Mixture of tropical forage grasses in pastures: agronomic and ecological aspects related to herbage production and productivity

Abstract

Forage grasses may be combined into functional groups (e.g. contrasting growth and perennation strategies) in such a way that when cultivated in associations they can result in reduced intra-annual variation in herbage production and maximize production potential of the system. In addition, the association can also favor plant biodiversity and augment the environmental services provided by the pastoral ecosystem. In spite of that, knowledge and information regarding tropical forage plants area almost nonexistent since the large majority of published material was produced in temperate and subtropical conditions. The objective of this project is to evaluate the stability; productive potential; tiller population dynamics; vertical distribution of botanical and morphological components in sward canopy; morphogenesis; root mass, distribution and growth; microbe diversity in the soil; soil physical and chemical traits; GHG emissions; nitrogen nutrition index; short term intake rate and nutritive value of the consumed herbage of a C4 grasses association relative to their monoculture. The three-consecutive pasture-growing seasons field experiment (February, 2020 - April, 2022) will be conducted at ESALQ/USP, Piracicaba, SP, as part of a thematic project to be carried out from January 2020 to December 2024. Treatments will correspond to three tropical forage grasses (Andropogon gayanus cv. Planaltina, Brachiaria brizantha cv. BRS Piatã and Panicum maximum cv. Massai) cultivated in monoculture and in association (the three species in equal proportions based on the number of viable seeds), and will be allocated to experimental units (180 m2 paddocks) according to a randomized complete block design, with four replications. All pastures (monocultures and association) will be managed under rotational grazing using the pre-grazing target height target of 35 cm and the post-grazing target height target equivalent to 50% of the pre-grazing height (17.5 cm). The data will be analyzed using the PROC MIXED of the SAS® 9.4 statistical package and, when appropriate, means comparison will be made using Student's "T" test with P<0.05. (AU)