Liquid fertilization and conventional fertilization on soil fertility and agronomic and morphophysiological characteristics of Brachiaria brizantha cv. Braúna grass
State University of Southwest of Bahia, BR45700-000, Itapetinga, Bahia, Brazil
*Correspondence: ingriidyduutra@gmail.com
Abstract:
The objective of this study was to evaluate the effect of liquid and conventional fertilization on soil fertility, assessed by regrowth, and on the morphophysiological characteristics of Brachiaria brizantha cv. Braúna. The experiment was conducted in a greenhouse at the State University of Southwest Bahia, in Itapetinga-BA, from December 2018 to April 2019. The experimental design adopted was completely randomized, with four replicates, totaling 24 experimental units, in a 2×3 factorial scheme, comprising two types of fertilization (liquid and conventional) and three regrowths, with cutting intervals of 21 days. The results revealed that conventional fertilization promoted an increase in the levels of calcium (Ca) and phosphorus (P) in the soil, which, in turn, positively impacted the sum of bases and base saturation, reaching values of 5.6 cmolc dm-3 and 54%, respectively, in the first regrowth. The dry mass production of the aerial part was influenced by both regrowth and the type of fertilization. A 27% reduction in dry mass production was observed from the first to the second regrowth, and a 16% reduction from the second to the third. On the other hand, conventional fertilization provided a 20% increase in dry mass production. The morphological variables of the plant were influenced by regrowth, with the exception of the leaf appearance rate (LAR), which did not present significant variations. A reduction in the other morphological variables was observed with each regrowth. Fertilization, in turn, influenced only the length of the flagellum leaf (LFL) and the total length of the tiller (TTL). The interaction between regrowth and fertilization was significant for leaf area, specific leaf area, leaf area index and leaf area ratio. The SPAD index, chlorophyll b and total chlorophyll contents were influenced by regrowth, with a progressive increase with each regrowth. Conventional fertilization promoted an increase in the SPAD index, with a value of 35.53, compared to 33.51 for liquid fertilization. The interaction between regrowth and fertilization was significant for the chlorophyll a:b ratio and carotenoids. The chlorophyll a:b ratio decreased with each regrowth. Conventional fertilization resulted in a 1.04% increase in crude protein content compared to liquid fertilization. Dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF) and ash contents were influenced by regrowth, with a progressive increase with each regrowth, except for ash, which showed a reduction. Regrowth demonstrated greater influence on the productive and morphophysiological characteristics of braúna grass. Conventional fertilization is recommended to promote improvements in soil fertility and increase the crude protein content of signal grass Brachiaria brizantha cv. Braúna.
Key words:
liquid fertilizer, nutritional composition, plant morphology, regrowth