Establishment of Sufficiency Ranges to Determine the Nutritional Status of ‘Gigante’ Forage Cactus Pear—Macronutrients

Determining the sufficiency range of essential macronutrients in plants is of utmost importance for successfully diagnosing the crop’s nutrient demands, thereby improving fertilizer recommendations. The aim of this study was to establish the macronutrients ranges in the cladodes for the evaluation of the nutritional status of ‘Gigante’ cactus pear. Macronutrients contents of cladodes and dry matter yield in 72 plots were used. The experiment consisted of four cattle manure rates (0, 30, 60, and 90 Mg ha-1 year-1), three spacings (1.00 × 0.50, 2.00 × 0.25, and 3.00 × 1.00 × 0.25 m) and two production cycles, arranged in a 4 × 3 × 2 factorial in randomized blocks, and three replicates. Sufficiency ranges of plots with dry matter ≥ 19.93 Mg ha-1 cycle-1 were determined as well as the mathematical chance for plots with dry matter ≥ 23.75 Mg ha-1 cycle-1 and the critical level. The sufficiency ranges, critical level and mathematical chance are, respectively, for each nutrient in g kg-1- N, 12.7-18.5; 14.4; 15.5-19.7; P, 1.0-1.8; 1.0; 0.4-1.7; K, 31.6-44.1; 31.9; 33.7-39.7; Ca, 23.2-32.8; 24.6; 25.0-29.6; Mg, 9.5-14.3; 10.2; 7.4-14.0; and S, 1.1-2.0; 1,1; 1.0-1.8. The mathematical chance model was adequate for all macronutrients except for P and Mg which showed low sufficiency range values. Sufficiency range and critical level of nutrients are useful for diagnosing macronutrient contents and improving the nutritional status of ‘Gigante’ forage cactus pear.