Alkaline hydrolyzable nitrogen and properties that dictate its distribution in paddy soil profiles

作     者：Gerson Laerson DRESCHER Leandro Souza DA SILVA Qamar SARFARAZ Gustavo DAL MOLIN Laura Brondani MARZARI Augusto Ferreira LOPES Cesar CELLA Daniela Basso FACCO Rodrigo Knevitz HAMMERSCHMITT Gerson Laerson DRESCHER;Leandro Souza DA SILVA;Qamar SARFARAZ;Gustavo DAL MOLIN;Laura Brondani MARZARI;Augusto Ferreira LOPES;Cesar CELLA;Daniela Basso FACCO;Rodrigo Knevitz HAMMERSCHMITT

作者机构：Department of Soil ScienceFederal University of Santa MariaSanta Maria 97105-900Brazil Federal University of Santa MariaCampus Cachoeira do SulCachoeira do Sul 96506-310Brazil 

出 版 物：《Pedosphere》 (土壤圈（英文版）)

年 卷 期：2020年第30卷第3期

页      面：326-335页

核心收录：

学科分类：0818[工学-地质资源与地质工程] 09[农学] 0903[农学-农业资源与环境] 0901[农学-作物学] 090301[农学-土壤学] 

基　　金：This study was financially supported(grant and scholarships)in part by the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior(CAPES)(Finance Code 001) Brazil.The authors gratefully acknowledge all students and staff for their contributions in the development of this research 

主　　题：fertilizer recommendation nitrogen availability nutrient management practices organo-mineral interaction Oryza sativa L. soil analysis soil organic matter 

摘      要：Nitrogen(N) is a key nutrient for rice production, and its bioavailability in paddy soils is strongly coupled to soil organic matter(SOM) cycling. A better understanding of potentially available N forms in soil, such as alkaline hydrolyzable N(AH-N), and their depth distribution will support the development of best management practices to improve the N use efficiency of rice while minimizing adverse environmental effects. Fifteen rice(Oryza sativa L.) fields from Southern Brazil were selected, and stratified soil samples were taken to a depth of 60 cm before crop establishment. Selected soil physical and chemical properties were analyzed to evaluate their relationships with AH-N contents in the soil profile. The AH-N contents below 20 cm varied extensively(increased,reduced, or constant) compared with that above 20 cm. Although clay and clay + silt contents were highly correlated to AH-N for some soils, the major property dictating AH-N distribution by depth was total N(TN), as the correlation between TN and AH-N was mainly by direct effect. The proportion of TN recovered as AH-N across sites and depths presented high amplitude, and thus AH-N was not a constant N pool across depths, indicating that AH-N can be affected by soil management practices even when TN showed no major changes. The distinct distribution of AH-N across soil sampling sites and depths indicates that depths greater than 20 cm should be considered when calibrating the AH-N index for N fertilizer recommendations for flooded rice in Southern Brazil.