Efecto del volumen de rastrojo remanente en el logro de resiembra de raigrás

This study addresses the dynamics of natural reseeding of annual ryegrass (Lolium multiflorum Lam.), focusing on the effect of summer fallow management through different levels of crop residue. The importance of this topic lies in optimizing ryegrass establishment via the seed bank, thus reducing costs and improving system sustainability.

The main objective was to evaluate whether the amount of residue left on the soil surface affects final plant establishment, to understand how it modifies environmental conditions (temperature, moisture, and radiation) during summer, and how this, in turn, influences seed dormancy dynamics, germination, and plant establishment from the seed bank.
The experiment was conducted from December 5, 2022, to April 3, 2023, at the INIA Glencoe Experimental Unit, located in the department of Paysandú (Latitude 32.02°S; Longitude 57.16°W). Sample processing was carried out at the Pasture Laboratory of INIA Tacuarembó (Route 5, km 386). A randomized complete block design (RCBD) was used, with four blocks and four treatments, resulting 16 experimental units (rectangular plots measuring 2 x 5.5 meters). Soil variables were measured (temperature at 1 cm and 3.5 cm depth, moisture at 3.5 cm and 20 cm), as well as intercepted radiation, seed dormancy status over time, final establishment percentage, and biomass production.

Results showed that higher residue levels created a moister and cooler surface environment, with greater interception of photosynthetically active radiation. Despite significant differences in soil temperature and moisture among treatments, no effects on the progression of seed dormancy were observed. Regardless of these environmental variations, the seed bank remained largely conserved until early March. In terms of germination, treatments with higher residue levels promoted earlier emergence, although this did not result in significant differences in the final number of established plants.

It is concluded that summer residue management alters soil conditions and may advance germination timing, but does not significantly affect autumn plant density. Therefore, under the evaluated conditions, residue volume did not result in clear agronomic advantages for ryegrass reseeding.