Fertilization and cover crop effects on soil nitrogen and plant nutrition in a young guarana plantation

Acta Amazonica

Lucerina Trujillo²  Johannes Lehmann¹  Manoel Da Silva Cravo²  André Luiz Atroch²  Firmino José Do Nascimento Filho² 

[1] ,Empresa Brasileira de Pesquisa Agropecuaria (Embrapa)Manaus,Brazil

关键词: acid tropical soil;    cover crop;    Brazilian Amazon;    fruit tree;    nitrogen leaching;    Amazônia brasileira;    Solos tropicais ácidos;    Plantas de Cobertura;    Fruteiras;    Lixiviação de Nitrogênio;   

DOI  :  10.1590/S0044-59672003000400001

来源: SciELO

【 摘 要 】

Fruit tree production is gaining an increasing importance in the central Amazon and elsewhere in the humid tropics, but very little is known about the nutrient dynamics in the soil-plant system. The present study quantified the effects of fertilization and cover cropping with a legume (Pueraria phaseoloides (Roxb.) Benth.) on soil nitrogen (N) dynamics and plant nutrition in a young guarana plantation (Paullinia cupana Kunth. (H.B. and K.) var. sorbilis (Mart.) Ducke) on a highly weathered Xanthic Ferralsol. Large subsoil nitrate (NO3-) accumulation at 0.3-3 m below the guarana plantation indicated N leaching from the topsoil. The NO3- contents to a depth of 2 m were 2.4 times greater between the trees than underneath unfertilized trees (P<0.05). The legume cover crop between the trees increased soil N availability as shown by elevated aerobic N mineralization and lower N immobilization in microbial biomass. The guarana N nutrition and yield did not benefit from the N input by biological fixation of atmospheric N2 by the legume cover (P>0.05). Even without a legume intercrop, large amounts of NO3- were found in the subsoil between unfertilized trees. Subsoil NO3- between the trees could be utilized, however, by fertilized guarana. This can be explained by a more vigorous growth of fertilized trees which had a larger nutrient demand and exploited a larger soil volume. With a legume cover crop, however, more mineral N was available at the topsoil which was leached into the subsoil and consequently accumulated at 0.3-3 m depth. Fertilizer additions of P and K were needed to increase subsoil NO3- use between trees.

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