Bruna Arruda

Phosphorus (P) management in tropical soil, such as found in Colombia, is critical due to the extreme fixation occurring in Andisols and Oxisols by Fe and Al oxides. To help with this macronutrient management, model tools, such as APSIM, DSSAT, EPIC, and SWAT, that simulate its dynamics through conceptual pools (labile, active, and stable) have been widely used. The objectives of this study were: i) to conduct a systematic review to compare the predictive capacity of various phosphorus simulation models applied under different soil and climate conditions worldwide; and ii) to identify the model most relevant for application in Colombian agricultural soils. In the Colombian context, APSIM stands out for its technical accuracy, explaining up to 87% of the variance in crop yields, whereas SWAT is effective in predicting sediment reductions of up to 26% in high Andean watersheds. Based on the results, it is recommended to prioritize APSIM and DSSAT for optimizing fertilization at the field scale, and SWAT for land-use planning. The coupling of platforms makes it possible to mitigate parametric uncertainty and manage accumulated residual phosphorus, whose environmental recovery may require a time horizon of several decades due to the persistence of the nutrient in the soil. The rigorous application of these tools will drive precision agriculture to ensure food security and climate resilience in Colombia.

Changes in the soil microbial community for studies of different novel communities can be promoted by different methodologies, among which soil autoclaving stands out as a quick and readily available tool. However, this procedure may also directly or indirectly alter nitrogen (N) and phosphorus (P) dynamics. The purposes of this study were as follows: (i) to characterize microbial activity after soil autoclaving through microbial ¹⁴CO₂-respiration; and (ii) to evaluate the effect of microbial manipulation and autoclaving on soil N and ³³P dynamics. For this, two sets of soil samples from two areas (forest and cultivated area) were used in the laboratory. Firstly, ¹⁴C-glucose was added to the soils and after 24 h five soil microbiomes were generated: AS (autoclaved soil), and AS re-inoculated with serial dilutions (w/v) prepared by successive mixing of soil suspensions in sterile deionized water obtaining 10⁻¹, 10⁻³, and 10⁻⁶, which generated the treatments AS + 10⁻¹, AS + 10⁻³, and AS + 10⁻⁶; and the treatment NS (non-autoclaved control), all incubated for 28 d. ¹⁴CO₂ emission was used to characterize microbial activity; additionally, N dynamics were assessed at the end of incubation. In a second assay, ³³P was applied to the soil before autoclaving and re-inoculation. Following further incubation (14 d), a ³³P chemical fractionation was performed. The following are based on the results: (i) ¹⁴CO₂ emission: microbial activity in the autoclaved soil is null, but after a reinoculation of AS + 10⁻¹ and AS + 10⁻³ soil dilution suspension, the ¹⁴CO₂-respiration is higher than in an NS. (ii) regarding the N dynamics, in autoclaved soils, the microbial levels increased N-NH₄⁺ concentration, with an evident increase in the AS + 10⁻³ and AS + 10⁻¹, and a reduction in the N-NO₃⁻ concentration in comparison to the NS. For ³³P, the autoclaving procedure itself reduced the ³³P lability, regardless of the levels of microbial community reinoculated.

The common bean (Phaseolus vulgaris L.) is a global staple, but to guarantee its provision, the crop water supply must be adequate, and bioinput application can benefit plants under drought. The objective was to evaluate the common bean’s response to bioinput application when it was cropped in soils with different water holding capacities submitted to a drought period. The greenhouse experiment used sandy loam and clayey soils. Seeds were sown, and 10 days after emergence (DAE), the treatments were applied: (i) no bioinput application or (ii) bioinput application (Priestia aryabhattai, re-applied at 46 DAE). The first plant growth evaluation was performed at 40 DAE. The irrigation maintained the crops’ needs until the beginning of flowering for all the treatments, when the irrigation was differentiated (for 10 days): (i) maintenance of irrigation or (ii) a drought period. A biochemical analysis was performed of superoxide dismutase activity [SOD], hydrogen peroxide [H₂O₂], peroxidase activity [POD], and malonaldehyde [MDA] production at 52 DAE. At 57 DAE, the second plant growth evaluation was performed, and the irrigation differentiation ended. Grain harvest followed physiological maturation. Priestia aryabhattai mitigated the drought stress in the common bean cropped in sandy soil by reducing the SOD, H₂O₂, and MDA production in comparison to no bioinput application. When it was cultivated in the clayey soil, the water availability was maintained for longer, reducing the plant’s dependency on bacteria for stress mitigation.

Here, we hypothesized the occurrence of a compensatory relationship between the application of P and different microbial communities in the soil, specifically in relation to the chemical and biological effects in the soil–plant–microorganisms’ interaction. We aimed to evaluate the plant–microbiota responses in plants grown in soils hosting distinct microbial communities and rates of P availability. Two experiments were carried out in a greenhouse. The first experiment evaluated four manipulated soil microbiome compositions, four P rates, and two plant species. Manipulated soil systems were obtained by the following: (i) autoclaving soil for 1 h at 121 °C (AS); (ii) inoculating AS with soil suspension dilution (AS + 10⁻³); (iii) heating natural soil at 80 °C for 1 h (NH80); or (iv) using natural soil (NS) without manipulation. The P rates added were 0, 20, 40, and 60 mg kg⁻¹, and the two plant species tested were grass (brachiaria) and leguminous (crotalaria). Inorganic labile P (P_AER), microbial P (P_MIC), acid phosphatase activity (AP_ASE), and shoot P uptake (P_UPT) were assessed for each system. Brachiaria presented a compensatory effect for P_UPT, whereby the addition of P under conditions of low microbial community enhanced P absorption capacity from the soil. However, in a system characterized by low P input, the increase in the soil biodiversity was insufficient to enhance brachiaria P_UPT. Likewise, crotalaria showed a higher P_UPT under high P application and low microbial community. The second experiment used three manipulated microbiome compositions: AS + 10⁻³; NH80; and NS and three P rates added: 0, 20, and 40 mg kg⁻¹. In addition, two treatments were set: without and with mycorrhiza inoculation. Brachiaria showed an increase in the P_UPT under low microbial communities (AS + 10⁻³; NH80) with P addition (20 and 40 mg kg⁻¹ of P), but no mycorrhization was observed. In the undisturbed microbial community (NS), under no P input (0 mg kg⁻¹ of P), brachiaria showed low mycorrhization and low P_UPT. Finally, NS and the recommended P input (40 mg kg⁻¹ of P) represented a balance between chemical and biological fertility, promoting the equilibrium between mycorrhization and P_UPT.

DOI: 10.22167/2675-6528-20230090E&S 2024, 5: e20230090 Aline Martineli Batista; Bruna Arruda; Thairís Gomes dos Santos; Antonio Carlos de Azevedo; Alexandre Barreto de Almeida O Brasil é o quinto maior produtor de tintas do mundo, sendo este um setor importante para a economia do país[1]. Entre os principais componentes das tintas estão os pigmentos, que lhes dão […]

Drought conditions have made it difficult for farmers to ensure the productivity of their crops. The objective of this study was to evaluate the potential of bioinputs in stress mitigation after a drought event in common beans. Two experiments were set up in a greenhouse. Firstly, two types of soils (clayey and sandy loam) were used. After seedling emergence, treatments were set: no bacteria inoculation (NB) and inoculation with Herbaspirillum frisingense AP21. Then, a differentiation on the irrigation (15 days) was performed with no water restriction (NWR) and with water restriction (WWR). Transpiration, stomatal conductance, leaf dry matter and proline were measured. Secondly, in the clayey soil, the bacteria treatments were NB, Herbaspirillum frisingense AP21, Rhizobium leguminosarum T88 and co-inoculation (AP21 + T88). A differentiation on the irrigation (15 days) was performed: NWR and WWR. Then, Fv/Fm, photosynthetic rate, proline and sugars were assessed, and the harvest occurred 97 days after emergence. For sandy loam soil bioinputs, they did not have an effect on the parameters evaluated. For clayey soil, H. frisingense AP21 increased the transpiration rate and stomatal conductance and hence improved the leaf dry matter in comparison to NB. Under WWR, the isolated inoculations of AP21 and T88 increased grain dry matter, but the co-inoculation showed low grain production, similar to no bacteria inoculation.

Due to the worldwide water supply crisis, sustainable strategies are required for a better use of this resource. The use of magnetic water has been shown to have potential for improving irrigation efficacy. However, a lack of modelling methods that correspond to the experimental results and minimize error is observed. This study aimed to estimate the replacement rates of magnetic water provided by irrigation for lettuce production using a mathematical model based on fuzzy logic and to compare multiple polynomial regression analysis and the fuzzy model. A greenhouse study was conducted with lettuce using two types of water, magnetic water (MW) and conventional water (CW), and five irrigation levels (25, 50, 75, 100 and 125%) of crop evapotranspiration. Plant samples for biometric lettuce were taken at 14, 21, 28 and 35 days after transplanting. The data were analyzed via multiple polynomial regression and fuzzy mathematical modeling, followed by an inference of the models and a comparison between the methods. The highest biometric values for lettuce were observed when irrigated with MW during the different phenological stage evaluated. The fuzzy model provided a more exact adjustment when compared to the multiple polynomial regressions.

Climate change is causing an increase in dry spells, altering rainfall patterns and soil moisture, and affecting water and nutrient plant uptake, which inevitably affects vegetable production. To mitigate this issue, some technologies that allow the maintenance of the ideal soil moisture for the uptake process are being investigated. Considering this, we hypothesize that the use of water treated with a magnetic field can increase water use efficiency in lettuce crop production. Thus, the present study aimed to evaluate the effect of the irrigation rate of magnetically treated water on biomass accumulation and nutrient uptake by lettuce plants. An experiment was conducted in a randomized block design with a 2 × 5 factorial arrangement of two water sources (conventional water and magnetically treated water) and five irrigation application rates to replace crop evaporation: 25, 50, 75, 100, and 125%, with five replicates. The use of magnetically treated water increased the concentrations of nitrogen and phosphorus in leaves, meaning that it induced higher nitrogen assimilation, leading to increases in agronomical characteristics (leaf number, fresh and dry shoot weight, fresh and dry root weight). The conclusions of this study showcase that magnetically treated water has beneficial effects on lettuce plants, improving their nutritional status and yield. Moreover, the results presented can lead to an increase in water use efficiency, thus optimizing irrigation management.

Intensive land-use change, the overgrazing of pastures, and the poor soil management in the Amazon region induce significant soil chemical degradation, causing alterations in the soil phosphorus (P) dynamics. Here, we studied the changes in P fractions and availability throughout the soil profile along a chronosequence composed of four study areas representing the typical land-use transition from forest to pasture for extensive cattle ranching in the Colombian Amazon region: (i) Forest—Deforested—Pasture 4 years old and Pasture established >25 years after deforestation. Soil samples collected at 0–10, 10–20, 20–30, and 30–40 cm depth were used for the sequential fractionation of P, determination of acid phosphatase activity and soil organic carbon (C) content, and calculation of C:organic P (Po) ratio and P stocks. Our results showed that the land-use change caused a decrease of 31.1% in the fractions of labile inorganic P, with the mineralization of organic P by phosphatase enzyme playing an essential role in the P availability. Although according to the C:Po ratio of the deeper layer the P seems to be sufficient to satisfy the plant needs of all the land uses assessed, the exploitation of soil nutrients in pastures reduced by 6.1% the moderately and non-labile P stock. Given the role of cattle ranching in the economy of tropical countries, it is imperative to adopt strategies of soil P management to improve P-use efficiency, avoiding the degradation of grazing land resources while ensuring the long-term sustainability of rangeland livestock and decrease further deforestation of the Amazon rainforest.