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Background: The production of aboveground biomass of sugarcane is mainly due to the interactions between edaphic, climatic, and genetic factors. Objective: To evaluate the growth of three sugarcane cultivars through the evaluation of yield and dry matter accumulation, during the template and soca cultivation cycles, in the supply area of the Santa Rosalía de la Chontalpa Sugar Mill. Methodology: In the supply area of the Santa Rosalia de la Chontalpa Sugar Mill (ISRCH), Tabasco, an experiment was established under rainfed conditions, during two cycles (plantilla and soca), with three cultivars (MEX69-290, MEX79-431 and CP72-2086), established in a eutric Fluvisol soil. In each plot, five observation sites of 30 x 30 m were set up, in which the production of stems and biomass was determined. Results: In the plant cycle, the cane yield at 450 days after sowing (DAS) followed the following order CP72-2086> MEX79-431> MEX69-290 with 144.73, 130.09 and 94.18 t ha-1, respectively. On the contrary, in ratoon 360 days after harvest (DAH), MEX69-290 presented higher stem yield. In ratoon cycle, the stems yield decreased 14.5, 30.9 and 32.5% for MEX69-290, MEX79-431 and CP72-2086, respectively, compared to the plant cycle. The maximum absolute growth rate reached by the evaluated cultivars was 187, 192 and 262 kg ha-1 day-1 at 210 DAS in the plant cycle and 193, 177 and 151 kg ha-1 day-1 at 180 DAH in ratoon cycle for MEX69-290, CP72-2086 and MEX79-431, respectively. Implications: This allows knowing the growth rate of sugarcane cultivation in the humid tropics. Conclusions: The yield and harvest index of sugarcane varies with respect to the age of the crop (Cycle) and the cultivar.

O objetivo deste trabalho é avaliar o consumo de nutrientes (CN) e exportação de nutrientes do campo através dos produtos colhidos (EN), visando estimar o balanço dos principais macronutrientes: nitrogênio (N), fósforo (P) e potássio (K) nos países da América Latina e Caribe (ALC). O balanço de nutrientes (BN) foi estimado pela quantidade de nutrientes que entra nos sistemas agrícolas pela adubação e fixação biológica de nitrogênio (FBN) em relação à quantidade que deixa o sistema pelos produtos colhidos, em cada um dos países da região. A região da ALC, com base em estatísticas oficiais correspondentes ao ano 2016, apresentou um balanço positivo de N, no entanto, em alguns países (Argentina, Bolívia e Paraguai) esse balanço foi negativo. A FBN é a principal fonte de N da agricultura latino-americana, respondendo por 62% (11,29 Mt N) do total de N (18,10 Mt N) que ingressa anualmente nos sistemas agrícolas. De um modo geral, o fornecimento de P via adubação na América Latina atenderam as exportações realizadas pelos produtos colhidos, com exceção dos países Argentina, Bolívia, Guatemala e México, os quais se utilizaram de reservas do solo para a nutrição das plantas. O K foi um dos nutrientes cuja aplicação não atende a demanda das culturas da região, apresentando balanços negativos em quase todos os países, exceto Brasil, Colômbia e Venezuela. Deve-se destacar que em muitos solos agrícolas na região, a disponibilidade de K ainda é alta. Os maiores cuidados com o uso de insumos, incluindo os fertilizantes, se dá com os cultivos de soja, milho, café, cana de açúcar e laranja, ficando o restante dependente da fertilidade natural dos solos, que em sua maioria já são pobres, colocando em risco a segurança alimentar.

Anthropogenic activities have greatly increased heavy metal pollution worldwide. Due to inadequate waste management, mining is one of the chief causes. One particularly affected area in Mexico is the “La Zacatecana” Lagoon, in the municipality of Guadalupe, Zacatecas. From colonial times until the mid-nineteenth century, about 20 million tons of mine tailings were deposited at this site. Here, we catalogue the heavy metal content and their distribution in soils and sediments of La Zacatecana. The mobility of lead in soils was also assayed by sequential extraction. Concentrations of the different metals analysed were as follows: Pb > Cr > As > Ni > Hg > Cd. Site VIII accumulated the highest amount of Pb (3070 mg·kg−1) sevenfold more than the limit established by the Mexican standards for agricultural soils (i.e., 400 mg·kg−1). On the other hand, the contents of Cd, Cr, and Ni were within the levels accepted by the above normativity, set at 37, 280, and 1600 mg·kg−1, respectively. Concentrations of Hg and Pb were highest in the north-northwest zone of the lagoon and decreased towards the southeast. Except for Site VIII where 30% of the Pb was in an interchangeable form or bound to carbonates, most Pb in La Zacatecana soils was present in an unavailable form, associated with Fe-Mn oxides.