Seasonal precipitation pattern analysis for decision support of agricultural irrigation management in Louisiana, USA

Authors: Sohoulande, Clement; CONGER, STACIA - LSU Agcenter; Szogi, Ariel; Stone, Kenneth; Martin, Jerry

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2021
Publication Date: 5/20/2021
Citation: Sohoulande Djebou, D.C., Conger, S., Szogi, A.A., Stone, K.C., Martin, J.H. 2021. Seasonal precipitation pattern analysis for decision support of agricultural irrigation management in Louisiana, USA. Agricultural Water Management. 254. https://doi.org/10.1016/j.agwat.2021.106970.
DOI: https://doi.org/10.1016/j.agwat.2021.106970

Interpretive Summary: Rainfed agriculture is often a challenge in many humid regions because of the irregular distribution of rains. Rainfall irregularity during crop growing seasons has a negative impact on crop yields. For that reason, many farmers compensate water deficits through irrigation. Because irrigation consumes valuable water resources, it is important to search water management strategies that improve rainwater use and reduce irrigation water withdrawals. However, rain patterns generally vary depending on locations and seasons. Therefore, a thorough understanding of crop exposure to water deficit during the seasons and locations is essential to improve agricultural water use efficiency. This study reports a framework that used seasonal rain patterns analyses to improve agricultural irrigation management at a regional scale. Specifically, a regionalization technique was applied to a 33-year data of seasonal rains totals and numbers of events in Louisiana to determine two rainfall regions with distinct characteristics. Within each region, functions were employed to approximate the actual probability distribution of seasonal rains. Estimates of crop water requirement for corn, soybean, cotton, grain sorghum, and sugarcane under both early and late planting scenarios were employed to evaluate the probabilities of crop exposure to water deficits during the growing seasons. The outcomes of this study, particularly the distinction of precipitation regions and the probabilistic evaluations are intended to support irrigation management recommendations for farmers across the state of Louisiana.

Technical Abstract: Rainfed agriculture is often a challenge in many humid regions due to the irregular distribution of precipitation events. Precipitation irregularity during crop growing seasons causes soil water deficits that negatively impact crop yields. To alleviate water stress, farmers are expected to compensate for water deficits through irrigation. Because irrigation consumes valuable water resources, it is critical to envision water management strategies that enhance precipitation water use and reduce irrigation water withdrawals. However, precipitation patterns generally vary depending on locations and seasons. Hence, a thorough understanding of crop exposure to water deficit in time and space is essential to improve agricultural water use efficiency. This study reports a framework that used seasonal precipitation patterns analyses to enhance agricultural irrigation management at a regional scale. Specifically, a spatial regionalization technique was applied to a 33-year gridded time series of seasonal precipitation totals and numbers of events in Louisiana to determine two precipitation regions with distinct characteristics. Within each region, kernel density estimators were employed to approximate the actual probability distribution of seasonal precipitations. Estimates of crop water requirement for corn, soybean, cotton, grain sorghum, and sugarcane under both early and late planting scenarios were employed to evaluate the probabilities of crop exposure to water deficits during the growing seasons. The outcomes of this study, particularly the distinction of precipitation regions and the probabilistic evaluation of crops exposure to water deficits are intended to support irrigation management recommendations for farmers across the state of Louisiana.