Ryegrass management in lowland areas on the establishment and development of soybean in succession

The objective of this work was to determine the effect of desiccation and haymaking periods in the off-season on the quality of hay produced and nutrient accumulation, as well as to quantify the effects of remaining dry mass on the establishment and development of soybean in lowland areas. The experiment was conducted in the field in the 2015/16 and 2016/17 growing season in the lowland area of the Federal University of Santa Maria, Rio Grande do Sul, Brazil. Two treatments of ryegrass management (hay and desiccation) in five periods and one fallow period were tested. The study implemented an experimental randomized block design. The following variables were measured in the off-season: ryegrass dry shoot mass, hay quality parameters, moisture and nutrient content in the soil. In addition, the initial population of plants, dry shoot mass, nodule dry mass and grain yield were determined in the soybean. The cultivation of ryegrass hay in lowland area is a viable alternative. However, it reduces the potassium content in the soil if it is not replaced by fertilization. The use of ryegrass, regardless of the period of haymaking or desiccation, increases the water retention in the soil, which promotes straw wrapping and/or mirroring of the soil in a year of elevated precipitation, with a consequent reduction of the initial plant population and soybean grain yield when compared to the fallow system.