TY - JOUR
T1 - Effect of water management on the vivianite content of paddy-rice roots
AU - Kusunoki, Ayako
AU - Nanzyo, Masami
AU - Kanno, Hitoshi
AU - Takahashi, Tadashi
N1 - Publisher Copyright:
© 2015 Japanese Society of Soil Science and Plant Nutrition.
PY - 2015/11/2
Y1 - 2015/11/2
N2 - Vivianite is a hydrated ferrous phosphate mineral that can form in reducing environments, and it was recently identified on aged paddy rice (Oryza sativa, L., cultivar Hitomebore) roots. However, the formation and dissolution of vivianite appear highly susceptible to the soil redox potential. We examined the effect of water management on the vivianite content of rice roots in three experimental micro (1 m2) paddy fields. The vivianite content of the roots was estimated using a method based on the alteration of vivianite after heating at 105°C for 48 h. This alteration steeply lowers the dissolution of phosphate from the roots in a mixed acid solution of 0.1 mol L−1 of hydrochloric acid (HCl) and 1 mol L−1 of acetic acid (CH3COOH). Efficiency of the method was confirmed regarding heating temperature and duration of heating. Using this method, we found that water management significantly influenced the vivianite content of the rice roots. The vivianite content of the rice roots was highest, i.e., 2.3 g phosphorus (P) kg−1 expressed by its estimated P content, when the paddy field was continuously flooded from May to until early September. After flooding stopped, the soil was gradually oxidized, leading to a decrease in vivianite content. In the micro plot exposed to midseason drainage, the vivianite content increased to the level of the continuously flooded plot after reflooding, and finally decreased after flooding was stopped in late August. The plots exposed to midseason drainage followed by intermittent irrigation presented the lowest vivianite contents among the three experimental paddy fields. These results confirm that increases and decreases in the vivianite contents of paddy-rice roots strongly depend on water management.
AB - Vivianite is a hydrated ferrous phosphate mineral that can form in reducing environments, and it was recently identified on aged paddy rice (Oryza sativa, L., cultivar Hitomebore) roots. However, the formation and dissolution of vivianite appear highly susceptible to the soil redox potential. We examined the effect of water management on the vivianite content of rice roots in three experimental micro (1 m2) paddy fields. The vivianite content of the roots was estimated using a method based on the alteration of vivianite after heating at 105°C for 48 h. This alteration steeply lowers the dissolution of phosphate from the roots in a mixed acid solution of 0.1 mol L−1 of hydrochloric acid (HCl) and 1 mol L−1 of acetic acid (CH3COOH). Efficiency of the method was confirmed regarding heating temperature and duration of heating. Using this method, we found that water management significantly influenced the vivianite content of the rice roots. The vivianite content of the rice roots was highest, i.e., 2.3 g phosphorus (P) kg−1 expressed by its estimated P content, when the paddy field was continuously flooded from May to until early September. After flooding stopped, the soil was gradually oxidized, leading to a decrease in vivianite content. In the micro plot exposed to midseason drainage, the vivianite content increased to the level of the continuously flooded plot after reflooding, and finally decreased after flooding was stopped in late August. The plots exposed to midseason drainage followed by intermittent irrigation presented the lowest vivianite contents among the three experimental paddy fields. These results confirm that increases and decreases in the vivianite contents of paddy-rice roots strongly depend on water management.
KW - paddy
KW - phosphate
KW - redox
KW - rice
KW - vivianite
UR - http://www.scopus.com/inward/record.url?scp=84949556019&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84949556019&partnerID=8YFLogxK
U2 - 10.1080/00380768.2015.1089787
DO - 10.1080/00380768.2015.1089787
M3 - Article
AN - SCOPUS:84949556019
VL - 61
SP - 910
EP - 916
JO - Soil Science and Plant Nutrition
JF - Soil Science and Plant Nutrition
SN - 0038-0768
IS - 6
ER -