Maize Growth as Influenced by 12 Different Biochars in a Cerrado Region (Brazil) Arenosol

English Abstract:

The climate in much of the state of Mato Grosso, Brazil, permits a year-round growing season. Maize grown during the dry season, known as segunda safra, currently accounts for 97% of all the maize grown in the state. However, since it is cultivated during the dry season, the segunda safra is vulnerable to changes in precipitation patterns. Therefore, improving soil water retention in the region’s Arenosols is of particular interest to local farmers. The potential of biochar (charcoal derived from waste biomass by pyrolysis) to increase soil water retention and crop growth has been observed under some conditions, and so its amendment to sandy soils could potentially be beneficial in this system. The biochars used in this study were derived from four feedstocks: cotton husks, eucalyptus sawmill residue, filtercake resulting from sugarcane distillation, and swine manure. The four feedstocks were converted to biochar under three different pyrolysis temperatures: 400°, 500°, and 600°C resulting in a total of 12 biochars (4 feedstocks x 3 temperatures of pyrolysis). Biochar was mixed at 5% dry weight to 8 kg of an Arenosol and placed in pots in a greenhouse at 30°C for 6 weeks. Pots were set up in a split-plot random block design with 4 benches split into 2 rows receiving dry season rainfall and wet season rainfall, respectively. Maize seeds were planted in all pots. Preliminary results show that maize planted in soil mixed with cotton biochars produced at 500°C and 600°C had the lowest germination rates (38 and 44 %, respectively, in dry season rainfall, and 69 and 50 %, respectively, in wet season rainfall). Factors that may have contributed to the low germination rates, such as high nutrient levels in the feedstock and high soil water retention, will be discussed. Data on plant biomass and DOC and NO₃ in leachate from pots receiving wet season rainfall will also be presented.