Assessment of soil nutrient deficiencies of rice in the rainfed and irrigated areas with the use of MOET [Minus One Element Technique]

Proper fertilizer management is critical to crop production. One of the considerations in fertilizer management is the assessment of the nutrients present in the soil , which can usually be done through laboratory analysis. However, it is not always accessible to farmers. The Minus One Element Technique (MOET) developed by PhilRice was proven to be an effective diagnostic tool in accessing the limiting nutrients in the soil. Hence MOET was used to access the soil in irrigated and rainfed areas in the Ilocos. In 2004, the soil limiting nutrients of five locations (Batac and Currimao in Ilocos Norte, Bantay and Sta. Catalina in Ilocos Sur and Pidigan in Abra) were analyzed. An on-station set-up was conducted during the dry season using corn, pepper, onion and rice. Likewise, on-farm experiments were conducted during the wet season using rice as test crop. Based on the result of the MOET, N and P were generally deficient in the five test locations. However, laboratory analysis showed that only N is deficient in the soil. Mn and Fe contents are very high and its beyond the critical level. The relatively high amount of Fe and Mn in the soil probably fixed the phosporus, which resulted in phosporus unavailability to the plants. Batac, Ilocos Norte and Bulag, Bantay, Ilocos Sur has multiple nutrient deficiencies, N, P, Cu, Fe, and Mn were found limiting in Batac; N, P, K, Zn, Ca, and Mg in Bulag. These are generally heavy textured soils. In Sta. Catalina, Ilocos Sur, Pidigan, Abra and Currimao, Ilocos Norte, N and P were the most limiting nutrient in the light textured soils. MOET can be used as diagnostic tool in assessing the soil nutrient deficiencies in the rainfed areas. Test crops like corn, onion, and pepper can be used in addition to rice. During the wet season, results of the field trial showed that N and P were generally deficient in the five test locations. In Bulag, Bantay and Pias Norte, Currimao, Ilocos Norte, increasing the amount of N from 81 kg to 175 kg did not increase rice yield. An increase of N from 96 kg to 124 kg in Pidigan, Abra did not significantly increase yield. Likewise in Sta. Catalina, 104 kg of N produced similar yield with those applied with 201 kg N. Hence, the lower levels are already the optimum. Application of 20 to 35 kg P is needed in the five locations. In all the location, rice did not respond to K application.