Soil Testing and Plant Analysis Relationships for Irrigated Chile Production.

In a field study of irrigated chile (Capsicum annum L.) production in southeastern Arizona and southwestern New Mexico from 2008 through 2009, soil and tissue test samples were analyzed for a full spectrum of nutrients at 16 different sites, including nitrogen (N) phosphorus (P), potassium (K), zinc (Zn), iron (Fe), and boron (B), with the objective of evaluating soil and tissue nutrient testing procedures and establishing basic testing guidelines and recommendations with respect to yield potentials.  Soil samples were collected before planting. Plant tissue samples for all plots were collected at the following four stages of growth: first bloom (FB), early bloom (EB), peak bloom (PB), and physiological maturity (PM).  All fertilizer and nutrient inputs were monitored, managed, and recorded within current Extension guidelines for irrigated chiles. Results for soil and tissue analysis were correlated to yield results. The results provide estimates for baselines which can be tested through subsequent calibration experiments for the development of recommendations for critical soil and tissue test values.  Minimum soil test nutrient values were identified as 10 ppm P, 110 ppm K, 0.3 ppm Zn, 2.0 ppm Fe, and 0.25 ppm B.  Minimum FB tissue test values were 0.2% P, 4.5% K, 10 ppm Zn, 80 ppm Fe, and 30 ppm B.  These soil test and plant nutrients values will be evaluated in subsequent experiments in an effort to better define fertilizer nutrient inputs in order to gain better nutrient management efficiencies in irrigated chile production systems.