Soil amendments such as limestone and gypsum can influence microbial carbon use efficiency (CUE) by altering nutrient stoichiometry, particularly nitrogen (N) and phosphorus (P). However, their effects beyond the topsoil, especially under no-till systems, remain unclear. This study assessed microbial CUE through substrate use efficiency (SUE) following glucose addition as a factor influencing carbon (C) sequestration potential. Two experiments were conducted in tropical soil. The first evaluated the addition of ¹⁴C-glucose (G) to soil treated with lime, lime + gypsum, and a control, with or without the addition of N. The second compared limestone + gypsum and control treatments, incorporating G with N and P. Soil microbial respiration (CO₂ emission) was measured after 14 and 42 days. In the surface soil (0–10 cm), CUE increased with limestone or limestone + gypsum when N was applied. In the subsoil (40–60 cm), these amendments enhanced CUE compared to untreated soil in the absence of N. Treatments with G+N+P or G+P improved CUE in the surface soil. At the same time, G+N+P increased CUE in the subsoil regardless of acidity alleviation. Differences in ¹⁴CO₂ evolution indicated higher microbial CUE with acidity correction. Balanced N and P applications significantly enhanced CUE, highlighting the importance of both soil acidity correction and nutrient availability for microbial carbon processing.

Intercropping grasses and legumes could be an important strategy for sustainable food production in tropical weathered soils. This study aimed to assess the impact of intercropping systems comprising maize and grass with or without a legume for silage production and overseeded black oat overseeded for lamb grazing on crop production, root development and soil fertility under no‐till (NT). The cropping systems consisted of maize intercropped with palisade grass ( Urochloa brizantha cv. Marandu) with or without pigeon pea ( Cajanus cajan ) in the summer/autumn and black oat ( Avena strigosa ) overseeded in row or broadcast with superficial incorporation in the winter/spring. Maize forage mass for ensiling, maize grain yield, crop straw on the soil surface, root development and soil fertility were assessed. Despite an atypical period of drought in the first year, the addition of the legume to the intercropping system increased forage accumulation for silage, maize grain yield and crop straw by 13%, 8% and 53%, respectively, and ensured adequate soil cover for the cycling of soil nutrients for the subsequent crops. Harrowing to incorporate broadcast black oat negatively impacted silage production, maize yield and root development and stimulated C mineralization. It suggests that adjusting the density of intercropped species is a potential management strategy for tropical regions subject to drought, but further studies are needed.

Background: Weeds compete with crops for resources, reducing agricultural productivity. Management practices involving cover crops and potassium fertilization can influence weed community dynamics. Objective: To evaluate the weed community in a Urochloa ruziziensis-sillage maize (Zea mays L.) for silage succession system, considering different potassium fertilizer (K) rates applied to the cover crop. Methods: During the fall-winter season, treatments included U. ruziziensis with six K rates (0, 30, 60, 90, 120, or 150 kg K2 O ha−1 as KCl) and [...] Background: Weeds compete with crops for resources, reducing agricultural productivity. Management practices involving cover crops and potassium fertilization can influence weed community dynamics. Objective: To evaluate the weed community in a Urochloa ruziziensis-sillage maize (Zea mays L.) for silage succession system, considering different potassium fertilizer (K) rates applied to the cover crop. Methods: During the fall-winter season, treatments included U. ruziziensis with six K rates (0, 30, 60, 90, 120, or 150 kg K2 O ha−1 as KCl) and

Liming is essential for achieving high crop yields in tropical acidic soils, but lime dissolution releases CO ₂ , whereas silicate slag does not, while gypsum improves subsoil fertility. Although the benefits of these amendments for soil fertility are well known, their combined effects on CO ₂ emissions and soil carbon (C) accumulation in cropping systems remain unclear. We evaluated the effects of lime and silicate applied alone or in combination with gypsum, in a soybean ( Glycine max L.) double‐cropped with maize ( Zea mays L.) intercropped with Urochloa ruziziensis system under no‐till (NT) and conventional tillage (CT), in two side‐by‐side field experiments. The experiments were conducted on a Typic Haplorthox in Southwestern Brazil over 2 years. Treatments included (i) lime, (ii) silicate slag, (iii) lime + gypsum, (iv) silicate slag + gypsum, and (v) control. Root and shoot dry matter, plant carbon (C) input, CO ₂ emissions, and soil C stocks were measured in the second‐year soybean season. The application of soil amendments increased shoot and root dry matter and C inputs under NT and CT but did not alter total C stocks across the soil profile. Cumulative CO ₂ emissions were not affected by soil amendments under NT; however, emissions increased with lime + gypsum under CT. Alleviating soil acidity in tropical cropping systems through the application of lime, silicate, and their combination with gypsum can enhance crop yields while reducing yield‐scaled (normalized) CO ₂ emissions.

The objective of this study was to evaluate the effect of an early application of potassium (K) fertilizer on pearl millet (Pennisetum glaucum L.) grown during fall/winter on the performance of maize (Zea mays L.) silage grown in succession. Using a randomized block design, in the fall/winter harvest, the plots were composed of millet and six doses of K (0, 30, 60, 90, 120 and 150 kg K2O ha-1) as muriate of potash (57% K2O) in addition to fallow. In the summer harvest, during the cultivation of maize, six doses of K2O were applied complementary to the doses applied in the autumn/winter harvest to total 120 kg K2O ha-1 (120, 90, 60, 30, 0) and 0 kg K2O ha-1 for the no cover treatment. An additional treatment that was planted to received the recommended fertilization amount (60 and 90 kg ha-1 of K2O for planting and broadcasting, respectively). For the millet, was evaluated plant height, green and dry biomass yields, and soil cover at 30, 60, 90 and 120 days after harvest . For maize, agronomic traits, leaf nutrient content and green and dry biomass yields were evaluated. The early application of K fertilizer did not alter the yield components of millet and silage maize. However, the straw produced by the millet was efficient at promoting soil cover in the off-season.