Nutrients Leaching in Briquetted NPK and Urea Super Granules and Its Effect on the Performance of Rice (Oryza sativa L.)

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Abstract

ABSTRACT Government policies in sub-Saharan Africa is geared towards intensification of rice production to reduce import. Intensification of production requires the use of inorganic fertilizers. Although the amount of nutrient lost through leaching has not been quantified to guide fertilizer use, briquetted formulations of chemical fertilizers are now being used to address nutrient leaching. This study is aimed at quantifying nutrients’ loss in different formulations and how it influences growth and yield of rice. The field experiment was conducted using clay-filled 0.28 m diameter passive wick lysimeters to collect leachates for laboratory analysis. The treatments consisted of urea super granule (USG), granular urea, briquetted NPK, granular NPK in two split applications using NPK and SA, all applied at 57.5- 22.5-11.3 kg ha-1. An untreated control was also kept. For the urea and USG, TSP and Murriate of potash (MOP) were added to supply P and K. The treatments were arranged in completely randomized design. Four rice seedlings were transplanted per lysimeter. Data collected on growth and reproductive parameters as well as nutrient content of the leachates were subjected to analysis of variance using Genstat Edition 18. Urea-based fertilizers recorded higher tiller and panicle number than NPK-based fertilizers. Grain number was not affected by the treatments. The USG and briquetted NPK lost 5% of N applied while granular urea and NPK lost 15% of N applied within 8 weeks after application. Phosphorus was the least leached nutrient, less than 0.2 kg/ha, whilst Potassium recorded the highest nutrient loss (3.7- 9.2 kg/ha). The study recommends the use of USG and briquetted NPK to address nutrient leaching in rice fields.