| dc.description.abstract | Rice plantation using SRI technique gives higher yield production than conventional rice plantation system, but its application does not grow well in Indonesia. In some areas, SRI was reported to have almost similar yield with the conventional. It was particularly occurred in plantation in rainy season with high dosage of organic material. In that field, the plant shows reddish yellow colored leaves. This symptom is regarded as specific indicator of manganese toxicity in rice. Organic material addition in high dosage decreases soil Eh and increases Fe and Mn solubility. However, Fe and Mn solubility does not always correlate with soil Eh and Fe2O3 and MnO2 content in soil. There were some areas which were estimated to have low content of MnO2 but the symptom is still observed. Therefore, the correlation of redox potential with Mn and Fe behavior in paddy soils which are enriched by organic material should be studied in order to determine measuring rod of potential Mn toxicity on rice. Soil samples in this research were taken from Cihideung (Bogor), Bobojong (Cianjur), Margakaya (Karawang), and Kaserangan (Serang). Organic material was added in various comparison into each sample, then the mixtures were flooded for several days. Eh and pH measurements were done during the flooding period. Fe and Mn contents in dry soil were determined with extraction using citric acid 2%, DTPA 0.005M, HCl 0.1N, and DCB. After flooding, Fe and Mn contents in soil were determined with DTPA 0.005M and HCl 0.1N. Fe and Mn contents in soil solution were also determined by AAS. The results showed that the decreasing of Eh was happened faster in soil having high value of pe+pH and low content of Fe2O3. Paddy soil of Cihideung (Bogor) which was added with organic material such as in SRI application has high potent to cause Mn toxicity in rice due to its high content of Mn and low Fe/Mn ratio. Fe and Mn in paddy soil from Margakaya (Karawang) and Kaserangan (Serang) were relatively low, so that those soils do not have potent to cause Mn toxicity on rice plant. Keywords: Mn toxicity, SRI, paddy field | id |
