Dinâmica do estrato herbáceo-subarbustivo em áreas de caatinga pastejadas por caprinos associada a adubação fosfatada do solo

Abstract

The Caatinga has a diversity of native species and high availability of plants of forage interest, however the structure and plant production vary according to environmental conditions and management. In order to evaluate the Caatinga under different doses of phosphate fertilization, from May 2019 to June 2020, an experiment was conducted at the Experimental Station of São João do Cariri, belonging to the Center for Agricultural Sciences of UFPB, in the city of São João do Cariri. The total experimental area used was 9.6 hectares, divided into three sub-areas of 3.2 hectares, which were submitted for 10 years (2007 to 2017) to different grazing intensities by goats: 10; 5 and; area without animals. During the experimental period there were no animals in the areas. For evaluation, each area was subjected to 4 treatments (control, 30, 60 and 90 kg of P2O5/há), these presented in five transects, three transects that received phosphate fertilization with 400m² (2m wide x 200m long) and two transects (control) with shorter length and minimum distance of 5 m so as not to be influenced by fertilization, where 10 samples were collected in each treatment, totaling 120 samples each month. After separation and identification, the species that showed greater availability (Aristida adscensionis, Diodia teres, Malvaceas and the Pool) were evaluated for frequency, dominance and forage mass. Fertilization promoted an increase in forage mass production in areas of Caatinga do Cariri in Paraíba, with emphasis on the dose of 90 kg of P2O5/há in 2020. At the month of April 2020 presented the highest mass production. Aristida had the highest frequency and dominance among species, while Diodia had the lowest relative frequency value in area 2 with 16.28%. For dominance, Aristida showed superiority among species, with an average of 30.50% in the evaluated areas. Assessing the relationship between year and species, the first two main components contributed with 89.1% to data variation. It was observed, greater availability of Aristida in area 2 in the year 2020 with an average of 58.293 g/m². Considering the relationship between year, area and P2O5 dose, the control treatment for the year 2019 had a lower forage mass value. In this sense, the doses of phosphate fertilization, together with high precipitation, promoted, regardless of the use of the area, a greater production of forage mass.