Summary: There is a need to replace components of substrates for the development of seedlings in forest nursery, with low-cost products and especially with local and renewable materials. Sugarcane bagasse biochar is lightweight, porous and has a high-water retention capacity. Therefore, the objective of this study was to evaluate the response of biochar based on sugarcane bagasse to produce white pine (Pinus greggii Engelm. ex Parl) plants under nursery conditions. Four treatments were evaluated: (a) biochar with forest soil, (b) forest substrate (composed of 12.5% peat moss, 12.5% agrolite, 25% vermiculite, 50% pine bark), (c) biochar with forest substrate, both in a 1:9 ratio (biochar:soil, biochar:substrate), and (d) forest soil. The effect of fertilization (N, P and K) and biochar on the performance of treatments in soil and forest substrate was evaluated. The growth variables evaluated were plant height, stem diameter, total aerial biomass, total root biomass, aerial/root biomass ratio, and the concentration of accumulated nutrients (N, P, Ca, K, Na and Mg) in the aerial and root parts. The results obtained indicate that as a consequence of the addition of biochar to the soil and fertilization, the height, diameter, biomass (aerial and total) of Pinus greggii were similar to obtained in forest substrate, alone or combined with biochar. These results were associated with the addition of biochar to the soil that increased the absorption of N and its concentration in the aerial biomass, and favored the availability of Mg, Ca, K and P, these last two elements added in fertilization. It is concluded that the combination of biochar and soil in a ratio (1: 9) (p/p) with the addition of fertilizer (N, P and K) can be used in the development of Pinus greggii Engelm ex Parl in the nursery.

Resumen: Existe la necesidad de sustituir componentes de los sustratos para el desarrollo de las plántulas en vivero forestal, por productos de bajo costo y sobre todo por materiales renovables. El biocarbón es liviano, poroso y presenta una alta capacidad de retención de agua. Por lo anterior, el objetivo de este estudio fue evaluar el uso de biocarbón a base de bagazo de caña de azúcar en la producción de plantas de pino prieto (Pinus greggii Engelm. ex Parl.), bajo condiciones de vivero. Se evaluaron cuatro tratamientos: (a) biocarbón con suelo forestal, (b) sustrato forestal (mezcla de 12.5% peat moss, 12.5% agrolita, 25% vermiculita y 50% corteza de pino), (c) biocarbón con sustrato forestal, ambos en una relación 1:9 (biocarbón:suelo, biocarbón:sustrato), y (d) suelo forestal solo. Se evaluó el efecto del biocarbón y de la fertilización (N, P y K) en el desempeño de los tratamientos en suelo y sustrato forestal. Las variables evaluadas fueron: altura de planta, diámetro de tallo, biomasa aérea, biomasa radical, biomasa total aérea, a relación biomasa aérea/radical; además la concentración de nutrientes acumulados (N, P, Ca, Mg, K y Na) en la parte aérea y radical. Los resultados obtenidos indican que como resultado de la adición de biocarbón al suelo y la fertilización, la altura, diámetro, biomasa (aérea y total) de pino prieto, fueron semejantes a las obtenidas en sustrato forestal, solo o combinado con biocarbón. Estos resultados se asociaron a la adición de biocarbón al suelo que incrementó la absorción de N y su concentración en la biomasa aérea, y favoreció la disponibilidad de Mg, Ca, K y P, éstos dos últimos elementos adicionados en la fertilización. Se concluye que la combinación de biocarbón y suelo en una relación (1:9) (p/p) con adición de fertilizante (N, P y K) puede ser empleado en el desarrollo de Pinus greggii Engelm ex Parl en vivero.

O objetivo deste trabalho foi construir um índice simples com base na presença/ausência de diferentes grupos da macrofauna edáfica para auxiliar na determinação da qualidade ecológica dos solos. O índice foi testado com dados de 20 locais do sul e centro do Estado de Tabasco, México, e foi observada uma correlação positiva entre o dados gerados pelo modelo e pelas observações de campo. O índice de qualidade de solo mostrou que diversos sistemas agroflorestais tiveram a mais alta qualidade de solo (1,0) e que os monocultivos sem árvores, como o de abacaxi, apresentaram a qualidade de solo mais baixa (0,08). Este modelo precisa ser melhor desenvolvido para ser aplicado eficientemente em sistemas que apresentam naturalmente baixas densidades de minhocas (<10 g m-2) e número elevado de espécies de minhocas (5-7), como ocorre em solos de floresta tropical, cujo índice de qualidade de solo apresentou valores médios (0,5). A aplicação desse índice precisará de um guia ilustrado para os seus usuários. Mais estudos são necessários para testar o seu emprego por fazendeiros.

The objective of this work was to construct a simple index based on the presence/absence of different groups of soil macrofauna to determine the ecological quality of soils. The index was tested with data from 20 sites in South and Central Tabasco, Mexico, and a positive relation between the model and the field observations was detected. The index showed that diverse agroforestry systems had the highest soil quality index (1.00), and monocrops without trees, such as pineapple, showed the lowest soil quality index (0.08). Further research is required to improve this model for natural systems that have very low earthworm biomass (<10 g m-2) and a high number of earthworm species (5-7), as it is in the tropical rain forest, whose soil quality index was medium (0.5). The application of this index will require an illustrated guide for its users. Further studies are required in order to test the use of this index by farmers.