QUALIDADE BIOLÓGICA DO SOLO DE SISTEMAS DE CULTIVO EM POMARES DE CITRUS DELICIOSA

Abstract

The citrus production is grown in Rio Grande do Sul under different croppingsystems, and their impact on soil quality is unknown. The aim of thisstudy was to evaluate some measures of environmental quality between differentmanagement systems of Citrus from Vale do Caí, RS with emphasison the production of tangerines ‘Montenegrina’ (Citrus deliciosa Tenore) bychemical and biological characterization of soils. The samples were collectedfrom five areas cultivated under different cropping types: organic cropping(PO), organic cropping in transition to biodynamic (POT), agroforestry cropping(PAF), conventional cropping (PC) and native forestry (MN) as a controltreatment in the Montenegro city, Rio Grande do Sul, at 0-10 cm of depth. Wedetermined the microbial biomass carbon (CBM), basal respiration (RB), theactivities of urease, acid phosphatase (FA) and the hydrolysis of fluoresceindiacetate (FDA). For all evaluations, the results were significantly higher inthe control area (MN). In CBM evaluations, the control obtained values of175.2 mg C Kg-1 of dry soil and the lowest value was found in CP at 34 mg CKg-1 of dry soil. The values of RB to system PAF (334.4 mg C-CO2 kg-1 of dry soil), PO (333.3 mg C-CO2 kg-1 of dry soil) and LPO (257.7 mg C-CO2 kg-1 soildried) were significantly lower against the control (728.7 mg C-CO2 kg-1 drysoil). In the urease evaluation, the systems POT and PO were significantlylower with values of 77.7 and 68.5 µg N-NH4 g-1 of dry soil 2 h-1 respectively,compared with the control (128 µg N-NH4 g-1 of dry soil 2 h-1). For cropping systems of PC and PAF, FA values obtained were almost three folds lower(541 and 427 µg p-nitrofenol g-1 dry soil h-1 respectively) when compared withthe control area. So the cropping systems, even the less intensive, were notable to maintain the same quality of soil microbiology that areas of the nativeforestry. This shows that soil quality indicators such as RB, the FA and ureasecan be important indicators in assessing the environmental quality of differentcropping systems of Citrus deliciosa.