Changes in soil respiration after application of in situ soil amendment and phosphate fertilizer under soybean cultivation at Ultisol South Lampung, Indonesia

Abstract

Several inputs are needed to increase the production of soybean in Ultisol. The Application of organic soil amendment will increase carbon, nutrients, and water stored in the soil. Besides, the soil structure becomes stable so that plants will be more tolerant of climate change. The higher organic C in the soil, the more fertile soils, the plants grow healthier and fertile, and then the emission of CO2 gas into the air can be suppressed. Therefore, this study aims to determine soil respiration (CO2) due to the application of in situ soil amendment and phosphate fertilizer. This research was conducted at the research station of BPTP Natar, South Lampung, from July to November 2019, arranged with random complete block design in two factorials. The first factor is the source of phosphate fertilizer is without P fertilizer, TSP fertilizer 200 kg ha-1, and rock phosphate 5 tons ha-1, and the second factor is the application of soil in situ amendments. i.e.: without the soil amendment, rice husk biochar 5 tons ha-1 (B1), organonitrofos compost 10 tons ha-1, and cow dung manure 10 tons ha-1. All experimental units were fertilized with urea at a dose of 50 kg ha-1 and KCl at a dose of 200 kg ha-1. The result showed that the highest soil respiration was obtained in the plot treated with rock phosphate and cow dung manure at the single factor. The combination of rock phosphate and cow dung manure resulted in the highest of soil respiration.