%0 Journal Article
%T Biological and Physicochemical Parameters Related to the Nitrogen Cycle in the Rhizospheric Soil of Native Potato (Solanum phureja) Crops of Colombia
%A Nathalia Fl¨®rez-Zapata
%A Daniel Uribe-V¨¦lez
%J Applied and Environmental Soil Science
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/847940
%X Nitrogen (N) plays an important role in agricultural production. This study was designed to evaluate the presence of cultivable N cycle-associated microorganisms (nitrogen-fixing bacteria¡ªNFB, proteolytic bacteria¡ªPR, ammonifiers¡ªAMO, ammonium-oxidizing bacteria¡ªAOB, nitrite-oxidizing bacteria¡ªNOB, and denitrifiers¡ªDEN), and their relationship with physical-chemical and agronomic soil descriptors, in Solanum phureja rhizospheric soil samples, from traditional and organic crop management farms. A cluster analysis with the physical and chemical properties of soil, allowed to identify the organic matter content as an important factor that determines the outcome of that grouping. Significant differences ( ) between farms were found in the abundance of this groups, but correlation analysis showed that proteolytic and nitrogen fixing bacteria were the main nitrogen associated functional groups affected by soils' physical-chemical characteristics. The amount of ammonia available is affected by the agricultural management strategy, which consequently affects the NFB abundance. Finally the results showed that PR, protease activity and soil properties related with organic matter transformation has a positive relationship with productivity, which given the high organic matter content of the Andean soils being studied, we conclude that nitrogen mineralization process has an important role in the nitrogen cycle and its bioavailability in this ecosystem. 1. Introduction Potato is the world¡¯s fourth most popular food crop and one of the most important agricultural products for Colombia; it occupies the ninth place in area sown regarding transitory crops and sixth place in production value [1]. Solanum phureja is a native potato representing around 10% of potato crops produced in Colombia (having around 25,000 hectares planted and 150,000 tons produced per year), making Colombia the highest producer of such native potato amongst Andean countries [2¨C4]. The regions where potato crops are planted in Colombia are characterized by having a cold to very cold climate, due to their high altitude in the Andean mountains (2,000 meters above sea level (masl) to 3,500 masl), where fragile ecosystems such as Paramo are located. Such climatic conditions define important soil characteristics since they limit organic matter¡¯s mineralization speed, this being one of the reasons for which the aforementioned soils are characterized by presenting high organic matter content (usually above 10%). The volcanic ash from andisols is considered to be the material of origin partially or
%U http://www.hindawi.com/journals/aess/2011/847940/