ABSTRACT Tamarind (Tamarindus indica L.) is a species with promising potential for commercial production; therefore, studies involving practices of conducting culture in the initial stage are essential. The present study aimed to evaluate different shading levels and substrate compositions in the seedling production of tamarind. The experimental design was completely randomized in a 4×4 factorial scheme, four levels of shading (0%, 18%, 30%, and 50%) and four substrates (pine bark-based substrate pure and mixed with 50% vermiculite, and sphagnum peat-based substrate pure and mixed with 50% vermiculite), with four replicates of four seedlings. Growth and biometric relationships were evaluated at 40 and 98 d after transplantation (DAT). The results reported that seedlings formed on the sphagnum peat-based substrate on pure or associated with vermiculite at 98 DAT had a height greater than 35 cm and a total 8.5 g DM. In contrast, seedlings produced in pine bark-based substrate did not reach 20 cm in height and had less than 3 g total DM. The condition of 30% and 50% shading promoted greater growth in height, reaching an average height greater than 40 cm, while in the full sun environment, seedlings showed an average of less than 35 cm; however, for the other variables, full sun environment did not differ from 30% shading, producing good quality seedlings. Thus, the cultivation of seedlings in an environment with 0% or 30% shading, associated with the sphagnum peat-based substrate pure or mixed with 50% vermiculite promoted the production of tamarind seedlings with vigorous growth. In the best environments, the best substrates increased, on average, 41.3% number of leaves, 80.5% shoot dry mass, 56.8% root dry mass, and 71.0% total dry mass. In the best substrates, the best environments increased, on average, 18.0% number of leaves, 20.7% shoot dry mass, 8.7% root dry mass, and 14.3% total dry mass.

ABSTRACT Most studies concerning biochar, which can enhance chemical, physical, and biological soil qualities and increase crop yields, are short-term experiments in controlled environments with temperate regions and sandy soils. Biochar amendment benefits for clayey soils in tropical climate regions are uncertain. Herein, field conditions in clayey soil were investigated for 28 months. Eucalyptus biochar was obtained from charcoal production and incorporated in soil with disc plows (0.00–0.20 m). Treatments comprised six single biochar application amounts–0 (control), 10, 20, 30, 40, and 50 Mg·ha-1. The experiments were conducted in April 2016, and corn was cultivated in 2016/17 and 2017/18. Soil samples were collected in 2018 for macro/micronutrient, bulk density, porosity, macroporosity, microporosity, water availability, and soil penetration resistance evaluations in the 0.00–0.05-, 0.05–0.10-, 0.10–0.20-, 0.20–0.30-, and 0.30–0.40-m layers. Chemicals P, K and Ca increased compared to the control. The K and Ca increases were related to the biochar composition (6% K and 2% Ca). Soil bulk density decreased by 0.07 kg·dm-3, and macro/microporosity (total porosity) increased linearly by 2.5% in the 0.05–0.10-m layer with increasing biochar application amount. Soil penetration resistance was unaffected. For each 1 Mg·ha-1 of biochar applied, a 500-L·ha-1 increase in available water occurred, which may be important for crops with low water demand and to overcome water restriction periods. chemical physical yields shortterm short term uncertain Herein 2 months 0.00–0.20 000020 0 00 20 (0.00–0.2 m. m . m) amounts0 amounts amounts– control, control , (control) 10 30 40 5 Mg·ha1. Mgha1 Mgha Mg·ha 1. Mg ha 2016 201617 17 2016/1 201718 2017 18 2017/18 201 macromicronutrient macro micronutrient macro/micronutrient porosity macroporosity microporosity availability 0.00–0.05, 000005 0.00–0.05 05 0.00–0.05- 0.05–0.10, 005010 0.05–0.10 0.05–0.10- 0.10–0.20, 010020 0.10–0.20 0.10–0.20- 0.20–0.30, 020030 0.20–0.30 0.20–0.30- 0.30–0.40m 030040m 0.30–0.40 layers P 6% 6 (6 Ca. Ca) 007 07 0.0 kg·dm3, kgdm3 kgdm kg·dm 3, kg dm 3 kg·dm-3 macromicroporosity total 25 2.5 0.05–0.10m 005010m amount unaffected Mg·ha1 Mg·ha- applied 500L·ha1 500Lha1 Lha 500 L·ha L 500-L·ha- occurred periods 0.00–0.2 00002 (0.00–0. (control 4 ha1 20161 2016/ 20171 2017/1 00000 0.00–0.0 00501 0.05–0.1 01002 0.10–0.2 02003 0.20–0.3 40m 030040 0.30–0.4 ( 0. dm3 kg·dm3 kg·dm- 2. 10m 500L 500L·ha 500Lha 500-L·ha 0.00–0. 0000 (0.00–0 2017/ 0050 0.05–0. 0100 0.10–0. 0200 0.20–0. 03004 0.30–0. 0.00–0 000 (0.00– 005 0.05–0 010 0.10–0 020 0.20–0 0300 0.30–0 0.00– (0.00 0.05– 01 0.10– 02 0.20– 030 0.30– 0.00 (0.0 0.05 0.10 0.20 03 0.30 (0. 0.1 0.2 0.3 (0