Formas e estádios de aplicação de adubação nitrogenada no desenvolvimento e produtividade da soja

Abstract

Objetivou-se verificar o efeito da aplicação de Nitrogênio mineral (N) na dose de 10 kg por hectare, via solo ou foliar, em diferentes estádios do desenvolvimento da soja. O experimento foi conduzido em área de cultivo comercial de soja, localizado no município de Sinop-MT, em delineamento de blocos casualizados (DBC) com dez tratamentos e quatro repetições. Os tratamentos estudados foram: testemunha sem N, aplicação na semeadura, em V2 a lanço em cobertura, V2 via foliar, V4 a lanço em cobertura, V4 foliar, R1 a lanço em cobertura, R1 foliar, R2 a lanço em cobertura e em R2 foliar. Foram avaliadas as variáveis teor de clorofila, massa seca de parte aérea, numero de nódulos, massa seca de nódulos, número de vagens, número de grãos por vagem, massa de mil grãos e produtividade. Os tratamentos com aplicação de N diferiram da testemunha para todas as variáveis, exceto para teor de clorofila. Para as variáveis número de vagens por planta, número de grãos por vagem, massa de mil grãos e produtividade de grãos todos os tratamentos com aplicação de N foram superiores à testemunha e as maiores respostas foram obtidas quando o N foi aplicado via foliar nos estádios V2 e R1.

Side dressing nitrogen fertilization in soybean in association with inoculation

“…A similar result was reported by Goss et al (2002), who did not find a reduction in the dry mass of nodes with doses up to 60 kg ha -1 of N via soil. The mean values for shoot and root dry matter are similar to those found by Pereira et al (2018), in which the supplementary fertilization with 10 kg ha -1 of N via foliar application during the V2 and R1 stages of soybean was of higher efficiency in increasing the productivity of soybean grains when compared with the control treatment with inoculation.…”

“…The mean for shoot dry matter, root dry matter, number of pods, number of seeds per pod, and mass of 1,000 grains -for which the inoculation treatments were statistically superior to the non-inoculation treatments -were similar to the values found by Pereira et al (2018). The authors found that the supplemental fertilization with foliar application of N (10 kg ha -1 ), in the stages V2 and R1 of soybean, wsd more efficient in increasing grain yield when compared with the control treatment with inoculation.…”

“…Thus, within the range of the studied nitrogen variation, the stem diameter increases linearly at the rate of 0.0131 mm for each kg of N, until the dose of 40 kg ha -1 . Pereira et al (2018), in turn, observed a significant difference in stem diameter with soil and foliar application in the R1 stage with doses of 10 kg ha -1 , but not with the application at the V4 stage. Notably, the larger stem diameter increases the plant's tolerance to tipping due to mechanical or environmental damage (RAIMUNDI, MOREIRA, TURRI;.…”

“…The experiment was carried out between October 2021 and February 2022, in a commercial area of soybean production in the municipality of Ipiranga do Norte, in the state of Mato Grosso (15° 35' 14" South, 56° 5' 51" West, 213 m altitude). The climate of the region is of type Aw according to Köppen classification (1948), characterized by the presence of two well-defined seasons, a rainy season (from October to April) and drought season (from May to September), and by the small annual thermal amplitude, with monthly averages ranging from 24°C to 27°C (PEREIRA et al, 2018). Figure 1 shows the means of the meteorological data of maximum temperature, average temperature, minimum temperatures, and rainfall (mm) accumulated during the period of the experiment, obtained by the meteorological station of the Brazilian Agricultural Research Corporation (Embrapa), the Agrosilvopastoral Unit, located in the municipality of Sinop, in the state of Mato Grosso, 160 km from the experiment.…”