Methodological aspects of soil sampling for local fertigation of vineyards in the Southern Steppe of Ukraine

Abstract

The article presents the results of research aimed atimproving the methodology of soil sampling for an objectiveassessment of nutrient availability in vineyards underlocal fertigation conditions. The relevance of the study isdetermined by the spatial heterogeneity of moisture andnutrient distribution in the root zone caused by drip irrigationand localized fertilizer application, which complicatesthe interpretation of agrochemical soil analysis. Purpose:to improve the methodology for selecting soil samplesfor an objective assessment of soil nutrient supply invineyards under local fertigation conditions. Methods.Sampling was carried out in accordance with the requirementsof national standards, ensuring representativenessof the sample. In soil samples, the reaction of thesoil solution (pH), the content of mobile forms of nitrogen,phosphorus and potassium were determined using currentstandard methods. Phenological observations, recordingof growth processes and assessment of biometric indicatorswere carried out using generally accepted methods inviticulture. Results. The research was conducted in thesouthern Steppe zone of Ukraine on irrigated table grapevineyards. The effect of soil sampling location relative to the vine row and inter-row spacing on soil reaction(pH) and the content of available nitrogen, phosphorus,and potassium was investigated. The correspondencebetween soil diagnostic data and nutrient content in planttissues was also evaluated using leaf tissue analysis.The results showed pronounced spatial gradients of soilpH and nutrient content under fertigation. Soil pH valuesincreased from 6.7–6.9 in the vine row to 7.1–7.2 in thecentre of the inter-row. The content of nitrate nitrogen inthe vine row exceeded that in the inter-row by 4–6 times,available phosphorus by 2.0–2.5 times, and potassium by10–30 %. At the same time, tissue diagnostics indicated aconsistently high level of plant nutrient supply, with nitrogencontent of 3.69–4.41 %, phosphorus 0.10–0.18 %,and potassium 0.82–1.14 %. Сonclusion. It was establishedthat soil sampling in the vine row near the dripirrigation line provides the most representative data ongrapevine nutrient status, whereas sampling in the centreof the inter-row under fertigation conditions is methodologicallyunjustified. The obtained results can be used tooptimize soil diagnostic approaches and improve nutrientmanagement systems in irrigated vineyards.