Taxa de crescimento e produção de forragem pela cana-de-açúcar RB867515

Abstract

Sugarcane has been widely used in cattle feed, and among the managerial and agricultural techniques proposed to increase sugarcane productivity, correction of soil acidity, adequate supply of nutrients, green manure or organic matter, planting more productive varieties and controlling pests and weeds. In the present work, nutrient cycling by sunn hemp, nutritional status and forage production by the RB867515 variety, in an intensive production system, were evaluated in sugarcane aged one and a half years. The crop that preceded the planting of sugarcane was sunn hemp, with the aim of improving the physical-chemical and biological properties of the soil. Right after the first spring rains, the soil was plowed, harrowed and subsoiled, followed by sowing sunn hemp. In February of the year following sowing, when sunn hemp was in the hard farinaceous grain phase, the accumulation of dry matter and nutrients in the aerial biomass of the legume was evaluated. Next, sunn hemp was incorporated into the soil, furrowing the land for planting sugarcane. Phosphate fertilizer was applied at the bottom of the planting furrow at a dose equivalent to 100 kg of P per hectare, followed by planting RB867515. In October, when the rainy season started again, potassium fertilizer was applied at a dose of 200 kg per hectare. Samplings to determine the rates of matter accumulation in the aerial part of RB867515 were carried out in five periods: October, December, February, April and July. In December, with the sugarcane in the maximum growth phase, the nutritional status of RB867515 was evaluated. In July, about a year and a half after planting, when the sugarcane was mature, the production of forage and industrialable stems was evaluated. Descriptive statistics (mean, minimum and maximum) were used for nutrient cycling by sunn hemp, while for dry matter accumulation an equation was obtained relating plant age to dry matter accumulation. Green manuring with sunn hemp in the area where RB867515 was implemented resulted in improvements in the physical, chemical and biological properties of the soil. The most recycled elements by sunn hemp were nitrogen and potassium, with average values of 319 and 245 kg per hectare, respectively. RB867515 had nutrient content in the leaf +3 considered adequate. In the production system adopted, the RB867515 had high productivity, with forage accumulation exceeding 160 t of natural matter per hectare, about 50 t of dry matter per hectare.

Keywords: Production systems, forage, family farming, sustainability.