Identification of Factors Most Important for Ammonia Emission from Fertilized Soils for Potato Production Using Principal Component Analysis
Ammonia (NH3) emissions from fertilized soils are a costly problem that is undermining agricultural and ecological sustainability worldwide. Ammonia emissions from crop production have been reliably documented in recent years. However, insufficient efforts have been made to determine the factors most influential in facilitating NH3 emissions. The goal of this study was to identify the principal factors facilitating NH3 emissions from fertilized soils for potato production by means of principal component analysis (PCA). A dataset consisting of 14 different variables and 600 determinations of NH3 emission rates was geometrically classified into 5 zones, and then analyzed with the PCA technique. The data used in this analysis originated from an incubation experiment involving four major potato production soils (two from Washington State and two from Florida, USA), five N sources, two soil water regimes, three incubation temperatures and five measurement dates of NH3 emission rates during 28 days of incubation: Day 1, 3, 7, 14, and 28. Ammonia emission rates was classified into five distinct zones. In the five zones the total variance in NH3 emission was accounted for as follows: soil particle size distribution, electrical conductivity (EC), field capacity, and bulk density, 47%; fertilizer sources, 15%; soil pH, 12%; and soil temperature and the soil water regime 9%. The effects of the principal components on NH3 emission in descending order were as follows:
soil type > fertilizer source > soil pH > soil temperature and water regime. Therefore, NH3 emissions could be reduced potentially with amendment of coarse textured agricultural soils to reduce their bulk density, selection of fertilizers to lessen those with the ammonium compounds, use of amendments to lower soil pH, and optimal water management.