Teor de macronutrientes e produtividade da soja influenciados pela compactação do solo e adubação fosfatada

Abstract

R E S U M OO objetivo neste trabalho foi avaliar a influência da compactação e adubação fosfatada sobre o teor de macronutrientes e produtividade de grãos de soja na Chapada dos Parecis-MT. O estudo foi realizado em Latossolo Vermelho, em delineamento em blocos casualizados, esquema fatorial 2x4x4 e três repetições, sendo duas formas de adubação fosfatada (a lanço e no sulco), quatro doses de P 2 O 5 (0, 50, 100 e 150 kg ha -1 ) e quatro estados de compactação (PT0, PT2, PT4 e PT8 -semeadura direta com compactação induzida por tráfego de trator em zero, duas, quatro e oito passadas, respectivamente). A compactação, a forma de adubação e as doses de P 2 O 5 influenciaram a disponibilidade de fósforo no solo e a absorção do elemento pela planta, sendo que nos sistemas mais compactados adubados a lanço os teores de P na soja ficaram abaixo dos limites considerados adequados. A compactação reduziu os teores N, P, Ca e Mg e aumentou ou teores de K e S e as doses de P 2 O 5 aumentaram os teores de Mg da parte aérea da soja. A adubação a lanço em áreas compactadas reduziu a eficiência da adubação fosfatada com consequente redução da produtividade de grãos da soja.Palavras-chave: adubação a lanço, Glycine max, nutrição mineral, resistência do solo à penetração. A B S T R A C TThe objective of this study was to evaluate the influence of compaction and phosphorus fertilization on the macronutrient tenor and productivity of soybeans in Chapada dos Parecis-MT. The study was conducted on Latossolo Vermellho, in a randomized block design, factorial 2x4x4 and three repetitions, two forms of phosphorus fertilization (broadcasted and groove), four doses of P 2 O 5 (0, 50, 100 and 150 kg ha -1 ) and four compaction levels (PT0, PT2, PT4 and PT8 -tillage with compression-induced tractor traffic at zero, two, four and eight strides, respectively). Compaction, the form of fertilizer and P 2 O 5 levels influenced the availability of phosphorus in the soil and the absorption of the element by the plant, and in the more compressed systems fertilized by throwing the P levels in soybeans were below the limits considered appropriate. The compaction reduced N, P, Ca and Mg and increased or K and S and P 2 O 5 doses increased the Mg content of the soybean shoot. Fertilization by throwing in compacted areas reduced the efficiency of phosphorus fertilization with consequent reduction in soybean yield.

Soybean Agronomic Performance and Soil Physical Attributes Under Tractor Traffic Intensities

“…The 0.00-0.10 m layer showed low mean values of macroporosity with 6 and 12 passes (0.07 and 0.08 m 3 m −3 ), which is lower than the minimum adequate for liquid and gas exchange between the external environment and soil (0.10 m 3 m −3 ) and considered critical for root growth in most crops. In this sense, Rossetti & Centurion (2013), Valadão et al (2015), and Valadão et al (2017), in studies carried out on clayey dystrophic Red Latosol, and Bergamin et al (2010), with a clayey dystroferric Red Latosol, found macroporosity values of 0.08 and 0.09 m 3 m −3 , respectively, after 6 tractor passes in the 0.00-0.10 m layer.…”

“…In addition, no water deficit was observed in the soil under no-tillage during the final stage of soybean filling (Figure 2). This increase in stem diameter and agronomic performance of soybean with 12 passes suggest that a possible compaction with traffic intensification could increase water retention, especially under water restriction, without risk of faster drying of the soil surface, preventing seedlings from deepening the roots and absorbing water in the soil profile (Valadão et al, 2017). Twelve 12 passes led to increases of 63.…”

“…Kirnak et al (2017) and Sivarajan et al (2018) found that the intensification of machinery traffic increased soil penetration resistance and density in the subsurface soil layer, with reduced plant height and soybean stem diameter, but without an effect on grain yield. On the other hand, Valadão et al (2017) found a decrease in soybean grain yield after four tractor passes.…”

“…These changes limit root growth and the area explored by the roots (Secco et al, 2009), reduce water and nutrient absorption (Valadão et al, 2017), hinder gas exchange for infiltration/drainage, decrease the infiltration rate and water flow in the soil (Zambrana et al, 2010), reduce growth (Kirnak et al, 2016) and soybean yield components (Trentin et al, 2018), and may decrease grain yield (Valadão et al, 2017).…”

The Influence of Oxisol Physics Parameters on Dry Matter Production in Grasses of Brachiaria Genus

“…The impact in the soil may compromise the growth of grasses, as a result of a mechanical barrier caused by compacted layers, resulting in a smaller portion of soil being explored by the roots and consequently less water and nutrients absortion by the plants (Richart et al, 2005(Richart et al, ). 2013Valadã o et al, 2015), leaf area reduction (Foloni et al, 2003), reduction in plant's height and lower aerial biomass production (Santos et al, 2013;Labegalini et al, 2016;Rosa et al, 2019) and lower levels of N, P, Ca and Mg in leaves (Valadã o et al, 2017).…”