Publication Date:
2013-12-11
Description:
We investigated the effects of charcoal under flooded (anoxic) rice cultivation at low and high fertilizer levels during 2 y in the Maranhão lowlands, eastern periphery of Amazonia. Two applications (at onset of first and second year) of 15 Mg ha –1 of fine (〈 2 mm) charcoal derived from the endocarp of the babassu ( Attalea speciosa Mart.) palm nut had little influence on soil fertility, rice growth, yield, and nutritional status. Exception to this were negative impacts of charcoal on first-year N availability, with lower sub-superficial soil NH availability paired with lower rice tissue N and a responsiveness of grain yields to (mainly N-) fertilization following charcoal application. This N-limitation effect was, however, limited to the first year and—though statistically significant—without agronomic relevance. The most consistent charcoal effect on flooded-soil fertility was the strong increase in K availability in the second year, at low and to a lesser extent at intermediate, but not at high fertilizer level. Low K concentrations of our charcoal exclude the possibility of direct K inputs via charcoal, suggesting other indirect mechanisms for K availability increases. Methane fluxes in the second year were significantly reduced (–43.8%) by charcoal application, charcoal-induced reductions were stronger under high- (–47.3%) than under low-fertilizer regime (–26.0%). Thus, charcoal could be a valuable tool for reducing methane emissions associated with intensely fertilized flooded rice, without significantly affecting grain yields.
Print ISSN:
1436-8730
Electronic ISSN:
1522-2624
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
