Integrating in-field measurements and remote sensing for improved resource use efficiencies in irrigated potato

Abstract

Precise management of input resources is important for economic and ecological sustainability of irrigated production systems in semi-arid climates. Resource use efficiencies vary substantially among potato (Solanum tuberosum L.) growers producing under relatively similar environmental conditions in South Africa. Determining the exact factors responsible for the substantial variability in resources use efficiency among irrigated potato fields can be instrumental in recommending better management options. The adoption and implementation of better resource management practices such as irrigation scheduling, use of decision support tools and remote sensing for effective crop monitoring is still lacking among potato growers partly due to a lack of awareness and knowledge. The aim of this study was to investigate the potential of combining in-field measurements, remote sensing, and yield prediction models to improve potato crop management and resource use efficiency. Detailed measurements were conducted in 30 commercial irrigated potato fields located in three production regions of South Africa from 2016 to 2022. Information, including water and nutrient inputs, drainage, nutrient leaching, crop growth variables, soil water dynamics and satellite-based normalized difference vegetation index (NDVI) was obtained during the various cropping seasons over the years. The variability in resources use efficiency, radiation use efficiency (RUE), the potential of estimating final tuber yield and crop evapotranspiration (ET) of potato from satellite-based NDVI, and soil water dynamics were assessed. Tuber yields varied among fields (35 – 118 t fresh tuber ha-1; 7.5 – 25 t tuber dry matter ha-1). The variation in tuber yields partly explained the variability in water and nutrient use efficiencies among fields. Moreover, differences in crop management decisions, soil type and weather conditions contributed to variations in water and nutrient use efficiencies. Radiation use efficiency of potato was not constant during the different growing seasons due to the negative effect of high maximum temperatures (> 30 oC) and high total solar radiation (> 25 MJ m-2 day-1). Satellite-based NDVI acquired at 75 days after planting and onwards was strongly associated with final tuber yield (R2 > 0.70; p < 0.05), and therefore, could be used to accurately estimate final tuber yield before harvest. Additionally, the satellite based NDVI showed potential of estimating potato crop coefficients and evapotranspiration (ET), which can be used to manage irrigation. Soil water storage and soil water deficit information of loamy sand and sandy soils indicated incidences of excessive water inputs in some fields and soil water shortages in others. It can be concluded that a combination of in-field measurements and remote sensing can provide useful information for the effective management of input resources in irrigated potato fields. This study highlights the potential of combining detailed field measurements with remote sensing data to achieve effective input resource management in irrigated potato production. By integrating these two sources of information, it may be possible to implement smart management strategies that optimize the use of resources and improve overall efficiency in a cropping system. The findings of this study demonstrate the value of using these integrated data sources to inform decision making and improve the sustainability of irrigated potato production systems.