was conducted for fall crop growing seasons in south Florida to quantity bi-weekly ETc and K (c) for bell pepper grown under shallow water table and plastic mulch environments using large drainage lysimeters. The ETc values varied from 205 to 320 mm with a seasonal average of 267 mm. Average K (c) values for bell pepper for development, mid-season, and late stages were 1.05, 1.21, and 1.28, respectively. Higher than literature initial K (c) values were due to rainfall and use of sub-irrigation system to maintain artificially high water table which results in high soil moisture in the bare soil area-such high moisture results in high evaporation. The K (c) values from this study were statistically higher than literature values. Use of literature K (c) values resulted in underestimating ETc by 27-37%. The K (c) values would provide improved estimates of sub-irrigated pepper ETc in subtropical Florida and elsewhere with similar environment.