Amanda Posselt Martins

High soil acidity and low nutrient availability in the deeper soil layers of no-tillage systems (NTS) can restrict crop yield potential. This study aimed to evaluate the impact of different soil acidity correction strategies and P and K application methods on the vertical variation of soil acidity, nutrient availability, and on corn and soybean yields. A randomized block factorial experiment was established in 2020 on a Plinthosol (Plintossolo Argilúvico Distrófico típico) under NTS since 2004. The first factor consisted of soil acidity correction strategies: (i) control, (ii) surface application of dolomitic limestone, (iii) surface application of calcium and magnesium oxide (CaO·MgO), and (iv) incorporation of dolomitic limestone to 0.20 m depth. The second factor corresponded to P and K application methods: (i) control without fertilization, (ii) in-furrow application, and (iii) surface broadcast application. The corrective amendment rates were calculated to raise the soil pH in the 0.00–0.20 m layer to 6.0. Six months after treatment application, soil samples were collected down to a depth of 0.40 m. Application of CaO·MgO increased soil pH, Ca ²⁺ +Mg ²⁺ +K ⁺ saturation, and Ca ²⁺ and Mg ²⁺ contents, but these effects were confined to the surface soil layer (0.00–0.10 m). In contrast, limestone incorporation reduced soil pH, and Ca ²⁺ +Mg ²⁺ +K ⁺ and Al ³⁺ saturation gradients over a greatest soil depth (0.00–0.15 m), demonstrating greater effectiveness than both surface-applied limestone and CaO·MgO. Improvements in soil acidity resulting from limestone incorporation led to a 66 % increase in corn yield compared to other correction strategies. Soil chemical properties were minimally affected by P and K application methods, with higher available P observed only in the 0.00–0.05 m layer under surface broadcast application. Nevertheless, in-furrow P and K fertilization increased corn yield by 35 % compared to surface application. Soybean yield was not influenced by any of the treatments. In soils with high subsurface acidity, incorporating soil amendments is essential for effective acidity correction and yield improvement, while in-furrow P and K fertilization remains an efficient strategy to sustain high crop yields.

Fertilizer recommendation systems in Brazil and Paraguay are based on soil analysis and correlation‐calibration experiments; however, they often recommend divergent phosphate fertilizer rates for the same crop and yield target. This study compares phosphate fertilizer recommendation systems for soybean [ Glycine max (L.) Merr.], wheat [ Triticum aestivum (L.)], and maize [ Zea mays (L.)], using standardized yield targets of 3, 4, and 10 Mg ha ⁻¹ , respectively. Eleven regional recommendations were evaluated: ten from Brazil and one from the Eastern Region of Paraguay. Most systems use the Mehlich‐1 method to extract available P, except São Paulo, which uses an anion exchange resin. The widespread use of Mehlich‐1 allows comparison of critical soil test values (CSTV) of P across tropical and subtropical soils. In several systems, CSTV declines with increasing clay content, likely due to extractor limitations and P readsorption during decantation, yet few recommendations explicitly incorporate P sorption capacity (e.g., clay content) when defining rates. Differences among calibration experiments have resulted in a wide range of CSTV (4–56 mg dm ⁻³ ) and recommended P ₂ O ₅ rates of 82–415 kg ha ⁻¹ for soybean (≈36–181 kg P ha ⁻¹ ), 87–329 kg ha ⁻¹ for wheat (≈38–144 kg P ha ⁻¹ ), and 118–362 kg ha ⁻¹ for maize (≈52–158 kg P ha ⁻¹ ). Mehlich‐1 thresholds above which phosphate fertilization becomes unnecessary also varied widely (5–35, 3–37, and 6–46 mg dm ⁻³ for soybean, wheat, and maize, respectively). These results highlight the need for minimum guidelines to harmonize soil P test interpretation and phosphate fertilizer recommendations, improving P use efficiency in Brazil and Paraguay.

Extreme weather events drive the revision of soil management and fertility assessment practices, aiming to conserve natural resources and reduce costs. This study evaluated soil fertility based on available nutrient contents, nutrient stocks, and nutrient budget in Luvisols under cultivation of silage corn and different conservationist management systems. We hypothesized that the nutrient stocks and budget approach provides a better understanding of nutrient dynamics, including the role of soil as a source or sink, compared with evaluation based solely [...] ABSTRACT Extreme weather events drive the revision of soil management and fertility assessment practices, aiming to conserve natural resources and reduce costs. This study evaluated soil fertility based on available nutrient contents, nutrient stocks, and nutrient budget in Luvisols under cultivation of silage corn and different conservationist management systems. We hypothesized that the nutrient stocks and budget approach provides a better understanding of nutrient dynamics, including the role of soil as a source or sink, compared with evaluation based solely

The objective of this work was to investigate nitrogen balance in a soybean-ryegrass system, influenced by off-season N fertilization, sheep grazing, and timing of phosphorus and potassium replacement. A long-term four-year experiment was conducted in a randomized complete block design with four replicates. The present study was carried out in the fourth crop season, when data from three replicates were collected. The split-plot experimental design was adopted. The plots were arranged in a 2x2 factorial arrangement, consisting of two grazing levels (grazed and ungrazed) and two times of P2O5 and K2O replacement (in summer or winter), whereas the subplots received different N rates (0, 50, 100, and 200 kg ha-1 N). The analyzed variables were total dry mass yield, N accumulation in ryegrass, and soybean metrics such as biological N fixation (BNF), grain yield, and partial N balance (PNB). The highest rates of N in ryegrass increased grain yield by 14% in grazed areas. The replacement of P2O5 and K2O in winter boosted grain yield by 11%. Off-season N fertilization increased N balance due to the increase in dry mass yield and N cycling, alleviating the negative PNB caused by soybean, regardless of the timing of P2O5 e K2O replacement and grazing or not by sheep.

Sustainable agricultural systems, such as integrated crop-livestock systems under no-tillage, represent effective strategies for improving the soil microbiota, promoting nutrient cycling, and leading to gains in crop yield. Despite that, little is known about maintaining yield only through microbiological pathways for accessing nutrient reserves (without mineral fertilization) in established systems. This study aimed to evaluate whether the absence of mineral fertilization for two consecutive years and grazing activity affect soil microbial activity. An additional aim was to evaluate whether biological cycling of nutrients maintains yield without mineral fertilization. A completely randomized block design was used in a 2 × 2 factorial arrangement in split-plots, in which the factors consisted of grazing activity (integrated crop-livestock production system – ICLS and system without winter grazing – NG) and mineral fertilization (with and without). The experiment began in 2017 with a ryegrass / soybean succession, and in the integrated crop-livestock production system, there was winter grazing with sheep. In the fertilization treatment, nitrogen fertilizer was applied to the ryegrass, and phosphorus and potassium were supplied to soybean. Absence of mineral fertilization was tested by not adding fertilizers for two consecutive years (2020 to 2022). Production system phases were characterized by two soil samplings, at the end of the pasture cycle (2021) and after the soybean harvest (2022), when soil microbiological and enzymatic analyses were performed. Ryegrass and soybean yields were also evaluated. Only soybean had a 13.7 % yield reduction under the ICLS without mineral fertilization and a 16 % reduction under the NG with mineral fertilization. The lack of mineral fertilization did not affect soil microbiology. Enzymatic activity was sensitive to different phases of the production system, and it was higher in the pasture phase. Additionally, soybean yield showed a strong correlation with the enzymes β-glucosidase (r = 0.90; p = 0.01) and arylsulfatase (r = 0.88; p = 0.05) in the NG system. Grazing activity did not always affect soil microbiology; however, when it did, it had a negative effect on the NG, particularly in the cropping phase. Soil microbiology remains unchanged in the absence of mineral fertilization in established soybean systems, and grazing systems (as ICLS) are more effective in maintaining microbial activity and yield compared with systems without winter grazing (NG).

System fertilization enhances logistics and phosphorus (P) use efficiency, but its effects in high P‐export systems, particularly regarding fertilization timing, placement, and distribution, remain unclear. This study evaluated P fertilization timing (90, 45, and 0 days before winter crop sowing [DBS]), placement (banded vs. broadcast), and spatial distribution (17 × 5 vs. 40 × 10 cm) in subtropical Oxisols with medium and high soil‐test P. Over 4 years, we assessed crop yields, partial phosphorus balance (PPB), and Mehlich‐1 available soil P (0–10 and 10–20 cm) under rotations of corn ( Zea mays L.), soybean ( Glycine max L.), and winter crops including black oat ( Avena strigosa Schreb.), barley ( Hordeum vulgare L.), vetch ( Vicia sativa L.), and fodder radish ( Raphanus sativus L.). Despite pronounced P stratification, yields and PPB were generally unaffected. In medium P soil, the 40 × 10 cm spacing increased P in the 10–20 cm layer to 61% of the critical value after 4 years. In high P soil, P application at winter sowing raised subsurface P to 4.5 mg dm ⁻³ . Soybean yield (5.2 Mg ha ⁻¹ ) and PPB (73%) peaked with 90 DBS banded fertilization. Anticipating fertilization by 90 days with 17 × 5 cm spacing improved soybean yield by 20% and PPB by 10% due to better surface P distribution. The 0–10 cm layer remained P‐rich and sufficient for grain yield. However, the benefits of 90 DBS were limited to two seasons. Long‐term studies are needed to refine system fertilization strategies in high‐output grain systems.

A busca por uma agricultura rentável e permanente passa pela valorização das fontes de nutrientes disponíveis regionalmente, o que fornece mais autonomia para o setor rural em relação à adubação. A compostagem conjunta de resíduos orgânicos e rochas moídas alia duas técnicas ancestrais, mas é pouco difundida. Este trabalho teve como objetivo avaliar um fertilizante produzido pela compostagem conjunta de resíduos orgânicos e pó de rocha. Os componentes utilizados para a produção do composto foram cama de bovino, silagem de milho, casca de café, gesso agrícola e pó de rocha de fonolito. A temperatura e a umidade do composto foram medidas diariamente. A realização da aeração foi feita com o compostador Jaguar JC 4000 e a umidificação foi realizada com um tanque pipa de 20 mil litros rebocável. As análises química, orgânica, biológica e sanitária indicaram que o processo de compostagem foi realizado de forma correta. Com isso, o composto produzido com fontes regionais de nutrientes possui boa qualidade e é passível de ser usado na agricultura, já que atende aos requisitos necessários para ser enquadrado como fertilizante orgânico composto classe A, mas notou-se que parte dos nutrientes do pó de rocha não foram disponibilizados pela compostagem, devido à sua mineralogia e à sua granulometria.

Bases are chemical species that donate electrons, accept protons, or release hydroxyls (OH–) in aqueous solution. In Soil Science, “base saturation”, “exchangeable bases” or “basic cations” has been widely used to distinguish Ca2+, Mg2+, Na+, and K+ from H+ and Al3+ cations. This terminology is confusing since none of these cations are truly a base in chemistry sense. However, in the absence of the proposition of a correct term, the term “base saturation” remains in use nowadays, causing confusion [...] ABSTRACT Bases are chemical species that donate electrons, accept protons, or release hydroxyls (OH–) in aqueous solution. In Soil Science, “base saturation”, “exchangeable bases” or “basic cations” has been widely used to distinguish Ca2+, Mg2+, Na+, and K+ from H+ and Al3+ cations. This terminology is confusing since none of these cations are truly a base in chemistry sense. However, in the absence of the proposition of a correct term, the term “base saturation” remains in use nowadays, causing confusion

Studies on lability of soil phosphorus (P) under integrated crop-livestock systems (ICLS) are still scarce, especially for deep soil layers (more than 0.20 m depth) and different managements in the crop and livestock phase. Distinct management in these phases may lead to a different distribution of soil P pools according to its lability (labile, moderately labile, less labile and residual) and, consequently, the P availability for plant nutrition. This study aimed to determine the soil P pools, by P [...] ABSTRACT Studies on lability of soil phosphorus (P) under integrated crop-livestock systems (ICLS) are still scarce, especially for deep soil layers (more than 0.20 m depth) and different managements in the crop and livestock phase. Distinct management in these phases may lead to a different distribution of soil P pools according to its lability (labile, moderately labile, less labile and residual) and, consequently, the P availability for plant nutrition. This study aimed to determine the soil P pools, by P