Nutrient Availability and Biological Properties of Paddy Soils Under Rainfed Traditional “Payatak” Farming Systems in Catubig Valley, Philippines

Abstract

To understand the long - term effects of payatak and conventional rice farming system on soil properties and soil quality, a soil survey was conducted in existing “payatak” and conventional rice fields in Catubig Valley, Northern Samar, Philippines. Chemical analyses revealed that soils under “payatak” are more acidic, with low EC , OM, and N content compared to those soils from conventional rice farms. However, available P and exchangeable K in “payatak” soils were higher than those in conventional. The available N varied sign ificantly with time and sampling area and the mineral N levels fluctuated greatly within three weeks after land preparation. The BiologEcoPlate™ and subsequent correlation analysis have shown a partial characterization of microbial functional community att ributed to several factors leading to differences in chemical properties of the two rice farming systems. These results imply that the levels of OM and the amount of exchangeable K could trigger a distinct microbial community functional structure. Variatio ns in soil pH, EC , and the amounts of nutrients have also caused a shift of the microbial functional diversity as represented by correlations between Shannon – Weaver indices. Overall, the results would indicate that long term “payatak” and conventional rice farming system would result in different soil nutrient status and distinct microbial functional community which may affect the overall productivity and soil quality. Further analysis should be done to establish the relationship between soil microbial prop erties data onto long term productivity in paddy soils. Keywords: Available P, Exchangeable bases, Microbial functional structure, N - mineralization, Soil enzyme activities