Nutritional efficiency modulated by nitrogen, phosphorus and harvest frequency in cactus pear

This study aimed to evaluate the nutrient utilization efficiency indexes by cactus pear cv. Gigante, fertilized with combinations of nitrogen (10, 70, 100, 130 and 190 kg ha-1 yr-1 N) and phosphorus (10, 70, 100, 130 and 190 kg ha-1 yr-1 P2O5) under two harvest frequencies (annual and biennial), in Quixadá and Tejuçuoca, Brazil. A randomized complete block design was adopted in split-plot arrangement with four replications. The combinations of levels of N and P influenced the nutritional efficiency indexes of the cactus pear cv. Gigante in the conditions of Quixadá and Tejuçuoca, in both harvest frequencies. In Quixadá, in the annual harvest frequency, the decreasing sequence of macronutrients utilization efficiency was: P > S > Mg > N > K > Ca. In the biennial harvest, the sequence was: P > N > Mg > S > K > Ca. In Tejuçuoca, in the annual harvest frequency, it was observed the following decreasing sequence of macronutrients utilization efficiency: P > Mg > S > N > K > Ca. In the biennial harvest, the observed sequence was: P > Mg > N > Ca > S > K. For both studied regions, in both harvest frequencies, annual and biennial, it was observed higher utilization efficiency for the micronutrient Zn and lower for Mn, with intermediate values for B > Fe. Low values of recovery of the applied nitrogen (ANR) and phosphorus (APR) were observed in the different environmental and management conditions, except for ANR in Tejuçuoca in the annual harvest. Generally, the combined levels N and P improve the recovery and agronomic efficiency of the N and P applied in both harvest managements in the regions of Quixadá and Tejuçuoca. The nutritional efficiency indexes in the cactus pear cv. Gigante vary with the harvest frequencies, in the semi-arid conditions.