Sampling variability of petiole nitrate in irrigated cotton

Abstract

Sampling variability of petiole nitrates was evaluated on commercial, furrow‐irrigated cotton fields in southern Arizona. Analysis of individual petioles shows that sampling from the first mature leaf is best and when the maturity of the leaf is in question, it is better to sample the next older leaf. Field sampling methods used by a growers’ association were evaluated and confidence levels of their estimations were determined.