Gloria Milena Rojas Plazas

Assessing the spatial variability of soil chemical attributes and yield is fundamental to understanding crop responses to site-specific management practices. This study aimed to analyze the spatial structure of soil chemical attributes and carrot yield, as well as their spatial correlation, under conventional management. The experiment was conducted in an irrigated carrot field, where one hundred sampling points were established on a regular 20 × 20 m grid. At each point, carrot yield and soil chemical attributes were evaluated. Statistical and geostatistical analyses were applied to the parameters studied. Average variability was observed in carrot yield. Phosphorus, potassium, electrical conductivity, and potential cation exchange capacity exhibited spatial dependence, with no evidence of nutrient deficiency in the area. The remaining attributes showed no spatial dependence within the 20 m grid, indicating the need for alternative sampling strategies. Among the analyzed variables, potential cation exchange capacity had a direct influence on the spatial variability of carrot yield, showing a positive spatial correlation. These results highlight the importance of spatial characterization of soil chemical attributes as a key tool for supporting precision agriculture.

The aim of this research was to evaluate the action of Azospirillum brasilense and jasmonic acid as mitigators of water stress caused by various irrigation levels in Creole corn crops. The experiment was conducted in a greenhouse using a completely randomized factorial design consisting of 2 levels of A. brasilense (absence and presence) x 3 doses of jasmonic acid x 3 irrigation depths determined by three evapotranspiration (ET0) multipliers (0.6, 0.8, and 1.0 of the evapotranspiration measured in the crop area). The design included 4 replicates, totaling 72 experimental units. Evaluations were carried out at the R6 physiological maturity stage for number of tassels, tassel branch number, number of leaves on the corn cob, and number of ears per plant. Analysis of variance showed significant difference among the variables studied. The irrigation depth of 0.8 of the evapotranspiration showed significant interactions between A. brasilense and jasmonic acid in reducing water stress in creole corn plants. The results for the irrigation depth 0.6 of the evapotranspiration, with the use of mitigators, showed smaller reductions in stress (11.91% reduction compared to 0.8 of the ET0). The treatment of 10 μmol L-1 jasmonic acid was the most favorable for reducing stress and consequently increasing the productivity of creole corn plants, coming closest to the estimated optimal dosage.

Understanding soil, plant attributes, and carrot crop dynamics is vital for optimizing site-specific management practices and enhancing crop yield and soil quality. This study aimed to ascertain the dependence and spatial variability between irrigated carrot yield and soil physical attributes in a clayey Oxisol. The research took place during the 2021 growing season in a commercial carrot production area in Campos Altos, MG, Brazil. One hundred sampling points were established within the irrigated area, distributed across a square expanse of 40,000 m², positioned at the centers of 20 × 20 m grids. The study revealed high yield in the irrigated carrot crop (99.74 t ha^-1) with moderate variability. Soil attributes displayed a range of heterogeneity, ranging from low to extremely high, contingent on the variable assessed, as determined by the coefficient of variation. Among the variables exhibiting spatial dependence, particle density exhibited a minimum range of 40 m, which is recommended for further studies on irrigated carrot cultivation in a clayey Oxisol. Total soil water availability demonstrated a positive spatial correlation and proved to be the recommended variable for estimating the spatial variability of carrot crop yield.

The collapse of the Fundão Dam in Mariana, MG, in 2015 introduced the challenge of using Technosol, a soil type formed by deposition of iron mining waste along the Doce River banks, for agricultural purposes. This study aimed to determine the optimal water depth for enhancing production of tropical forage, Megathyrsus maximus cv. Mombasa, when grown on iron ore tailings. Additionally, it sought to establish a crop coefficient applicable to the edaphoclimatic conditions of Viçosa, MG, Brazil. The experiment was conducted throughout the summer, fall, and winter of 2022, employing 21 drainage lysimeters. A completely randomized experimental design was adopted, featuring six treatment groups (plants in Technosol receiving water depths ranging from 20 to 120% of the crop’s evapotranspiration, as derived from the control treatment), along with a control group (plants in Latosol with a depth of 100%), each with three repetitions. Our findings showed that irrigation must replace 40% of the crop evapotranspiration. Moreover, cultivating in Technosol resulted in a reduction of productive capacity by 37.39% during the summer/fall and fall seasons. For Mombasa grass grown in Oxisol, crop coefficients of 1.2 during the summer and 1.5 during the fall and winter are advised.

Mabea fistulifera Mart. (common name: canudo-de-pito) belongs to the Euphorbiaceae family and is a native tree species in Brazil showing a high potential to recover degraded lands. This study aimed to evaluate the distribution and spatial correlation between the dendrometric parameters of the M. fistulifera plants and the physical attributes of the soil through geostatistics. The study was carried out at the Paulista State University (UNESP), in the city of Selvíria, MS, Brazil, in a typical dystrophic Red Oxisol with a clayey texture. The following properties were analyzed: for soil, penetration resistance, gravimetric moisture, particle density, and, for plants, circumference and diameter at breast height (measured at 130 cm above the ground), tree height, and total volume of the tree. An experiment grid was introduced with 35 sample points spaced 13 m x 13 m. Two soil samples were taken at each point, at 0.00 - 0.10 m and 0.10 - 0.20 m depth. Descriptive data analysis and spatial dependence analysis were carried out through semivariogram adjustments and kriging maps. The dendrometric properties of the species M. fistulifera and the soil gravimetric moisture content showed spatial dependence. The spherical semivariogram model best explained the spatial structure of circumference at breast height, diameter at breast height, tree volume, and soil gravimetric moisture. There was an emphasis on the correlation between the total volume of the tree as a function of the diameter at breast height, showing a moderate spatial dependence. Furthermore, the tree diameter at breast height proved to be a good indicator for determining the total height of the M. fistulifera tree.

O milho nos tempos contemporâneos tornou-se o grão mais produzido no mundo. Portanto esse trabalho objetivou avaliar o efeito da absorção de fósforo nas características biométricas e produtivas da cultura do milho nas fases V6, V8, florescimento e colheita. Os atributos avaliados foram: teor de fósforo, massa fresca de folha no florescimento, massa fresca de caule no florescimento, massa seca de folha no florescimento, massa seca de caule no florescimento, massa seca do caule, massa fresca do caule, massa fresca da folha na colheita, massa seca da folha, massa fresca de folha em V6, massa seca de folha em V6, massa fresca de caule em V6, massa seca de caule em V6, massa seca de caule em V8, massa fresca de caule em V8, massa fresca de folha em V8, massa seca de folha em V8. Através da análise de trilha foi permitido estabelecer correlações entres estas variáveis que são indicativos de produtividade e qualidade do milho. Resultados mostram pela correlação de Pierson que massa fresca de caule e massa seca de caule nas diferentes fases estudadas, apresentam altos níveis de correlação positiva indicando que suas massas frescas e secas tendem, após testes e análises, ter proximidade de relações. Como conclusões, compreende-se que de maneira direta e positiva o fósforo obteve maior correlação com o peso médio de grãos. Efeito direto e negativo apenas massa fresca de folha no florescimento obteve resultados consideráveis em relação ao teor de fósforo.