Relationships among land use, relief and soil fertility at watershed scale

Revista Brasileira de Engenharia Agrícola e Ambiental

Galvão, Sandra R. da S.¹  Salcedo, Ignacio H.¹  Santos, Antonio C. dos² 

[1] UFPE, Recife;Universidade Federal do Tocantins, Araguaína

关键词: fodder;    subsistence agriculture;    pasture;    phosphorus;    potassium    INTRODUÇÃO A exploração intensiva de áreas com agricultura ou pecuária familiar de subsistência;    normalmente está associada à degradação do ambiente (Silva;    2000;    Fraga & Salcedo;    2004);    esta degradação é representada pela perda de biodiversidade;    pela queda na fertilidade do solo e pela intensificação dos processos erosivos em relação às condições encontradas sob vegetação original (Santos;    2004;    Fraga & Salcedo;    2004);   

DOI  :  10.1590/S1415-43662008000500003

学科分类：农业科学（综合）

来源: Universidade Federal de Campina Grande * Centro de Ciencias e Tecnologia

【 摘 要 】

Productivity in subsistence agricultural systems relies on natural soil fertility levels. Under strongly undulated relief conditions, it is expected that soil fertility will be determined not only by land use, but also by the position in the landscape. To study these relationships 260 single soil samples (0-20 cm) from the Vaca Brava watershed, Paraiba, representing combinations of three land uses, five positions in the landscape and five textures were analyzed for extractable P, exchangeable bases and soil acidity. Ca and Mg comprised 75-80% of exchangeable cations, K and Na between 10 and 15% and H+Al 10%. The average pH was 5.5, while extractable P (Mehlich-1) averaged 3.8 mg kg-1 soil. Although land use, relief and texture exerted significant effects (p < 0.05) upon certain nutrient concentrations, in a broad sense the watershed appeared relatively uniform. The main effect of land use resulted from the use of animal manure in areas of subsistence agriculture and fodder, which were preferentially located at the base of stopes and low lands positions. Approximately 80% of the samples were low in extractable P, while 70% had medium levels of extractable K. However, when available K was estimated by the K/(Ca+Mg)0,5 ratio, most samples were classified as low.

【 授权许可】

CC BY-NC