Lodo da indústria de gelatina e ureia na adubação de forrageiras tropicais

Abstract

Pasture is the traditional diet of cattle and is their main source of nutrients. However, pasture fertilization is essential to ensure productivity, quantity, and quality of forage. Thus, the use of waste such as gelatin sludge, which has some nutrients similar to mineral fertilizers, is a low-cost alternative with potential as a nitrogen fertilizer. With this in mind, the aim of the study was to identify the main changes in the productivity and nutritional value of Massai and Marandu grasses because of using gelatin sludge as a source of nitrogen fertilizer. The experiment was conducted in a greenhouse with five treatments: three doses of gelatin sludge (0, 200, and 300 m3 ha-1 ), one organomineral treatment (sludge: 100 m3 ha-1 + 60 mg dm-3 N), one mineral fertilizer treatment (100 mg dm-3 N) in a completely randomized experimental design with six replications. Pot with a capacity of 6 dm-3 were used, filled with Red-Dystrophic Latosol, clay textured. The sludge was incubated in the top 5 cm of soil. The seeds were planted directly into the pots and fertilized them with simple superphosphate (300 mg dm-3 ). Fifteen days after emergence. The crop was thinned to five plants per pot. The uniformity cut was made twenty days following the thinning. Plant and stem height, tiller number, leaf number, leaf/stem ratio, chlorophyll index, dry mass (leaves, roots, and residue), crude protein content, indigestible neutral detergent fiber, neutral and acid detergent fiber, macronutrients, and micronutrients were all assessed. The Massai grass showed the greatest plant height with mineral fertilizer. Fertilizing with organomineral recorded the highest number of tillers. The dose of 300 m3 ha-1 promoted the highest number of green leaves and leaves per tiller and chlorophyll index. Leaf dry mass, total dry mass production, and root dry mass were influenced by nitrogen fertilization, with higher values for these variables in the mineral treatments. The P and Mg content varied (P<0.05) in the doses of 0, 200, and 300 m3 ha-1 gelatin sludge when compared to organomineral and mineral, and the K, B, Cu, Fe, Mn, and Zn content in the leaf tissue were not affected (P>0.05) by nitrogen fertilization in all treatments. In the case of Marandu grass, there was a linear effect for the doses of gelatin sludge on plant height, stem, number of tillers, leaves, leaves per tiller, and leaf/stem ratio, and when compared to the highest dose (300 m3 ha-1 ), there was no difference for the variables plant height, number of green leaves, and leaves/tiller. The dry mass of the leaf, stem, aerial part, and total dry mass production also showed a linear adjustment for the doses of gelatin sludge, with higher values being observed for these variables with mineral fertilizer when compared to the higher doses of gelatin and organomineral. Crude protein showed a positive linear effect, and there was a reduction in neutral and acid detergent fiber. The levels of P, Mg, S, Cu, and Fe were not influenced by the doses of gelatin sludge, but the highest dose showed an increase in P levels when compared to the organomineral and mineral doses. The DLG dose of 300 m3 ha-1 applied after cutting to Massai and Marandu grasses affects stem height, number of leaves, leaves/tillers, and chlorophyll index. The growth and development of the aerial part of Marandu grass are stimulated by the application of DLG 300 m3 ha-1 after cutting, with a linear increase in biomass production and nutritional value compared to DLG 0 and 200 m3 ha-1 . The mineral fertilizer provides a higher concentration of N, increasing the CP content, but the CP contents of the organomineral and DLG 300 are within the recommended range, and there is no change in the levels of NDF and ADF in the dry matter of Massai and Marandu grasses.