Published in Scientific Papers. Series "Management, Economic Engineering in Agriculture and rural development", Vol. 22 ISSUE 4
Written by Mihai Valentin HERBEI, Florin SALA

The study used the technique based on remote sensing to analyze and study the dynamics of an alfalfa crop and to estimate the production of fresh biomass in the climatic conditions of the agricultural year 2021-2022. Alfalfa culture in year III, was under non-irrigated cultivated conditions, in the perimeter of DER, University of Life Sciences "King Michael I" from Timisoara, Romania. A period between March 22 and July 23, 2022 was considered, the period during which 14 sets of images from the Sentinel 2 system were acquired. Based on the spectral information contained in the images, the MSAVI, NDMI, NDVI and NBR indices were calculated to characterize the dynamics of the alfalfa crop and estimate the production of fresh biomass. Three harvests (mowing) were made, on May 25 with a production of 10 t ha-1 fresh biomass, on July 1 with a production of 7.5 t ha^-1 fresh biomass and on July 26 with a production of 7.5 t ha^-1 fresh biomass. Spline models have described most accurately and under statistical safety conditions ( for MSAVI; for NDMI; for NDVI; for NBR) the dynamics of the indices calculated in relation to the time during the study period, also associated with the moments of fresh biomass harvested. The regression analysis facilitated obtaining predictive models of fresh biomass production, under statistical safety conditions (RMSEP=0.019289 for the combination of MSAVI and NDMI). 3D and isoquants graphic models described the variation of biomass production in relation to the pairs of indices used in the analysis.

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