Effect of green revolution technology from 1970 to 2003 on sawah soil properties in Java, Indonesia, 1: Carbon and nitrogen distribution under different land management and soil types

Many countries have reported that green revolution (GR) technology caused some adverse effects on agricultural lands, but there is no research on the effects of GR in Indonesia. To evaluate the effect of GR technology on sawah soil in Indonesia, a comparative study between seedfarms, where GR technology has been continuously applied, and non-seedfarms was conducted in Java as a pioneer place of GR technology in Indonesia and, in particular, on the carbon and nitrogen status in sawah soils. The term sawah refers to a leveled and bounded rice field with an inlet and outlet for irrigation and drainage. Soil samples collected by Kawaguchi and Kyuma in 1970 and new samples taken in 2003 from the same sites or sites close to the 1970 sampling sites were analyzed and compared. During the period 1970-2003 the land-use pattern of sawah in seedfarms and non-seedfarms did not change, but cultivation intensity increased. The results showed that total carbon (TC) and total nitrogen (TN) contents significantly increased from 31.90 to 40.42 Mg /ha and from 3.04 to 3.97 Mg /ha, respectively, and TC and TN were mostly found accumulated in the surface soil layer. The difference in land management practices between seedfarms and non-seedfarms affected the change in TC and TN content in the 0-20 cm soil layer from 1970 to 2003. In seedfarms, where rice had been planted in a monoculture system, TC and TN contents in the 0-20 cm soil layer increased from 34.50 to 39.24 Mg /ha and from 3.16 to 3.95 Mg /ha, respectively. In non-seedfarms, TC and TN increased more than in seedfarms from 29.77 to 41.37 Mg /ha and from 2.94 to 3.98 Mg /ha, respectively. Within the 0-100 cm soil layer, TC and TN increased from 92.68 to 112.83 Mg /ha and from 9.34 to 12.03 Mg /ha and from 79.60 to 114.86 Mg /ha and from 8.93 to 11.44 Mg /ha for seedfarms and non-seedfarms, respectively. No significant difference was observed between the two main soil types, Inceptisols and Vertisols, in Java. Intensive use of sawah over a long time may eliminate the original difference in the properties of these two soil types.