Predicting N Mineralization Using the Direct Steam Distillation Method in Flooded Soils
Flooded rice is a highly relevant in the State of Rio Grande do Sul (RS) where 1.07 million hectares were cropped in 2012/13 season producing 8 million tons, which represented 69% of the national production. Nitrogen recommendation for upland or flooded rice in RS is based on soil organic matter (SOM) content but, nevertheless, yield has not presented high correlation with SOM recently. Therefore, studies are in place to develope methods and plant/soil parameters more efficient to predict N availability along the crop cycle or even prior seeding time. This project aims to evaluate the ability of the Direct Steam Distillation method in predicting N mineralization in flooded soils of RS.
IPNI-2014-BRA-64
25 Mar 2015
2014 Annual Interpretive Summary
Assessment of N from soil organic matter mineralization is crucial to the understanding of N availability to crops, maximizing N-use efficiency, and minimizing environmental impacts. This project aims to evaluate the ability of the Direct Steam Distillation (DSD) method to predict alkaline hydrolysis N forms in floodplain soils in the state of Rio Grande do Sul, Brazil. Representative soil samples (32) were collected for an incubation trial (40 degree C for four weeks). A greenhouse trial is under development to measure N uptake by rice shoots.
Results have shown a wide range of mineralized N (from 55 to 317 mg N/kg) due to the distinct properties of soils. The estimate of N release using DSD was similar to mineralized N regardless of physical, chemical or mineralogical features of the soils. The DSD method was able to detect the effect of clay variation among soils on N mineralization.