Perdas de carbono orgânico, potássio e solo em Neossolo Flúvico sob diferentes sistemas de manejo no semi-árido

Abstract

A perda de nutrientes contidos no sedimento da enxurrada, al�m de representar preju�zo econ�mico para o produtor � um fator de degrada��o ambiental. O objetivo deste trabalho foi quantificar as perdas de carbono org�nico e pot�ssio no sedimento da eros�o h�drica e verificar suas rela��es com as perdas de solo. Consideraram-se diferentes t�cnicas de manejo, campo nativo e solo descoberto, no bioma caatinga, no semi-�rido. Simularam-se chuvas com intensidades de 60 mm h-1 sobre os seguintes tratamentos: cultivo em n�vel (N) com barramentos de pedra entre cada fileira de plantio; cultivo morro abaixo (MA); cultivo em n�vel com cobertura morta (CM), de palha de feij�o; parcelas desmatadas (D) e com cobertura natural (CN). A cultura utilizada foi o feijoeiro (Phaseolus vulgaris L.). Os teores de carbono org�nico se correlacionaram linear e positivamente com as taxas de perda de solo nos tratamentos com alto coeficiente de determina��o. As perdas de carbono org�nico epot�ssio foram elevadas nos sistemas n�o conservacionistas de manejo do solo em rela��o � ado��o de pr�ticas conservacionistas simples, ressaltando-se a import�ncia dessas t�cnicas para aumento de produ��o agr�cola.Nutrient loss through sediments from outwash not only represents an economical impact for the farmer, but also an environmental impact factor. The aim of this work was to quantify organic carbon and potassium losses in the sediments from water erosion and verify their relationships to soil losses. Distinct management techniques natural cover and bare soil, in the �caatinga� biome, in the semi-arid zone, have been considered. Artificial rainfall was applied with 60 mm h-1 intensity to the following treatments: Leveled cropping (N) with stone barriers between every two consecutive cropping rows; hillslope cropping (MA); leveled cropping with mulching (CM), using bean straw; bare soil plots (D) and natural cover (CN). Bean (Phaseollus vulgaris L.) crop was utilized. The organic carbon contents were linearly and positively correlated to soil losses rates in the treatments, presenting high determination coefficient. Both organic carbon and potassium losses have been higher in the non-conservative practices pointing out the importance of such techniques towards an agricultural production increase.