Changes in lowland paddy soil fertility in the Philippines after 50 years of the Green Revolution

作者：Atsushi Nakao, Fukiko Masai, Nicola Timbas, Simplicio M. Medina, Susumu S. Abe, Sota Tanaka, Junta Yanai · 发表于：Soil Science & Plant Nutrition · 年份：2021 · DOI：10.1080/00380768.2021.1947118 · 被引用次数：13 · 研究领域：Rice Cultivation and Yield Improvement、Soil Carbon and Nitrogen Dynamics、Agriculture, Soil, Plant Science

The Green Revolution (GR) made a major contribution to increasing the rice yield in the Philippines from 1.3 t ha−1 in 1966 to 4.0 t ha−1 in 2018, but the changes in paddy soil fertility that occurred during this 50-year period remain unknown. We collected 37 soil samples from the plow layers of paddy fields in Luzon, Leyte, Panay, and Mindanao in the Philippines in 2016 and 2017 (the ‘2010s’) and compared their fertility-related soil properties with published data for soil samples collected from the same or nearby sampling sites in 1969 (the ‘1960s’). Paddy soils in the Philippines had relatively high exchangeable calcium (Ca) and magnesium (Mg) content, cation exchange capacity (CEC), available silicon (Si) content, and total carbon (C) and nitrogen (N) content, reflecting their indigenous pedological background. We found that the 2010s soils had a lower available N content, particularly in wetter regions, despite the high input of N fertilizers, whereas the available phosphorus (P) showed a six-fold increase from the 1960s to the 2010s. The total potassium (K) content had significantly decreased during this period, possibly due to the mining effect of intensive farming with K-deficient fertilization. The 2010s soils contained a greater silt content and higher proportion of smectite in the clay fraction, which may have been transported from upstream via irrigation water. The increase in smectite corresponded with a significant increase in the cation exchange capacity, despi...