ABSTRACT Forage biomass production and water storage (WS) was evaluated in 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) in annual (AH) and biennial (BH) harvest frequencies, in Quixadá and Tejuçuoca, Brazil. A randomized complete block design was used in a split-plot arrangement with four replications. In Quixadá, the maximum total forage biomass (TFB) recorded in the AH was 3,522.9 kg ha−1 yr−1 for the N/P2O5 combination of 134.6/190.0 kg ha−1 yr−1, and in the BH, the maximum TFB of 1,583.2 kg ha−1 yr−1 was recorded for the N/P2O5 combination of 114.6/136.8 kg ha−1 yr−1. In Tejuçuoca, the maximum TFB recorded in the AH was 9,783.0 kg ha−1 yr−1 for the N/P2O5 combination of 137.7/190.0 kg ha−1 yr−1, and in the BH, the maximum TFB of 12,124.0 kg ha−1 yr−1 was recorded for the N/P2O5 combination of 190.0/56.8 kg ha−1 yr−1. In Quixadá, the maximum WS recorded in the AH was 39.1 kg ha−1 mm−1 for the N/P2O5 combination of 161.0/190.0 kg ha−1 yr−1, and in the BH, the maximum WS of 11.3 kg ha−1 mm−1 was recorded for the N/P2O5 combination of 113.5/158.7 kg ha−1 yr−1. In Tejuçuoca, the maximum WS recorded in the AH was 196.1 kg ha−1 mm−1 for the N/P2O5 combination of 190.0/190.0 kg ha−1 yr−1, and in the BH, the maximum WS of 265.5 kg ha−1 mm−1 was recorded for the N/P2O5 combination of 190.0/10.0 kg ha−1 yr−1. To achieve the persistence and longevity of the cactus pear cv. Gigante, the management with BH and fertilization with the N/P2O5 combination of 114.6/136.8 kg ha−1 yr−1 (in regions similar to Quixadá) and N/P2O5 combination of 190.0/56.8 kg ha−1 yr−1 (in regions similar to Tejuçuoca) is recommended.

RESUMO A adubação balanceada é fator de importância comprovada na otimização do crescimento e produtividade das culturas. Objetivou-se avaliar o fluxo de biomassa e a eficiência de uso da chuva na palma forrageira cv. Gigante, adubada com combinações de doses de nitrogênio (10; 70; 100; 130 e 190 kg ha-1 ano-1 de N) e fósforo (10; 70; 100; 130 e 190 kg ha-1 ano-1 de P2O5), nas frequências de colheita anual e bianual, nas regiões de Quixadá e Tejuçuoca, no Ceará. Utilizou-se delineamento em blocos casualizados, em arranjo de parcelas subdivididas, com quatro repetições. Em Quixadá e Tejuçuoca, as combinações de N e P e frequências de colheita influenciaram as taxas de produções de diferentes ordens de cladódios e a eficiência de uso da chuva na palma forrageira. Em Quixadá, na colheita anual, verificou-se taxa de produção de forragem (TPF) de 10,3 kg ha-1 dia-1 na combinação N/P2O5 de 190,0/190,0 kg ha-1 ano-1 e na colheita bianual, observou-se máxima TPF de 4,6 kg ha-1 dia-1 na combinação N/P2O5 de 114,6/136,8 kg ha-1 ano-1. Em Tejuçuoca, na colheita anual, constatou-se máxima TPF de 30,0 kg ha-1 dia-1 na combinação N/P2O5 de 137,5/190,0 kg ha-1 ano-1 e na colheita bianual, registrou-se maior TPF de 38,0 kg ha-1 dia-1 na combinação N/P2O5 de 190,0/33,4 kg ha-1 ano-1. As taxas de produções de biomassa e eficiência de uso da chuva são otimizadas com o balanço de doses combinadas de nitrogênio e fósforo.

ABSTRACT Balanced fertilization is an important factor in optimizing the growth and productivity of crops. This study aimed to evaluate biomass flow and rain use efficiency in cactus pear cv. Gigante fertilized with combinations of nitrogen (10; 70; 100; 130 and 190 kg ha-1 year-1 N) and phosphorus (10; 70; 100; 130 and 190 kg ha-1 year-1 P2O5), in two harvest frequencies (annual and biennal), in the regions of Quixadá and Tejuçuoca, in Ceará. This was a split-plot randomized block design, with four replicates. In Quixadá and Tejuçuoca, the N and P combinations and harvest frequencies influenced the productions rates of different cladode orders and rain use efficiency in cactus pear. In Quixadá, in the annual harvest, the forage production rate (FPR) was 10.3 kg ha-1 day-1 in the N/P2O5 combination at 190.0/190.0 kg ha-1 year-1 and in the biennal harvest, the maximum FPR was 4.6 kg ha-1 day-1 in the N/P2O5 combination at 114.6/136.8 kg ha-1 year-1. In relation to the annual harvest in the municipality of Tejuçuoca, the maximum FPR was 30.0 kg ha-1 day-1 in the N/P2O5 combination at 137.5/190.0 kg ha-1 year-1 and in the biennal harvest, the maximum FPR observed was 38.0 kg ha-1 day-1 with the N/P2O5 combination of 190.0/33.4 kg ha-1 year-1. The biomass productions rate and rain use efficiency are optimized with the balance of combined levels of nitrogen and phosphorus.