Beneficial Effect of Biochar on Irrigated Dwarf-Green Coconut Tree

The coconut tree is considered one of the greatest consumers of irrigation water, ranging from 100 to 240 L day(-1). The objective of the present study was to evaluate the effect of biochar application on decreased irrigation water needs in a 2-year irrigated dwarf coconut palm orchard field experiment. Biochar was characterized chemically and by electron microscope images. Biochar morphology presented several micropores indicating water retention potential. Amounts of biochar were tested (0, 5, 10, 20, 40 g of biochar per kg of soil), representing 0.0; 0.5; 1.0; 2.0; and 4.0 kg per plant. Micro sprinkler irrigation started following the planting of the 90-day old hybrid dwarf coconut seedlings. The impacts of the application of the biochar on the chemical attributes of the soil, biometry of the coconut plants, water storage in the 0-0.3 m soil layer, and the volume of irrigation water required by treatment were evaluated. After two years (2017 and 2018), the application of the biochar resulted in no statistically significant differences in the chemical attributes of the soil and biometric variables of plants between different treatments. The volume of annual irrigation water per plant versus biochar quantity demonstrated a decreasing effect, due to the increase of soil water storage. The dose of 40 g of biochar per kg of soil presented the highest two-year average soil water retention (0-0.3 m layer) among treatments (34, 36, 34, 38, and 45 mm, respectively), resulting in lower 2-year irrigation water demand (28, 36, 29, 28 and 20 L plant(-1) day(-1), respectively).