Husnain, Aflizar, Darmawan, Masunaga T
Indonesia is one of the biggest rice producing countries in the world after China and India (FAS-USDA 2010). In fact, as much as 1.750 thousand MT rice was imported in 2010 (FAS-USDA 2010). Despite of political concern, decreasing arable land for agriculture and degradation of soil fertility might be responsible for the deficit of national rice supply.
Since the last 10 years, government has implemented the balance fertilization by recommended site specific fertilization of N, P and K for rice plant. However, maintaining N, P and K alone without consider other nutrient such as Silica (Si) and micro elements has led imbalances of nutrient in soil. Moreover, high intensity of rice cultivation (mostly 2-3 times a year) without sufficient nutrient replenishment is also responsible for the degradation of soil productivity.
Rice plant obviously required Si to maintain healthy growth and high productivity. Although Si was recognised as the non essential element for rice plant, but rice plant uptake Si ranged from 230 to 470 kg Si ha-1, two times higher than N uptake (Savant et al. 1997). The main role of Si for rice plant has been reported including its role against plant disease (Ishizuka and Hayakawa 1951; Kawashima 1927; Miyake and Takahashi 1983). However, the function of Si in soil fertility and plant physiology is not fully recognized.
In case of Indonesia, the survey of available Si in soil and irrigation water were recently reported. Darmawan et al. (2007) reported that available Si in rice soils in Java Island over the past three decades has decreased by approximately 11-20%. In addition, Husnain et al. (2008) has found that lower soil Si content was found in intensive rice field where enormous Si uptake was not following by sufficient Si replenishment. Although there was no report on the deficiency of Si in Indonesian sawah soil, the huge loss of rice production due to plant diseases and failed to harvest might be an indication of the imbalance of nutrients, particularly Si.
In this paper we discussed about soil Si availability in Java and Sumatra Islands in relation to the parent material and the relationship of Si in soil and rice plant. This paper may provide the information on how to manage Si as nutrient for rice and other Si accumulated plants in term of sustainability of food crop production in Indonesia.
Paper published in Proceedings Of The 5th International Conference On Silicon In Agriculture.