Performance of soybean in hydromorphic and nonhydromorphic soil under irrigated or rainfed conditions

Abstract

-The objective of this work was to evaluate soybean cultivation in a hydromorphic or nonhydromorphic soil, with or without supplemental irrigation. Field experiments were carried out with the TECIRGA 6070RR and A 6411RG cultivars in highlands (nonhydromorphic soils) and lowlands (hydromorphic soils), which are traditionally cultivated with irrigated rice. The following parameters were determined in both soybean cultivars: leaf area index, developmental stages, dry matter partition, and leaf gas exchange. Low water stresses, which commonly occur either by deficit or excess in soybean areas cultivated in hydromorphic soils, do not affect the development and partitioning of dry matter; however, they cause reductions in stomatal conductance, photosynthetic rate, and leaf area evolution. Growing soybean in lowlands exposes plants to water stress, even in years with well-distributed rainfall during the growing season, due to the low water storage capacity of these soils.Index terms: Glycine max, gas exchange, irrigation, lowlands. Desempenho da soja cultivada em solo hidromórfico e não hidromórfico com ou sem irrigaçãoResumo -O objetivo deste trabalho foi avaliar o cultivo de soja em solo hidromórfico ou não hidromórfico, com ou sem irrigação suplementar. Experimentos em campo com as cultivares TECIRGA 6070RR e A 6411RG foram realizados em terras altas (solos não hidromórficos) e em terras baixas (solos hidromórficos), que são tradicionalmente cultivadas com arroz irrigado. Determinaram-se, nas duas cultivares de soja, os seguintes parâmetros: índice de área foliar, estágios de desenvolvimento, partição de matéria seca e quantificação das trocas gasosas em nível foliar. Pequenos estresses hídricos, que comumente ocorrem por deficit ou excesso em áreas de soja cultivada em solo hidromórfico, não influenciam o desenvolvimento e a partição de matéria seca; porém, provocam reduções da condutância estomática, da taxa fotossintética e da evolução da área foliar. O cultivo de soja em solos hidromórficos faz com que as plantas sejam expostas ao estresse hídrico, até mesmo em anos com precipitação de chuvas bem distribuída ao longo da estação de crescimento, em razão da baixa capacidade de armazenamento de água desses solos.Termos para indexação: Glycine max, trocas gasosas, irrigação, terras baixas.

Biophysical and management factors causing yield gap in soybean in the subtropics of Brazil

“…Precipitation in BZs III, IV, and V were also close to 600 mm, but with larger variability during the growing season, with standard deviation above 200 mm (Figure 4d). Buffer zones VI, VII, and IX had lowest Ya and precipitation of around 400 mm, in addition to shallow soils with low water storage capacity (Da Rocha et al, 2017;Sartori et al, 2016;Streck et al, 2008).…”

Irrigation Water Management Techniques for Lowland Furrow-Irrigated Soybean in Southern Brazil

“…Compared with the results obtained by (3,565 kg ha -1 in the 2014/15 growing season) and Fin et al (2018) (over 4,000 kg ha -1 in the 2015/16 growing season), who also used raised seedbeds in lowlands, however, both seasons without water deficit due to regular rainfall distribution, the grain yield (3,361.3 kg ha -1 ) obtained in this study with non-irrigated soybean indicates the risk of grain yield losses in years with irregular or insufficient rainfall, without an irrigation system. Rocha et al (2017) attribute the highest risk of water stress in lowlands to the low water storage capacity of these soils.…”

“…Water supplementation for soybean crop in lowland fields is an important strategy. Rainfall variability in the southern half of Rio Grande do Sul (RS) and the low storage capacity of water in lowland soils, owing to successive soil preparations for irrigated rice, justify the use of an irrigation system (Zanon et al, 2016;Rocha et al, 2017). The water catchment and conduction structures used for rice irrigation in these areas favor the adoption of surface irrigation systems for soybean, as this minimize initial investments and facilitate the return of rotation with rice crops.…”

Water balance for determination of excess water in soybean cultivated in lowland soils

“…High demand for vegetable protein and favorable economic condition enables the expansion of soybean cultivation in areas that were not traditionally cultivated, i.e., the lowland areas in southern Brazil (Rocha et al, 2017;Sartori et al, 2016), entailing 1/3 of the area traditionally sown with irrigated rice (IRGA, 2019). In addition, crop rotation is an alternative to control weed infestations (Scherner et al, 2018;Fraga et al, 2019), break pest and disease cycles, improve soil conditions for plant development and increase the sustainability of the system (Goulart et al, 2020) Imperfectly drained soils (Planosols) predominate in these areas due to the water table being close to the surface (Streck et al, 2008).…”

“…However, lowland studies have shown that soybean roots are concentrated in superficial layers, which requires redefinition of the layer utilized for the soil available water capacity (AWC) calculation. For example, there are reports that the taproot reached a maximum depth of 230 mm (Marchesan et al, 2013) and between 130 mm and 300 mm (Rocha et al, 2017).…”