“Without bamboo, the land dies”: Biomass, litterfall, and soil organic matter dynamics of a Javanese bamboo talun-kebun system

Abstract

The biomass, litterfall, and soil organic matter dynamics during a complete bamboo talun-kebun rotation cycle were studied in West Java, Indonesia. This cycle consisted of 1 year of mixed species vegetable cropping (kebun) after the removal of bamboo, followed by 1 year of cassava, and 4 years of bamboo fallow (talun): a total cycle length of 6 years. In general, fruit and pod biomass constituted the highest percentage (38–68%) of the total crop biomass of 8.4 Mg ha −1 accumulated during the first year cropping. Cassava yielded a total of 4.6 Mg ha −1 of roots and tubers during the second year cropping from a total biomass accumulation of 6.7 Mg ha −1. An experimental second year of cassava cropping without any fertilization caused a decline in the yield of roots and tubers to 60% less than the comparable value for the first year of cassava. Weeds, which reached a maximum biomass value of 1.8 Mg ha −1 at the end of the first year cropping, were all but eliminated from the later stages of the bamboo talun. The total biomass of bamboo increased with increasing age and reached 76.6 Mg ha −1 after 6 years. The distribution of total bamboo biomass between above- and below-ground components also varied with age. At 16 months after bamboo harvest, above-ground biomass accounted for 6% of the bamboo total mass. By the end of the 4-year bamboo fallow, 6 years after the bamboo harvest, 59% of the bamboo biomass was above-ground. In the final year of the bamboo talun stage, total above-ground litterfall was estimated at 4.7 Mg ha −1, while the forest floor mass was 13.5 Mg ha −1. There was an increase of approximately 7 Mg ha −1 of soil organic matter in the surface 25 cm of soil during the 4-year fallow. The historical, sustained success of the system with minimal external inputs of fertilizer appears to be closely related to the growth habit and biogeochemical characteristics of the bamboo, i.e. its rapid biomass accumulation, the accumulation of its litter, and the extremely high biomass of fine roots. This study provides scientific support for the traditional saying of the local farmers: “without bamboo, the land dies”.