Characterization and Rate of Rice Husk Application for Crop Production

Abstract

To avoid environmental nuisance, mankind faces the challenge of managing the large quantities of waste produced by modern agriculture. In Nigeria, huge rice husk dumps are commonly found around rice mills. Fresh rice husk were used as manure in "fertilizing" loamy sand soil at the rate of 0, 20, 25, 30, 35, 40, 45, 50, 55, and 60 tonnes per hectare. The experiment was laid in a Randomized Complete Block Design in 2007 and 2008. In 2007, there was a general trend of plant height increasing from zero treatment to 35 t/ha after which fluctuations set in. The mean plant height fluctuated more in 2008 though the different rates of application were significantly different. The optimum application rate to obtain best plant height at 4 and 6 weeks after planting was obtained at 30t/ha. The optimum yield of 2.02t/ha was obtained in 2007 from fields manured with 40t/ha. In 2008, the optimum yield of 2.18 t/ha was obtained from fields manured with 35t/ha. Characterization of the rice husk showed that they were very rich in organic carbon, total nitrogen, available phosphorus, and the exchangeable bases especially calcium and magnesium. Where the husk pH was extremely acid (4.1), the exchangeable acidity was correspondingly high (16.8) compared to where the pH was slightly acid (6.5) with an exchangeable acidity of 0.22 cmol/kg. Some chemical properties of the soil increased (e.g. P) after harvest i. e. more than what was found before cultivation while other properties remained similar to contents found before cultivation showing little or no depletion at the end of the cropping season. Apart from guaranteeing average yield, rice husk has the potential of leaving the soil not or slightly depleted. It is therefore a highly sustainable material for crop production and maintaining soil health.