Long-Term Effect of Crop Succession Systems on Soil Chemical and Physical Attributes and Soybean Yield

Abstract

Most soybean producers in the Cerrado biome use the direct seeding system, making it essential to cultivate cash or cover crops in the off-season, to promote soil protection, as well as increase organic matter, which is directly related to improvements in the chemical and physical characteristics of these soils. In this sense, this work was conducted in Jataí, state of Goias, Brazil, to evaluate the physical-chemical attributes of the soil and the performance of soybeans cultivated in different crop succession systems cultivated for 6 years in the region of Jataí, GO. The experimental design was randomized blocks with four plots and four replications; the crops that followed soybeans were arranged as follows: T1-corn (Zea mays); T2-pearl millet (Pennisetum glaucum); T3-Urochloa ruziziensis; and T4-corn + Urochloa ruziziensis. Soybean yield components and grain yield were evaluated in two harvests (2020/2021 and 2021/2022). Deformed and undisturbed soil samples were collected in 2022 to assess soil fertility and for physical analysis. The data were subjected to analysis of variance (F test) and the means were compared using the Tukey test at 5% probability. The soybean-millet succession system stood out for the chemical and physical attributes of the soil: calcium, magnesium, base saturation, hydrogen + aluminum, and total porosity. The crop succession system did not affect yield for the two years analyzed, but the accumulated grain yields were higher in the crop succession soybean/corn intercropped. The results highlight the importance of using cover crops in improving the physical and chemical qualities of the soil in the long term. However, in the Cerrado, there is a predominance of the soybean/corn succession system motivated by financial issues to the detriment of the qualitative aspects of the soil, in which the introduction of Urochloa ruziziensis in intercropping with corn would improve the chemical attributes of the soil and have a long-term impact on the accumulated grain production.

Keywords: Glycine max; Urochloa ruziziensis; cover crops; crop–livestock integration; pearl millet.

Figure 1

Soil organic Matter (OM) soil acidity (pH), potential acidity (H  +  Al) and phosphor (P) in layers 0.0–0.05, 0.05–0.10, 0.10–0.20 and 0.20–0.40 m depth, after soybean growing season 2021/2022 in function of the crop-production systems. Jataí, GO. Horizontal bars indicate the least significant difference of Tukey test (p < 0 .05) for each depth and “ns” indicates that the ANOVA was not significant.

Figure 2

Potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺) and sum of bases (SB) in layers 0.0–0.05, 0.05–0.10, 0.10–0.20 and 0.20–0.40 m depth, after soybean growing season 2021/2022 as a function of the crop-production systems. Jataí, GO. Horizontal bars indicate the least significant difference of Tukey test (p < 0.05) for each depth and “ns” indicates that the ANOVA was not significant.

Figure 3

Cation exchange capacity (CEC) and base saturation (BS) in layers 0.0–0.05, 0.05–0.10, 0.10–0.20 and 0.20–0.40 m depth, after soybean growing season 2021/2022 in function of the crop-production systems. Jataí, GO. Horizontal bars indicate the least significant difference of Tukey test (p < 0.05) for each depth.

Figure 4

Bulk density (BK), particle density (PD), total porosity (TP) in layers 0.0–0.05, 0.05–0.10, 0.10–0.20 and 0.20–0.40 m depth, after soybean growing season 2021/2022 as a function of the crop-production systems. Jataí, GO. Horizontal bars indicate the least significant difference of Tukey test (p < 0.05) for each depth and “ns” indicates that the ANOVA was not significant.

Figure 5

Weighted mean diameter (WMD) in layer 0.0–0.20 m, after soybean growing season 2021/2022 as a function of the crop-production systems. Jataí, GO. Different letters represent significative difference between the treatments.

Figure 6

Plant final population (POP) and Yield (Y) as a function of crop succession systems, averages for growing season 2020/2021 and 2021/2022. Jataí, GO. Different letters represent significative differences between the treatments.

Figure 7

Schematic of crop succession systems and experiment timeline.